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Wang D, Cai J, Pei Q, Yan Z, Zhu F, Zhao Z, Liu R, Guo X, Sun T, Liu J, Tian Y, Liu H, Shao X, Huang J, Hao X, Chang Q, Luo Z, Jing D. Gut microbial alterations in arginine metabolism determine bone mechanical adaptation. Cell Metab 2024; 36:1252-1268.e8. [PMID: 38718794 DOI: 10.1016/j.cmet.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 02/02/2024] [Accepted: 04/09/2024] [Indexed: 06/07/2024]
Abstract
Although mechanical loading is essential for maintaining bone health and combating osteoporosis, its practical application is limited to a large extent by the high variability in bone mechanoresponsiveness. Here, we found that gut microbial depletion promoted a significant reduction in skeletal adaptation to mechanical loading. Among experimental mice, we observed differences between those with high and low responses to exercise with respect to the gut microbial composition, in which the differential abundance of Lachnospiraceae contributed to the differences in bone mechanoresponsiveness. Microbial production of L-citrulline and its conversion into L-arginine were identified as key regulators of bone mechanoadaptation, and administration of these metabolites enhanced bone mechanoresponsiveness in normal, aged, and ovariectomized mice. Mechanistically, L-arginine-mediated enhancement of bone mechanoadaptation was primarily attributable to the activation of a nitric-oxide-calcium positive feedback loop in osteocytes. This study identifies a promising anti-osteoporotic strategy for maximizing mechanical loading-induced skeletal benefits via the microbiota-metabolite axis.
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Affiliation(s)
- Dan Wang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China; Faculty of Life Sciences, Northwest University, Xi'an 710069, China
| | - Jing Cai
- College of Basic Medicine, Shaanxi University of Chinese Medicine, Xianyang 712046, China.
| | - Qilin Pei
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Zedong Yan
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Feng Zhu
- Center for Translational Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
| | - Zhe Zhao
- Center for Translational Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
| | - Ruobing Liu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Xiangyang Guo
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Tao Sun
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Juan Liu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Yulan Tian
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Hongbo Liu
- Department of Hematology, Affiliated Hospital of Northwest University Xi'an Third Hospital, Xi'an 710016, China
| | - Xi Shao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Jinghui Huang
- Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Xiaoxia Hao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Qi Chang
- Department of Orthopaedics, The 989(th) Hospital of the People's Liberation Army Joint Service Support Force, Luoyang 471031, China.
| | - Zhuojing Luo
- Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
| | - Da Jing
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China; Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China; The Ministry of Education Key Laboratory of Hazard Assessment and Control in Special Operational Environment, Fourth Military Medical University, Xi'an 710032, China.
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Barak MM. Cortical and Trabecular Bone Modeling and Implications for Bone Functional Adaptation in the Mammalian Tibia. Bioengineering (Basel) 2024; 11:514. [PMID: 38790379 PMCID: PMC11118124 DOI: 10.3390/bioengineering11050514] [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: 04/23/2024] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 05/26/2024] Open
Abstract
Bone modeling involves the addition of bone material through osteoblast-mediated deposition or the removal of bone material via osteoclast-mediated resorption in response to perceived changes in loads by osteocytes. This process is characterized by the independent occurrence of deposition and resorption, which can take place simultaneously at different locations within the bone due to variations in stress levels across its different regions. The principle of bone functional adaptation states that cortical and trabecular bone tissues will respond to mechanical stimuli by adjusting (i.e., bone modeling) their morphology and architecture to mechanically improve their mechanical function in line with the habitual in vivo loading direction. This principle is relevant to various research areas, such as the development of improved orthopedic implants, preventative medicine for osteopenic elderly patients, and the investigation of locomotion behavior in extinct species. In the present review, the mammalian tibia is used as an example to explore cortical and trabecular bone modeling and to examine its implications for the functional adaptation of bones. Following a short introduction and an exposition on characteristics of mechanical stimuli that influence bone modeling, a detailed critical appraisal of the literature on cortical and trabecular bone modeling and bone functional adaptation is given. By synthesizing key findings from studies involving small mammals (rodents), large mammals, and humans, it is shown that examining both cortical and trabecular bone structures is essential for understanding bone functional adaptation. A combined approach can provide a more comprehensive understanding of this significant physiological phenomenon, as each structure contributes uniquely to the phenomenon.
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Affiliation(s)
- Meir M Barak
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, NY 11548, USA
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Machireddy M, Oberman AG, DeBiase L, Stephens M, Li J, Littlepage LE, Niebur GL. Controlled mechanical loading affects the osteocyte transcriptome in porcine trabecular bone in situ. Bone 2024; 181:117028. [PMID: 38309412 PMCID: PMC10923013 DOI: 10.1016/j.bone.2024.117028] [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: 10/10/2023] [Revised: 01/09/2024] [Accepted: 01/29/2024] [Indexed: 02/05/2024]
Abstract
INTRODUCTION Osteocytes modulate bone adaptation in response to mechanical stimuli imparted by the deforming bone tissue in which they are encased by communicating with osteoclasts and osteoblasts as well as other osteocytes in the lacuna-canalicular network through secreted cytokines and chemokines. Understanding the transcriptional response of osteocytes to mechanical stimulation in situ could identify new targets to inhibit bone loss or enhance bone formation in the presence of diseases like osteoporosis or metastatic cancer. We compared the mechanically regulated transcriptional response of osteocytes in trabecular bone following one or three days of controlled mechanical loading. METHODS Porcine trabecular bone explants were cultured in a bioreactor for 48 h and subsequently loaded twice a day for one day or 3 days. RNA was isolated and sequenced, and the Tuxedo suite was used to identify differentially expressed genes and pathway analysis was conducted using Ingenuity Pathway Analysis (IPA). RESULTS There were about 4000 differentially expressed genes following in situ culture relative to fresh bone. One hundred six genes were differentially expressed between the loaded and non-loaded groups following one day of loading compared to 913 genes after 3 d of loading. Only 45 of these were coincident between the two time points, indicating an evolving transcriptome. Clustering and principal component analysis indicated differences between the loaded and non-loaded groups after 3 d of loading. DISCUSSION With sustained loading, there was a nine-fold increase in the number of differentially expressed genes, suggesting that osteocytes respond to loading through sequential activation of downstream genes in the same pathways. The differentially expressed genes were related to osteoarthritis, osteocyte, and chondrocyte signaling pathways. We noted that NFkB and TNF signaling are affected by early loading and this may drive downstream effects on the mechanobiological response. Moreover, these genes may regulate catabolic effects of mechanical disuse through their actions on pre-osteoclasts in the bone marrow niche.
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Affiliation(s)
- Meghana Machireddy
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, University of Notre Dame, IN 46556, USA
| | - Alyssa G Oberman
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, University of Notre Dame, IN 46556, USA
| | - Lucas DeBiase
- Dept. of Aerospace and Mechanical Engineering, University of Notre Dame, IN 46556, USA
| | - Melissa Stephens
- Genomics and Bioinformatics Core Facility, University of Notre Dame, IN 46556, USA
| | - Jun Li
- Dept. of Applied Mathematics, Computations, and Statistics, University of Notre Dame, IN 46556, USA
| | - Laurie E Littlepage
- Dept. of Chemistry and Biochemistry, University of Notre Dame, IN 46556, USA; Harper Cancer Research Institute, University of Notre Dame, IN 46556, USA
| | - Glen L Niebur
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, University of Notre Dame, IN 46556, USA; Harper Cancer Research Institute, University of Notre Dame, IN 46556, USA; Dept. of Aerospace and Mechanical Engineering, University of Notre Dame, IN 46556, USA.
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4
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Kitase Y, Vallejo JA, Dallas SL, Xie Y, Dallas M, Tiede-Lewis L, Moore D, Meljanac A, Kumar C, Zhao C, Rosser J, Brotto M, Johnson ML, Liu Z, Wacker MJ, Bonewald L. Body weight influences musculoskeletal adaptation to long-term voluntary wheel running during aging in female mice. Aging (Albany NY) 2022; 15:308-352. [PMID: 36403149 PMCID: PMC9925690 DOI: 10.18632/aging.204390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/02/2022] [Indexed: 11/19/2022]
Abstract
Frailty is the hallmark of aging that can be delayed with exercise. The present studies were initiated based on the hypothesis that long-term voluntary wheel running (VWR) in female mice from 12 to 18 or 22 months of age would have beneficial effects on the musculoskeletal system. Mice were separated into high (HBW) and low (LBW) body weight based on final body weights upon termination of experiments. Bone marrow fat was significantly higher in HBW than LBW under sedentary conditions, but not with VWR. HBW was more protective for soleus size and function than LBW under sedentary conditions, however VWR increased soleus size and function regardless of body weight. VWR plus HBW was more protective against muscle loss with aging. Similar effects of VWR plus HBW were observed with the extensor digitorum longus, EDL, however, LBW with VWR was beneficial in improving EDL fatigue resistance in 18 mo mice and was more beneficial with regards to muscle production of bone protective factors. VWR plus HBW maintained bone in aged animals. In summary, HBW had a more beneficial effect on muscle and bone with aging especially in combination with exercise. These effects were independent of bone marrow fat, suggesting that intrinsic musculoskeletal adaptions were responsible for these beneficial effects.
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Affiliation(s)
- Yukiko Kitase
- Department of Anatomy, Cell Biology and Physiology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
| | - Julian A. Vallejo
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
- Department of Biomedical Sciences, School of Medicine, University of Missouri, Kansas City, MO 64108, USA
| | - Sarah L. Dallas
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - Yixia Xie
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - Mark Dallas
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - LeAnn Tiede-Lewis
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - David Moore
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - Anthony Meljanac
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - Corrine Kumar
- Department of Anatomy, Cell Biology and Physiology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
| | - Carrie Zhao
- Department of Anatomy, Cell Biology and Physiology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
| | - Jennifer Rosser
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - Marco Brotto
- Bone-Muscle Research Center, College of Nursing and Health Innovation, University of Texas, Arlington, TX 76019, USA
| | - Mark L. Johnson
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
| | - Ziyue Liu
- Department of Biostatistics and Health Data Science, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
| | - Michael J. Wacker
- Department of Biomedical Sciences, School of Medicine, University of Missouri, Kansas City, MO 64108, USA
| | - Lynda Bonewald
- Department of Orthopaedic Surgery, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
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5
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Guerriere KI, Castellani CM, Popp KL, Bouxsein ML, Hughes JM. Unraveling the physiologic paradoxes that underlie exercise prescription for stress fracture prevention. Exp Biol Med (Maywood) 2022; 247:1833-1839. [PMID: 35983839 PMCID: PMC9679355 DOI: 10.1177/15353702221112108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The effects of exercise on stress fracture risk are paradoxical. Exercise can promote both bone formation and resorption, which in turn, can reduce and increase risk of stress fractures, respectively. We review classic and current literature that suggests that the processes that underlie these responses to exercise are distinct. Bone remodeling involves osteoclastic resorption of fatigue-damaged bone, coupled with subsequent bone deposition to replace the damaged tissue. Bone modeling involves the independent action of osteoblasts and osteoclasts forming or resorbing bone, respectively, on a surface. In the formation mode, modeling results in increased bone stiffness, strength, and resistance to fatigue. Both the remodeling and modeling responses to exercise require significant time for newly deposited bone to fully mineralize. We propose that recognizing these two distinct physiologic pathways and their related time courses reveals the theoretical basis to guide exercise prescription to promote bone health during periods of heightened stress fracture risk. Such guidance may include minimizing rapid increases in the duration of repetitive exercises that may cause fatigue damage accrual, such as long-distance running and marching. Rather, limiting initial exercise characteristics to those known to stimulate bone formation, such as short-duration, moderate-to-high impact, dynamic, and multidirectional activities with rest insertion, may increase the fatigue resistance of bone and consequently minimize stress fracture risk.
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Affiliation(s)
- Katelyn I Guerriere
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Colleen M Castellani
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Kristin L Popp
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA,Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA,Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - Mary L Bouxsein
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA,Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA,Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center, Boston, MA 02210, USA,Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - Julie M Hughes
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA,Julie M Hughes.
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6
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Buettmann EG, Goldscheitter GM, Hoppock GA, Friedman MA, Suva LJ, Donahue HJ. Similarities Between Disuse and Age-Induced Bone Loss. J Bone Miner Res 2022; 37:1417-1434. [PMID: 35773785 PMCID: PMC9378610 DOI: 10.1002/jbmr.4643] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 06/17/2022] [Accepted: 06/24/2022] [Indexed: 11/07/2022]
Abstract
Disuse and aging are known risk factors associated with low bone mass and quality deterioration, resulting in increased fracture risk. Indeed, current and emerging evidence implicate a large number of shared skeletal manifestations between disuse and aging scenarios. This review provides a detailed overview of current preclinical models of musculoskeletal disuse and the clinical scenarios they seek to recapitulate. We also explore and summarize the major similarities between bone loss after extreme disuse and advanced aging at multiple length scales, including at the organ/tissue, cellular, and molecular level. Specifically, shared structural and material alterations of bone loss are presented between disuse and aging, including preferential loss of bone at cancellous sites, cortical thinning, and loss of bone strength due to enhanced fragility. At the cellular level bone loss is accompanied, during disuse and aging, by increased bone resorption, decreased formation, and enhanced adipogenesis due to altered gap junction intercellular communication, WNT/β-catenin and RANKL/OPG signaling. Major differences between extreme short-term disuse and aging are discussed, including anatomical specificity, differences in bone turnover rates, periosteal modeling, and the influence of subject sex and genetic variability. The examination also identifies potential shared mechanisms underlying bone loss in aging and disuse that warrant further study such as collagen cross-linking, advanced glycation end products/receptor for advanced glycation end products (AGE-RAGE) signaling, reactive oxygen species (ROS) and nuclear factor κB (NF-κB) signaling, cellular senescence, and altered lacunar-canalicular connectivity (mechanosensation). Understanding the shared structural alterations, changes in bone cell function, and molecular mechanisms common to both extreme disuse and aging are paramount to discovering therapies to combat both age-related and disuse-induced osteoporosis. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Evan G Buettmann
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Galen M Goldscheitter
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Gabriel A Hoppock
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Michael A Friedman
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Larry J Suva
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Henry J Donahue
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA
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7
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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.
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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
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8
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Yang H, Bullock WA, Myhal A, DeShield P, Duffy D, Main RP. Cancellous Bone May Have a Greater Adaptive Strain Threshold Than Cortical Bone. JBMR Plus 2021; 5:e10489. [PMID: 33977205 PMCID: PMC8101616 DOI: 10.1002/jbm4.10489] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/24/2021] [Accepted: 03/09/2021] [Indexed: 01/12/2023] Open
Abstract
Strain magnitude has a controlling influence on bone adaptive response. However, questions remain as to how and if cancellous and cortical bone tissues respond differently to varied strain magnitudes, particularly at a molecular level. The goal of this study was to characterize the time‐dependent gene expression, bone formation, and structural response of the cancellous and cortical bone of female C57Bl/6 mice to mechanical loading by applying varying load levels (low: −3.5 N; medium: −5.2 N; high: −7 N) to the skeleton using a mouse tibia loading model. The loading experiment showed that cortical bone mass at the tibial midshaft was significantly enhanced following all load levels examined and bone formation activities were particularly elevated at the medium and high loads applied. In contrast, for the proximal metaphyseal cancellous bone, only the high load led to significant increases in bone mass and bone formation indices. Similarly, expression of genes associated with inhibition of bone formation (e.g., Sost) was altered in the diaphyseal cortical bone at all load levels, but in the metaphyseal cortico‐cancellous bone only by the high load. Finite element analysis determined that the peak tensile or compressive strains that were osteogenic for the proximal cancellous bone under the high load were significantly greater than those that were osteogenic for the midshaft cortical tissues under the low load. These results suggest that the magnitude of the strain stimulus regulating structural, cellular, and molecular responses of bone to loading may be greater for the cancellous tissues than for the cortical tissues. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life Beijing University of Technology Beijing China
| | | | - Alexandra Myhal
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences Purdue University West Lafayette IN USA
| | - Philip DeShield
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences Purdue University West Lafayette IN USA
| | - Daniel Duffy
- Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
| | - Russell P Main
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences Purdue University West Lafayette IN USA.,Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
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9
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Curtis KJ, Schiavi J, Mc Garrigle MJ, Kumar V, McNamara LM, Niebur GL. Mechanical stimuli and matrix properties modulate cancer spheroid growth in three-dimensional gelatin culture. J R Soc Interface 2020; 17:20200568. [PMID: 33323051 PMCID: PMC7811591 DOI: 10.1098/rsif.2020.0568] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
Most patients who succumb to cancer have metastases to bone that contribute to their death. Cancer cells that metastasize to bone are regularly subjected to mechanical stimuli that may affect their proliferation, growth and protein expression. Understanding why some cancer cells thrive in this environment could provide insight into new approaches to prevent or treat metastasis to bone. We used 4T1 cells as a model of breast cancer cells, and implanted them in gelatin hydrogels with moduli of 1 or 2.7 kPa to mimic the properties of bone marrow. The constructs were subjected to either perfusion of media through the hydrogel or combined perfusion and cyclic mechanical compression for 1 h d-1 for 4 d. Controls were cultured in free-swelling conditions. The cells formed spheroids during the 4 d of culture, with larger spheroids in the statically cultured constructs than in perfusion or compressed constructs. In stiffer gelatin, smaller spheroids formed in compressed constructs than perfusion alone, while compression had no effect compared to perfusion in the softer gelatin. Immunostaining indicated that the spheroids expressed osteopontin, parathyroid hormone-related protein and fibronectin, which are all hallmarks of bone metastasis. The proliferative marker Ki67 was present in all spheroids on day 4. In the 1 kPa gelatin, Ki67 staining intensity was greater in the statically cultured, free-swelling constructs than in bioreactor culture, regardless of dynamic compression. By contrast, proliferation was higher in the compressed gelatins compared to perfusion alone in the 2.7 kPa constructs, although the spheroids were smaller, on average. This suggests the stiffer gelatin may restrict spheroid growth at the same time that it enhances mechanobiological signalling during compression. Taken together, 4T1 breast cancer cells are mechanically sensitive, and mechanical stimuli can alter their proliferation and protein expression within soft materials with mechanical properties similar to bone marrow. As such, both in vivo and in vitro models of cancer metastasis should consider the role of the mechanical environment in the bone.
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Affiliation(s)
- Kimberly J. Curtis
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, Harper Cancer Research Institute, University of Notre Dame, IN 46556, USA
| | - Jessica Schiavi
- Mechanobiology and Medical Devices Research Group, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Myles J. Mc Garrigle
- Mechanobiology and Medical Devices Research Group, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Vatsal Kumar
- Mechanobiology and Medical Devices Research Group, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Laoise M. McNamara
- Mechanobiology and Medical Devices Research Group, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Glen L. Niebur
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, Harper Cancer Research Institute, University of Notre Dame, IN 46556, USA
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, IN 46556, USA
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10
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Carina V, Della Bella E, Costa V, Bellavia D, Veronesi F, Cepollaro S, Fini M, Giavaresi G. Bone's Response to Mechanical Loading in Aging and Osteoporosis: Molecular Mechanisms. Calcif Tissue Int 2020; 107:301-318. [PMID: 32710266 DOI: 10.1007/s00223-020-00724-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/08/2020] [Indexed: 02/07/2023]
Abstract
Mechanotransduction is pivotal in the maintenance of homeostasis in different tissues and involves multiple cell signaling pathways. In bone, mechanical stimuli regulate the balance between bone formation and resorption; osteocytes play a central role in this regulation. Dysfunctions in mechanotransduction signaling or in osteocytes response lead to an imbalance in bone homeostasis. This alteration is very relevant in some conditions such as osteoporosis and aging. Both are characterized by increased bone weakness due to different causes, for example, the increase of osteocyte apoptosis that cause an alteration of fluid space, or the alteration of molecular pathways. There are intertwined yet very different mechanisms involved among the cell-intrinsic effects of aging on bone, the cell-intrinsic and tissue-level effects of estrogen/androgen withdrawal on bone, and the effects of reduced mechanical loading on bone, which are all involved to some degree in how aged bone fails to respond properly to stress/strain compared to younger bone. This review aims at clarifying how the cellular and molecular pathways regulated and induced in bone by mechanical stimulation are altered with aging and in osteoporosis, to highlight new possible targets for antiresorptive or anabolic bone therapeutic approaches.
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Affiliation(s)
- Valeria Carina
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy.
| | | | - Viviana Costa
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Daniele Bellavia
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Francesca Veronesi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Simona Cepollaro
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Milena Fini
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Gianluca Giavaresi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
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11
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Scheuren AC, D'Hulst G, Kuhn GA, Masschelein E, Wehrle E, De Bock K, Müller R. Hallmarks of frailty and osteosarcopenia in prematurely aged PolgA (D257A/D257A) mice. J Cachexia Sarcopenia Muscle 2020; 11:1121-1140. [PMID: 32596975 PMCID: PMC7432580 DOI: 10.1002/jcsm.12588] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/14/2020] [Accepted: 02/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Frailty is a geriatric syndrome characterized by increased susceptibility to adverse health outcomes. One major determinant thereof is the gradual weakening of the musculoskeletal system and the associated osteosarcopenia. To improve our understanding of the underlying pathophysiology and, more importantly, to test potential interventions aimed at counteracting frailty, suitable animal models are needed. METHODS To evaluate the relevance of prematurely aged PolgA(D257A/D257A) mice as a model for frailty and osteosarcopenia, we quantified the clinical mouse frailty index in PolgA(D257A/D257A) and wild-type littermates (PolgA(+/+) , WT) with age and concertedly assessed the quantity and quality of bone and muscle tissue. Lastly, the anabolic responsiveness of skeletal muscle, muscle progenitors, and bone was assessed. RESULTS PolgA(D257A/D257A) accumulated health deficits at a higher rate compared with WT, resulting in a higher frailty index at 40 and 46 weeks of age (+166%, +278%, P < 0.0001), respectively, with no differences between genotypes at 34 weeks. Concomitantly, PolgA(D257A/D257A) displayed progressive musculoskeletal deterioration such as reduced bone and muscle mass as well as impaired functionality thereof. In addition to lower muscle weights (-14%, P < 0.05, -23%, P < 0.0001) and fibre area (-20%, P < 0.05, -22%, P < 0.0001) at 40 and 46 weeks, respectively, PolgA(D257A/D257A) showed impairments in grip strength and concentric muscle forces (P < 0.05). PolgA(D257A/D257A) mutation altered the acute response to various anabolic stimuli in skeletal muscle and muscle progenitors. While PolgA(D257A/D257A) muscles were hypersensitive to eccentric contractions as well as leucine administration, shown by larger downstream signalling response of the mechanistic target of rapamycin complex 1, myogenic progenitors cultured in vitro showed severe anabolic resistance to leucine and robust impairments in cell proliferation. Longitudinal micro-computed tomography analysis of the sixth caudal vertebrae showed that PolgA(D257A/D257A) had lower bone morphometric parameters (e.g. bone volume fraction, trabecular, and cortical thickness, P < 0.05) as well as reduced remodelling activities (e.g. bone formation and resorption rate, P < 0.05) compared with WT. When subjected to 4 weeks of cyclic loading, young but not aged PolgA(D257A/D257A) caudal vertebrae showed load-induced bone adaptation, suggesting reduced mechanosensitivity with age. CONCLUSIONS PolgA(D257A/D257A) mutation leads to hallmarks of age-related frailty and osteosarcopenia and provides a powerful model to better understand the relationship between frailty and the aging musculoskeletal system.
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Affiliation(s)
| | - Gommaar D'Hulst
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | | | - Evi Masschelein
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Esther Wehrle
- Institute for BiomechanicsETH ZurichZurichSwitzerland
| | - Katrien De Bock
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Ralph Müller
- Institute for BiomechanicsETH ZurichZurichSwitzerland
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12
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Jung H, Akkus O. Diffuse microdamage in bone activates anabolic response by osteoblasts via involvement of voltage-gated calcium channels. J Bone Miner Metab 2020; 38:151-160. [PMID: 31493248 DOI: 10.1007/s00774-019-01042-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 08/03/2019] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Matrix damage sustained by bone tissue is repaired by the concerted action of bone cells. Previous studies have reported extracellular calcium ([Ca2+]E) efflux to originate from regions of bone undergoing diffuse microdamage termed as "diffuse microdamage-induced calcium efflux" (DMICE). DMICE has also been shown to activate and increase intracellular calcium ([Ca2+]I) signaling in osteoblasts via the involvement of voltage-gated calcium channels (VGCC). Past studies have assessed early stage (< 1 h) responses of osteoblasts to DMICE. The current study tested the hypothesis that DMICE has longer-term sustained effect such that it induces anabolic response of osteoblasts. MATERIALS AND METHODS Osteoblasts derived from mouse calvariae were seeded on devitalized bovine bone wafers. Localized diffuse damage was induced in the vicinity of cells by bending. The response of osteoblasts to DMICE was evaluated by testing gene expression, protein synthesis and mineralized nodule formation. RESULTS Cells on damaged bone wafers showed a significant increase in RUNX2 and Osterix expression compared to non-loaded control. Also, RUNX2 and Osterix expression were suppressed significantly when the cells were treated with bepridil, a non-selective VGCC inhibitor, prior to loading. Significantly higher amounts of osteocalcin and mineralized nodules were synthesized by osteoblasts on diffuse damaged bone wafers, while bepridil treatment resulted in a significant decrease in osteocalcin production and mineralized nodule formation. CONCLUSION In conclusion, this study demonstrated that DMICE activates anabolic responses of osteoblasts through activation of VGCC. Future studies of osteoblast response to DMICE in vivo will help to clarify how bone cells repair diffuse microdamage.
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Affiliation(s)
- Hyungjin Jung
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Ozan Akkus
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Department of Orthopedics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
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13
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Main RP, Shefelbine SJ, Meakin LB, Silva MJ, van der Meulen MC, Willie BM. Murine Axial Compression Tibial Loading Model to Study Bone Mechanobiology: Implementing the Model and Reporting Results. J Orthop Res 2020; 38:233-252. [PMID: 31508836 PMCID: PMC9344861 DOI: 10.1002/jor.24466] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/23/2019] [Indexed: 02/04/2023]
Abstract
In vivo, tibial loading in mice is increasingly used to study bone adaptation and mechanotransduction. To achieve standardized and defined experimental conditions, loading parameters and animal-related factors must be considered when performing in vivo loading studies. In this review, we discuss these loading and animal-related experimental conditions, present methods to assess bone adaptation, and suggest reporting guidelines. This review originated from presentations by each of the authors at the workshop "Developing Best Practices for Mouse Models of In Vivo Loading" during the Preclinical Models Section at the Orthopaedic Research Society Annual Meeting, San Diego, CA, March 2017. Following the meeting, the authors engaged in detailed discussions with consideration of relevant literature. The guidelines and recommendations in this review are provided to help researchers perform in vivo loading experiments in mice, and thus further our knowledge of bone adaptation and the mechanisms involved in mechanotransduction. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:233-252, 2020.
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Affiliation(s)
- Russell P. Main
- Department of Basic Medical Sciences and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA,Corresponding author: Russell Main ()
| | - Sandra J. Shefelbine
- Department of Bioengineering, Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA
| | - Lee B. Meakin
- Bristol Veterinary School, University of Bristol, Langford, Bristol BS40 5DU, UK
| | - Matthew J. Silva
- Departments of Orthopaedic Surgery and Biomedical Engineering, Musculoskeletal Research Center, Washington University, Saint Louis, MO, USA
| | - Marjolein C.H van der Meulen
- Meinig School of Biomedical Engineering and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | - Bettina M. Willie
- Research Centre, Shriners Hospital for Children-Canada, Department of Pediatric Surgery, McGill University, Montreal, Canada
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14
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Coulombe JC, Senwar B, Ferguson VL. Spaceflight-Induced Bone Tissue Changes that Affect Bone Quality and Increase Fracture Risk. Curr Osteoporos Rep 2020; 18:1-12. [PMID: 31897866 DOI: 10.1007/s11914-019-00540-y] [Citation(s) in RCA: 4] [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] [Indexed: 01/02/2023]
Abstract
PURPOSE OF REVIEW Bone mineral density and systemic factors are used to assess skeletal health in astronauts. Yet, even in a general population, these measures fail to accurately predict when any individual will fracture. This review considers how long-duration human spaceflight requires evaluation of additional bone structural and material quality measures that contribute to microgravity-induced skeletal fragility. RECENT FINDINGS In both humans and small animal models following spaceflight, bone mass is compromised via reduced bone formation and elevated resorption levels. Concurrently, bone structural quality (e.g., trabecular microarchitecture) is diminished and the quality of bone material is reduced via impaired tissue mineralization, maturation, and maintenance (e.g., mediated by osteocytes). Bone structural and material quality are both affected by microgravity and may, together, jeopardize astronaut operational readiness and lead to increased fracture risk upon return to gravitational loading. Future studies need to directly evaluate how bone quality combines with diminished bone mass to influence bone strength and toughness (e.g., resistance to fracture). Bone quality assessment promises to identify novel biomarkers and therapeutic targets.
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Affiliation(s)
- Jennifer C Coulombe
- Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, CO, 80309, USA
- BioFrontiers Institute, University of Colorado, UCB 596, Boulder, CO, 80309, USA
- BioServe Space Technologies, University of Colorado, UCB 429, Boulder, CO, 80309, USA
| | - Bhavya Senwar
- Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, CO, 80309, USA
- BioFrontiers Institute, University of Colorado, UCB 596, Boulder, CO, 80309, USA
- BioServe Space Technologies, University of Colorado, UCB 429, Boulder, CO, 80309, USA
| | - Virginia L Ferguson
- Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, CO, 80309, USA.
- BioFrontiers Institute, University of Colorado, UCB 596, Boulder, CO, 80309, USA.
- BioServe Space Technologies, University of Colorado, UCB 429, Boulder, CO, 80309, USA.
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15
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Morrell AE, Robinson ST, Silva MJ, Guo XE. Mechanosensitive Ca 2+ signaling and coordination is diminished in osteocytes of aged mice during ex vivo tibial loading. Connect Tissue Res 2020; 61:389-398. [PMID: 31931640 PMCID: PMC7785095 DOI: 10.1080/03008207.2020.1712377] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Purpose: The osteocyte is considered the major mechanosensor in bone, capable of detecting forces at a cellular level to coordinate bone formation and resorption. The pathology of age-related bone loss, a hallmark of osteoporosis, is attributed in part to impaired osteocyte mechanosensing. However, real-time evidence of the effect of aging on osteocyte responses to mechanical load is lacking. Intracellular calcium (Ca2+) oscillations have been characterized as an early mechanosensitive response in osteocytes in systems of multiple scales and thus can serve as a real-time measure of osteocyte mechanosensitivity. Our objective was to utilize an ex vivo model to investigate potentially altered mechanosensing in the osteocyte network with aging.Methods: Tibiae were explanted from young-adult (5 mo) and aged (22 mo) female mice and incubated with Fluo-8 AM to visualize osteocyte intracellular Ca2+. Whole tibiae were cyclically loaded while in situ osteocyte Ca2+ dynamics were simultaneously imaged with confocal microscopy. Responsive osteocyte percentage and Ca2+ peak characteristics were quantified, as well as signaling synchrony between paired cells in the field of view.Results: Fewer osteocytes responded to mechanical loading in aged mice compared to young-adult and did so in a delayed manner. Osteocytes from aged mice also lacked the well-correlated relationship between Ca2+ signaling synchrony and cell-cell distance exhibited by young-adult osteocytes.Conclusions: We have demonstrated, for the first time, real-time evidence of the diminished mechanosensing and lack of signaling coordination in aged osteocyte networks in tibial explants, which may contribute to pathology of age-induced bone loss.
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Affiliation(s)
- Andrea E. Morrell
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Samuel T. Robinson
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Matthew J. Silva
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA,Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
| | - X. Edward Guo
- Department of Biomedical Engineering, Columbia University, New York, NY, USA,Corresponding author: X. Edward Guo, PhD, Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, Mail Code 8904,1210 Amsterdam Avenue, New York, NY 10027, USA.
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16
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Strain Distribution Evaluation of Rat Tibia under Axial Compressive Load by Combining Strain Gauge Measurement and Finite Element Analysis. Appl Bionics Biomech 2019; 2019:1736763. [PMID: 31871486 PMCID: PMC6913262 DOI: 10.1155/2019/1736763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 10/16/2019] [Accepted: 11/12/2019] [Indexed: 11/18/2022] Open
Abstract
This study is aimed at providing an effective method for determining strain-load relationship and at quantifying the strain distribution within the whole tibia under axial compressive load on rats. Rat tibial models with axial compressive load were designed. Strains in three directions (0°, 45°, and 90°) at the proximal shaft of the tibia were measured by using a strain gauge rosette, which was used to calculate the maximum and minimum principal strains. Moreover, the strain at the midshaft of the tibia was measured by a single-element strain gauge. The slopes of the strain-load curves with different peak loads were calculated to assess the stability of the strain gauge measurement. Mechanical environment in the whole tibia by the axial compressive load was quantified using finite element analysis (FEA) based on microcomputed tomography images. The von Mises elastic strain distributions of the whole tibiae were evaluated. Slopes of the strain-load curves showed no significant differences among different peak loads (ANOVA; P > 0.05), indicating that the strain-load relationship obtained from the strain gauge measurement was reasonable and stable. The FEA results corresponded to the experimental results with an error smaller than 15% (paired Student's t-test, P > 0.05), signifying that the FEA can simulate the experiment reasonably. FEA results showed that the von Mises elastic strain was the lowest in the middle and gradually increased to both sides along the lateral direction, with the maximal von Mises elastic strain being observed on the posterior side under the distal tibiofibular synostosis. The method of strain gauge measurements and FEA used in this study can provide a feasible way to obtain the mechanical environment of the tibiae under axial compressive load on the rats and serve as a reference for further exploring the mechanical response of the bone by axial compressive load.
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17
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Rizzuto E, Peruzzi B, Giudice M, Urciuoli E, Pittella E, Piuzzi E, Musarò A, Del Prete Z. Detection of the Strains Induced in Murine Tibias by Ex Vivo Uniaxial Loading with Different Sensors. SENSORS 2019; 19:s19235109. [PMID: 31766596 PMCID: PMC6928746 DOI: 10.3390/s19235109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/15/2019] [Accepted: 11/19/2019] [Indexed: 11/16/2022]
Abstract
In this paper, the characterization of the main techniques and transducers employed to measure local and global strains induced by uniaxial loading of murine tibiae is presented. Micro strain gauges and digital image correlation (DIC) were tested to measure local strains, while a moving coil motor-based length transducer was employed to measure relative global shortening. Local strain is the crucial parameter to be measured when dealing with bone cell mechanotransduction, so we characterized these techniques in the experimental conditions known to activate cell mechanosensing in vivo. The experimental tests were performed using tibia samples excised from twenty-two C57BL/6 mice. To evaluate measurement repeatability we computed the standard deviation of ten repetitive compressions to the mean value. This value was lower than 3% for micro strain gauges, and in the range of 7%-10% for DIC and the length transducer. The coefficient of variation, i.e., the standard deviation to the mean value, was about 35% for strain gauges and the length transducer, and about 40% for DIC. These results provided a comprehensive characterization of three methodologies for local and global bone strain measurement, suggesting a possible field of application on the basis of their advantages and limitations.
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Affiliation(s)
- Emanuele Rizzuto
- Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, 00184 Rome, Italy;
- Correspondence: ; Tel.: +39-06-4458-5273
| | - Barbara Peruzzi
- Multifactorial Disease and Complex Phenotype Research Area, Children’s Hospital Bambino Gesù, 00146 Rome, Italy; (B.P.); (E.U.)
| | | | - Enrica Urciuoli
- Multifactorial Disease and Complex Phenotype Research Area, Children’s Hospital Bambino Gesù, 00146 Rome, Italy; (B.P.); (E.U.)
| | - Erika Pittella
- Department of Information, Telecommunication and Electronic Engineering, Sapienza University of Rome, 00184 Rome, Italy; (E.P.); (E.P.)
| | - Emanuele Piuzzi
- Department of Information, Telecommunication and Electronic Engineering, Sapienza University of Rome, 00184 Rome, Italy; (E.P.); (E.P.)
| | - Antonio Musarò
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, 00161 Rome, Italy;
| | - Zaccaria Del Prete
- Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, 00184 Rome, Italy;
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18
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Cabahug-Zuckerman P, Liu C, Cai C, Mahaffey I, Norman SC, Cole W, Castillo AB. Site-Specific Load-Induced Expansion of Sca-1 +Prrx1 + and Sca-1 -Prrx1 + Cells in Adult Mouse Long Bone Is Attenuated With Age. JBMR Plus 2019; 3:e10199. [PMID: 31667455 PMCID: PMC6808224 DOI: 10.1002/jbm4.10199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 02/04/2023] Open
Abstract
Aging is associated with significant bone loss and increased fracture risk, which has been attributed to a diminished response to anabolic mechanical loading. In adults, skeletal progenitors proliferate and differentiate into bone‐forming osteoblasts in response to increasing mechanical stimuli, though the effects of aging on this response are not well‐understood. Here we show that both adult and aged mice exhibit load‐induced periosteal bone formation, though the response is significantly attenuated with age. We also show that the acute response of adult bone to loading involves expansion of Sca‐1+Prrx1+ and Sca‐1−Prrx1+ cells in the periosteum. On the endosteal surface, loading enhances proliferation of both these cell populations, though the response is delayed by 2 days relative to the periosteal surface. In contrast to the periosteum and endosteum, the marrow does not exhibit increased proliferation of Sca‐1+Prrx1+ cells, but only of Sca‐1−Prrx1+ cells, underscoring fundamental differences in how the stem cell niche in distinct bone envelopes respond to mechanical stimuli. Notably, the proliferative response to loading is absent in aged bone even though there are similar baseline numbers of Prrx1 + cells in the periosteum and endosteum, suggesting that the proliferative capacity of progenitors is attenuated with age, and proliferation of the Sca‐1+Prrx1+ population is critical for load‐induced periosteal bone formation. These findings provide a basis for the development of novel therapeutics targeting these cell populations to enhance osteogenesis for overcoming age‐related bone loss. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Pamela Cabahug-Zuckerman
- Department of Orthopaedic Surgery NYU Langone Health, New York University New York NY USA.,Department of Biomedical Engineering Tandon School of Engineering, New York University New York NY USA.,Rehabilitation Research and Development Veterans Affairs New York Harbor Healthcare System New York NY USA
| | - Chao Liu
- Department of Orthopaedic Surgery NYU Langone Health, New York University New York NY USA.,Department of Biomedical Engineering Tandon School of Engineering, New York University New York NY USA.,Rehabilitation Research and Development Veterans Affairs New York Harbor Healthcare System New York NY USA
| | - Cinyee Cai
- Department of Orthopaedic Surgery NYU Langone Health, New York University New York NY USA.,Department of Biomedical Engineering Tandon School of Engineering, New York University New York NY USA
| | - Ian Mahaffey
- Rehabilitation Research and Development Veterans Affairs Palo Alto Healthcare System Palo Alto CA USA
| | - Stephanie C Norman
- Rehabilitation Research and Development Veterans Affairs Palo Alto Healthcare System Palo Alto CA USA
| | - Whitney Cole
- Rehabilitation Research and Development Veterans Affairs Palo Alto Healthcare System Palo Alto CA USA
| | - Alesha B Castillo
- Department of Orthopaedic Surgery NYU Langone Health, New York University New York NY USA.,Department of Biomedical Engineering Tandon School of Engineering, New York University New York NY USA.,Rehabilitation Research and Development Veterans Affairs New York Harbor Healthcare System New York NY USA
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19
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Jiang F, Jalali A, Deguchi C, Chen A, Liu S, Kondo R, Minami K, Horiuchi T, Li BY, Robling AG, Chen J, Yokota H. Finite-element analysis of the mouse proximal ulna in response to elbow loading. J Bone Miner Metab 2019; 37:419-429. [PMID: 30062431 PMCID: PMC6353704 DOI: 10.1007/s00774-018-0943-y] [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: 05/02/2018] [Accepted: 07/13/2018] [Indexed: 10/28/2022]
Abstract
Bone is a mechano-sensitive tissue that alters its structure and properties in response to mechanical loading. We have previously shown that application of lateral dynamic loads to a synovial joint, such as the knee and elbow, suppresses degradation of cartilage and prevents bone loss in arthritis and postmenopausal mouse models, respectively. While loading effects on pathophysiology have been reported, mechanical effects on the loaded joint are not fully understood. Because the direction of joint loading is non-axial, not commonly observed in daily activities, strain distributions in the laterally loaded joint are of great interest. Using elbow loading, we herein characterized mechanical responses in the loaded ulna focusing on the distribution of compressive strain. In response to 1-N peak-to-peak loads, which elevate bone mineral density and bone volume in the proximal ulna in vivo, we conducted finite-element analysis and evaluated strain magnitude in three loading conditions. The results revealed that strain of ~ 1000 μstrain (equivalent to 0.1% compression) or above was observed in the limited region near the loading site, indicating that the minimum effective strain for bone formation is smaller with elbow loading than axial loading. Calcein staining indicated that elbow loading increased bone formation in the regions predicted to undergo higher strain.
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Affiliation(s)
- Feifei Jiang
- Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Aydin Jalali
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL220, Indianapolis, IN, 46202, USA
| | - Chie Deguchi
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL220, Indianapolis, IN, 46202, USA
- Graduate School of Engineering, Mie University, Mie, 514, Japan
| | - Andy Chen
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL220, Indianapolis, IN, 46202, USA
| | - Shengzhi Liu
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL220, Indianapolis, IN, 46202, USA
- Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Rika Kondo
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL220, Indianapolis, IN, 46202, USA
- Osaka University Graduate School of Medicine, Suita, Osaka, 565, Japan
| | - Kazumasa Minami
- Osaka University Graduate School of Medicine, Suita, Osaka, 565, Japan
| | | | - Bai-Yan Li
- Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Jie Chen
- Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Hiroki Yokota
- Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA.
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL220, Indianapolis, IN, 46202, USA.
- Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin, 150081, China.
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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20
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Yang H, Xu X, Bullock W, Main RP. Adaptive changes in micromechanical environments of cancellous and cortical bone in response to in vivo loading and disuse. J Biomech 2019; 89:85-94. [PMID: 31047696 DOI: 10.1016/j.jbiomech.2019.04.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 10/27/2022]
Abstract
The skeleton accommodates changes in mechanical environments by increasing bone mass under increased loads and decreasing bone mass under disuse. However, little is known about the adaptive changes in micromechanical behavior of cancellous and cortical tissues resulting from loading or disuse. To address this issue, in vivo tibial loading and hindlimb unloading experiments were conducted on 16-week-old female C57BL/6J mice. Changes in bone mass and tissue-level strains in the metaphyseal cancellous and midshaft cortical bone of the tibiae, resulting from loading or unloading, were determined using microCT and finite element (FE) analysis, respectively. We found that loading- and unloading-induced changes in bone mass were more pronounced in the cancellous than cortical bone. Simulated FE-loading showed that a greater proportion of elements experienced relatively lower longitudinal strains following load-induced bone adaptation, while the opposite was true in the disuse model. While the magnitudes of maximum or minimum principal strains in the metaphyseal cancellous and midshaft cortical bone were not affected by loading, strains oriented with the long axis were reduced in the load-adapted tibia suggesting that loading-induced micromechanical benefits were aligned primarily in the loading direction. Regression analyses demonstrated that bone mass was a good predictor of bone tissue strains for the cortical bone but not for the cancellous bone, which has complex microarchitecture and spatially-variant strain environments. In summary, loading-induced micromechanical benefits for cancellous and cortical tissues are received primarily in the direction of force application and cancellous bone mass may not be related to the micromechanics of cancellous bone.
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Affiliation(s)
- Haisheng Yang
- Department of Biomedical Engineering, School of Life Science and Bioengineering, Beijing University of Technology, Intelligent Physiological Measurement and Clinical Translation Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
| | - Xiaoyu Xu
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, IN, USA; Weldon School of Biomedical Engineering, Purdue University, IN, USA.
| | | | - Russell P Main
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, IN, USA; Weldon School of Biomedical Engineering, Purdue University, IN, USA.
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21
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Yang PF, Huang LW, Nie XT, Yang Y, Wang Z, Ren L, Xu HY, Shang P. Moderate tibia axial loading promotes discordant response of bone composition parameters and mechanical properties in a hindlimb unloading rat model. JOURNAL OF MUSCULOSKELETAL & NEURONAL INTERACTIONS 2018; 18:152-164. [PMID: 29855437 PMCID: PMC6016500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVES The purpose of the present study was to characterize the dynamic alterations of bone composition parameters and mechanical properties to disuse and mechanical intervention. METHODS A tail suspension hindlimb unloading model and an in vivo axial tibia loading model in rats were used. A moderate mechanical loading that was capable of engendering 800 µε tibia strain was applied to the right tibia of rats in both control and hindlimb unloading group across 28 days of the experimental period. The contralateral tibia served as control. RESULTS Hindlimb unloading led to bone loss in tibia from day 14. Bone mineral density, mineral content and mechanical properties responded differently with microstructure to disuse in timing course. Mechanical loading of 800 µε tibia strain failed to alter the bone of the control group, but minimized the detrimental effects of unloading by completely prohibiting the decrease of bone mineral content and main mechanical properties after 28 days. Less obvious influence of mechanical loading on bone microstructure was found. CONCLUSIONS The moderate mechanical loading is not able to stimulate the mechanical response of healthy tibia, but indeed lead to discordant recovery of bone composition parameters and mechanical properties.
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Affiliation(s)
- Peng-Fei Yang
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China,Research & Development Institute in Shenzhen, Northwestern Polytechnical University, Xi’an, China
| | - Ling-Wei Huang
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Xiao-Tong Nie
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China,Research & Development Institute in Shenzhen, Northwestern Polytechnical University, Xi’an, China
| | - Yue Yang
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Zhe Wang
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China,Research & Development Institute in Shenzhen, Northwestern Polytechnical University, Xi’an, China
| | - Li Ren
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China,Research & Development Institute in Shenzhen, Northwestern Polytechnical University, Xi’an, China
| | - Hui-Yun Xu
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China,Research & Development Institute in Shenzhen, Northwestern Polytechnical University, Xi’an, China
| | - Peng Shang
- Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China,Research & Development Institute in Shenzhen, Northwestern Polytechnical University, Xi’an, China,Corresponding author: Prof. Peng Shang, Research & Development Institute in Shenzhen, School of Life Sciences, Northwestern Polytechnical University, Youyi Xilu 127, 707#, 710072, Xi’an, China E-mail:
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22
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Gaio N, Martino A, Toth Z, Watson JT, Nicolaou D, McBride-Gagyi S. Masquelet technique: The effect of altering implant material and topography on membrane matrix composition, mechanical and barrier properties in a rat defect model. J Biomech 2018; 72:53-62. [PMID: 29510858 PMCID: PMC5895482 DOI: 10.1016/j.jbiomech.2018.02.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/12/2018] [Accepted: 02/18/2018] [Indexed: 12/26/2022]
Abstract
The Masquelet technique is a surgical procedure to regenerate segmental bone defects. The two-phase treatment relies on the production of a vascularized foreign-body membrane to support bone grafts over three times larger than the traditional maximum. Historically, the procedure has always utilized a bone cement spacer to evoke membrane production. However, membrane formation can easily be effected by implant surface properties such as material and topology. This study sought to determine if the membrane's mechanical or barrier properties are affected by changing the spacer material to titanium or roughening the surface finish. Ten-week-old, male Sprague Dawley rats were given an externally stabilized, 6 mm femur defect which was filled with a pre-made spacer of bone cement (PMMA) or titanium (TI) with a smooth (∼1 μm) or roughened (∼8 μm) finish. After 4 weeks of implantation, the membranes were harvested, and the matrix composition, tensile mechanics, shrinkage, and barrier function was assessed. Roughening the spacers resulted in significantly more compliant membranes. TI spacers created membranes that inhibited solute transport more. There were no differences between groups in collagen or elastin distribution. This suggests that different membrane characteristics can be created by altering the spacer surface properties. Surgeons may unknowingly effecting membrane formation via bone cement preparation techniques.
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Affiliation(s)
- Natalie Gaio
- Department of Orthopaedic Surgery, Saint Louis University School of Medicine, 1402 S. Grand Blvd, Schwitalla Hall M176, St. Louis, MO 63132, USA
| | - Alice Martino
- Department of Orthopaedic Surgery, Saint Louis University School of Medicine, 1402 S. Grand Blvd, Schwitalla Hall M176, St. Louis, MO 63132, USA
| | - Zacharie Toth
- Department of Orthopaedic Surgery, Saint Louis University School of Medicine, 1402 S. Grand Blvd, Schwitalla Hall M176, St. Louis, MO 63132, USA
| | - J Tracy Watson
- Department of Orthopaedic Surgery, Saint Louis University School of Medicine, 1402 S. Grand Blvd, Schwitalla Hall M176, St. Louis, MO 63132, USA
| | - Daemeon Nicolaou
- Department of Orthopaedic Surgery, Saint Louis University School of Medicine, 1402 S. Grand Blvd, Schwitalla Hall M176, St. Louis, MO 63132, USA
| | - Sarah McBride-Gagyi
- Department of Orthopaedic Surgery, Saint Louis University School of Medicine, 1402 S. Grand Blvd, Schwitalla Hall M176, St. Louis, MO 63132, USA.
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23
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Javaheri B, Carriero A, Wood M, De Souza R, Lee PD, Shefelbine S, Pitsillides AA. Transient peak-strain matching partially recovers the age-impaired mechanoadaptive cortical bone response. Sci Rep 2018; 8:6636. [PMID: 29703931 PMCID: PMC5924380 DOI: 10.1038/s41598-018-25084-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/16/2018] [Indexed: 12/14/2022] Open
Abstract
Mechanoadaptation maintains bone mass and architecture; its failure underlies age-related decline in bone strength. It is unclear whether this is due to failure of osteocytes to sense strain, osteoblasts to form bone or insufficient mechanical stimulus. Mechanoadaptation can be restored to aged bone by surgical neurectomy, suggesting that changes in loading history can rescue mechanoadaptation. We use non-biased, whole-bone tibial analyses, along with characterisation of surface strains and ensuing mechanoadaptive responses in mice at a range of ages, to explore whether sufficient load magnitude can activate mechanoadaptation in aged bone. We find that younger mice adapt when imposed strains are lower than in mature and aged bone. Intriguingly, imposition of short-term, high magnitude loading effectively primes cortical but not trabecular bone of aged mice to respond. This response was regionally-matched to highest strains measured by digital image correlation and to osteocytic mechanoactivation. These data indicate that aged bone’s loading response can be partially recovered, non-invasively by transient, focal high strain regions. Our results indicate that old murine bone does respond to load when the loading is of sufficient magnitude, and bones’ age-related adaptation failure may be due to insufficient mechanical stimulus to trigger mechanoadaptation.
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Affiliation(s)
- Behzad Javaheri
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK.
| | - Alessandra Carriero
- The City College of New York, Department of Biomedical Engineering, 160 Convent Avenue, New York, NY, 10031, USA
| | - Maria Wood
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK
| | - Roberto De Souza
- Universidade Federal de Mato Grosso (UFMT), Departamento de Clínica, Av. Fernando Corrêa da Costa, 2367 - Boa Esperança, Cuiabá, 78060-900, Brazil
| | - Peter D Lee
- Manchester X-Ray Imaging Facility, University of Manchester, Research Complex at Harwell, RAL, Didcot, OX11 0FA, UK
| | - Sandra Shefelbine
- Department of Mechanical and Industrial Engineering, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
| | - Andrew A Pitsillides
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK
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24
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Carriero A, Pereira A, Wilson A, Castagno S, Javaheri B, Pitsillides A, Marenzana M, Shefelbine S. Spatial relationship between bone formation and mechanical stimulus within cortical bone: Combining 3D fluorochrome mapping and poroelastic finite element modelling. Bone Rep 2018; 8:72-80. [PMID: 29904646 PMCID: PMC5997173 DOI: 10.1016/j.bonr.2018.02.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Bone is a dynamic tissue and adapts its architecture in response to biological and mechanical factors. Here we investigate how cortical bone formation is spatially controlled by the local mechanical environment in the murine tibia axial loading model (C57BL/6). We obtained 3D locations of new bone formation by performing ‘slice and view’ 3D fluorochrome mapping of the entire bone and compared these sites with the regions of high fluid velocity or strain energy density estimated using a finite element model, validated with ex-vivo bone surface strain map acquired ex-vivo using digital image correlation. For the comparison, 2D maps of the average bone formation and peak mechanical stimulus on the tibial endosteal and periosteal surface across the entire cortical surface were created. Results showed that bone formed on the periosteal and endosteal surface in regions of high fluid flow. Peak strain energy density predicted only the formation of bone periosteally. Understanding how the mechanical stimuli spatially relates with regions of cortical bone formation in response to loading will eventually guide loading regime therapies to maintain or restore bone mass in specific sites in skeletal pathologies. 3D spatial representation of new bone formation after loading is shown by fluorochrome mapping of the entire mouse tibia Regions of new bone formation spatially associate with regions of high strain and fluid mechanical stimulus in a FE model The FE model was validated with the strains on the bone surface determined ex-vivo using digital image correlation Regions of new bone formation co-localize in sites of peak fluid flow, both endosteally and periosteally Peak strain energy density was able to predict only periosteal bone formation
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Affiliation(s)
- A. Carriero
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
- Corresponding author at: Department of Biomedical Engineering, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - A.F. Pereira
- Department of Bioengineering, Imperial College London, UK
- Graduate School of Biomedical Engineering, University of New South Wales, Australia
| | - A.J. Wilson
- Department of Life Science, Imperial College London, UK
| | - S. Castagno
- Department of Medicine, Imperial College London, UK
| | - B. Javaheri
- Department of Comparative Biomedical Sciences, Royal Veterinary College, UK
| | - A.A. Pitsillides
- Department of Comparative Biomedical Sciences, Royal Veterinary College, UK
| | - M. Marenzana
- Department of Bioengineering, Imperial College London, UK
| | - S.J. Shefelbine
- Department of Mechanical and Industrial Engineering and Department of Bioengineering, Northeastern University, Boston, MA, USA
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25
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Sun D, Brodt MD, Zannit HM, Holguin N, Silva MJ. Evaluation of loading parameters for murine axial tibial loading: Stimulating cortical bone formation while reducing loading duration. J Orthop Res 2018; 36:682-691. [PMID: 28888055 PMCID: PMC5839947 DOI: 10.1002/jor.23727] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 08/31/2017] [Indexed: 02/04/2023]
Abstract
Classic studies in bone mechanobiology have established the importance of loading parameters on the anabolic response. Most of these early studies were done using loading methods not currently in favor, and using non-murine species. Our objective was to re-examine the effects of several loading parameters on the response of cortical bone using the contemporary murine axial tibial compression model. We subjected tibias of 5-month old, female C57Bl/6 mice to cyclic (4 Hz) mechanical loading and examined bone formation responses using dynamic and static histomorphometry. First, using a reference protocol of 1,200 cycles/day, 5 days/week for 2 weeks, we confirmed the significant influence of peak strain magnitude on periosteal mineralizing surface (Ps.MS/BS) and bone formation rate (Ps.BFR/BS) (p < 0.05, ANOVA). There was a significant induction of periosteal lamellar bone at a lower threshold of approx. -1,000 μϵ and a transition from lamellar-woven bone near -2,000 μϵ. In contrast, on the endocortical surface, bone formation indices did not exhibit a load magnitude-dependent response and no incidence of woven bone. Next, we found that reducing daily cycle number from 1,200 to 300 to 60 did not diminish the bone formation response (p > 0.05). On the other hand, reducing the daily frequency of loading from 5 consecutive days/week to 3 alternate days/week significantly diminished the periosteal response, from a loading-induced increase in Ps.MS/BS of 38% (loaded vs. control) for 5 days/week to only 15% for 3 days/week (p < 0.05). Finally, we determined that reducing the study duration from 2 to 1 weeks of loading did not affect bone formation outcomes. In conclusion, cyclic loading to -1,800 μϵ peak strain, at 4 Hz and 60 cycles/day for 5 consecutive days (1 week) induces an increase in periosteal lamellar bone formation with minimal incidence of woven bone in 5-month-old C57Bl/6 female mice. Our results provide a basis for reduction of loading duration (daily cycles and study length) without loss of anabolic effect as measured by dynamic histomorphometry. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:682-691, 2018.
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Affiliation(s)
- David Sun
- Department of Orthopaedic Surgery, Washington University in Saint
Louis, Saint Louis, Missouri,Department of Biomedical Engineering, Washington University in Saint
Louis, Saint Louis, Missouri
| | - Michael D. Brodt
- Department of Orthopaedic Surgery, Washington University in Saint
Louis, Saint Louis, Missouri
| | - Heather M. Zannit
- Department of Orthopaedic Surgery, Washington University in Saint
Louis, Saint Louis, Missouri,Department of Biomedical Engineering, Washington University in Saint
Louis, Saint Louis, Missouri
| | - Nilsson Holguin
- Department of Orthopaedic Surgery, Washington University in Saint
Louis, Saint Louis, Missouri
| | - Matthew J. Silva
- Department of Orthopaedic Surgery, Washington University in Saint
Louis, Saint Louis, Missouri,Department of Biomedical Engineering, Washington University in Saint
Louis, Saint Louis, Missouri,Correspondence To: Matthew J. Silva, Ph.D.,
, Dept. of Orthopaedic Surgery/Campus Box
8233, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO
63110
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26
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Curtis KJ, Coughlin TR, Mason DE, Boerckel JD, Niebur GL. Bone marrow mechanotransduction in porcine explants alters kinase activation and enhances trabecular bone formation in the absence of osteocyte signaling. Bone 2018; 107:78-87. [PMID: 29154967 DOI: 10.1016/j.bone.2017.11.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/10/2017] [Accepted: 11/13/2017] [Indexed: 01/12/2023]
Abstract
Bone is a dynamic tissue that can adapt its architecture in response to mechanical signals under the control of osteocytes, which sense mechanical deformation of the mineralized bone. However, cells in the marrow are also mechanosensitive and may contribute to load-induced bone adaptation, as marrow is subjected to mechanical stress during bone deformation. We investigated the contribution of mechanotransduction in marrow cells to trabecular bone formation by applying low magnitude mechanical stimulation (LMMS) to porcine vertebral trabecular bone explants in an in situ bioreactor. The bone formation rate was higher in stimulated explants compared to unloaded controls which represent a disuse condition (CNT). However, sclerostin protein expression in osteocytes was not different between groups, nor was expression of osteocytic mechanoregulatory genes SOST, IGF-1, CTGF, and Cyr61, suggesting the mechanoregulatory program of osteocytes was unaffected by the loading regime. In contrast, c-Fos, a gene indicative of mechanical stimulation, was upregulated in the marrow cells of mechanically stimulated explants, while the level of activated c-Jun decreased by 25%. The activator protein 1 (AP-1) transcription factor is a heterodimer of c-Fos and c-Jun, which led us to investigate the expression of the downstream target gene cyclin-D1, a gene associated with cell cycle progression and osteogenesis. Cyclin-D1 gene expression in the stimulated marrow was approximately double that of the controls. The level of phosphorylated PYK2, a purported inhibitor of osteoblast differentiation, also decreased in marrow cells from stimulated explants. Taken together, mechanotransduction in marrow cells induced trabecular bone formation independent of osteocyte signaling. Identifying the specific cells and signaling pathways involved, and verifying them with inhibition of specific signaling molecules, could lead to potential therapeutic targets for diseases characterized by bone loss.
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Affiliation(s)
- Kimberly J Curtis
- Tissue Mechanics Laboratory, University of Notre Dame, IN, 46556, USA; Bioengineering Graduate Program, University of Notre Dame, IN, 46556, USA
| | - Thomas R Coughlin
- Tissue Mechanics Laboratory, University of Notre Dame, IN, 46556, USA; Bioengineering Graduate Program, University of Notre Dame, IN, 46556, USA
| | - Devon E Mason
- Bioengineering Graduate Program, University of Notre Dame, IN, 46556, USA
| | - Joel D Boerckel
- Bioengineering Graduate Program, University of Notre Dame, IN, 46556, USA
| | - Glen L Niebur
- Tissue Mechanics Laboratory, University of Notre Dame, IN, 46556, USA; Bioengineering Graduate Program, University of Notre Dame, IN, 46556, USA.
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27
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Scheuren A, Wehrle E, Flohr F, Müller R. Bone mechanobiology in mice: toward single-cell in vivo mechanomics. Biomech Model Mechanobiol 2017; 16:2017-2034. [PMID: 28735414 DOI: 10.1007/s10237-017-0935-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Accepted: 07/11/2017] [Indexed: 01/27/2023]
Abstract
Mechanically driven bone (re)modeling is a multiscale process mediated through complex interactions between multiple cell types and their microenvironments. However, the underlying mechanisms of how cells respond to mechanical signals are still unclear and are at the focus of the field of bone mechanobiology. Traditionally, this complex process has been addressed by reducing the system to single scales and cell types. It is only recently that more integrative approaches have been established to study bone mechanobiology across multiple scales in which mechanical load at the organ level is related to molecular responses at the cellular level. The availability of mouse loading models and imaging techniques with improved spatial and temporal resolution has made it possible to track dynamic bone (re)modeling at the tissue and cellular level in vivo. Coupled with advanced computational models, the (re)modeling activities at the tissue scale can be associated with the mechanical microenvironment. However, methods are lacking to link the molecular responses of different cell types to their local mechanical microenvironment and bone (re)modeling activities occurring at the tissue scale. With recent improvements in "omics" technologies and single-cell molecular biology, it is now possible to sequence the complete genome and transcriptome of single cells. These technologies offer unique opportunities to comprehensively investigate the cellular transcriptional profiles within their specific microenvironment. By combining single-cell "omics" technologies with well-established tissue-scale models of bone mechanobiology, we propose a mechanomics approach to locally analyze the transcriptome of single cells with respect to their local 3D mechanical in vivo environment.
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Affiliation(s)
- Ariane Scheuren
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Esther Wehrle
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Felicitas Flohr
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland.
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28
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Yang H, Embry RE, Main RP. Effects of Loading Duration and Short Rest Insertion on Cancellous and Cortical Bone Adaptation in the Mouse Tibia. PLoS One 2017; 12:e0169519. [PMID: 28076363 PMCID: PMC5226737 DOI: 10.1371/journal.pone.0169519] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 12/19/2016] [Indexed: 11/19/2022] Open
Abstract
The skeleton's osteogenic response to mechanical loading can be affected by loading duration and rest insertion during a series of loading events. Prior animal loading studies have shown that the cortical bone response saturates quickly and short rest insertions between load cycles can enhance cortical bone formation. However, it remains unknown how loading duration and short rest insertion affect load-induced osteogenesis in the mouse tibial compressive loading model, and particularly in cancellous bone. To address this issue, we applied cyclic loading (-9 N peak load; 4 Hz) to the tibiae of three groups of 16 week-old female C57BL/6 mice for two weeks, with a different number of continuous load cycles applied daily to each group (36, 216 and 1200). A fourth group was loaded under 216 daily load cycles with a 10 s rest insertion after every fourth cycle. We found that as few as 36 load cycles per day were able to induce osteogenic responses in both cancellous and cortical bone. Furthermore, while cortical bone area and thickness continued to increase through 1200 cycles, the incremental increase in the osteogenic response decreased as load number increased, indicating a reduced benefit of the increasing number of load cycles. In the proximal metaphyseal cancellous bone, trabecular thickness increased with load up to 216 cycles. We also found that insertion of a 10 s rest between load cycles did not improve the osteogenic response of the cortical or cancellous tissues compared to continuous loading in this model given the age and sex of the mice and the loading parameters used here. These results suggest that relatively few load cycles (e.g. 36) are sufficient to induce osteogenic responses in both cortical and cancellous bone in the mouse tibial loading model. Mechanistic studies using the mouse tibial loading model to examine bone formation and skeletal mechanobiology could be accomplished with relatively few load cycles.
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Affiliation(s)
- Haisheng Yang
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Rachel E. Embry
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Russell P. Main
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, United States of America
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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29
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Holguin N, Brodt MD, Silva MJ. Activation of Wnt Signaling by Mechanical Loading Is Impaired in the Bone of Old Mice. J Bone Miner Res 2016; 31:2215-2226. [PMID: 27357062 PMCID: PMC5397287 DOI: 10.1002/jbmr.2900] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/24/2016] [Accepted: 06/27/2016] [Indexed: 01/18/2023]
Abstract
Aging diminishes bone formation engendered by mechanical loads, but the mechanism for this impairment remains unclear. Because Wnt signaling is required for optimal loading-induced bone formation, we hypothesized that aging impairs the load-induced activation of Wnt signaling. We analyzed dynamic histomorphometry of 5-month-old, 12-month-old, and 22-month-old C57Bl/6JN mice subjected to multiple days of tibial compression and corroborated an age-related decline in the periosteal loading response on day 5. Similarly, 1 day of loading increased periosteal and endocortical bone formation in young-adult (5-month-old) mice, but old (22-month-old) mice were unresponsive. These findings corroborated mRNA expression of genes related to bone formation and the Wnt pathway in tibias after loading. Multiple bouts (3 to 5 days) of loading upregulated bone formation-related genes, e.g., Osx and Col1a1, but older mice were significantly less responsive. Expression of Wnt negative regulators, Sost and Dkk1, was suppressed with a single day of loading in all mice, but suppression was sustained only in young-adult mice. Moreover, multiple days of loading repeatedly suppressed Sost and Dkk1 in young-adult, but not in old tibias. The age-dependent response to loading was further assessed by osteocyte staining for Sclerostin and LacZ in tibia of TOPGAL mice. After 1 day of loading, fewer osteocytes were Sclerostin-positive and, corroboratively, more osteocytes were LacZ-positive (Wnt active) in both 5-month-old and 12-month-old mice. However, although these changes were sustained after multiple days of loading in 5-month-old mice, they were not sustained in 12-month-old mice. Last, Wnt1 and Wnt7b were the most load-responsive of the 19 Wnt ligands. However, 4 hours after a single bout of loading, although their expression was upregulated threefold to 10-fold in young-adult mice, it was not altered in old mice. In conclusion, the reduced bone formation response of aged mice to loading may be due to failure to sustain Wnt activity with repeated loading. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Nilsson Holguin
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA
| | - Michael D Brodt
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA
| | - Matthew J Silva
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
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Laurent MR, Dubois V, Claessens F, Verschueren SMP, Vanderschueren D, Gielen E, Jardí F. Muscle-bone interactions: From experimental models to the clinic? A critical update. Mol Cell Endocrinol 2016; 432:14-36. [PMID: 26506009 DOI: 10.1016/j.mce.2015.10.017] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/13/2015] [Accepted: 10/20/2015] [Indexed: 02/06/2023]
Abstract
Bone is a biomechanical tissue shaped by forces from muscles and gravitation. Simultaneous bone and muscle decay and dysfunction (osteosarcopenia or sarco-osteoporosis) is seen in ageing, numerous clinical situations including after stroke or paralysis, in neuromuscular dystrophies, glucocorticoid excess, or in association with vitamin D, growth hormone/insulin like growth factor or sex steroid deficiency, as well as in spaceflight. Physical exercise may be beneficial in these situations, but further work is still needed to translate acceptable and effective biomechanical interventions like vibration therapy from animal models to humans. Novel antiresorptive and anabolic therapies are emerging for osteoporosis as well as drugs for sarcopenia, cancer cachexia or muscle wasting disorders, including antibodies against myostatin or activin receptor type IIA and IIB (e.g. bimagrumab). Ideally, increasing muscle mass would increase muscle strength and restore bone loss from disuse. However, the classical view that muscle is unidirectionally dominant over bone via mechanical loading is overly simplistic. Indeed, recent studies indicate a role for neuronal regulation of not only muscle but also bone metabolism, bone signaling pathways like receptor activator of nuclear factor kappa-B ligand (RANKL) implicated in muscle biology, myokines affecting bone and possible bone-to-muscle communication. Moreover, pharmacological strategies inducing isolated myocyte hypertrophy may not translate into increased muscle power because tendons, connective tissue, neurons and energy metabolism need to adapt as well. We aim here to critically review key musculoskeletal molecular pathways involved in mechanoregulation and their effect on the bone-muscle unit as a whole, as well as preclinical and emerging clinical evidence regarding the effects of sarcopenia therapies on osteoporosis and vice versa.
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Affiliation(s)
- Michaël R Laurent
- Gerontology and Geriatrics, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium; Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium; Centre for Metabolic Bone Diseases, University Hospitals Leuven, 3000 Leuven, Belgium.
| | - Vanessa Dubois
- Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Frank Claessens
- Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Sabine M P Verschueren
- Research Group for Musculoskeletal Rehabilitation, Department of Rehabilitation Science, KU Leuven, 3000 Leuven, Belgium
| | - Dirk Vanderschueren
- Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Evelien Gielen
- Gerontology and Geriatrics, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium; Centre for Metabolic Bone Diseases, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Ferran Jardí
- Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium
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31
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Longitudinal imaging of the ageing mouse. Mech Ageing Dev 2016; 160:93-116. [PMID: 27530773 DOI: 10.1016/j.mad.2016.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 07/30/2016] [Accepted: 08/04/2016] [Indexed: 12/13/2022]
Abstract
Several non-invasive imaging techniques are used to investigate the effect of pathologies and treatments over time in mouse models. Each preclinical in vivo technique provides longitudinal and quantitative measurements of changes in tissues and organs, which are fundamental for the evaluation of alterations in phenotype due to pathologies, interventions and treatments. However, it is still unclear how these imaging modalities can be used to study ageing with mice models. Almost all age related pathologies in mice such as osteoporosis, arthritis, diabetes, cancer, thrombi, dementia, to name a few, can be imaged in vivo by at least one longitudinal imaging modality. These measurements are the basis for quantification of treatment effects in the development phase of a novel treatment prior to its clinical testing. Furthermore, the non-invasive nature of such investigations allows the assessment of different tissue and organ phenotypes in the same animal and over time, providing the opportunity to study the dysfunction of multiple tissues associated with the ageing process. This review paper aims to provide an overview of the applications of the most commonly used in vivo imaging modalities used in mouse studies: micro-computed-tomography, preclinical magnetic-resonance-imaging, preclinical positron-emission-tomography, preclinical single photon emission computed tomography, ultrasound, intravital microscopy, and whole body optical imaging.
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Kelly NH, Schimenti JC, Ross FP, van der Meulen MCH. Transcriptional profiling of cortical versus cancellous bone from mechanically-loaded murine tibiae reveals differential gene expression. Bone 2016; 86:22-9. [PMID: 26876048 PMCID: PMC4833881 DOI: 10.1016/j.bone.2016.02.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 12/19/2022]
Abstract
Mechanical loading is an anabolic stimulus that increases bone mass, and thus a promising method to counteract osteoporosis-related bone loss. The mechanism of this anabolism remains unclear, and needs to be established for both cortical and cancellous envelopes individually. We hypothesized that cortical and cancellous bone display different gene expression profiles at baseline and in response to mechanical loading. To test this hypothesis, the left tibiae of 10-week-old female C57Bl/6 mice were subjected to one session of axial tibial compression (9N, 1200cycles, 4Hz triangle waveform) and euthanized 3 and 24h following loading. The right limb served as the contralateral control. We performed RNA-seq on marrow-free metaphyseal samples from the cortical shell and the cancellous core to determine differential gene expression at baseline (control limb) and in response to load. Differential expression was verified with qPCR. Cortical and cancellous bone exhibited distinctly different transcriptional profiles basally and in response to mechanical loading. More genes were differentially expressed with loading at 24h with more genes downregulated at 24h than at 3h in both tissues. Enhanced Wnt signaling dominated the response in cortical bone at 3 and 24h, but in cancellous bone only at 3h. In cancellous bone at 24h many muscle-related genes were downregulated. These findings reveal key differences between cortical and cancellous genetic regulation in response to mechanical loading. Future studies at different time points and multiple loading sessions will add to our knowledge of cortical and cancellous mechanotransduction with the potential to identify new targets for mouse genetic knockout studies and drugs to treat osteoporosis.
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Affiliation(s)
- Natalie H Kelly
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, 105 Upson Hall, Ithaca, NY 14853, USA; Nancy E and Peter C Meinig School of Biomedical Engineering, Cornell University, 101 Weill Hall, Ithaca, NY 14853, USA.
| | - John C Schimenti
- College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
| | - F Patrick Ross
- Research Division, Hospital for Special Surgery, 541 East 71st St., New York, NY 10021, USA.
| | - Marjolein C H van der Meulen
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, 105 Upson Hall, Ithaca, NY 14853, USA; Nancy E and Peter C Meinig School of Biomedical Engineering, Cornell University, 101 Weill Hall, Ithaca, NY 14853, USA; Research Division, Hospital for Special Surgery, 541 East 71st St., New York, NY 10021, USA.
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Stadelmann VA, Brun J, Bonnet N. Preclinical mouse models for assessing axial compression of long bones during exercise. BONEKEY REPORTS 2015; 4:768. [PMID: 26788286 PMCID: PMC4704463 DOI: 10.1038/bonekey.2015.138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 10/22/2015] [Indexed: 11/09/2022]
Abstract
The aim of this laboratory method is to describe two approaches for the investigation of bone responses to mechanical loading in mice in vivo. The first is running exercise, because it is easily translatable clinically, and the second is axial compression of the tibia, because it is precisely controllable. The effects of running exercise, and in general physical activity, on bone tissue have been shown to be both direct through mechanical loading (ground impact and muscle tension) and indirect through metabolic changes. Therefore, running exercise has been considered the most convenient preclinical model for demonstrating the general idea that exercise is good for bone health, either early in age for increasing peak bone mass or later in age by slowing down bone loss. However, numerous combinations of protocols have been reported, which makes it difficult to formulate a simple take-home message. This laboratory method also provides a detailed description of in vivo direct mechanical axial compression of the mouse tibia. The effects of mechanical loading depend on the force (strain), frequency, waveform and duration of application, and they range from bone anabolism with low bone remodeling, inducing lamellar bone accumulation, to bone catabolism with high bone remodeling, leading to microdamage, woven bone formation and bone loss. Direct in vivo loading models are extensively used to study mechanotransduction pathways, and contribute by this way to the development of new bone anabolism treatments. Although it is particularly difficult to assemble an internationally adopted protocol description, which would give reproducible bone responses, here we have attempted to provide a comprehensive guide for best practice in performing running exercise and direct in vivo mechanical loading in the laboratory.
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Affiliation(s)
| | - Julia Brun
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospitals & Faculty of Medicine, Geneva, Switzerland
| | - Nicolas Bonnet
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospitals & Faculty of Medicine, Geneva, Switzerland
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Abstract
Trans-sutural distraction osteogenesis (TSDO) has been successfully used to correct midfacial hypoplasia in growing patients for years. The effects of TSDO, however, remain difficult to predict in adult patients. The aim of this study was to determine the biologic basis for the age-related increase in difficulty of performing TSDO. A total of 45 male Sprague Dawley (SD) rats were obtained in 3 age groups: 4 weeks old (4W, N = 15), 3 months old (3M, N = 15), and 13 months old (13M, N = 15). The zygomaticomaxillary sutures (ZMS) were dissected, and their morphology was evaluated by histology and micro-computed tomography (micro-CT). Quantitative real-time polymerase chain reaction of the ZMS and blood samples taken from the abdominal aorta were also used to assess the effects of age at the molecular level. Compared with the 4W rats, the number of fibroblasts in the ZMS was decreased, the bone plate adjacent to the ZMS was thicker, and the texture was denser in the 13M rats. Micro-computed tomography analysis showed the density of the ZMS was significantly increased in the 13M group (P < 0.05). The density ratio of the ZMS to the adjacent bone was increased from 0.14:1 in the 4M group to 0.54:1 in the 13M group. The gene expression of osteocalcin (OC) was significantly lower at 13M than at 3M (P < 0.05). The OC and alkaline phosphatase (ALP) serum levels were significantly lower at 13M than at 4W (P < 0.05). During aging, the decreased osteogenesis activity both systemically and locally may be the biologic effect that limits the application of TSDO in older patients.
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Anisotropic properties of human cortical bone with osteogenesis imperfecta. Biomech Model Mechanobiol 2015; 15:155-67. [DOI: 10.1007/s10237-015-0727-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 09/07/2015] [Indexed: 10/23/2022]
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Berman AG, Clauser CA, Wunderlin C, Hammond MA, Wallace JM. Structural and Mechanical Improvements to Bone Are Strain Dependent with Axial Compression of the Tibia in Female C57BL/6 Mice. PLoS One 2015; 10:e0130504. [PMID: 26114891 PMCID: PMC4482632 DOI: 10.1371/journal.pone.0130504] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/19/2015] [Indexed: 01/26/2023] Open
Abstract
Strain-induced adaption of bone has been well-studied in an axial loading model of the mouse tibia. However, most outcomes of these studies are restricted to changes in bone architecture and do not explore the mechanical implications of those changes. Herein, we studied both the mechanical and morphological adaptions of bone to three strain levels using a targeted tibial loading mouse model. We hypothesized that loading would increase bone architecture and improve cortical mechanical properties in a dose-dependent fashion. The right tibiae of female C57BL/6 mice (8 week old) were compressively loaded for 2 weeks to a maximum compressive force of 8.8N, 10.6N, or 12.4N (generating periosteal strains on the anteromedial region of the mid-diaphysis of 1700 με, 2050 με, or 2400 με as determined by a strain calibration), while the left limb served as an non-loaded control. Following loading, ex vivo analyses of bone architecture and cortical mechanical integrity were assessed by micro-computed tomography and 4-point bending. Results indicated that loading improved bone architecture in a dose-dependent manner and improved mechanical outcomes at 2050 με. Loading to 2050 με resulted in a strong and compelling formation response in both cortical and cancellous regions. In addition, both structural and tissue level strength and energy dissipation were positively impacted in the diaphysis. Loading to the highest strain level also resulted in rapid and robust formation of bone in both cortical and cancellous regions. However, these improvements came at the cost of a woven bone response in half of the animals. Loading to the lowest strain level had little effect on bone architecture and failed to impact structural- or tissue-level mechanical properties. Potential systemic effects were identified for trabecular bone volume fraction, and in the pre-yield region of the force-displacement and stress-strain curves. Future studies will focus on a moderate load level which was largely beneficial in terms of cortical/cancellous structure and cortical mechanical function.
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Affiliation(s)
- Alycia G Berman
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States of America
| | - Creasy A Clauser
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States of America
| | - Caitlin Wunderlin
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States of America
| | - Max A Hammond
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America
| | - Joseph M Wallace
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States of America; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America; Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN, United States of America
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37
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Birkhold AI, Razi H, Weinkamer R, Duda GN, Checa S, Willie BM. Monitoring in vivo (re)modeling: a computational approach using 4D microCT data to quantify bone surface movements. Bone 2015; 75:210-21. [PMID: 25746796 DOI: 10.1016/j.bone.2015.02.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/06/2015] [Accepted: 02/25/2015] [Indexed: 10/23/2022]
Abstract
Bone undergoes continual damage repair and structural adaptation to changing external loads with the aim of maintaining skeletal integrity throughout life. The ability to monitor bone (re)modeling would allow for a better understanding in how various pathologies and interventions affect bone turnover and subsequent bone strength. To date, however, current methods to monitor bone (re)modeling over time and in space are limited. We propose a novel method to visualize and quantify bone turnover, based on in vivo microCT imaging and a 4D computational approach. By in vivo tracking of spatially correlated formation and resorption sites over time it classifies bone restructuring into (re)modeling sequences, the spatially and temporally linked sequences of formation, resorption and quiescent periods on the bone surface. The microCT based method was validated using experimental data from an in vivo mouse tibial loading model and ex vivo data of the mouse tibia. In this application, the method allows the visualization of time-resolved cortical (re)modeling and the quantification of short-term and long-term modeling on the endocortical and periosteal surface at the mid-diaphysis of loaded and control mice tibiae. Both short-term and long-term modeling processes, independent formation and resorption events, could be monitored and modeling (spatially not correlated formation and resorption) and remodeling (resorption followed by new formation at the same site) could be distinguished on the bone surface. This novel method that combines in vivo microCT with a computational approach is a powerful tool to monitor bone turnover in animal models now and is waiting to be applied to human patients in the near future.
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Affiliation(s)
- Annette I Birkhold
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
| | - Hajar Razi
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
| | - Richard Weinkamer
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Science Park Potsdam-Golm, 14424 Potsdam, Germany.
| | - Georg N Duda
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
| | - Sara Checa
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - Bettina M Willie
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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38
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Lambers FM, Kuhn G, Weigt C, Koch KM, Schulte FA, Müller R. Bone adaptation to cyclic loading in murine caudal vertebrae is maintained with age and directly correlated to the local micromechanical environment. J Biomech 2014; 48:1179-87. [PMID: 25543278 DOI: 10.1016/j.jbiomech.2014.11.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 08/17/2014] [Accepted: 11/17/2014] [Indexed: 11/25/2022]
Abstract
The ability of the skeleton to adapt to mechanical stimuli (mechanosensitivity) has most often been investigated at the whole-bone level, but less is known about the local mechanoregulation of bone remodeling at the bone surface, especially in context of the aging skeleton. The aim of this study was to determine the local and global mechanosensitivity of the sixth caudal vertebra during cyclic loading (8 N, three times per week, for six weeks) in mice aged 15, 52, and 82 weeks at the start of loading. Bone adaptation was monitored with in vivo micro-computed tomography. Strain energy density (SED), assumed as the mechanical stimulus for bone adaptation, was determined with micro-finite element models. Mechanical loading had a beneficial effect on the bone microstructure and bone stiffness in all age groups. Mineralizing surface was on average 13% greater (p<0.05) in loaded than control groups in 15- and 82-week-old mice, but not for 52-week-old mice. SED at the start of loading correlated to the change in bone volume fraction in the following 6 weeks for loaded groups (r(2)=0.69-0.85) but not control groups. At the local level, SED was 14-20% greater (p<0.01) at sites of bone formation, and 15-20% lower (p<0.01) at sites of bone resorption compared to quiescent bone surfaces for all age groups, indicating SED was a stimulus for bone adaptation. Taken together, these results support that mechanosensitivity is maintained with age in caudal vertebrae of mice at a local and global level. Since age-related bone loss was not observed in caudal vertebrae, results from the current study might not be translatable to aged humans.
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Affiliation(s)
- Floor M Lambers
- Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
| | - Gisela Kuhn
- Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
| | - Claudia Weigt
- Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
| | - Kathleen M Koch
- Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
| | | | - Ralph Müller
- Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
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39
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Kelly NH, Schimenti JC, Patrick Ross F, van der Meulen MCH. A method for isolating high quality RNA from mouse cortical and cancellous bone. Bone 2014; 68:1-5. [PMID: 25073031 PMCID: PMC4281890 DOI: 10.1016/j.bone.2014.07.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 07/18/2014] [Accepted: 07/19/2014] [Indexed: 12/23/2022]
Abstract
The high incidence of fragility fractures in cortico-cancellous bone locations, plus the fact that individual skeletal sites exhibit different responsiveness to load and disease, emphasizes the need to document separately gene expression in cortical and cancellous bone. A further confounding factor is marrow contamination since its high cellularity may effect gene expression measurements. We isolated RNA from cortical and cancellous bone of intact mouse tibiae, and also after marrow removal by flushing or centrifugation. RNA isolated from cancellous bone by each method was sufficient for gene expression analysis. Centrifugation removed contaminating cells more efficiently than flushing, as indexed by histology and decreased expression of Icam4, a highly expressed erythroid gene. In contrast, centrifuged cortical bone had 12- and 13- fold higher expression of the bone-related genes Col1a1 and Bglap, while levels in marrow-free cancellous bone were 30- and 31-fold higher when compared to bone where marrow was left intact. Furthermore, cortical bone had higher expression of Col1a1 and Bglap than cancellous bone. Thus, RNA isolated by this novel approach can reveal site-specific changes in gene expression in cortical and cancellous bone sites.
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Affiliation(s)
- Natalie H Kelly
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, 105 Upson Hall, Ithaca, NY 14853, USA; Department of Biomedical Engineering, Cornell University, 101 Weill Hall, Ithaca, NY 14853, USA.
| | - John C Schimenti
- College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
| | - F Patrick Ross
- Research Division, Hospital for Special Surgery, 541 East 71st St., New York, NY 10021, USA.
| | - Marjolein C H van der Meulen
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, 105 Upson Hall, Ithaca, NY 14853, USA; Department of Biomedical Engineering, Cornell University, 101 Weill Hall, Ithaca, NY 14853, USA; Research Division, Hospital for Special Surgery, 541 East 71st St., New York, NY 10021, USA.
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40
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Birkhold AI, Razi H, Duda GN, Weinkamer R, Checa S, Willie BM. Mineralizing surface is the main target of mechanical stimulation independent of age: 3D dynamic in vivo morphometry. Bone 2014; 66:15-25. [PMID: 24882735 DOI: 10.1016/j.bone.2014.05.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/21/2014] [Accepted: 05/23/2014] [Indexed: 11/26/2022]
Abstract
Mechanical loading can increase cortical bone mass by shifting the balance between bone formation and resorption towards increased formation. With advancing age resorption outpaces formation resulting in a net loss in cortical bone mass. How cortical bone (re)modeling - especially resorption - responds to mechanical loading with aging remains unclear. In this study, we investigated age-related changes in the modulation of cortical bone formation and resorption sites by mechanical loading. Using in vivo microCT we determined the kinetics of three dimensional formation and resorption parameters. To analyze age-associated adaptation, the left tibiae of young, adult and elderly female C57BL/6 mice were cyclically loaded for 2weeks. Our data showed that in the nonloaded limbs, cortical bone loss with age is the result of an imbalance of resorption to formation thickness, while the surface of resorption is comparable to formation. Loading has a much stronger effect on formation than on resorption; more specifically this effect is due to an increase in formation surface with mechanical stimulation. This is the only effect of loading which is conserved into old age. The resorption thickness is independent of loading in all age groups. Using this novel image analysis technique, we were able for the first time to quantify age-related changes in cortical (re)modeling and the adaptive capacity to mechanics. Most likely a therapy against age-related bone loss combining physical exercise and pharmaceuticals is most efficient if they each act on different parameters of the (re)modeling process. Despite some differences in skeletal aging between mice and humans, our results would suggest that physical exercise in old individuals can positively influence only the formation side of (re) modeling.
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Affiliation(s)
- Annette I Birkhold
- Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
| | - Hajar Razi
- Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
| | - Georg N Duda
- Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
| | | | - Sara Checa
- Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | - Bettina M Willie
- Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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41
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Wu P, Holguin N, Silva MJ, Fu M, Liao W, Sandell LJ. Early response of mouse joint tissue to noninvasive knee injury suggests treatment targets. Arthritis Rheumatol 2014; 66:1256-65. [PMID: 24470303 DOI: 10.1002/art.38375] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 01/16/2014] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Joint trauma can lead to a spectrum of acute lesions, including cartilage degradation, ligament or meniscus tears, and synovitis, all potentially associated with osteoarthritis (OA). This study was undertaken to generate and validate a murine model of knee joint trauma following noninvasive controlled injurious compression in vivo. METHODS The right knees of 8-week-old mice were placed in a hyperflexed position and subjected to compressive joint loading at 1 of 3 peak forces (3N, 6N, or 9N) for 60 cycles in a single loading period and harvested on days 5, 9, and 14 after loading (n = 3-5 for each time point and for each loading). The left knees were not loaded and were used as the contralateral control. Histologic, immunohistochemical, and enzyme-linked immunosorbent assay analyses were performed to evaluate acute pathologic features in chondrocyte viability, cartilage matrix metabolism, synovial reaction, and serum cartilage oligomeric matrix protein (COMP) levels. RESULTS Acute joint pathology was associated with increased injurious loads. All loading regimens induced chondrocyte apoptosis, cartilage matrix degradation, disruption of cartilage collagen fibril arrangement, and increased levels of serum COMP. We also observed that 6N loading induced mild synovitis by day 5, whereas at 9N, with tearing of the anterior cruciate ligament, severe posttraumatic synovitis and ectopic cartilage formation were observed. CONCLUSION We have established a murine model of knee joint trauma with different degrees of overloading in vivo. Our results suggest that immediate therapies particularly targeted to apoptosis and synovial cell proliferation could affect the acute posttraumatic reaction to potentially limit chronic consequences and OA.
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Affiliation(s)
- P Wu
- Washington University School of Medicine, St. Louis, Missouri; First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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42
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The influence of age on adaptive bone formation and bone resorption. Biomaterials 2014; 35:9290-301. [PMID: 25128376 DOI: 10.1016/j.biomaterials.2014.07.051] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/23/2014] [Indexed: 12/11/2022]
Abstract
Bone is a tissue with enormous adaptive capacity, balancing resorption and formation processes. It is known that mechanical loading shifts this balance towards an increased formation, leading to enhanced bone mass and mechanical performance. What is not known is how this adaptive response to mechanical loading changes with age. Using dynamic micro-tomography, we show that structural adaptive changes of trabecular bone within the tibia of living mice subjected to two weeks of in vivo cyclic loading are altered by aging. Comparisons of 10, 26 and 78 weeks old animals reveal that the adaptive capacity diminishes. Strikingly, adaptation was asymmetric in that loading increases formation more than it reduces resorption. This asymmetry further shifts the (re)modeling balance towards a net bone loss with age. Loading results in a major increase in the surface area of mineralizing bone. Interestingly, the resorption thickness is independent of loading in trabecular bone in all age groups. This data suggests that during youth, mechanical stimulation induces the recruitment of bone modeling cells whereas in old age, only bone forming cells are affected. These findings provide mechanistic insights into the processes that guide skeletal aging in mice as well as in other mammals.
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Holguin N, Brodt MD, Sanchez ME, Silva MJ. Aging diminishes lamellar and woven bone formation induced by tibial compression in adult C57BL/6. Bone 2014; 65:83-91. [PMID: 24836737 PMCID: PMC4091978 DOI: 10.1016/j.bone.2014.05.006] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 11/23/2022]
Abstract
Aging purportedly diminishes the ability of the skeleton to respond to mechanical loading, but recent data show that old age did not impair loading-induced accrual of bone in BALB/c mice. Here, we hypothesized that aging limits the response of the tibia to axial compression over a range of adult ages in the commonly used C57BL/6. We subjected the right tibia of old (22 month), middle-aged (12 month) and young-adult (5 month) female C57BL/6 mice to peak periosteal strains (measured near the mid-diaphysis) of -2200 με and -3000 με (n=12-15/age/strain) via axial tibial compression (4 Hz, 1200 cycles/day, 5 days/week, 2 weeks). The left tibia served as a non-loaded, contralateral control. In mice of every age, tibial compression that engendered a peak strain of -2200 με did not alter cortical bone volume but loading to a peak strain of -3000 με increased cortical bone volume due in part to woven bone formation. Both loading magnitudes increased total volume, medullary volume and periosteal bone formation parameters (MS/BS, BFR/BS) near the cortical midshaft. Compared to the increase in total volume and bone formation parameters of 5-month mice, increases were less in 12- and 22-month mice by 45-63%. Moreover, woven bone incidence was greatest in 5-month mice. Similarly, tibial loading at -3000 με increased trabecular BV/TV of 5-month mice by 18% (from 0.085 mm3/mm3), but trabecular BV/TV did not change in 12- or 22-month mice, perhaps due to low initial BV/TV (0.032 and 0.038 mm3/mm3, respectively). In conclusion, these data show that while young-adult C57BL/6 mice had greater periosteal bone formation following loading than middle-aged or old mice, aging did not eliminate the ability of the tibia to accrue cortical bone.
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Affiliation(s)
- Nilsson Holguin
- Department of Orthopedics, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA.
| | - Michael D Brodt
- Department of Orthopedics, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA.
| | - Michelle E Sanchez
- Department of Orthopedics, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA
| | - Matthew J Silva
- Department of Orthopedics, Musculoskeletal Research Center, Washington University, St. Louis, MO, USA; Department of Biomedical Engineering, Washington University, St. Louis, MO, USA.
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Jing D, Baik AD, Lu XL, Zhou B, Lai X, Wang L, Luo E, Guo XE. In situ intracellular calcium oscillations in osteocytes in intact mouse long bones under dynamic mechanical loading. FASEB J 2013; 28:1582-92. [PMID: 24347610 DOI: 10.1096/fj.13-237578] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Osteocytes have been hypothesized to be the major mechanosensors in bone. How in situ osteocytes respond to mechanical stimuli is still unclear because of technical difficulties. In vitro studies have shown that osteocytes exhibited unique calcium (Ca(2+)) oscillations to fluid shear. However, whether this mechanotransduction phenomenon holds for in situ osteocytes embedded within a mineralized bone matrix under dynamic loading remains unknown. Using a novel synchronized loading/imaging technique, we successfully visualized in real time and quantified Ca(2+) responses in osteocytes and bone surface cells in situ under controlled dynamic loading on intact mouse tibia. The resultant fluid-induced shear stress on the osteocyte in the lacunocanalicular system (LCS) was also quantified. Osteocytes, but not surface cells, displayed repetitive Ca(2+) spikes in response to dynamic loading, with spike frequency and magnitude dependent on load magnitude, tissue strain, and shear stress in the LCS. The Ca(2+) oscillations were significantly reduced by endoplasmic reticulum (ER) depletion and P2 purinergic receptor (P2R)/phospholipase C (PLC) inhibition. This study provides direct evidence that osteocytes respond to in situ mechanical loading by Ca(2+) oscillations, which are dependent on the P2R/PLC/inositol trisphosphate/ER pathway. This study develops a novel approach in skeletal mechanobiology and also advances our fundamental knowledge of bone mechanotransduction.
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Affiliation(s)
- Da Jing
- 1351 Engineering Terrace, Mail Code 8904, 1210 Amsterdam Ave., Columbia University, New York, NY 10027, USA.
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Experimental and finite element analysis of strains induced by axial tibial compression in young-adult and old female C57Bl/6 mice. J Biomech 2013; 47:451-7. [PMID: 24268312 DOI: 10.1016/j.jbiomech.2013.10.052] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 10/29/2013] [Accepted: 10/31/2013] [Indexed: 11/22/2022]
Abstract
Axial compression of the mouse tibia is used to study strain-adaptive bone (re)modeling. In some studies, comparisons between mice of different ages are of interest. We characterized the tibial deformation and force-strain relationships in female C57Bl/6 mice at 5-, 12- and 22-months age. A three-gauge experimental method was used to determine the strain distribution at the mid-diaphysis, while specimen-specific finite element analysis was used to examine strain distribution along the tibial length. The peak strains in the tibial mid-diaphyseal cross-section are compressive and occur at the postero-lateral apex. The magnitudes of these peak compressive strains are 1.5 to 2 times those on the opposite, antero-medial face (a site often used for strain gauge placement). For example, -10 N force applied to a 5-months old mouse engenders a peak compressive strain of -2800 µε and a tensile strain on the antero-medial face of +1450 µε. The orientation of the neutral axis at the mid-diaphysis did not differ with age (p=0.46), indicating a similar deformation mode in young and old tibiae. On the other hand, from 5- to 22-months there is a 25% reduction in cortical thickness and moment of inertia (p<0.05), resulting in significantly greater tibial strain magnitudes in older mice for equivalent applied force (p<0.05). We conclude that comparisons of tibial loading responses in young-adult and old C57Bl/6 tibiae are facilitated by similar deformation pattern across ages, but that modest adjustment of force levels is required to engender matching peak strains.
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Connexin43 modulates post-natal cortical bone modeling and mechano-responsiveness. BONEKEY REPORTS 2013; 2:446. [PMID: 24422141 DOI: 10.1038/bonekey.2013.180] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/17/2013] [Accepted: 09/24/2013] [Indexed: 11/08/2022]
Abstract
Recent advances have established connexin43 (Cx43) as a key regulator of osteoblast function and of bone response to mechanical stimuli. Work by independent laboratories has consistently demonstrated postnatal development of larger than normal cross-section of long bones after conditional ablation of the Cx43 gene, Gja1, selectively in osteoblasts and/or osteocytes. This phenotype is caused by excessive endocortical bone resorption associated with periosteal expansion and cortical thinning. Review of published data suggests that the earlier in the osteogenic lineage is Gja1 deleted, the more severe is the cortical phenotype, implying functional roles of Cx43 at different stages of the osteoblast differentiation program. Such cortical modeling abnormalities resemble the changes occurring in the cortex upon disuse or aging. Indeed, Cx43 deficiency desensitizes endocortical osteoclasts from activation induced by removal of mechanical load, thus preventing medullary area expansion. The action of Cx43 on cancellous bone is controversial. Furthermore, the absence of Cx43 in osteoblasts and osteocytes results in activation of periosteal bone formation at lower strains than in wild-type bones, suggesting that Cx43 deficiency increased cortical sensitivity to mechanical load. Thus, Cx43 modulates cortical bone modeling in homeostatic conditions and in response to mechanical load by restraining both endocortical bone resorption and periosteal bone formation. Cx43 may represent a novel pharmacologic target for improving cortical bone strength through modulation of mechano-responsiveness.
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Holguin N, Brodt MD, Sanchez ME, Kotiya AA, Silva MJ. Adaptation of tibial structure and strength to axial compression depends on loading history in both C57BL/6 and BALB/c mice. Calcif Tissue Int 2013; 93:211-21. [PMID: 23708853 PMCID: PMC3748612 DOI: 10.1007/s00223-013-9744-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 05/05/2013] [Indexed: 11/25/2022]
Abstract
Tibial compression can increase murine bone mass. However, loading protocols and mouse strains differ between studies, which may contribute to conflicting results. We hypothesized that bone accrual is influenced more by loading history than by mouse strain or animal handling. The right tibiae of 4-month-old C57BL/6 and BALB/c mice were subjected to axial compression (10 N, 3 days/week, 6 weeks). Left tibiae served as contralateral controls to calculate relative changes: (loaded - control)/control. The WashU protocol applied 60 cycles/day, at 2 Hz, with a 10-s rest-insertion between cycles; the Cornell/HSS protocol applied 1,200 cycles/day, at 6.7 Hz, with a 0.1-s rest-insertion. Because sham loading, sedation, and transportation did not affect tibial morphology, unhandled mice served as age-matched controls (AC). Both loading protocols were anabolic for cortical bone, but Cornell/HSS loading elicited a more rapid response that was greater than WashU loading by 13 %. By 6 weeks, cortical bone volume of each loading group was greater than of AC (average + 16 %) and not different from each other. Ultimate displacement and energy to fracture were greater in tibiae loaded by either protocol, and ultimate force was greater with Cornell/HSS loading. At 6 weeks, independent of mouse strain, the WashU protocol produced minimal trabecular bone and the trabecular bone volume fraction of Cornell/HSS tibiae was greater than that of AC by 65 % and that of WashU by 44 %. We concluded that tibial adaptation to loading was more influenced by waveform than mouse strain or animal handling and therefore may have targeted similar osteogenic mechanisms in C57BL/6 and BALB/c mice.
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Affiliation(s)
- Nilsson Holguin
- Department of Orthopaedic Surgery, Washington University, 425 S Euclid Ave., St. Louis, MO 63110, USA.
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Willie BM, Birkhold AI, Razi H, Thiele T, Aido M, Kruck B, Schill A, Checa S, Main RP, Duda GN. Diminished response to in vivo mechanical loading in trabecular and not cortical bone in adulthood of female C57Bl/6 mice coincides with a reduction in deformation to load. Bone 2013; 55:335-46. [PMID: 23643681 DOI: 10.1016/j.bone.2013.04.023] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Revised: 04/03/2013] [Accepted: 04/26/2013] [Indexed: 11/19/2022]
Abstract
Bone loss occurs during adulthood in both women and men and affects trabecular bone more than cortical bone. The mechanism responsible for trabecular bone loss during adulthood remains unexplained, but may be due at least in part to a reduced mechanoresponsiveness. We hypothesized that trabecular and cortical bone would respond anabolically to loading and that the bone response to mechanical loading would be reduced and the onset delayed in adult compared to postpubescent mice. We evaluated the longitudinal adaptive response of trabecular and cortical bone in postpubescent, young (10 week old) and adult (26 week old) female C57Bl/6J mice to axial tibial compression using in vivo microCT (days 0, 5, 10, and 15) and dynamic histomorphometry (day 15). Loading elicited an anabolic response in both trabecular and cortical bone in young and adult mice. As hypothesized, trabecular bone in adult mice exhibited a reduced and delayed response to loading compared to the young mice, apparent in trabecular bone volume fraction and architecture after 10 days. No difference in mechanoresponsiveness of the cortical bone was observed between young and adult mice. Finite element analysis showed that load-induced strain was reduced with age. Our results suggest that trabecular bone loss that occurs in adulthood may in part be due to a reduced mechanoresponsiveness in this tissue and/or a reduction in the induced tissue deformation which occurs during habitual loading. Therapeutic approaches that address the mechanoresponsiveness of the bone tissue may be a promising and alternate strategy to maintain trabecular bone mass during aging.
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Affiliation(s)
- Bettina M Willie
- Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Germany.
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Weatherholt AM, Fuchs RK, Warden SJ. Cortical and trabecular bone adaptation to incremental load magnitudes using the mouse tibial axial compression loading model. Bone 2013; 52:372-9. [PMID: 23111313 PMCID: PMC3513639 DOI: 10.1016/j.bone.2012.10.026] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/18/2012] [Accepted: 10/19/2012] [Indexed: 11/17/2022]
Abstract
The mouse tibial axial compression loading model has recently been described to allow simultaneous exploration of cortical and trabecular bone adaptation within the same loaded element. However, the model frequently induces cortical woven bone formation and has produced inconsistent results with regards to trabecular bone adaptation. The aim of this study was to investigate bone adaptation to incremental load magnitudes using the mouse tibial axial compression loading model, with the ultimate goal of revealing a load that simultaneously induced lamellar cortical and trabecular bone adaptation. Adult (16 weeks old) female C57BL/6 mice were randomly divided into three load magnitude groups (5, 7 and 9N), and had their right tibia axially loaded using a continuous 2-Hz haversine waveform for 360 cycles/day, 3 days/week for 4 consecutive weeks. In vivo peripheral quantitative computed tomography was used to longitudinally assess midshaft tibia cortical bone adaptation, while ex vivo micro-computed tomography and histomorphometry were used to assess both midshaft tibia cortical and proximal tibia trabecular bone adaptation. A dose response to loading magnitude was observed within cortical bone, with increasing load magnitude inducing increasing levels of lamellar cortical bone adaptation within the upper two thirds of the tibial diaphysis. Greatest cortical bone adaptation was observed at the midshaft where there was a 42% increase in estimated mechanical properties (polar moment of inertia) in the highest (9N) load group. A dose response to load magnitude was not clearly evident within trabecular bone, with only the highest load (9N) being able to induce measureable adaptation (31% increase in trabecular bone volume fraction at the proximal tibia). The ultimate finding was that a load of 9N (engendering a tensile strain of 1833 με on medial surface of the midshaft tibia) was able to simultaneously induce measurable lamellar cortical and trabecular bone adaptation when using the mouse tibial axial compression loading model in 16 week old female C57BL/6 mice. This finding will help plan future studies aimed at exploring simultaneous lamellar cortical and trabecular bone adaptation within the same loaded element.
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Affiliation(s)
- Alyssa M. Weatherholt
- Center for Translational Musculoskeletal Research, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
| | - Robyn K. Fuchs
- Center for Translational Musculoskeletal Research, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Stuart J. Warden
- Center for Translational Musculoskeletal Research, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Corresponding author: Stuart J. Warden, PT, PhD, FACSM, Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, 1140 W. Michigan Street, CF-326, Indianapolis, IN 46202, USA. Phone: +1-317-278-8401; Fax: +1-317-278-1876;
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Abstract
Bone responds to supraphysiological mechanical loads by increasing bone formation. Depending on the applied strain magnitude (and other loading parameters) the response can be either adaptive (mostly lamellar bone) or injury (mostly woven bone). Seminal studies of Hert, Lanyon, and Rubin originally established the basic "rules" of bone mechanosensitivity. These were reinforced by subsequent studies using non-invasive rodent loading models, most notably by Turner et al. More recent work with these models have been able to explore the structural, transcriptional, and molecular mechanisms which distinguish the two responses (lamellar vs. woven). Wnt/Lrp signaling has emerged as a key mechanoresponsive pathway for lamellar bone. However, there is still much to study with regard to effects of ageing, osteocytes, other signaling pathways, and the molecular regulation that modulates lamellar vs. woven bone formation. This review summarizes not only the historical findings but also the current data for these topics.
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