1
|
Jagga S, Hughes A, Manoochehri Arash N, Sorsby M, Brooks DJ, Divieti Pajevic P, Liu ES. NFATc1 Is Required for Vitamin D- and Phosphate-Mediated Regulation of Osteocyte Lacuno-Canalicular Remodeling. Endocrinology 2024; 165:bqae087. [PMID: 39024412 DOI: 10.1210/endocr/bqae087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/20/2024]
Abstract
Osteocytes are embedded in lacunae and connected by canaliculi (lacuno-canalicular network, LCN). Bones from mice with X-linked hypophosphatemia (Hyp), which have impaired production of 1,25 dihydroxyvitamin D (1,25D) and hypophosphatemia, have abnormal LCN structure that is improved by treatment with 1,25D or an anti-FGF23 targeting antibody, supporting roles for 1,25D and phosphate in regulating LCN remodeling. Bones from mice lacking the vitamin D receptor (VDR) in osteocytes (Vdrf/f;Dmp1Cre+) and mice lacking the sodium phosphate transporter 2a (Npt2aKO), which have low serum phosphate with high serum 1,25D, have impaired LCN organization, demonstrating that osteocyte-specific actions of 1,25D and hypophosphatemia regulate LCN remodeling. In osteoclasts, nuclear factor of activated T cells cytoplasmic 1 (NFATc1) is critical for stimulating bone resorption. Since osteocytes also resorb matrix, we hypothesize that NFATc1 plays a role in 1,25D and phosphate-mediated LCN remodeling. Consistent with this, 1,25D and phosphate suppress Nfatc1 mRNA expression in IDG-SW3 osteocytes, and knockdown of Nfatc1 expression in IDG-SW3 cells blocks 1,25D- and phosphate-mediated suppression of matrix resorption gene expression and 1,25D- and phosphate-mediated suppression of RANKL-induced acidification of the osteocyte microenvironment. To determine the role of NFATc1 in 1,25D- and phosphate-mediated LCN remodeling in vivo, histomorphometric analyses of tibiae from mice lacking osteocyte-specific Nfatc1 in Vdrf/f;Dmp1Cre+ and Npt2aKO mice were performed, demonstrating that bones from these mice have decreased lacunar size and expression of matrix resorption genes, and improved canalicular structure compared to Vdrf/f;Dmp1Cre+ and Npt2aKO control. This study demonstrates that NFATc1 is necessary for 1,25D- and phosphate-mediated regulation of LCN remodeling.
Collapse
Affiliation(s)
- Supriya Jagga
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Ashleigh Hughes
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Niusha Manoochehri Arash
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Melissa Sorsby
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Daniel J Brooks
- Harvard Medical School, Boston, MA 02115, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Paola Divieti Pajevic
- Department of Translational Dental Medicine, Boston University School of Dental Medicine, Boston, MA 02118, USA
| | - Eva S Liu
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|
2
|
Sieverts M, Yee C, Nemani M, Parkinson DY, Alliston T, Acevedo C. Spatial control of perilacunar canalicular remodeling during lactation. Sci Rep 2024; 14:14655. [PMID: 38918485 PMCID: PMC11199490 DOI: 10.1038/s41598-024-63645-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 05/30/2024] [Indexed: 06/27/2024] Open
Abstract
Osteocytes locally remodel their surrounding tissue through perilacunar canalicular remodeling (PLR). During lactation, osteocytes remove minerals to satisfy the metabolic demand, resulting in increased lacunar volume, quantifiable with synchrotron X-ray radiation micro-tomography (SRµCT). Although the effects of lactation on PLR are well-studied, it remains unclear whether PLR occurs uniformly throughout the bone and what mechanisms prevent PLR from undermining bone quality. We used SRµCT imaging to conduct an in-depth spatial analysis of the impact of lactation and osteocyte-intrinsic MMP13 deletion on PLR in murine bone. We found larger lacunae undergoing PLR are located near canals in the mid-cortex or endosteum. We show lactation-induced hypomineralization occurs 14 µm away from lacunar edges, past a hypermineralized barrier. Our findings reveal that osteocyte-intrinsic MMP13 is crucial for lactation-induced PLR near lacunae in the mid-cortex but not for whole-bone resorption. This research highlights the spatial control of PLR on mineral distribution during lactation.
Collapse
Affiliation(s)
- Michael Sieverts
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, 84112, USA
| | - Cristal Yee
- Department of Orthopedic Surgery, University of California, San Francisco, CA, 94131, USA
| | - Minali Nemani
- Department of Orthopedic Surgery, University of California, San Francisco, CA, 94131, USA
| | | | - Tamara Alliston
- Department of Orthopedic Surgery, University of California, San Francisco, CA, 94131, USA
| | - Claire Acevedo
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
- Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA, 92161, USA.
| |
Collapse
|
3
|
Wang ZX, Lin X, Cao J, Liu YW, Luo ZW, Rao SS, Wang Q, Wang YY, Chen CY, Zhu GQ, Li FXZ, Tan YJ, Hu Y, Yin H, Li YY, He ZH, Liu ZZ, Yuan LQ, Zhou Y, Wang ZG, Xie H. Young osteocyte-derived extracellular vesicles facilitate osteogenesis by transferring tropomyosin-1. J Nanobiotechnology 2024; 22:208. [PMID: 38664789 PMCID: PMC11046877 DOI: 10.1186/s12951-024-02367-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 02/22/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Bone marrow mesenchymal stem cells (BMSCs) can undergo inadequate osteogenesis or excessive adipogenesis as they age due to changes in the bone microenvironment, ultimately resulting in decreased bone density and elevated risk of fractures in senile osteoporosis. This study aims to investigate the effects of osteocyte senescence on the bone microenvironment and its influence on BMSCs during aging. RESULTS Primary osteocytes were isolated from 2-month-old and 16-month-old mice to obtain young osteocyte-derived extracellular vesicles (YO-EVs) and senescent osteocyte-derived EVs (SO-EVs), respectively. YO-EVs were found to significantly increase alkaline phosphatase activity, mineralization deposition, and the expression of osteogenesis-related genes in BMSCs, while SO-EVs promoted BMSC adipogenesis. Neither YO-EVs nor SO-EVs exerted an effect on the osteoclastogenesis of primary macrophages/monocytes. Our constructed transgenic mice, designed to trace osteocyte-derived EV distribution, revealed abundant osteocyte-derived EVs embedded in the bone matrix. Moreover, mature osteoclasts were found to release osteocyte-derived EVs from bone slices, playing a pivotal role in regulating the functions of the surrounding culture medium. Following intravenous injection into young and elderly mouse models, YO-EVs demonstrated a significant enhancement of bone mass and biomechanical strength compared to SO-EVs. Immunostaining of bone sections revealed that YO-EV treatment augmented the number of osteoblasts on the bone surface, while SO-EV treatment promoted adipocyte formation in the bone marrow. Proteomics analysis of YO-EVs and SO-EVs showed that tropomyosin-1 (TPM1) was enriched in YO-EVs, which increased the matrix stiffness of BMSCs, consequently promoting osteogenesis. Specifically, the siRNA-mediated depletion of Tpm1 eliminated pro-osteogenic activity of YO-EVs both in vitro and in vivo. CONCLUSIONS Our findings suggested that YO-EVs played a crucial role in maintaining the balance between bone resorption and formation, and their pro-osteogenic activity declining with aging. Therefore, YO-EVs and the delivered TPM1 hold potential as therapeutic targets for senile osteoporosis.
Collapse
Affiliation(s)
- Zhen-Xing Wang
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
- National Clinical Research Center for Geriatric Disorders (Xiangya Hospital), Changsha, 410008, Hunan, China
| | - Xiao Lin
- The Second Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Jia Cao
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
- National Clinical Research Center for Geriatric Disorders (Xiangya Hospital), Changsha, 410008, Hunan, China
| | - Yi-Wei Liu
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - Zhong-Wei Luo
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - Shan-Shan Rao
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
- National Clinical Research Center for Geriatric Disorders (Xiangya Hospital), Changsha, 410008, Hunan, China
| | - Qiang Wang
- Department of Laboratory Medicine, Affiliated Zhejiang Hospital, Zhejiang University School of Medicine, Hangzhou, 310013, Zhejiang, China
| | - Yi-Yi Wang
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - Chun-Yuan Chen
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
- National Clinical Research Center for Geriatric Disorders (Xiangya Hospital), Changsha, 410008, Hunan, China
| | - Guo-Qiang Zhu
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - Fu-Xing-Zi Li
- The Second Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Yi-Juan Tan
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - Yin Hu
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Hao Yin
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - You-You Li
- Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Ze-Hui He
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
| | - Zheng-Zhao Liu
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China
- National Clinical Research Center for Geriatric Disorders (Xiangya Hospital), Changsha, 410008, Hunan, China
| | - Ling-Qing Yuan
- The Second Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Yong Zhou
- Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Zheng-Guang Wang
- Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China.
| | - Hui Xie
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
- Hunan Key Laboratory of Angmedicine, Changsha, 410008, Hunan, China.
- National Clinical Research Center for Geriatric Disorders (Xiangya Hospital), Changsha, 410008, Hunan, China.
| |
Collapse
|
4
|
Schurman CA, Kaya S, Dole N, Luna NMM, Castillo N, Potter R, Rose JP, Bons J, King CD, Burton JB, Schilling B, Melov S, Tang S, Schaible E, Alliston T. Aging impairs the osteocytic regulation of collagen integrity and bone quality. Bone Res 2024; 12:13. [PMID: 38409111 PMCID: PMC10897167 DOI: 10.1038/s41413-023-00303-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 10/31/2023] [Accepted: 11/13/2023] [Indexed: 02/28/2024] Open
Abstract
Poor bone quality is a major factor in skeletal fragility in elderly individuals. The molecular mechanisms that establish and maintain bone quality, independent of bone mass, are unknown but are thought to be primarily determined by osteocytes. We hypothesize that the age-related decline in bone quality results from the suppression of osteocyte perilacunar/canalicular remodeling (PLR), which maintains bone material properties. We examined bones from young and aged mice with osteocyte-intrinsic repression of TGFβ signaling (TβRIIocy-/-) that suppresses PLR. The control aged bone displayed decreased TGFβ signaling and PLR, but aging did not worsen the existing PLR suppression in male TβRIIocy-/- bone. This relationship impacted the behavior of collagen material at the nanoscale and tissue scale in macromechanical tests. The effects of age on bone mass, density, and mineral material behavior were independent of osteocytic TGFβ. We determined that the decline in bone quality with age arises from the loss of osteocyte function and the loss of TGFβ-dependent maintenance of collagen integrity.
Collapse
Affiliation(s)
- Charles A Schurman
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, 94143, USA
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Serra Kaya
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA
| | - Neha Dole
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA
| | - Nadja M Maldonado Luna
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, 94143, USA
| | - Natalia Castillo
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA
| | - Ryan Potter
- Washington University in St Louis, Department of Orthopedics, St. Louis, MO, 63130, USA
| | - Jacob P Rose
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Joanna Bons
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | | | - Jordan B Burton
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | | | - Simon Melov
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Simon Tang
- Washington University in St Louis, Department of Orthopedics, St. Louis, MO, 63130, USA
| | - Eric Schaible
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA.
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, 94143, USA.
| |
Collapse
|
5
|
Fricke HP, Krajco CJ, Perry MJ, Brettingen LJ, Wake LA, Charles JF, Hernandez LL. Fluoxetine treatment during the postpartal period may have short-term impacts on murine maternal skeletal physiology. Front Pharmacol 2023; 14:1244580. [PMID: 38074149 PMCID: PMC10701399 DOI: 10.3389/fphar.2023.1244580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023] Open
Abstract
Postpartum depression affects many individuals after parturition, and selective serotonin reuptake inhibitors (SSRIs) are often used as the first-line treatment; however, both SSRIs and lactation are independently associated with bone loss due to the role of serotonin in bone remodeling. Previously, we have established that administration of the SSRI fluoxetine during the peripartal period results in alterations in long-term skeletal characteristics. In the present study, we treated mice with either a low or high dose of fluoxetine during lactation to determine the consequences of the perturbation of serotonin signaling during this time period on the dam skeleton. We found that lactational fluoxetine exposure affected both cortical and trabecular parameters, altered gene expression and circulating markers of bone turnover, and affected mammary gland characteristics, and that these effects were more pronounced in the dams that were exposed to the low dose of fluoxetine in comparison to the high dose. Fluoxetine treatment during the postpartum period in rodents had short term effects on bone that were largely resolved 3 months post-weaning. Despite the overall lack of long-term insult to bone, the alterations in serotonin-driven lactational bone remodeling raises the question of whether fluoxetine is a safe option for the treatment of postpartum depression.
Collapse
Affiliation(s)
- Hannah P. Fricke
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI, United States
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Chandler J. Krajco
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Molly J. Perry
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Lauren J. Brettingen
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Lella A. Wake
- Departments of Orthopedics and Medicine, Brigham and Women’s Hospital, Boston, MA, United States
| | - Julia F. Charles
- Departments of Orthopedics and Medicine, Brigham and Women’s Hospital, Boston, MA, United States
| | - Laura L. Hernandez
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI, United States
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, United States
| |
Collapse
|
6
|
Yildirim G, Bergamo ETP, Poudel SB, Ruff RR, Dixit M, Hu B, Mijares DQ, Witek L, Chlebek C, Harrison DE, Strong R, Miller RA, Ladiges W, Bromage TG, Rosen CJ, Yakar S. Long-term effects of canagliflozin treatment on the skeleton of aged UM-HET3 mice. GeroScience 2023; 45:1933-1951. [PMID: 37166526 PMCID: PMC10400751 DOI: 10.1007/s11357-023-00803-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 04/18/2023] [Indexed: 05/12/2023] Open
Abstract
Sodium glucose cotransporter-2 inhibitors (SGLT2is) promote urinary glucose excretion and decrease plasma glucose levels independent of insulin. Canagliflozin (CANA) is an SGLT2i, which is widely prescribed, to reduce cardiovascular complications, and as a second-line therapy after metformin in the treatment of type 2 diabetes mellitus. Despite the robust metabolic benefits, reductions in bone mineral density (BMD) and cortical fractures were reported for CANA-treated subjects. In collaboration with the National Institute on Aging (NIA)-sponsored Interventions Testing Program (ITP), we tested skeletal integrity of UM-HET3 mice fed control (137 mice) or CANA-containing diet (180 ppm, 156 mice) from 7 to 22 months of age. Micro-computed tomography (micro-CT) revealed that CANA treatment caused significant thinning of the femur mid-diaphyseal cortex in both male and female mice, did not affect trabecular bone architecture in the distal femur or the lumbar vertebra-5 in male mice, but was associated with thinning of the trabeculae at the distal femur in CANA-treated female mice. In male mice, CANA treatment is associated with significant reductions in cortical bone volumetric BMD by micro-CT, and by quantitative backscattered scanning electron microscopy. Raman microspectroscopy, taken at the femur mid-diaphyseal posterior cortex, showed significant reductions in the mineral/matrix ratio and an increased carbonate/phosphate ratio in CANA-treated male mice. These data were supported by thermogravimetric assay (TGA) showing significantly decreased mineral and increased carbonate content in CANA-treated male mice. Finally, the sintered remains of TGA were subjected to X-ray diffraction and showed significantly higher fraction of whitlockite, a calcium orthophosphate mineral, which has higher resorbability than hydroxyapatite. Overall, long-term CANA treatment compromised bone morphology and mineral composition of bones, which likely contribute to increased fracture risk seen with this drug.
Collapse
Affiliation(s)
- Gozde Yildirim
- David B. Kriser Dental Center, Department of Molecular Pathobiology, New York University College of Dentistry, 345 East 24Th Street, New York, NY 10010-4086 USA
| | - Edmara T. P. Bergamo
- David B. Kriser Dental Center, Biomaterials Division, Department of Molecular Pathobiology, NYU College of Dentistry, New York, NY 10010-4086 USA
| | - Sher Bahadur Poudel
- David B. Kriser Dental Center, Department of Molecular Pathobiology, New York University College of Dentistry, 345 East 24Th Street, New York, NY 10010-4086 USA
| | - Ryan R. Ruff
- David B. Kriser Dental Center, Department of Epidemiology and Health Promotion, New York University College of Dentistry, New York, NY 10010-4086 USA
| | - Manisha Dixit
- David B. Kriser Dental Center, Department of Molecular Pathobiology, New York University College of Dentistry, 345 East 24Th Street, New York, NY 10010-4086 USA
| | - Bin Hu
- David B. Kriser Dental Center, Department of Molecular Pathobiology, New York University College of Dentistry, 345 East 24Th Street, New York, NY 10010-4086 USA
| | - Dindo Q. Mijares
- David B. Kriser Dental Center, Biomaterials Division, Department of Molecular Pathobiology, NYU College of Dentistry, New York, NY 10010-4086 USA
| | - Lukasz Witek
- David B. Kriser Dental Center, Biomaterials Division, Department of Molecular Pathobiology, NYU College of Dentistry, New York, NY 10010-4086 USA
- Department of Biomedical Engineering, Tandon School of Engineering New York University, Brooklyn, NY 11201 USA
| | - Carolyn Chlebek
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, USA
| | | | - Randy Strong
- Geriatric Research, Education and Clinical Center and Research Service, South Texas Veterans Health Care System, San Antonio, TX USA
- Barshop Institute for Longevity and Aging Studies and Department of Pharmacology, The University of Texas Health Science Center, San Antonio, TX USA
| | - Richard A. Miller
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, MI USA
| | - Warren Ladiges
- Department of Comparative Medicine, School of Medicine, University of Washington, Seattle, WA USA
| | - Timothy G. Bromage
- David B. Kriser Dental Center, Department of Molecular Pathobiology, New York University College of Dentistry, 345 East 24Th Street, New York, NY 10010-4086 USA
| | - Clifford J. Rosen
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, USA
| | - Shoshana Yakar
- David B. Kriser Dental Center, Department of Molecular Pathobiology, New York University College of Dentistry, 345 East 24Th Street, New York, NY 10010-4086 USA
| |
Collapse
|
7
|
Kaya S, Bailey KN, Schurman CA, Evans DS, Alliston T. Bone-cartilage crosstalk informed by aging mouse bone transcriptomics and human osteoarthritis genome-wide association studies. Bone Rep 2023; 18:101647. [PMID: 36636109 PMCID: PMC9830153 DOI: 10.1016/j.bonr.2022.101647] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/28/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
Subchondral bone participates in crosstalk with articular cartilage to maintain joint homeostasis, and disruption of either tissue results in overall joint degeneration. Among the subchondral bone changes observed in osteoarthritis (OA), subchondral bone plate (SBP) thickening has a time-dependent relationship with cartilage degeneration and has recently been shown to be regulated by osteocytes. Here, we evaluate the effect of age on SBP thickness and cartilage degeneration in aging mice. We find that SBP thickness significantly increases by 18-months of age, corresponding temporally with increased cartilage degeneration. To identify factors in subchondral bone that may participate in bone cartilage crosstalk or OA, we leveraged mouse transcriptomic data from one joint tissue compartment - osteocyte-enriched bone - to search for enrichment with human OA in UK Biobank and Arthritis Research UK Osteoarthritis Genetics (arcOGEN) GWAS using the mouse2human (M2H, www.mouse2human.org) strategy. Genes differentially expressed in aging mouse bone are significantly enriched for human OA, showing joint site-specific (knee vs. hip) relationships, exhibit temporal associations with age, and unique gene clusters are implicated in each type of OA. Application of M2H identifies genes with known and unknown functions in osteocytes and OA development that are clinically associated with human OA. Altogether, this work prioritizes genes with a potential role in bone/cartilage crosstalk for further mechanistic study based on their association with human OA in GWAS.
Collapse
Affiliation(s)
- Serra Kaya
- Department of Orthopaedic Surgery, University of California San Francisco, CA, United States of America
| | - Karsyn N. Bailey
- Department of Orthopaedic Surgery, University of California San Francisco, CA, United States of America
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA, United States of America
| | - Charles A. Schurman
- Department of Orthopaedic Surgery, University of California San Francisco, CA, United States of America
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA, United States of America
| | - Daniel S. Evans
- California Pacific Medical Center Research Institute, San Francisco, CA, United States of America
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California San Francisco, CA, United States of America
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA, United States of America
| |
Collapse
|
8
|
Sang W, Ural A. Evaluating the Role of Canalicular Morphology and Perilacunar Region Properties on Local Mechanical Environment of Lacunar-Canalicular Network Using Finite Element Modeling. J Biomech Eng 2023; 145:1156059. [PMID: 36629002 DOI: 10.1115/1.4056655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 01/07/2023] [Indexed: 01/12/2023]
Abstract
Physiological and pathological processes such as aging, diseases, treatments, and lactation can alter lacunar-canalicular network (LCN) morphology and perilacunar region properties. These modifications can impact the mechanical environment of osteocytes which in turn can influence osteocyte mechanosensitivity and the remodeling process. In this study, we aim to evaluate how the modifications in the canalicular morphology, lacunar density, and the perilacunar region properties influence the local mechanical environment of LCN and the apparent bone properties using three-dimensional finite element (FE) modeling. The simulation results showed that a 50% reduction in perilacunar elastic modulus led to about 7% decrease in apparent elastic modulus of the bone. The increase in canalicular density, length, and diameter did not influence the strain amplification in the models but they increased the amount of highly strained bone around LCN. Change in lacunar density did not influence the strain amplification and the amount of highly strained regions on LCN surfaces. Reduction in perilacunar elastic modulus increased both the strain amplification and the volume of highly strained tissue around and on the surface of LCN. The FE models of LCN in this study can be utilized to quantify the influence of modifications in canalicular morphology, lacunar density, and perilacunar region properties on the apparent bone properties and the local mechanical environment of LCN. Although this is a numerical study with idealized models, it provides important information on how mechanical environment of osteocytes is influenced by the modifications in LCN morphology and perilacunar region properties due to physiological and pathological processes.
Collapse
Affiliation(s)
- Wen Sang
- Department of Mechanical Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085
| | - Ani Ural
- Department of Mechanical Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085
| |
Collapse
|
9
|
Peurière L, Mastrandrea C, Vanden-Bossche A, Linossier MT, Thomas M, Normand M, Lafage-Proust MH, Vico L. Hindlimb unloading in C57BL/6J mice induces bone loss at thermoneutrality without change in osteocyte and lacuno-canalicular network. Bone 2023; 169:116640. [PMID: 36526262 DOI: 10.1016/j.bone.2022.116640] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/13/2022] [Accepted: 11/30/2022] [Indexed: 12/15/2022]
Abstract
Impaired mechanical stimuli during hindlimb unloading (HLU) are believed to exacerbate osteocyte paracrine regulation of osteoclasts. We hypothesized that bone loss and deterioration of the osteocyte lacuno-canalicular network are attenuated in HLU mice housed at thermoneutrality (28 °C) compared with those housed at ambient temperature (22 °C). Following acclimatization, 20-week-old male C57BL/6J mice were submitted to HLU or kept in pair-fed control cages (CONT), for 5 days (5d) or 14d, at 22 °C or 28 °C. In the femur distal metaphysis, thermoneutral CONT mice had higher bone volume (p = 0.0007, BV/TV, in vivo μCT, vs. 14dCONT22) whilst osteoclastic surfaces of CONT and HLU were greater at 22 °C (5dCONT22 + 53 %, 5dHLU22 + 50 %, 14dCONT22 + 186 %, 14dHLU22 + 104 %, vs matching 28 °C group). In the femur diaphysis and at both temperatures, 14dHLU exhibited thinner cortices distally or proximally compared to controls; the mid-diaphysis being thicker at 28 °C than at 22 °C in all groups. Expression of cortical genes for proteolytic enzyme (Mmp13), markers for osteoclastogenic differentiation (MCSF, RANKL), and activity (TRAP, Ctsk) were increased following 22 °C HLU, whereas only Ctsk expression was increased following 28 °C HLU. Expression of cortical genes for apoptosis, senescence, and autophagy were not elevated following HLU at any temperature. Osteocyte density at the posterior mid-diaphysis was similar between groups, as was the proportion of empty lacunae (<0.5 %). However, analysis of the lacuno-canalicular network (LCN, fluorescein staining) revealed unstained areas in the 14dHLU22 group only, suggesting disrupted LCN flow in this group alone. In conclusion, 28 °C housing influences the HLU bone response but does not prevent bone loss. Furthermore, our results do not show osteocyte senescence or death, and at thermoneutrality, HLU-induced bone resorption is not triggered by osteoclastic activators RANKL and MCSF.
Collapse
Affiliation(s)
- Laura Peurière
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France.
| | - Carmelo Mastrandrea
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Arnaud Vanden-Bossche
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Marie-Thérèse Linossier
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Mireille Thomas
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Myriam Normand
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Marie-Hélène Lafage-Proust
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Laurence Vico
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| |
Collapse
|
10
|
Brent MB. Pharmaceutical treatment of bone loss: From animal models and drug development to future treatment strategies. Pharmacol Ther 2023; 244:108383. [PMID: 36933702 DOI: 10.1016/j.pharmthera.2023.108383] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/18/2023] [Accepted: 03/09/2023] [Indexed: 03/17/2023]
Abstract
Animal models are fundamental to advance our knowledge of the underlying pathophysiology of bone loss and to study pharmaceutical countermeasures against it. The animal model of post-menopausal osteoporosis from ovariectomy is the most widely used preclinical approach to study skeletal deterioration. However, several other animal models exist, each with unique characteristics such as bone loss from disuse, lactation, glucocorticoid excess, or exposure to hypobaric hypoxia. The present review aimed to provide a comprehensive overview of these animal models to emphasize the importance and significance of investigating bone loss and pharmaceutical countermeasures from perspectives other than post-menopausal osteoporosis only. Hence, the pathophysiology and underlying cellular mechanisms involved in the various types of bone loss are different, and this might influence which prevention and treatment strategies are the most effective. In addition, the review sought to map the current landscape of pharmaceutical countermeasures against osteoporosis with an emphasis on how drug development has changed from being driven by clinical observations and enhancement or repurposing of existing drugs to today's use of targeted anti-bodies that are the result of advanced insights into the underlying molecular mechanisms of bone formation and resorption. Moreover, new treatment combinations or repurposing opportunities of already approved drugs with a focus on dabigatran, parathyroid hormone and abaloparatide, growth hormone, inhibitors of the activin signaling pathway, acetazolamide, zoledronate, and romosozumab are discussed. Despite the considerable progress in drug development, there is still a clear need to improve treatment strategies and develop new pharmaceuticals against various types of osteoporosis. The review also highlights that new treatment indications should be explored using multiple animal models of bone loss in order to ensure a broad representation of different types of skeletal deterioration instead of mainly focusing on primary osteoporosis from post-menopausal estrogen deficiency.
Collapse
Affiliation(s)
- Mikkel Bo Brent
- Department of Biomedicine, Aarhus University, Denmark, Wilhelm Meyers Allé 3, 8000 Aarhus C, Denmark.
| |
Collapse
|
11
|
Athonvarangkul D, Wysolmerski JJ. Crosstalk within a brain-breast-bone axis regulates mineral and skeletal metabolism during lactation. Front Physiol 2023; 14:1121579. [PMID: 36875035 PMCID: PMC9979219 DOI: 10.3389/fphys.2023.1121579] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/27/2023] [Indexed: 02/18/2023] Open
Abstract
To support the increased calcium demands for milk production during lactation, a dramatic and reversible physiological response occurs to alter bone and mineral metabolism. This coordinated process involves a brain-breast-bone axis that integrates hormonal signals that allow for adequate calcium delivery to milk yet also protects the maternal skeletal from excessive bone loss or decreases in bone quality or function. Here, we review the current knowledge on the crosstalk between the hypothalamus, mammary gland, and skeleton during lactation. We discuss the rare entity of pregnancy and lactation associated osteoporosis and consider how the physiology of bone turnover in lactation may impact the pathophysiology of postmenopausal osteoporosis. Further understanding of the regulators of bone loss during lactation, particularly in humans, may provide insights into new therapies for osteoporosis and other diseases of excess bone loss.
Collapse
Affiliation(s)
- Diana Athonvarangkul
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | | |
Collapse
|
12
|
Histological Assessment of Endochondral Ossification and Bone Mineralization. ENDOCRINES 2023. [DOI: 10.3390/endocrines4010006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Finely tuned cartilage mineralization, endochondral ossification, and normal bone formation are necessary for normal bone growth. Hypertrophic chondrocytes in the epiphyseal cartilage secrete matrix vesicles, which are small extracellular vesicles initiating mineralization, into the intercolumnar septa but not the transverse partitions of the cartilage columns. Bone-specific blood vessels invade the unmineralized transverse septum, exposing the mineralized cartilage cores. Many osteoblast precursors migrate to the cartilage cores, where they synthesize abundant bone matrices, and mineralize them in a process of matrix vesicle-mediated bone mineralization. Matrix vesicle-mediated mineralization concentrates calcium (Ca) and inorganic phosphates (Pi), which are converted into hydroxyapatite crystals. These crystals grow radially and are eventually get out of the vesicles to form spherical mineralized nodules, leading to collagen mineralization. The influx of Ca and Pi into the matrix vesicle is regulated by several enzymes and transporters such as TNAP, ENPP1, PiT1, PHOSPHO1, annexins, and others. Such matrix vesicle-mediated mineralization is regulated by osteoblastic activities, synchronizing the synthesis of organic bone material. However, osteocytes reportedly regulate peripheral mineralization, e.g., osteocytic osteolysis. The interplay between cartilage mineralization and vascular invasion during endochondral ossification, as well as that of osteoblasts and osteocytes for normal mineralization, appears to be crucial for normal bone growth.
Collapse
|
13
|
Blouin S, Misof BM, Mähr M, Fratzl-Zelman N, Roschger P, Lueger S, Messmer P, Keplinger P, Rauch F, Glorieux FH, Berzlanovich A, Gruber GM, Brugger PC, Shane E, Recker RR, Zwerina J, Hartmann MA. Osteocyte lacunae in transiliac bone biopsy samples across life span. Acta Biomater 2023; 157:275-287. [PMID: 36549635 DOI: 10.1016/j.actbio.2022.11.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/23/2022]
Abstract
Osteocytes act as bone mechanosensors, regulators of osteoblast/osteoclast activity and mineral homeostasis, however, knowledge about their functional/morphological changes throughout life is limited. We used quantitative backscattered electron imaging (qBEI) to investigate osteocyte lacunae sections (OLS) as a 2D-surrogate characterizing the osteocytes. OLS characteristics, the density of mineralized osteocyte lacunae (i.e., micropetrotic osteocytes, md.OLS-Density in nb/mm2) and the average degree of mineralization (CaMean in weight% calcium) of cortex and spongiosa were analyzed in transiliac biopsy samples from healthy individuals under 30 (n=59) and over 30 years (n=50) (i.e., before and after the age of peak bone mass, respectively). We found several differences in OLS-characteristics: 1). Inter-individually between the age groups: OLS-Density and OLS-Porosity were reduced by about 20% in older individuals in spongiosa and in cortex versus younger probands (both, p < 0.001). 2). Intra-individually between bone compartments: OLS-Density was higher in the cortex, +18.4%, p < 0.001 for younger and +7.6%, p < 0.05 for older individuals. Strikingly, the most frequent OLS nearest-neighbor distance was about 30 µm in both age groups and at both bone sites revealing a preferential organization of osteocytes in clusters. OLS-Density was negatively correlated with CaMean in both spongiosa and cortex (both, p < 0.001). Few mineralized OLS were found in young individuals along with an increase of md.OLS-Density with age. In summary, this transiliac bone sample analysis of 200000 OLS from 109 healthy individuals throughout lifespan reveals several age-related differences in OLS characteristics. Moreover, our study provides reference data from healthy individuals for different ages to be used for diagnosis of bone abnormalities in diseases. STATEMENT OF SIGNIFICANCE: Osteocytes are bone cells embedded in lacunae within the mineralized bone matrix and have a key role in the bone metabolism and the mineral homeostasis. Not easily accessible, we used quantitative backscattered electron imaging to determine precisely number and shape descriptors of the osteocyte lacunae in 2D. We analyzed transiliac biopsy samples from 109 individuals with age distributed from 2 to 95 years. Compact cortical bone showed constantly higher lacunar density than cancellous bone but the lacunar density in both bone tissue decreased with age before the peak bone mass age at 30 years and stabilized or even increased after this age. This extensive study provides osteocyte lacunae reference data from healthy individuals usable for bone pathology diagnosis.
Collapse
Affiliation(s)
- Stéphane Blouin
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria.
| | - Barbara M Misof
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Matthias Mähr
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Nadja Fratzl-Zelman
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Paul Roschger
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Sonja Lueger
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Phaedra Messmer
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Petra Keplinger
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Frank Rauch
- Shriners Hospital for Children and McGill University, Montreal, ON QC, H4A 0A9, Canada
| | - Francis H Glorieux
- Shriners Hospital for Children and McGill University, Montreal, ON QC, H4A 0A9, Canada
| | - Andrea Berzlanovich
- Unit of Forensic Gerontology, Center of Forensic Medicine, Medical University of Vienna, Vienna, Austria
| | - Gerlinde M Gruber
- Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Peter C Brugger
- Center for Anatomy and Cell Biology, Department of Anatomy, Medical University of Vienna, Vienna, Austria
| | - Elizabeth Shane
- Department of Medicine, Division of Endocrinology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Robert R Recker
- Osteoporosis Research Center, Creighton University, Omaha, Nebraska, USA
| | - Jochen Zwerina
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| | - Markus A Hartmann
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria & Vienna Bone and Growth Center, Vienna, Austria
| |
Collapse
|
14
|
Heveran CM, Boerckel JD. Osteocyte Remodeling of the Lacunar-Canalicular System: What's in a Name? Curr Osteoporos Rep 2023; 21:11-20. [PMID: 36512204 PMCID: PMC11223162 DOI: 10.1007/s11914-022-00766-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/18/2022] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW Osteocytes directly modify the bone surrounding the expansive lacunar-canalicular system (LCS) through both resorption and deposition. The existence of this phenomenon is now widely accepted, but is referred to as "osteocyte osteolysis," "LCS remodeling," and "perilacunar remodeling," among other names. The uncertainty in naming this physiological process reflects the many persistent questions about why and how osteocytes interact with local bone matrix. The goal of this review is to examine the purpose and nature of LCS remodeling and its impacts on multiscale bone quality. RECENT FINDINGS While LCS remodeling is clearly important for systemic calcium mobilization, this process may have additional potential drivers and may impact the ability of bone to resist fracture. There is abundant evidence that the osteocyte can resorb and replace bone mineral and does so outside of extreme challenges to mineral homeostasis. The impacts of the osteocyte on organic matrix are less certain, especially regarding whether osteocytes produce osteoid. Though multiple lines of evidence point towards osteocyte production of organic matrix, definitive work is needed. Recent high-resolution imaging studies demonstrate that LCS remodeling influences local material properties. The role of LCS remodeling in the maintenance and deterioration of bone matrix quality in aging and disease are active areas of research. In this review, we highlight current progress in understanding why and how the osteocyte removes and replaces bone tissue and the consequences of these activities to bone quality. We posit that answering these questions is essential for evaluating whether, how, when, and why LCS remodeling may be manipulated for therapeutic benefit in managing bone fragility.
Collapse
Affiliation(s)
- C M Heveran
- Department of Mechanical & Industrial Engineering, Montana State University, Bozeman, USA.
| | - J D Boerckel
- Department of Orthopaedic Surgery, Department of Bioengineering, University of Pennsylvania School of Medicine, Philadelphia, USA.
| |
Collapse
|
15
|
Allahyari P, Silani M, Yaghoubi V, Milovanovic P, Schmidt FN, Busse B, Qwamizadeh M. On the fracture behavior of cortical bone microstructure: The effects of morphology and material characteristics of bone structural components. J Mech Behav Biomed Mater 2023; 137:105530. [PMID: 36334581 DOI: 10.1016/j.jmbbm.2022.105530] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/29/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022]
Abstract
Bone encompasses a complex arrangement of materials at different length scales, which endows it with a range of mechanical, chemical, and biological capabilities. Changes in the microstructure and characteristics of the material, as well as the accumulation of microcracks, affect the bone fracture properties. In this study, two-dimensional finite element models of the microstructure of cortical bone were considered. The eXtended Finite Element Method (XFEM) developed by Abaqus software was used for the analysis of the microcrack propagation in the model as well as for local sensitivity analysis. The stress-strain behavior obtained for the different introduced models was substantially different, confirming the importance of bone tissue microstructure for its failure behavior. Considering the role of interfaces, the results highlighted the effect of cement lines on the crack deflection path and global fracture behavior of the bone microstructure. Furthermore, bone micromorphology and areal fraction of cortical bone tissue components such as osteons, cement lines, and pores affected the bone fracture behavior; specifically, pores altered the crack propagation path since increasing porosity reduced the maximum stress needed to start crack propagation. Therefore, cement line structure, mineralization, and areal fraction are important parameters in bone fracture. The parameter-wise sensitivity analysis demonstrated that areal fraction and strain energy release rate had the greatest and the lowest effect on ultimate strength, respectively. Furthermore, the component-wise sensitivity analysis revealed that for the areal fraction parameter, pores had the greatest effect on ultimate strength, whereas for the other parameters such as elastic modulus and strain energy release rate, cement lines had the most important effect on the ultimate strength. In conclusion, the finding of the current study can help to predict the fracture mechanisms in bone by taking the morphological and material properties of its microstructure into account.
Collapse
Affiliation(s)
- P Allahyari
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - M Silani
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
| | - V Yaghoubi
- Structural Integrity & Composites, Faculty of Aerospace Engineering, Delft University of Technology, 2629 HS, Delft, Netherlands
| | - P Milovanovic
- Center of Bone Biology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - F N Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 22529, Hamburg, Germany; Interdisciplinary Competence Center for Interface Research (ICCIR), University Medical Center Hamburg-Eppendorf, 22529, Hamburg, Germany
| | - B Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 22529, Hamburg, Germany; Interdisciplinary Competence Center for Interface Research (ICCIR), University Medical Center Hamburg-Eppendorf, 22529, Hamburg, Germany
| | - M Qwamizadeh
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 22529, Hamburg, Germany; Interdisciplinary Competence Center for Interface Research (ICCIR), University Medical Center Hamburg-Eppendorf, 22529, Hamburg, Germany.
| |
Collapse
|
16
|
Dixit M, Louis LD, Basta-Pljakic J, Yildirim G, Poudel SB, Kumararaja F, List EO, Duran SO, Kopchick JJ, Ruff RR, Schaffler MB, Yakar S. Lifelong Excess in GH Elicits Sexually Dimorphic Effects on Skeletal Morphology and Bone Mechanical Properties. J Bone Miner Res 2022; 37:2201-2214. [PMID: 36069368 PMCID: PMC9712242 DOI: 10.1002/jbmr.4699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 08/29/2022] [Accepted: 09/03/2022] [Indexed: 11/09/2022]
Abstract
Excess in growth hormone (GH) levels, seen in patients with acromegaly, is associated with increases in fractures. This happens despite wider bones and independent of bone mineral density. We used the bovine GH (bGH) transgenic mice, which show constitutive excess in GH and insulin-like growth factor 1 (IGF-1) in serum and tissues, to study how lifelong increases in GH and IGF-1 affect skeletal integrity. Additionally, we crossed the acid labile subunit (ALS) null (ALSKO) to the bGH mice to reduce serum IGF-1 levels. Our findings indicate sexually dimorphic effects of GH on cortical and trabecular bone. Male bGH mice showed enlarged cortical diameters, but with marrow cavity expansion and thin cortices as well as increased vascular porosity that were associated with reductions in diaphyseal strength and stiffness. In contrast, female bGH mice presented with significantly smaller-diameter diaphysis, with greater cortical bone thickness and with a slightly reduced tissue elastic modulus (by microindentation), ultimately resulting in overall stronger, stiffer bones. We found increases in C-terminal telopeptide of type 1 collagen and procollagen type 1 N propeptide in serum, independent of circulating IGF-1 levels, indicating increased bone remodeling with excess GH. Sexual dimorphism in response to excess GH was also observed in the trabecular bone compartment, particularly at the femur distal metaphysis. Female bGH mice preserved their trabecular architecture during aging, whereas trabecular bone volume in male bGH mice significantly reduced and was associated with thinning of the trabeculae. We conclude that pathological excess in GH results in sexually dimorphic changes in bone architecture and gains in bone mass that affect whole-bone mechanical properties, as well as sex-specific differences in bone material properties. © 2022 American Society for Bone and Mineral Research (ASBMR).
Collapse
Affiliation(s)
- Manisha Dixit
- David B. Kriser Dental Center, Department of Molecular Pathobiology New York University College of Dentistry New York, NY 10010-4086
| | - Leeann D Louis
- Department of Biomedical Engineering, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Jelena Basta-Pljakic
- Department of Biomedical Engineering, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Gozde Yildirim
- David B. Kriser Dental Center, Department of Molecular Pathobiology New York University College of Dentistry New York, NY 10010-4086
| | - Sher-Bahadur Poudel
- David B. Kriser Dental Center, Department of Molecular Pathobiology New York University College of Dentistry New York, NY 10010-4086
| | - Fancy Kumararaja
- David B. Kriser Dental Center, Department of Molecular Pathobiology New York University College of Dentistry New York, NY 10010-4086
| | - Edward O List
- Edison Biotechnology Institute, and Dept. of Biomedical Sciences, Ohio University, Athens, OH
| | - Silvana Ortiz Duran
- Edison Biotechnology Institute, and Dept. of Biomedical Sciences, Ohio University, Athens, OH
| | - John J Kopchick
- Edison Biotechnology Institute, and Dept. of Biomedical Sciences, Ohio University, Athens, OH
| | - Ryan R Ruff
- David B. Kriser Dental Center, Department of Epidemiology and Health Promotion, New York University College of Dentistry New York, NY 10010-4086
| | - Mitchell B Schaffler
- Department of Biomedical Engineering, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Shoshana Yakar
- David B. Kriser Dental Center, Department of Molecular Pathobiology New York University College of Dentistry New York, NY 10010-4086
| |
Collapse
|
17
|
Quantifying how altered lacunar morphology and perilacunar tissue properties influence local mechanical environment of osteocyte lacunae using finite element modeling. J Mech Behav Biomed Mater 2022; 135:105433. [DOI: 10.1016/j.jmbbm.2022.105433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/09/2022] [Accepted: 08/26/2022] [Indexed: 11/23/2022]
|
18
|
Allison H, O'Sullivan L, McNamara L. Temporal changes in cortical microporosity during estrogen deficiency associated with perilacunar resorption and osteocyte apoptosis: A pilot study. Bone Rep 2022; 16:101590. [PMID: 35663377 PMCID: PMC9156983 DOI: 10.1016/j.bonr.2022.101590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/13/2022] [Accepted: 05/14/2022] [Indexed: 02/07/2023] Open
Abstract
Osteocytes can actively regulate bone microporosity, through either perilacunar resorption or micropetrosis following apoptosis. Osteocyte apoptosis is more prevalent in estrogen deficiency and changes in the lacunar-canalicular network of osteocytes have been reported. Temporal changes in bone mineralisation and osteocytes cellular strains occur, which might be associated with osteocyte-driven microporosity changes, although time dependant changes in bone microporosity are not yet fully understood. In this pilot study we conducted micro-CT analysis, backscatter electron imaging and histological analysis of femoral cortical bone form an ovariectomized rat model of osteoporosis to investigate whether estrogen deficiency causes temporal changes in lacunar and vascular porosity. We also assessed MMP14 expression, lacunar occupancy and mineral infilling, as indicators of perilacunar resorption and micropetrosis. We report temporal changes in cortical microporosity in estrogen deficiency. Specifically, canalicular and vascular porosity initially increased (4 weeks post-OVX), coinciding with the period of rapid bone loss, whereas in the longer term (14 weeks post-OVX) lacunar and canalicular diameter decreased. Interestingly, these changes coincided with an increased prevalence of empty lacunae and osteocyte lacunae were observed to be more circular with a mineralised border around the lacunar space. In addition we report an increase in MMP14+ osteocytes, which also suggests active matrix degradation by these cells. Together these results provide an insight into the temporal changes in cortical microporosity during estrogen deficiency and suggest the likelihood of occurrence of both perilacunar resorption and osteocyte apoptosis leading to micropetrosis. We propose that microporosity changes arise due to processes driven by distinct populations of osteocytes, which are either actively resorbing their matrix or have undergone apoptosis and are infilling lacunae by micropetrosis.
Collapse
Key Words
- BMDD, Bone mineral density distribution
- BSEM
- BSEM, Backscattered scanning electron microscopy
- BV, Bone volume
- Dm, Diameter
- Estrogen deficiency
- Lacunar
- Lc, Lacunar
- MMP, Matrix metalloproteases
- Micro-CT, Micro computed tomography
- Microporosity
- OVX, Ovariectomized
- PLR, Perilacunar resorption
- Sp, spacing
- TRAP, Tartrate-resistant acid phosphatase
- TV, Total volume
- Tb, Trabecular
- Th, Thickness
- V Ca, Vascular canal
- Vascular canals
- micro-CT
- με, Microstrain (ε ×10−6)
Collapse
Affiliation(s)
- H. Allison
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Science and Engineering, National University of Ireland Galway, Ireland
| | - L.M. O'Sullivan
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Science and Engineering, National University of Ireland Galway, Ireland
| | - L.M. McNamara
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Science and Engineering, National University of Ireland Galway, Ireland
| |
Collapse
|
19
|
Moriishi T, Komori T. Osteocytes: Their Lacunocanalicular Structure and Mechanoresponses. Int J Mol Sci 2022; 23:ijms23084373. [PMID: 35457191 PMCID: PMC9032292 DOI: 10.3390/ijms23084373] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/13/2022] [Accepted: 04/13/2022] [Indexed: 11/29/2022] Open
Abstract
Osteocytes connect with neighboring osteocytes and osteoblasts through their processes and form an osteocyte network. Shear stress on osteocytes, which is induced by fluid flow in the lacunae and canaliculi, has been proposed as an important mechanism for mechanoresponses. The lacunocanalicular structure is differentially developed in the compression and tension sides of femoral cortical bone and the compression side is more organized and has denser and thinner canaliculi. Mice with an impaired lacunocanalicular structure may be useful for evaluation of the relationship between lacunocanalicular structure and mechanoresponses, although their bone component cells are not normal. We show three examples of mice with an impaired lacunocanalicular structure. Ablation of osteocytes by diphtheria toxin caused massive osteocyte apoptosis, necrosis or secondary necrosis that occurred after apoptosis. Osteoblast-specific Bcl2 transgenic mice were found to have a reduced number of osteocyte processes and canaliculi, which caused massive osteocyte apoptosis and a completely interrupted lacunocanalicular network. Osteoblast-specific Sp7 transgenic mice were also revealed to have a reduced number of osteocyte processes and canaliculi, as well as an impaired, but functionally connected, lacunocanalicular network. Here, we show the phenotypes of these mice in physiological and unloaded conditions and deduce the relationship between lacunocanalicular structure and mechanoresponses.
Collapse
Affiliation(s)
- Takeshi Moriishi
- Department of Cell Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan;
| | - Toshihisa Komori
- Department of Molecular Bone Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan
- Correspondence: ; Tel.: +81-95-819-7637; Fax: +81-95-819-7638
| |
Collapse
|
20
|
Kaya S, Schurman CA, Dole NS, Evans DS, Alliston T. Prioritization of Genes Relevant to Bone Fragility Through the Unbiased Integration of Aging Mouse Bone Transcriptomics and Human GWAS Analyses. J Bone Miner Res 2022; 37:804-817. [PMID: 35094432 PMCID: PMC9018503 DOI: 10.1002/jbmr.4516] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 12/20/2021] [Accepted: 01/17/2022] [Indexed: 11/10/2022]
Abstract
Identifying new genetic determinants of bone mineral density (BMD) and fracture promises to yield improved diagnostics and therapies for bone fragility. However, prioritizing candidate genes from genome-wide screens can be challenging. To overcome this challenge, we prioritized mouse genes that are differentially expressed in aging mouse bone based on whether their human homolog is associated with human BMD and/or fracture. Unbiased RNA-seq analysis of young and old male C57BL/6 mouse cortical bone identified 1499, 1685, and 5525 differentially expressed genes (DEGs) in 1, 2, and 2.5-year-old bone, relative to 2-month-old bone, respectively. Gene-based scores for heel ultrasound bone mineral density (eBMD) and fracture were estimated using published genome-wide association studies (GWAS) results of these traits in the UK Biobank. Enrichment analysis showed that mouse bone DEG sets for all three age groups, relative to young bone, are significantly enriched for eBMD, but only the oldest two DEG sets are enriched for fracture. Using gene-based scores, this approach prioritizes among thousands of DEGs by a factor of 5- to 100-fold, yielding 10 and 21 genes significantly associated with fracture in the two oldest groups of mouse DEGs. Though these genes were not the most differentially expressed, they included Sost, Lrp5, and others with well-established functions in bone. Several others have, as yet, unknown roles in the skeleton. Therefore, this study accelerates identification of new genetic determinants of bone fragility by prioritizing a clinically relevant and experimentally tractable number of candidate genes for functional analysis. Finally, we provide a website (www.mouse2human.org) to enable other researchers to easily apply our strategy. © 2022 American Society for Bone and Mineral Research (ASBMR).
Collapse
Affiliation(s)
- Serra Kaya
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
| | - Charles A. Schurman
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA
| | - Neha S. Dole
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
| | - Daniel S. Evans
- California Pacific Medical Center Research Institute, San Francisco, CA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA
| |
Collapse
|
21
|
Emami AJ, Sebastian A, Lin YY, Yee CS, Osipov B, Loots GG, Alliston T, Christiansen BA. Altered canalicular remodeling associated with femur fracture in mice. J Orthop Res 2022; 40:891-900. [PMID: 34129247 PMCID: PMC8671555 DOI: 10.1002/jor.25119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/05/2021] [Accepted: 05/31/2021] [Indexed: 02/04/2023]
Abstract
We previously showed that femur fracture in mice caused a reduction in bone volume at distant skeletal sites within 2 weeks post-fracture. Osteocytes also have the ability to remodel their surrounding bone matrix through perilacunar/canalicular remodeling (PLR). If PLR is altered systemically following fracture, this could affect bone mechanical properties and increase fracture risk at all skeletal sites. In this study, we investigated whether lacunar-canalicular microstructure and the rate of PLR are altered in the contralateral limb following femoral fracture in mice. We hypothesized that femoral fracture would accelerate PLR by 2 weeks postfracture, followed by partial recovery by 4 weeks. We used histological evaluation and high-resolution microcomputed tomography to quantify the morphology of the lacunar-canalicular network at the contralateral tibia, and we used quantitative real-time polymerase chain reaction (RT-PCR) and RNA-seq to measure the expression of PLR-associated genes in the contralateral femur. We found that at both 2 and 4 weeks postfracture, canalicular width was significantly increased by 18.6% and 16.6%, respectively, in fractured mice relative to unfractured controls. At 3 days and 4 weeks post-fracture, we observed downregulation of PLR-associated genes; RNA-seq analysis at 3 days post-fracture showed a deceleration of bone formation and mineralization in the contralateral limb. These data demonstrate notable canalicular changes following fracture that could affect bone mechanical properties. These findings expand our understanding of systemic effects of fracture and how biological and structural changes at distant skeletal sites may contribute to increased fracture risk following an acute injury.
Collapse
Affiliation(s)
- Armaun J. Emami
- University of California Davis Health, Department of Orthopaedic Surgery
| | - Aimy Sebastian
- Lawrence Livermore National Laboratory, Physical & Life Sciences Directorate
| | - Yu-Yang Lin
- University of California Davis Health, Department of Orthopaedic Surgery
| | - Cristal S. Yee
- University of California San Francisco, Department of Orthopaedic Surgery
| | - Benjamin Osipov
- University of California Davis Health, Department of Orthopaedic Surgery
| | - Gabriela G. Loots
- Lawrence Livermore National Laboratory, Physical & Life Sciences Directorate
| | - Tamara Alliston
- University of California San Francisco, Department of Orthopaedic Surgery
| | | |
Collapse
|
22
|
Rux CJ, Vahidi G, Darabi A, Cox LM, Heveran CM. Perilacunar bone tissue exhibits sub-micrometer modulus gradation which depends on the recency of osteocyte bone formation in both young adult and early-old-age female C57Bl/6 mice. Bone 2022; 157:116327. [PMID: 35026452 PMCID: PMC8858864 DOI: 10.1016/j.bone.2022.116327] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/19/2021] [Accepted: 01/07/2022] [Indexed: 11/18/2022]
Abstract
Osteocytes resorb and replace bone local to the lacunar-canalicular system (LCS). However, whether osteocyte remodeling impacts bone quality adjacent to the LCS is not understood. Further, while aging is well-established to decrease osteocyte viability and truncate LCS geometry, it is unclear if aging also decreases perilacunar bone quality. To address these questions, we employed atomic force microscopy (AFM) to generate nanoscale-resolution modulus maps for cortical femur osteocyte lacunae from young (5-month) and early-old-age (22-month) female C57Bl/6 mice. AFM-mapped lacunae were also imaged with confocal laser scanning microscopy to determine which osteocytes recently deposited bone as determined by the presence of fluorochrome labels administered 2d and 8d before euthanasia. Modulus gradation with distance from the lacunar wall was compared for labeled (i.e., bone forming) and non-labeled lacunae in both young and aged mice. All mapped lacunae showed sub-microscale modulus gradation, with peak modulus values 200-400 nm from the lacunar wall. Perilacunar modulus gradations depended on the recency of osteocyte bone formation (i.e., the presence of labels). For both ages, 2d-labeled perilacunar bone had lower peak and bulk modulus compared to non-labeled perilacunar bone. Lacunar length reduced with age, but lacunar shape and size were not strong predictors of modulus gradation. Our findings demonstrate for the first time that osteocyte perilacunar remodeling impacts bone tissue modulus, one contributor to bone quality. Given the immense scale of the LCS, differences in perilacunar modulus resulting from osteocyte remodeling activity may affect the quality of a substantial amount of bone tissue.
Collapse
Affiliation(s)
- Caleb J Rux
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America; UC Berkeley-UCSF Graduate Program in Bioengineering, United States of America
| | - Ghazal Vahidi
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - Amir Darabi
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - Lewis M Cox
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - Chelsea M Heveran
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America.
| |
Collapse
|
23
|
Abstract
Bone is an outstanding, well-designed composite. It is constituted by a multi-level structure wherein its properties and behavior are dependent on its composition and structural organization at different length scales. The combination of unique mechanical properties with adaptive and self-healing abilities makes bone an innovative model for the future design of synthetic biomimetic composites with improved performance in bone repair and regeneration. However, the relation between structure and properties in bone is very complex. In this review article, we intend to describe the hierarchical organization of bone on progressively greater scales and present the basic concepts that are fundamental to understanding the arrangement-based mechanical properties at each length scale and their influence on bone’s overall structural behavior. The need for a better understanding of bone’s intricate composite structure is also highlighted.
Collapse
|
24
|
Sang W, Li Y, Guignon J, Liu XS, Ural A. Structural role of osteocyte lacunae on mechanical properties of bone matrix: A cohesive finite element study. J Mech Behav Biomed Mater 2022; 125:104943. [PMID: 34736032 PMCID: PMC8670554 DOI: 10.1016/j.jmbbm.2021.104943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/05/2021] [Accepted: 10/26/2021] [Indexed: 01/03/2023]
Abstract
Despite the extensive studies on biological function of osteocytes, there are limited studies that evaluated the structural role of osteocyte lacunae on local mechanical properties of the bone matrix. As a result, the goal of this study was to elucidate the independent contribution of osteocyte lacunae structure on mechanical properties and fracture behavior of the bone matrix uncoupled from its biological effects and bone tissue composition variation. This study combined cohesive finite element modeling with experimental data from a lactation rat model to evaluate the influence of osteocyte lacunar area porosity, density, size, axis ratio, and orientation on the elastic modulus, ultimate strength, and ultimate strain of the bone matrix as well as on local crack formation and propagation. It also performed a parametric study to isolate the influence of a single osteocyte lacunae structural property on the mechanical properties of the bone matrix. The experimental measurements demonstrated statistically significant differences in lacunar size between ovariectomized rats with lactation history and virgin groups (both ovariectomized and intact) and in axis ratio between rats with lactation history and virgins. There were no differences in mechanical properties between virgin and lactation groups as determined by the finite element simulations. However, there were statistically significant linear relationships between the physiological range of osteocyte lacunar area porosity, density, size, and orientation and the elastic modulus and ultimate strength of the bone matrix in virgin and lactation rats. The parametric study also revealed similar but stronger relationships between elastic modulus and ultimate strength and lacunar density, size, and orientation. The simulations also demonstrated that the osteocyte lacunae guided the crack propagation through local stress concentrations. In summary, this study enhanced the limited knowledge on the structural role of osteocyte lacunae on local mechanical properties of the bone matrix. These data are important in gaining a better understanding of the mechanical implications of the local modifications due to osteocytes in the bone matrix.
Collapse
Affiliation(s)
- Wen Sang
- Department of Mechanical Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA, USA
| | - Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 332A Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA, USA
| | - Jane Guignon
- Department of Mechanical Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA, USA
| | - X Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 332A Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA, USA
| | - Ani Ural
- Department of Mechanical Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA, USA.
| |
Collapse
|
25
|
Dixit M, Duran‐Ortiz S, Yildirim G, Poudel SB, Louis LD, Bartke A, Schaffler MB, Kopchick JJ, Yakar S. Induction of somatopause in adult mice compromises bone morphology and exacerbates bone loss during aging. Aging Cell 2021; 20:e13505. [PMID: 34811875 PMCID: PMC8672783 DOI: 10.1111/acel.13505] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/31/2021] [Accepted: 09/29/2021] [Indexed: 12/23/2022] Open
Abstract
Somatopause refers to the gradual declines in growth hormone (GH) and insulin‐like growth factor‐1 throughout aging. To define how induced somatopause affects skeletal integrity, we used an inducible GH receptor knockout (iGHRKO) mouse model. Somatopause, induced globally at 6 months of age, resulted in significantly more slender bones in both male and female iGHRKO mice. In males, induced somatopause was associated with progressive expansion of the marrow cavity leading to significant thinning of the cortices, which compromised bone strength. We report progressive declines in osteocyte lacunar number, and increases in lacunar volume, in iGHRKO males, and reductions in lacunar number accompanied by ~20% loss of overall canalicular connectivity in iGHRKO females by 30 months of age. Induced somatopause did not affect mineral/matrix ratio assessed by Raman microspectroscopy. We found significant increases in bone marrow adiposity and high levels of sclerostin, a negative regulator of bone formation in iGHRKO mice. Surprisingly, however, despite compromised bone morphology, osteocyte senescence was reduced in the iGHRKO mice. In this study, we avoided the confounded effects of constitutive deficiency in the GH/IGF‐1 axis on the skeleton during growth, and specifically dissected its effects on the aging skeleton. We show here, for the first time, that induced somatopause compromises bone morphology and the bone marrow environment.
Collapse
Affiliation(s)
- Manisha Dixit
- David B. Kriser Dental Center Department of Molecular Pathobiology New York University College of Dentistry New York New York NY USA
| | - Silvana Duran‐Ortiz
- Edison Biotechnology Institute and Dept. of Biomedical Sciences Ohio University Athens OH USA
| | - Godze Yildirim
- David B. Kriser Dental Center Department of Molecular Pathobiology New York University College of Dentistry New York New York NY USA
| | - Sher Bahadur Poudel
- David B. Kriser Dental Center Department of Molecular Pathobiology New York University College of Dentistry New York New York NY USA
| | - Leeann D. Louis
- Department of Biomedical Engineering City College of New York New York NY USA
| | - Andrzej Bartke
- Southern Illinois University School of Medicine Springfield IL USA
| | | | - John J. Kopchick
- Edison Biotechnology Institute and Dept. of Biomedical Sciences Ohio University Athens OH USA
| | - Shoshana Yakar
- David B. Kriser Dental Center Department of Molecular Pathobiology New York University College of Dentistry New York New York NY USA
| |
Collapse
|
26
|
Lai X, Chung R, Li Y, Liu XS, Wang L. Lactation alters fluid flow and solute transport in maternal skeleton: A multiscale modeling study on the effects of microstructural changes and loading frequency. Bone 2021; 151:116033. [PMID: 34102350 PMCID: PMC8276854 DOI: 10.1016/j.bone.2021.116033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/23/2021] [Accepted: 06/01/2021] [Indexed: 01/02/2023]
Abstract
The female skeleton undergoes significant material and ultrastructural changes to meet high calcium demands during reproduction and lactation. Through the peri-lacunar/canalicular remodeling (PLR), osteocytes actively resorb surrounding matrix and enlarge their lacunae and canaliculi during lactation, which are quickly reversed after weaning. How these changes alter the physicochemical environment of osteocytes, the most abundant and primary mechanosensing cells in bone, are not well understood. In this study, we developed a multiscale poroelastic modeling technique to investigate lactation-induced changes in stress, fluid pressurization, fluid flow, and solute transport across multiple length scales (whole bone, porous midshaft cortex, lacunar-canalicular pore system (LCS), and pericellular matrix (PCM) around osteocytes) in murine tibiae subjected to axial compression at 3 N peak load (~320 με) at 0.5, 2, or 4 Hz. Based on previously reported skeletal anatomical measurements from lactating and nulliparous mice, our models demonstrated that loading frequency, LCS porosity, and PCM density were major determinants of fluid and solute flows responsible for osteocyte mechanosensing, cell-cell signaling, and metabolism. When loaded at 0.5 Hz, lactation-induced LCS expansion and potential PCM reduction promoted solute transport and osteocyte mechanosensing via primary cilia, but suppressed mechanosensing via fluid shear and/or drag force on the cell membrane. Interestingly, loading at 2 or 4 Hz was found to overcome the mechanosensing deficits observed at 0.5 Hz and these counter effects became more pronounced at 4 Hz and with sparser PCM in the lactating bone. Synergistically, higher loading frequency (2, 4 Hz) and sparser PCM enhanced flow-mediated mechanosensing and diffusion/convection of nutrients and signaling molecules for osteocytes. In summary, lactation-induced structural changes alter the local environment of osteocytes in ways that favor metabolism, mechanosensing, and post-weaning recovery of maternal bone. Thus, osteocytes play a role in balancing the metabolic and mechanical functions of female skeleton during reproduction and lactation.
Collapse
Affiliation(s)
- Xiaohan Lai
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China.
| | - Rebecca Chung
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Xiaowei Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware, United States.
| |
Collapse
|
27
|
Muñoz A, Docaj A, Ugarteburu M, Carriero A. Poor bone matrix quality: What can be done about it? Curr Osteoporos Rep 2021; 19:510-531. [PMID: 34414561 DOI: 10.1007/s11914-021-00696-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/27/2021] [Indexed: 12/12/2022]
Abstract
PURPOSE OF THE REVIEW Bone's ability to withstand load resisting fracture and adapting to it highly depends on the quality of its matrix and its regulators. This review focuses on the contribution of bone quality to fracture resistance and possible therapeutic targets for skeletal fragility in aging and disease. RECENT FINDINGS The highly organized, hierarchical composite structure of bone extracellular matrix together with its (re)modeling mechanisms and microdamage dynamics determines its stiffness, strength, and toughness. Aging and disease affect the biological processes regulating bone quality, thus resulting in defective extracellular matrix and bone fragility. Targeted therapies are being developed to restore bone's mechanical integrity. However, their current limitations include low tissue selectivity and adverse side effects. Biological and mechanical insights into the mechanisms controlling bone quality, together with advances in drug delivery and studies in animal models, will accelerate the development and translation to clinical application of effective targeted-therapeutics for bone fragility.
Collapse
Affiliation(s)
- Asier Muñoz
- Department of Biomedical Engineering, The City College of New York, 160 Convent Avenue, Steinman Bldg. Room 403C, New York, NY, 10031, USA
| | - Anxhela Docaj
- Department of Biomedical Engineering, The City College of New York, 160 Convent Avenue, Steinman Bldg. Room 403C, New York, NY, 10031, USA
| | - Maialen Ugarteburu
- Department of Biomedical Engineering, The City College of New York, 160 Convent Avenue, Steinman Bldg. Room 403C, New York, NY, 10031, USA
| | - Alessandra Carriero
- Department of Biomedical Engineering, The City College of New York, 160 Convent Avenue, Steinman Bldg. Room 403C, New York, NY, 10031, USA.
| |
Collapse
|
28
|
Li Y, de Bakker CMJ, Lai X, Zhao H, Parajuli A, Tseng WJ, Pei S, Meng T, Chung R, Wang L, Liu XS. Maternal bone adaptation to mechanical loading during pregnancy, lactation, and post-weaning recovery. Bone 2021; 151:116031. [PMID: 34098162 PMCID: PMC8504362 DOI: 10.1016/j.bone.2021.116031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/25/2021] [Accepted: 06/01/2021] [Indexed: 12/16/2022]
Abstract
The maternal skeleton undergoes dramatic bone loss during pregnancy and lactation, and substantial bone recovery post-weaning. The structural adaptations of maternal bone during reproduction and lactation exert a better protection of the mechanical integrity at the critical load-bearing sites, suggesting the importance of physiological load-bearing in regulating reproduction-induced skeletal alterations. Although it is suggested that physical exercise during pregnancy and breastfeeding improves women's physical and psychological well-being, its effects on maternal bone health remain unclear. Therefore, the objective of this study was to investigate the maternal bone adaptations to external mechanical loading during pregnancy, lactation, and post-weaning recovery. By utilizing an in vivo dynamic tibial loading protocol in a rat model, we demonstrated improved maternal cortical bone structure in response to dynamic loading at tibial midshaft, regardless of reproductive status. Notably, despite the minimal loading responses detected in the trabecular bone in virgins, rat bone during lactation experienced enhanced mechano-responsiveness in both trabecular and cortical bone compartments when compared to rats at other reproductive stages or age-matched virgins. Furthermore, our study showed that the lactation-induced elevation in osteocyte peri-lacunar/canalicular remodeling (PLR) activities led to enlarged osteocyte lacunae. This may result in alterations in interstitial fluid flow-mediated mechanical stimulation on osteocytes and an elevation in solute transport through the lacunar-canalicular system (LCS) during high-frequency dynamic loading, thus enhancing mechano-responsiveness of maternal bone during lactation. Taken together, findings from this study provide important insights into the relationship between reproduction- and lactation-induced skeletal changes and external mechanical loading, emphasizing the importance of weight-bearing exercise on maternal bone health during reproduction and postpartum.
Collapse
Affiliation(s)
- Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Chantal M J de Bakker
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States; Department of Radiology, Cumming School of Medicine, McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada
| | - Xiaohan Lai
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Hongbo Zhao
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ashutosh Parajuli
- Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Wei-Ju Tseng
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Shaopeng Pei
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States; Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Tan Meng
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Rebecca Chung
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Liyun Wang
- Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - X Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
| |
Collapse
|
29
|
Jackson E, Lara-Castillo N, Akhter MP, Dallas M, Scott JM, Ganesh T, Johnson ML. Osteocyte Wnt/β-catenin pathway activation upon mechanical loading is altered in ovariectomized mice. Bone Rep 2021; 15:101129. [PMID: 34584905 PMCID: PMC8455641 DOI: 10.1016/j.bonr.2021.101129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 09/09/2021] [Indexed: 11/23/2022] Open
Abstract
Estrogen levels decline in both sexes with age, but more dramatically in females. Activation of the Wnt/β-catenin signaling pathway is central to the regulation of bone mass accrual and maintenance and in response to mechanical loading. Using the ovariectomized mouse model we examined the effect of estrogen loss on the osteocyte's ability to activate the Wnt/β-catenin pathway following mechanical loading. Female TOPGAL mice underwent ovariectomy (OVX) (n = 10) or sham surgery (n = 10) at 16 weeks of age. Four weeks post-surgery, a single loading session (global strain of 2200 με for 100 cycles at 2 Hz) was performed on the right forearm with the left as a non-loaded control. Mice (n = 5) were sacrificed at 1 or 24 hr post-load. Ulnae were stained for β-catenin activation, femurs were used for μCT and 3-pt bending/biomechanical testing, and tibiae were used for histology analysis and to determine osteocyte lacunar size using SEM and high resolution micro-XCT. A 2.2-fold increase in β-catenin signaling activation was observed 24 hr post-load in the Sham group but did not occur in the OVX group. The OVX group versus control had significant losses (p < 0.05) in trabecular BMD (−8%), BV/TV (−35%) and thickness (−23%), along with cortical thickness (−6%) and periosteal perimeter (−4%). The OVX group had significantly higher trabecular bone osteoclast numbers (63%), OCS/BS (77%) and N.OC/BPm (94%) and a significant decrease in osteoblast number (53%), OBS/BS (37%) and N.OB/BPm (40%) compared to the sham group (p < 0.05). Cortical bone lacunar number/lacunar volume and bone biomechanical properties did not change between groups. Given that the ulna is a cortical bone loading model and the lack of changes in osteocyte lacunar number/volume in cortical bone, which would alter strains experienced by osteocytes, these data suggest the absence of estrogen resulted in intrinsic changes in the ability of the osteocyte to respond to mechanical load, rather than changes in the biomechanical and architectural properties of bone. In vivo mechanical loading activates β-catenin signaling in osteocytes. Ovariectomy induced estrogen loss attenuates in vivo loading induced β-catenin signaling in osteocytes. Changes in bone material and architectural properties do not appear to explain attenuated pathway activation. Our data suggests estrogen loss alters the intrinsic ability of the osteocyte to respond to mechanical load.
Collapse
Affiliation(s)
- Erica Jackson
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
| | | | - Mohammed P. Akhter
- Creighton University, Osteoporosis Research Center, Omaha, NE 68122, United States of America
| | - Mark Dallas
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
| | - JoAnna M. Scott
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
| | - Thiagarajan Ganesh
- UMKC, School of Computing and Engineering, Kansas City, MO 64110, United States of America
| | - Mark L. Johnson
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
- Corresponding author.
| |
Collapse
|
30
|
Jähn-Rickert K, Zimmermann EA. Potential Role of Perilacunar Remodeling in the Progression of Osteoporosis and Implications on Age-Related Decline in Fracture Resistance of Bone. Curr Osteoporos Rep 2021; 19:391-402. [PMID: 34117624 DOI: 10.1007/s11914-021-00686-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/22/2021] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW We took an interdisciplinary view to examine the potential contribution of perilacunar/canalicular remodeling to declines in bone fracture resistance related to age or progression of osteoporosis. RECENT FINDINGS Perilacunar remodeling is most prominent as a result of lactation; recent advances further elucidate the molecular players involved and their effect on bone material properties. Of these, vitamin D and calcitonin could be active during aging or osteoporosis. Menopause-related hormonal changes or osteoporosis therapies affect bone material properties and mechanical behavior. However, investigations of lacunar size or osteocyte TRAP activity with age or osteoporosis do not provide clear evidence for or against perilacunar remodeling. While the occurrence and potential role of perilacunar remodeling in aging and osteoporosis progression are largely under-investigated, widespread changes in bone matrix composition in OVX models and following osteoporosis therapies imply osteocytic maintenance of bone matrix. Perilacunar remodeling-induced changes in bone porosity, bone matrix composition, and bone adaptation could have significant implications for bone fracture resistance.
Collapse
Affiliation(s)
- Katharina Jähn-Rickert
- Heisenberg Research Group, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 55a, 22529, Hamburg, Germany.
- Mildred Scheel Cancer Career Center Hamburg, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Elizabeth A Zimmermann
- Faculty of Dentistry, McGill University, Strathcona Anatomy and Dentistry Building, 3640 Rue University, Montreal, Canada.
| |
Collapse
|
31
|
Schurman CA, Verbruggen SW, Alliston T. Disrupted osteocyte connectivity and pericellular fluid flow in bone with aging and defective TGF-β signaling. Proc Natl Acad Sci U S A 2021; 118:e2023999118. [PMID: 34161267 PMCID: PMC8237574 DOI: 10.1073/pnas.2023999118] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Skeletal fragility in the elderly does not simply result from a loss of bone mass. However, the mechanisms underlying the concurrent decline in bone mass, quality, and mechanosensitivity with age remain unclear. The important role of osteocytes in these processes and the age-related degeneration of the intricate lacunocanalicular network (LCN) in which osteocytes reside point to a primary role for osteocytes in bone aging. Since LCN complexity severely limits experimental dissection of these mechanisms in vivo, we used two in silico approaches to test the hypothesis that LCN degeneration, due to aging or an osteocyte-intrinsic defect in transforming growth factor beta (TGF-β) signaling (TβRIIocy-/-), is sufficient to compromise essential osteocyte responsibilities of mass transport and exposure to mechanical stimuli. Using reconstructed confocal images of bone with fluorescently labeled osteocytes, we found that osteocytes from aged and TβRIIocy-/- mice had 33 to 45% fewer, and more tortuous, canaliculi. Connectomic network analysis revealed that diminished canalicular density is sufficient to impair diffusion even with intact osteocyte numbers and overall LCN architecture. Computational fluid dynamics predicts that the corresponding drop in shear stress experienced by aged or TβRIIocy-/- osteocytes is highly sensitive to canalicular surface area but not tortuosity. Simulated expansion of the osteocyte pericellular space to mimic osteocyte perilacunar/canalicular remodeling restored predicted shear stress for aged osteocytes to young levels. Overall, these models show how loss of LCN volume through LCN pruning may lead to impaired fluid dynamics and osteocyte exposure to mechanostimulation. Furthermore, osteocytes emerge as targets of age-related therapeutic efforts to restore bone health and function.
Collapse
Affiliation(s)
- Charles A Schurman
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA 94143
| | - Stefaan W Verbruggen
- Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom, E1 4NS
- Department of Mechanical Engineering, University of Sheffield, Sheffield, United Kingdom, S1 3JD
- The Insigneo Institute for In Silico Medicine, University of Sheffield, Sheffield, United Kingdom, S1 3JD
- Department of Biomedical Engineering, Columbia University in the City of New York, New York, NY 10027
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143;
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA 94143
| |
Collapse
|
32
|
Yuan Y, Jagga S, Martins JS, Rana R, Pajevic PD, Liu ES. Impaired 1,25 dihydroxyvitamin D3 action and hypophosphatemia underlie the altered lacuno-canalicular remodeling observed in the Hyp mouse model of XLH. PLoS One 2021; 16:e0252348. [PMID: 34043707 PMCID: PMC8158930 DOI: 10.1371/journal.pone.0252348] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022] Open
Abstract
Osteocytes remodel the perilacunar matrix and canaliculi. X-linked hypophosphatemia (XLH) is characterized by elevated serum levels of fibroblast growth factor 23 (FGF23), leading to decreased 1,25 dihydroxyvitamin D3 (1,25D) production and hypophosphatemia. Bones from mice with XLH (Hyp) have enlarged osteocyte lacunae, enhanced osteocyte expression of genes of bone remodeling, and impaired canalicular structure. The altered lacuno-canalicular (LCN) phenotype is improved with 1,25D or anti-FGF23 antibody treatment, pointing to roles for 1,25D and/or phosphate in regulating this process. To address whether impaired 1,25D action results in LCN alterations, the LCN phenotype was characterized in mice lacking the vitamin D receptor (VDR) in osteocytes (VDRf/f;DMP1Cre+). Mice lacking the sodium phosphate transporter NPT2a (NPT2aKO) have hypophosphatemia and high serum 1,25D levels, therefore the LCN phenotype was characterized in these mice to determine if increased 1,25D compensates for hypophosphatemia in regulating LCN remodeling. Unlike Hyp mice, neither VDRf/f;DMP1Cre+ nor NPT2aKO mice have dramatic alterations in cortical microarchitecture, allowing for dissecting 1,25D and phosphate specific effects on LCN remodeling in tibial cortices. Histomorphometric analyses demonstrate that, like Hyp mice, tibiae and calvariae in VDRf/f;DMP1Cre+ and NPT2aKO mice have enlarged osteocyte lacunae (tibiae: 0.15±0.02μm2(VDRf/f;DMP1Cre-) vs 0.19±0.02μm2(VDRf/f;DMP1Cre+), 0.12±0.02μm2(WT) vs 0.18±0.0μm2(NPT2aKO), calvariae: 0.09±0.02μm2(VDRf/f;DMP1Cre-) vs 0.11±0.02μm2(VDRf/f;DMP1Cre+), 0.08±0.02μm2(WT) vs 0.13±0.02μm2(NPT2aKO), p<0.05 all comparisons) and increased immunoreactivity of bone resorption marker Cathepsin K (Ctsk). The osteocyte enriched RNA isolated from tibiae in VDRf/f;DMP1Cre+ and NPT2aKO mice have enhanced expression of matrix resorption genes that are classically expressed by osteoclasts (Ctsk, Acp5, Atp6v0d2, Nhedc2). Treatment of Ocy454 osteocytes with 1,25D or phosphate inhibits the expression of these genes. Like Hyp mice, VDRf/f;DMP1Cre+ and NPT2aKO mice have impaired canalicular organization in tibia and calvaria. These studies demonstrate that hypophosphatemia and osteocyte-specific 1,25D actions regulate LCN remodeling. Impaired 1,25D action and low phosphate levels contribute to the abnormal LCN phenotype observed in XLH.
Collapse
Affiliation(s)
- Ye Yuan
- Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Supriya Jagga
- Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Janaina S. Martins
- Harvard Medical School, Boston, Massachusetts, United States of America
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Rakshya Rana
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Paola Divieti Pajevic
- Department of Translational Dental Medicine, Boston University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Eva S. Liu
- Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
33
|
Vahidi G, Rux C, Sherk VD, Heveran CM. Lacunar-canalicular bone remodeling: Impacts on bone quality and tools for assessment. Bone 2021; 143:115663. [PMID: 32987198 PMCID: PMC7769905 DOI: 10.1016/j.bone.2020.115663] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/23/2020] [Accepted: 09/23/2020] [Indexed: 01/06/2023]
Abstract
Osteocytes can resorb as well as replace bone adjacent to the expansive lacunar-canalicular system (LCS). Suppressed LCS remodeling decreases bone fracture toughness, but it is unclear how altered LCS remodeling impacts bone quality. The first goal of this review is to assess how LCS remodeling impacts LCS morphology as well as the composition and mechanical properties of surrounding bone tissue. The second goal is to compare tools available for the assessment of bone quality at length-scales that are physiologically-relevant to LCS remodeling. We find that changes to LCS morphology occur in response to a variety of physiological conditions and diseases and can be classified in two general phenotypes. In the 'aging phenotype', seen in aging and in some disuse models, the LCS is truncated and osteocytes apoptosis is increased. In the 'osteocytic osteolysis' phenotype, which is adaptive in some physiological settings and possibly maladaptive in others, the LCS enlarges and osteocytes generally maintain viability. Bone composition and mechanical properties vary near the osteocyte and change with at least some conditions that alter LCS morphology. However, few studies have evaluated bone composition and mechanical properties close to the LCS and so the impacts of LCS remodeling phenotypes on bone tissue quality are still undetermined. We summarize the current understanding of how LCS remodeling impacts LCS morphology, tissue-scale bone composition and mechanical properties, and whole-bone material properties. Tools are compared for assessing tissue-scale bone properties, as well as the resolution, advantages, and limitations of these techniques.
Collapse
Affiliation(s)
- G Vahidi
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - C Rux
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America
| | - V D Sherk
- Department of Orthopedics, University of Colorado Anschutz School of Medicine, United States of America
| | - C M Heveran
- Department of Mechanical & Industrial Engineering, Montana State University, United States of America.
| |
Collapse
|
34
|
Dole NS, Yee CS, Schurman CA, Dallas SL, Alliston T. Assessment of Osteocytes: Techniques for Studying Morphological and Molecular Changes Associated with Perilacunar/Canalicular Remodeling of the Bone Matrix. Methods Mol Biol 2021; 2230:303-323. [PMID: 33197021 PMCID: PMC9165628 DOI: 10.1007/978-1-0716-1028-2_17] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Recent advances have revived interest in the concept of osteocyte perilacunar/canalicular remodeling (PLR) and have motivated efforts to identify the mechanisms regulating this process in bone in the context of normal physiology and pathological conditions. Here, we describe several methods that are evaluating morphological changes associated with PLR function of osteocytes.
Collapse
Affiliation(s)
- Neha S Dole
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, USA
| | - Cristal S Yee
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, USA
| | - Charles A Schurman
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, USA
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, USA
| | - Sarah L Dallas
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri Kansas City, Kansas City, MO, USA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, USA.
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, USA.
| |
Collapse
|
35
|
Thrailkill KM, Bunn RC, Uppuganti S, Ray P, Popescu I, Kalaitzoglou E, Fowlkes JL, Nyman JS. Canagliflozin, an SGLT2 inhibitor, corrects glycemic dysregulation in TallyHO model of T2D but only partially prevents bone deficits. Bone 2020; 141:115625. [PMID: 32890778 PMCID: PMC7852344 DOI: 10.1016/j.bone.2020.115625] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/12/2020] [Accepted: 08/31/2020] [Indexed: 12/14/2022]
Abstract
Higher fracture risk in type 2 diabetes (T2D) is attributed to disease-specific deficits in micro-structural and material properties of bone, although the primary cause is not yet established. The TallyHO (TH) mouse is a polygenic model of early-onset T2D and obesity analogous to adolescent-onset T2D in humans. Due to incomplete penetrance of the phenotype, ~25% of male TH mice never develop hyperglycemia, providing a strain-matched, non-diabetic control. Utilizing this model of T2D, we examined the impact of glucose-lowering therapy with canagliflozin (CANA) on diabetic bone. Male TH mice with or without hyperglycemia (High BG, Low BG) were monitored from ~8 to 20 weeks of age, and compared to age-matched, male, TH mice treated with CANA from ~8 to 20 weeks of age. At 20 weeks, untreated TH mice with high BG [High BG: 687 ± 106 mg/dL] exhibited lower body mass, decrements in cortical bone of the femur (decreased cross-sectional area and thickness; increased porosity) and in trabecular bone of the femur metaphysis and L6 vertebra (decreased bone volume fraction, thickness, and tissue mineral density), as well as decrements in cortical and vertebral bone strength (decreased yield force and ultimate force) when compared to untreated TH mice with low BG [Low BG: 290 ± 98 mg/dL; p < 0.0001]. CANA treatment was metabolically advantageous, normalizing body mass, BG and HbA1c to values comparable to the Low BG group. With drug-induced glycemic improvement, cortical area and thickness were significantly higher in the CANA than in the High BG group, but deficits in strength persisted with lower yield force and yield stress (partially independent of bone geometry) in the CANA group. Additionally, CANA only partially prevented the T2D-related loss in trabecular bone volume fraction. Taken together, these findings suggest that the ability of CANA to lower glucose and normalized glycemic control ameliorates diabetic bone disease but not fully.
Collapse
Affiliation(s)
- Kathryn M Thrailkill
- University of Kentucky Barnstable Brown Diabetes Center and the Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, United States of America.
| | - R Clay Bunn
- University of Kentucky Barnstable Brown Diabetes Center and the Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, United States of America
| | - Sasidhar Uppuganti
- VA Tennessee Valley Health Care System, Department of Orthopaedic Surgery & Rehabilitation, Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN 37232, United States of America
| | - Philip Ray
- University of Kentucky Barnstable Brown Diabetes Center and the Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, United States of America
| | - Iuliana Popescu
- University of Kentucky Barnstable Brown Diabetes Center and the Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, United States of America
| | - Evangelia Kalaitzoglou
- University of Kentucky Barnstable Brown Diabetes Center and the Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, United States of America
| | - John L Fowlkes
- University of Kentucky Barnstable Brown Diabetes Center and the Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, United States of America
| | - Jeffry S Nyman
- VA Tennessee Valley Health Care System, Department of Orthopaedic Surgery & Rehabilitation, Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN 37232, United States of America
| |
Collapse
|
36
|
Buss DJ, Reznikov N, McKee MD. Crossfibrillar mineral tessellation in normal and Hyp mouse bone as revealed by 3D FIB-SEM microscopy. J Struct Biol 2020; 212:107603. [DOI: 10.1016/j.jsb.2020.107603] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 08/10/2020] [Accepted: 08/12/2020] [Indexed: 02/05/2023]
|
37
|
Dole NS, Yee CS, Mazur CM, Acevedo C, Alliston T. TGFβ Regulation of Perilacunar/Canalicular Remodeling Is Sexually Dimorphic. J Bone Miner Res 2020; 35:1549-1561. [PMID: 32282961 PMCID: PMC9126317 DOI: 10.1002/jbmr.4023] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 03/14/2020] [Accepted: 03/21/2020] [Indexed: 12/12/2022]
Abstract
Bone fragility is the product of defects in bone mass and bone quality, both of which show sex-specific differences. Despite this, the cellular and molecular mechanisms underpinning the sexually dimorphic control of bone quality remain unclear, limiting our ability to effectively prevent fractures, especially in postmenopausal osteoporosis. Recently, using male mice, we found that systemic or osteocyte-intrinsic inhibition of TGFβ signaling, achieved using the 9.6-kb DMP1 promoter-driven Cre recombinase (TβRIIocy-/- mice), suppresses osteocyte perilacunar/canalicular remodeling (PLR) and compromises bone quality. Because systemic TGFβ inhibition more robustly increases bone mass in female than male mice, we postulated that sex-specific differences in bone quality could likewise result, in part, from dimorphic regulation of PLR by TGFβ. Moreover, because lactation induces PLR, we examined the effect of TGFβ inhibition on the female skeleton during lactation. In contrast to males, female mice that possess an osteocyte-intrinsic defect in TGFβ signaling were protected from TGFβ-dependent defects in PLR and bone quality. The expression of requisite PLR enzymes, the lacunocanalicular network (LCN), and the flexural strength of female TβRIIocy-/- bone was intact. With lactation, however, bone loss and induction in PLR and osteocytic parathyroid hormone type I receptor (PTHR1) expression, were suppressed in TβRIIocy-/- bone, relative to the control littermates. Indeed, differential control of PTHR1 expression, by TGFβ and other factors, may contribute to dimorphism in PLR regulation in male and female TβRIIocy-/- mice. These findings provide key insights into the sex-based differences in osteocyte PLR that underlie bone quality and highlight TGFβ signaling as a crucial regulator of lactation-induced PLR. © 2020 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Neha S Dole
- Department of Orthopaedic Surgery, University of California, San Francisco (UCSF), San Francisco, CA, USA
| | - Cristal S Yee
- Department of Orthopaedic Surgery, University of California, San Francisco (UCSF), San Francisco, CA, USA
| | - Courtney M Mazur
- Department of Orthopaedic Surgery, University of California, San Francisco (UCSF), San Francisco, CA, USA.,University of California (UC) Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA, USA
| | - Claire Acevedo
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco (UCSF), San Francisco, CA, USA
| |
Collapse
|
38
|
Jandl NM, von Kroge S, Stürznickel J, Baranowsky A, Stockhausen KE, Mushumba H, Beil FT, Püschel K, Amling M, Rolvien T. Large osteocyte lacunae in iliac crest infantile bone are not associated with impaired mineral distribution or signs of osteocytic osteolysis. Bone 2020; 135:115324. [PMID: 32198110 DOI: 10.1016/j.bone.2020.115324] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 02/29/2020] [Accepted: 03/16/2020] [Indexed: 12/13/2022]
Abstract
The enlargement of osteocyte lacunae via osteocytic osteolysis was previously detected in situations of increased calcium demand (e.g., lactation, vitamin D deficiency). However, it is unclear whether similar processes occur also in the growing infantile skeleton and how this is linked to the mineral distribution within the bone matrix. Human iliac crest biopsies of 30 subjects (0-6 months, n = 14; 2-8 years, n = 6 and 18-25 years, n = 10) were acquired. Bone microarchitecture was assessed by micro-CT, while cellular bone histomorphometry was performed on undecalcified histological sections. Quantitative backscattered electron imaging (qBEI) was conducted to determine the bone mineral density distribution (BMDD) as well as osteocyte lacunar size and density. We additionally evaluated cathepsin K positive osteocytes using immunohistochemistry. Infantile bone was characterized by various signs of ongoing bone development such as higher bone (re)modeling, lower cortical and trabecular thickness compared to young adults. Importantly, a significantly higher osteocyte lacunar density and increased lacunar area were detected. Large osteocyte lacunae were associated with a more heterogeneous bone mineral density distribution of the trabecular bone matrix due to the presence of hypermineralized cartilage remnants, whereas the mean mineralization (i.e., CaMean) was not different in infantile bone. Absence of cathepsin K expression in osteocyte lacunae indicated nonexistent osteocytic osteolysis. Taken together, we demonstrated that the overall mineralization distribution in infantile bone is not altered compared to young adults besides high trabecular mineralization heterogeneity. Our study also provides important reference values for bone microstructure, BMDD and osteocyte characteristics in infants, children and young adults. Infantile bone displays large osteocyte lacunae indicating a developmental phenomenon rather than osteocytic osteolysis. Larger osteocytes may have superior mechanosensory abilities to enable bone adaption during growth.
Collapse
Affiliation(s)
- Nico Maximilian Jandl
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany; Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529 Hamburg, Germany
| | - Simon von Kroge
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529 Hamburg, Germany
| | - Julian Stürznickel
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529 Hamburg, Germany
| | - Anke Baranowsky
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529 Hamburg, Germany
| | - Kilian Elia Stockhausen
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529 Hamburg, Germany
| | - Herbert Mushumba
- Department of Legal Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529 Hamburg, Germany
| | - Frank Timo Beil
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Klaus Püschel
- Department of Legal Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529 Hamburg, Germany
| | - Michael Amling
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Tim Rolvien
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany; Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529 Hamburg, Germany.
| |
Collapse
|
39
|
Wilkens MR, Nelson CD, Hernandez LL, McArt JA. Symposium review: Transition cow calcium homeostasis—Health effects of hypocalcemia and strategies for prevention. J Dairy Sci 2020; 103:2909-2927. [DOI: 10.3168/jds.2019-17268] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/18/2019] [Indexed: 12/14/2022]
|
40
|
Creecy A, Damrath JG, Wallace JM. Control of Bone Matrix Properties by Osteocytes. Front Endocrinol (Lausanne) 2020; 11:578477. [PMID: 33537002 PMCID: PMC7848033 DOI: 10.3389/fendo.2020.578477] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 12/01/2020] [Indexed: 12/13/2022] Open
Abstract
Osteocytes make up 90-95% of the cellular content of bone and form a rich dendritic network with a vastly greater surface area than either osteoblasts or osteoclasts. Osteocytes are well positioned to play a role in bone homeostasis by interacting directly with the matrix; however, the ability for these cells to modify bone matrix remains incompletely understood. With techniques for examining the nano- and microstructure of bone matrix components including hydroxyapatite and type I collagen becoming more widespread, there is great potential to uncover novel roles for the osteocyte in maintaining bone quality. In this review, we begin with an overview of osteocyte biology and the lacunar-canalicular system. Next, we describe recent findings from in vitro models of osteocytes, focusing on the transitions in cellular phenotype as they mature. Finally, we describe historical and current research on matrix alteration by osteocytes in vivo, focusing on the exciting potential for osteocytes to directly form, degrade, and modify the mineral and collagen in their surrounding matrix.
Collapse
Affiliation(s)
- Amy Creecy
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States
| | - John G. Damrath
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Joseph M. Wallace
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States
- *Correspondence: Joseph M. Wallace,
| |
Collapse
|
41
|
Chen H, Zhang J, Wang Y, Cheuk KY, Hung ALH, Lam TP, Qiu Y, Feng JQ, Lee WYW, Cheng JCY. Abnormal lacuno-canalicular network and negative correlation between serum osteocalcin and Cobb angle indicate abnormal osteocyte function in adolescent idiopathic scoliosis. FASEB J 2019; 33:13882-13892. [PMID: 31626573 PMCID: PMC6894095 DOI: 10.1096/fj.201901227r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022]
Abstract
Adolescent idiopathic scoliosis (AIS) is a prevalent spinal deformity occurring during peripubertal growth period that affects 1-4% of adolescents globally without clear etiopathogenetic mechanism. Low bone mineral density is an independent and significant prognostic factor for curve progression. Currently, the cause underlying low bone mass in AIS remains elusive. Osteocytes play an important role in bone metabolism and mineral homeostasis, but its role in AIS has not been studied. In the present study, iliac bone tissues were harvested from 21 patients with AIS (mean age of 14.3 ± 2.20 yr old) with a mean Cobb angle of 55.6 ± 10.61° and 13 non-AIS controls (mean age of 16.5 ± 4.79 yr old) intraoperatively. Acid-etched scanning electron microscopy (SEM) images of AIS demonstrated abnormal osteocytes that were more rounded and cobblestone-like in shape and were aligned in irregular clusters with shorter and disorganized canaliculi. Further quantitative analysis with FITC-Imaris technique showed a significant reduction in the canalicular number and length as well as an increase in lacunar volume and area in AIS. SEM with energy-dispersive X-ray spectroscopy analysis demonstrated a lower calcium-to-phosphorus ratio at the perilacunar/canalicular region. Moreover, microindentaion results revealed lower values of Vickers hardness and elastic modulus in AIS when compared with controls. In addition, in the parallel study of 99 AIS (27 with severe Cobb angle of 65.8 ± 14.1° and 72 with mild Cobb angle of 26.6 ± 9.1°) with different curve severity, the serum osteocalcin level was found to be significantly and negatively associated with the Cobb angle. In summary, the findings in this series of studies demonstrated the potential link of abnormal osteocyte lacuno-canalicular network structure and function to the observed abnormal bone mineralization in AIS, which may shed light on etiopathogenesis of AIS.-Chen, H., Zhang, J., Wang, Y., Cheuk, K.-Y., Hung, A. L. H., Lam, T.-P., Qiu, Y., Feng, J. Q., Lee, W. Y. W., Cheng, J. C. Y. Abnormal lacuno-canalicular network and negative correlation between serum osteocalcin and Cobb angle indicate abnormal osteocyte function in adolescent idiopathic scoliosis.
Collapse
Affiliation(s)
- Huanxiong Chen
- Department of Spine and Osteopathic Surgery, The
First Affiliated Hospital of Hainan Medical University, Hai-kou, China
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Jiajun Zhang
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Yujia Wang
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Ka-Yee Cheuk
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Alec L. H. Hung
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Tsz-Ping Lam
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Yong Qiu
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
- Spine Surgery, Nanjing Drum Tower Hospital,
Nanjing University, Nanjing, China
| | - Jian Q. Feng
- Department of Biomedical Sciences, Texas
A&M College of Dentistry, Dallas, Texas, USA
| | - Wayne Y. W. Lee
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| | - Jack C. Y. Cheng
- Department of Orthopaedics and Traumatology, S. H.
Ho Scoliosis Research Laboratory, The Chinese University of Hong Kong, Shatin, NT,
Hong Kong, China
- Joint Scoliosis Research Center of The Chinese
University of Hong Kong–Nanjing University, The Chinese University of Hong
Kong, Hong Kong, China
| |
Collapse
|
42
|
Liu XS, Wang L, de Bakker CMJ, Lai X. Mechanical Regulation of the Maternal Skeleton during Reproduction and Lactation. Curr Osteoporos Rep 2019; 17:375-386. [PMID: 31755029 PMCID: PMC7373497 DOI: 10.1007/s11914-019-00555-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW This review summarizes recently published data on the effects of pregnancy and lactation on bone structure, mechanical properties, and mechano-responsiveness in an effort to elucidate how the balance between the structural and metabolic functions of the skeleton is achieved during these physiological processes. RECENT FINDINGS While pregnancy and lactation induce significant changes in bone density and structure to provide calcium for fetal/infant growth, the maternal physiology also comprises several innate compensatory mechanisms that allow for the maintenance of skeletal mechanical integrity. Both clinical and animal studies suggest that pregnancy and lactation lead to adaptations in cortical bone structure to allow for rapid calcium release from the trabecular compartment while maintaining whole bone stiffness and strength. Moreover, extents of lactation-induced bone loss and weaning-induced recovery are highly dependent on a given bone's load-bearing function, resulting in better protection of the mechanical integrity at critical load-bearing sites. The recent discovery of lactation-induced osteocytic perilacunar/canalicular remodeling (PLR) indicates a new means for osteocytes to modulate mineral homeostasis and tissue-level mechanical properties of the maternal skeleton. Furthermore, lactation-induced PLR may also play an important role in maintaining the maternal skeleton's load-bearing capacity by altering osteocyte's microenvironment and modulating the transmission of anabolic mechanical signals to osteocytes. Both clinical and animal studies show that parity and lactation have no adverse, or a positive effect on bone strength later in life. The skeletal effects during pregnancy and lactation reflect an optimized balance between the mechanical and metabolic functions of the skeleton.
Collapse
Affiliation(s)
- X Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 332A Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA, USA.
| | - Liyun Wang
- Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Chantal M J de Bakker
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Xiaohan Lai
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| |
Collapse
|
43
|
Mazur CM, Woo JJ, Yee CS, Fields AJ, Acevedo C, Bailey KN, Kaya S, Fowler TW, Lotz JC, Dang A, Kuo AC, Vail TP, Alliston T. Osteocyte dysfunction promotes osteoarthritis through MMP13-dependent suppression of subchondral bone homeostasis. Bone Res 2019; 7:34. [PMID: 31700695 PMCID: PMC6828661 DOI: 10.1038/s41413-019-0070-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 07/25/2019] [Accepted: 07/29/2019] [Indexed: 12/28/2022] Open
Abstract
Osteoarthritis (OA), long considered a primary disorder of articular cartilage, is commonly associated with subchondral bone sclerosis. However, the cellular mechanisms responsible for changes to subchondral bone in OA, and the extent to which these changes are drivers of or a secondary reaction to cartilage degeneration, remain unclear. In knee joints from human patients with end-stage OA, we found evidence of profound defects in osteocyte function. Suppression of osteocyte perilacunar/canalicular remodeling (PLR) was most severe in the medial compartment of OA subchondral bone, with lower protease expression, diminished canalicular networks, and disorganized and hypermineralized extracellular matrix. As a step toward evaluating the causality of PLR suppression in OA, we ablated the PLR enzyme MMP13 in osteocytes while leaving chondrocytic MMP13 intact, using Cre recombinase driven by the 9.6-kb DMP1 promoter. Not only did osteocytic MMP13 deficiency suppress PLR in cortical and subchondral bone, but it also compromised cartilage. Even in the absence of injury, osteocytic MMP13 deficiency was sufficient to reduce cartilage proteoglycan content, change chondrocyte production of collagen II, aggrecan, and MMP13, and increase the incidence of cartilage lesions, consistent with early OA. Thus, in humans and mice, defects in PLR coincide with cartilage defects. Osteocyte-derived MMP13 emerges as a critical regulator of cartilage homeostasis, likely via its effects on PLR. Together, these findings implicate osteocytes in bone-cartilage crosstalk in the joint and suggest a causal role for suppressed perilacunar/canalicular remodeling in osteoarthritis.
Collapse
Affiliation(s)
- Courtney M. Mazur
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA 94143 USA
| | - Jonathon J. Woo
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
| | - Cristal S. Yee
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
| | - Aaron J. Fields
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
| | - Claire Acevedo
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112 USA
| | - Karsyn N. Bailey
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA 94143 USA
| | - Serra Kaya
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
| | - Tristan W. Fowler
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
| | - Jeffrey C. Lotz
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA 94143 USA
| | - Alexis Dang
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- San Francisco Veterans Affairs Medical Center, San Francisco, CA 94121 USA
| | - Alfred C. Kuo
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- San Francisco Veterans Affairs Medical Center, San Francisco, CA 94121 USA
| | - Thomas P. Vail
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143 USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA 94143 USA
| |
Collapse
|
44
|
Olvera D, Stolzenfeld R, Fisher E, Nolan B, Caird MS, Kozloff KM. Pamidronate Administration During Pregnancy and Lactation Induces Temporal Preservation of Maternal Bone Mass in a Mouse Model of Osteogenesis Imperfecta. J Bone Miner Res 2019; 34:2061-2074. [PMID: 31310351 PMCID: PMC6854294 DOI: 10.1002/jbmr.3831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/25/2019] [Accepted: 07/03/2019] [Indexed: 01/25/2023]
Abstract
During pregnancy and lactation, the maternal skeleton undergoes significant bone loss through increased resorption to provide the necessary calcium supply to the developing fetus and suckling neonate. This period of skeletal vulnerability has not been clearly associated with increased maternal fracture risk, but these physiological conditions can exacerbate an underlying metabolic bone condition like osteogenesis imperfecta. Although bisphosphonates (BPs) are commonly used in postmenopausal women, there are cases where premenopausal women taking BPs become pregnant. Given BPs' long half-life, there is a need to establish how BPs affect the maternal skeleton during periods of demanding metabolic bone changes that are critical for the skeletal development of their offspring. In the present study, pamidronate- (PAM-) amplified pregnancy-induced bone mass gains and lactation-induced bone loss were prevented. This preservation of bone mass was less robust when PAM was administered at late stages of lactation compared with early pregnancy and first day of lactation. Pregnancy-induced osteocyte osteolysis was also observed and was unaffected with PAM treatment. No negative skeletal effects were observed in offspring from PAM-treated dams despite lactation-induced bone loss prevention. These findings provide important insight into (1) a treatment window for when PAM is most effective in preserving maternal bone mass, and (2) the maternal changes in bone metabolism that maintain calcium homeostasis crucial for fetal and neonatal bone development. © 2019 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Diana Olvera
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Rachel Stolzenfeld
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Emily Fisher
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Bonnie Nolan
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Michelle S Caird
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Kenneth M Kozloff
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
45
|
Heveran CM, Schurman CA, Acevedo C, Livingston EW, Howe D, Schaible EG, Hunt HB, Rauff A, Donnelly E, Carpenter RD, Levi M, Lau AG, Bateman TA, Alliston T, King KB, Ferguson VL. Chronic kidney disease and aging differentially diminish bone material and microarchitecture in C57Bl/6 mice. Bone 2019; 127:91-103. [PMID: 31055118 PMCID: PMC6760860 DOI: 10.1016/j.bone.2019.04.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 03/15/2019] [Accepted: 04/26/2019] [Indexed: 12/31/2022]
Abstract
Chronic kidney disease (CKD) is a common disease of aging and increases fracture risk over advanced age alone. Aging and CKD differently impair bone turnover and mineralization. We thus hypothesize that the loss of bone quality would be greatest with the combination of advanced age and CKD. We evaluated bone from young adult (6 mo.), middle-age (18 mo.), and old (24 mo.) male C57Bl/6 mice three months following either 5/6th nephrectomy, to induce CKD, or Sham procedures. CKD exacerbated losses of cortical and trabecular microarchitecture associated with aging. Aging and CKD each resulted in thinner, more porous cortices and fewer and thinner trabeculae. Bone material quality was also reduced with CKD, and these changes to bone material were distinct from those due to age. Aging reduced whole-bone flexural strength and modulus, micrometer-scale nanoindentation modulus, and nanometer-scale tissue and collagen strain (small-angle x-ray scattering [SAXS]. By contrast, CKD reduced work to fracture and variation in bone tissue modulus and composition (Raman spectroscopy), and increased percent collagen strain. The increased collagen strain burden was associated with loss of toughness in CKD. In addition, osteocyte lacunae became smaller, sparser, and more disordered with age for Sham mice, yet these age-related changes were not clearly observed in CKD. However, for CKD, larger lacunae positively correlated with increased serum phosphate levels, suggesting that osteocytes play a role in systemic mineral homeostasis. This work demonstrates that CKD reduces bone quality, including microarchitecture and bone material properties, and that loss of bone quality with age is compounded by CKD. These findings may help reconcile why bone mass does not consistently predict fracture in the CKD population, as well as why older individuals with CKD are at high risk of fragility.
Collapse
Affiliation(s)
- Chelsea M Heveran
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, United States of America
| | - Charles A Schurman
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, United States of America
| | - Claire Acevedo
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Eric W Livingston
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, United States of America
| | - Danielle Howe
- Department of Biomedical Engineering, The College of New Jersey, Ewing, NJ, United States of America
| | - Eric G Schaible
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Heather B Hunt
- Department of Materials Science & Engineering, Cornell University, Ithaca, NY, United States of America
| | - Adam Rauff
- Department of Bioengineering, University of Colorado, Denver, CO, United States of America
| | - Eve Donnelly
- Department of Materials Science & Engineering, Cornell University, Ithaca, NY, United States of America
| | - R Dana Carpenter
- Department of Mechanical Engineering, University of Colorado, Denver, CO, United States of America
| | - Moshe Levi
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington D.C., United States of America
| | - Anthony G Lau
- Department of Biomedical Engineering, The College of New Jersey, Ewing, NJ, United States of America
| | - Ted A Bateman
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, United States of America
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, United States of America
| | - Karen B King
- Department of Orthopaedics, University of Colorado School of Medicine, Aurora, CO, United States of America
| | - Virginia L Ferguson
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, United States of America.
| |
Collapse
|
46
|
Wittig NK, Birkbak ME, Bach-Gansmo FL, Pacureanu A, Wendelboe MH, Brüel A, Thomsen JS, Birkedal H. No Signature of Osteocytic Osteolysis in Cortical Bone from Lactating NMRI Mice. Calcif Tissue Int 2019; 105:308-315. [PMID: 31147741 DOI: 10.1007/s00223-019-00569-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/25/2019] [Indexed: 01/13/2023]
Abstract
The roles of osteocytes in bone homeostasis have garnered increasing attention since it has been realized that osteocytes communicate with other organs. It has long been debated whether and/or to which degree osteocytes can break down the bone matrix surrounding them in a process called osteocytic osteolysis. Osteocytic osteolysis has been indicated to be induced by a number of skeletal challenges including lactation in CD1 and C57BL/6 mice, whereas immobilization-induced osteocytic osteolysis is still a matter of controversy. Motivated by the wish to understand this process better, we studied osteocyte lacunae in lactating NMRI mice, which is a widely used outbred mouse strain. Surprisingly, no trace of osteocytic osteolysis could be detected in tibial or femoral cortical bone either by 3D investigation by synchrotron nanotomography, by studies of lacunar cross-sectional areas using scanning electron microscopy, or by light microscopy. These results lead us to conclude that osteocytic osteolysis does not occur in NMRI mice as a response to lactation, in turn suggesting that osteocytic osteolysis may not play a generic role in mobilizing calcium during lactation.
Collapse
Affiliation(s)
- Nina Kølln Wittig
- Department of Chemistry and iNANO, Aarhus University, Gustav Wieds vej 14, 8000, Aarhus C, Denmark
| | - Mie Elholm Birkbak
- Department of Chemistry and iNANO, Aarhus University, Gustav Wieds vej 14, 8000, Aarhus C, Denmark
| | - Fiona Linnea Bach-Gansmo
- Department of Chemistry and iNANO, Aarhus University, Gustav Wieds vej 14, 8000, Aarhus C, Denmark
| | - Alexandra Pacureanu
- European Synchrotron Radiation Facility, 71, Avenue des Martyrs, CS 40220, 38043, Grenoble Cedex 9, France
| | - Mette Høegh Wendelboe
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark
| | - Annemarie Brüel
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark
| | - Jesper Skovhus Thomsen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark
| | - Henrik Birkedal
- Department of Chemistry and iNANO, Aarhus University, Gustav Wieds vej 14, 8000, Aarhus C, Denmark.
| |
Collapse
|
47
|
Abstract
PURPOSE OF REVIEW In perilacunar/canalicular remodeling (PLR), osteocytes dynamically resorb, and then replace, the organic and mineral components of the pericellular extracellular matrix. Given the enormous surface area of the osteocyte lacuna-canalicular network (LCN), PLR is important for maintaining homeostasis of the skeleton. The goal of this review is to examine the motivations and critical considerations for the analysis of PLR, in both in vitro and in vivo systems. RECENT FINDINGS Morphological approaches alone are insufficient to elucidate the complex mechanisms regulating PLR in the healthy skeleton and in disease. Understanding the role and regulation of PLR will require the incorporation of standardized PLR outcomes as a routine part of skeletal phenotyping, as well as the development of improved molecular and cellular outcomes. Current PLR outcomes assess PLR enzyme expression, the LCN, and bone matrix composition and organization, among others. Here, we discuss current PLR outcomes and how they have been applied to study PLR induction and suppression in vitro and in vivo. Given the role of PLR in skeletal health and disease, integrated analysis of PLR has potential to elucidate new mechanisms by which osteocytes participate in skeletal health and disease.
Collapse
Affiliation(s)
- Cristal S Yee
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Avenue, San Francisco, CA, 94143, USA
| | - Charles A Schurman
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Avenue, San Francisco, CA, 94143, USA
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, 94143, USA
| | - Carter R White
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Avenue, San Francisco, CA, 94143, USA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Avenue, San Francisco, CA, 94143, USA.
- UC Berkeley/UCSF Graduate Program in Bioengineering, San Francisco, CA, 94143, USA.
| |
Collapse
|
48
|
Ross RD, Meagher MJ, Sumner DR. Calcium restriction during lactation has minimal effects on post-weaning mineral metabolism and bone recovery. J Bone Miner Metab 2019; 37:648-657. [PMID: 30361872 PMCID: PMC6548698 DOI: 10.1007/s00774-018-0969-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/09/2018] [Indexed: 10/28/2022]
Abstract
Dietary calcium (Ca) restriction during lactation in the rat, which induces intra-cortical and endocortical remodeling, has been proposed as a model to study bone matrix maturation in the adult skeleton. The purpose of this study was to assess the effects of dietary Ca restriction during lactation on post-weaning mineral metabolism and bone formation. Mated female Sprague-Dawley rats were randomized into groups receiving either 0.6% Ca (lactation/normal Ca) or 0.01% Ca (lactation/low Ca) diets during lactation. Virgin animals fed normal Ca were used as controls (virgin/normal Ca). At the time of weaning, animals on the low Ca diet were returned to normal Ca and cohorts of all three groups were sacrificed at days 0, 1, 2, 7, and 14 post-weaning. Lactation caused bone loss, particularly at the endocortical surface, but the amount was not affected by dietary Ca. Rats in the lactation/low Ca group had increased cortical porosity compared to the other groups, particularly within the size range of secondary osteons. Dietary Ca restriction during lactation did not affect post-weaning bone formation kinetics or serum Ca and phosphate levels. In both lactation groups, there was a transient increase in phosphate and fibroblast growth factor 23 (FGF23) post-weaning, which trended toward virgin/normal Ca levels over time. Thus, the additional challenge of low dietary Ca during lactation to induce intra-cortical remodeling in the rat has minimal effects on bone formation kinetics and mineral metabolism during the post-weaning period, providing further justification for this model to study matrix maturation in the adult skeleton.
Collapse
Affiliation(s)
- Ryan D Ross
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, USA
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA
| | - Matthew J Meagher
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, USA
| | - D Rick Sumner
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, USA.
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA.
| |
Collapse
|
49
|
Wittig NK, Laugesen M, Birkbak ME, Bach-Gansmo FL, Pacureanu A, Bruns S, Wendelboe MH, Brüel A, Sørensen HO, Thomsen JS, Birkedal H. Canalicular Junctions in the Osteocyte Lacuno-Canalicular Network of Cortical Bone. ACS NANO 2019; 13:6421-6430. [PMID: 31095362 DOI: 10.1021/acsnano.8b08478] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The osteocyte lacuno-canalicular network (LCN) is essential for bone remodeling because osteocytes regulate cell recruitment. This has been proposed to occur through liquid-flow-induced shear forces in the canaliculi. Models of the LCN have thus far assumed that it contains canaliculi connecting the osteocyte lacunae. However, here, we reveal that enlarged spaces occur at places where several canaliculi cross; we name these spaces canalicular junctions. We characterize them in detail within mice cortical bone using synchrotron nanotomography at two length scales, with 50 and 130 nm voxel size, and show that canalicular junctions occur at a density similar to that of osteocyte lacunae and that canalicular junctions tend to cluster. Through confocal laser scanning microscopy, we show that canalicular junctions are widespread as we have observed them in cortical bone from several species, even though the number density of the canalicular junctions was not universal. Fluid flow simulations of a simple model system with and without a canalicular junction clearly show that liquid mass transport and flow velocities are altered by the presence of canalicular junctions. We suggest that these canalicular junctions may play an important role in osteocyte communication and possibly also in canalicular fluid flow. Therefore, we believe that they constitute an important component in the bone osteocyte network.
Collapse
Affiliation(s)
| | | | | | | | | | - Stefan Bruns
- Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø , Denmark
| | | | | | | | | | | |
Collapse
|
50
|
Shah FA, Ruscsák K, Palmquist A. 50 years of scanning electron microscopy of bone-a comprehensive overview of the important discoveries made and insights gained into bone material properties in health, disease, and taphonomy. Bone Res 2019; 7:15. [PMID: 31123620 PMCID: PMC6531483 DOI: 10.1038/s41413-019-0053-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 02/06/2023] Open
Abstract
Bone is an architecturally complex system that constantly undergoes structural and functional optimisation through renewal and repair. The scanning electron microscope (SEM) is among the most frequently used instruments for examining bone. It offers the key advantage of very high spatial resolution coupled with a large depth of field and wide field of view. Interactions between incident electrons and atoms on the sample surface generate backscattered electrons, secondary electrons, and various other signals including X-rays that relay compositional and topographical information. Through selective removal or preservation of specific tissue components (organic, inorganic, cellular, vascular), their individual contribution(s) to the overall functional competence can be elucidated. With few restrictions on sample geometry and a variety of applicable sample-processing routes, a given sample may be conveniently adapted for multiple analytical methods. While a conventional SEM operates at high vacuum conditions that demand clean, dry, and electrically conductive samples, non-conductive materials (e.g., bone) can be imaged without significant modification from the natural state using an environmental scanning electron microscope. This review highlights important insights gained into bone microstructure and pathophysiology, bone response to implanted biomaterials, elemental analysis, SEM in paleoarchaeology, 3D imaging using focused ion beam techniques, correlative microscopy and in situ experiments. The capacity to image seamlessly across multiple length scales within the meso-micro-nano-continuum, the SEM lends itself to many unique and diverse applications, which attest to the versatility and user-friendly nature of this instrument for studying bone. Significant technological developments are anticipated for analysing bone using the SEM.
Collapse
Affiliation(s)
- Furqan A. Shah
- Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Krisztina Ruscsák
- Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Anders Palmquist
- Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|