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Novak S, Tanigawa H, Singh V, Root SH, Schmidt TA, Hankenson KD, Kalajzic I. Endothelial to mesenchymal Notch signaling regulates skeletal repair. JCI Insight 2024; 9:e181073. [PMID: 38781018 DOI: 10.1172/jci.insight.181073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 05/15/2024] [Indexed: 05/25/2024] Open
Abstract
We present a transcriptomic analysis that provides a better understanding of regulatory mechanisms within the healthy and injured periosteum. The focus of this work is on characterizing early events controlling bone healing during formation of periosteal callus on day 3 after fracture. Building on our previous findings showing that induced Notch1 signaling in osteoprogenitors leads to better healing, we compared samples in which the Notch 1 intracellular domain is overexpressed by periosteal stem/progenitor cells, with control intact and fractured periosteum. Molecular mechanisms and changes in skeletal stem/progenitor cells (SSPCs) and other cell populations within the callus, including hematopoietic lineages, were determined. Notably, Notch ligands were differentially expressed in endothelial and mesenchymal populations, with Dll4 restricted to endothelial cells, whereas Jag1 was expressed by mesenchymal populations. Targeted deletion of Dll4 in endothelial cells using Cdh5CreER resulted in negative effects on early fracture healing, while deletion in SSPCs using α-smooth muscle actin-CreER did not impact bone healing. Translating these observations into a clinically relevant model of bone healing revealed the beneficial effects of delivering Notch ligands alongside the osteogenic inducer, BMP2. These findings provide insights into the regulatory mechanisms within the healthy and injured periosteum, paving the way for novel translational approaches to bone healing.
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Affiliation(s)
- Sanja Novak
- Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine, UConn Health, Farmington, Connecticut, USA
| | - Hitoshi Tanigawa
- Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine, UConn Health, Farmington, Connecticut, USA
| | - Vijender Singh
- Institute for Systems Genomics, Computational Biology Core, UConn, Storrs, Connecticut, USA
| | - Sierra H Root
- Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine, UConn Health, Farmington, Connecticut, USA
| | - Tannin A Schmidt
- Biomedical Engineering Department, School of Dental Medicine, UConn Health, Farmington, Connecticut, USA
| | - Kurt D Hankenson
- Department of Orthopaedic Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ivo Kalajzic
- Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine, UConn Health, Farmington, Connecticut, USA
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2
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Xiao CL, Liu LL, Tang W, Liu WY, Wu LY, Zhao K. Reduction of the trans-cortical vessel was associated with bone loss, another underlying mechanism of osteoporosis. Microvasc Res 2024; 152:104650. [PMID: 38123064 DOI: 10.1016/j.mvr.2023.104650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/01/2023] [Accepted: 12/14/2023] [Indexed: 12/23/2023]
Abstract
RATIONALE Numerous studies have established a robust association between bone morrow microvascular diseases and osteoporosis. This study sought to investigate the relationship between alterations in trans-cortical vessel (TCVs) and the onset of osteoporosis in various mouse models. METHODS Aged mice, ovariectomized mice, and db/db mice, were utilized as osteoporosis models. TCVs in the tibia were detected using tissue clearing and light sheet fluorescence microscopy imaging. Femurs bone mass were analyzed using micro-CT scanning. Correlations between the number of TCVs and bone mass were analyzed using Pearson correlation analysis. RESULTS All osteoporosis mouse models showed a significant reduction in the number of TCVs compared to the control group. Correlation analysis revealed a positive association between the number of TCVs and bone mass. TCVs were also expressed high levels of CD31 and EMCN proteins as type H vessels. CONCLUSIONS This study underscores a consistent correlation between the number of TCVs and bone mass. Moreover, TCVs may serve as a potential biomarker for bone mass evaluation.
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Affiliation(s)
- Chun-Lin Xiao
- Department of Orthopaedics, First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, PR China
| | - Lu-Lin Liu
- Department of Orthopaedics, First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, PR China
| | - Wen Tang
- Department of Orthopaedics, First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, PR China
| | - Wu-Yang Liu
- Department of Orthopaedics, First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, PR China
| | - Long-Yan Wu
- Ganzhou People's Hospital, Ganzhou, PR China.
| | - Kai Zhao
- Department of Orthopaedics, First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, PR China; Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China.
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3
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Lv Z, Zhang J, Liang S, Zhou C, Hu D, Brooks DJ, Bouxsein ML, Lanske B, Kostenuik P, Gori F, Baron R. Comparative study in estrogen-depleted mice identifies skeletal and osteocyte transcriptomic responses to abaloparatide and teriparatide. JCI Insight 2023; 8:e161932. [PMID: 37870958 PMCID: PMC10619488 DOI: 10.1172/jci.insight.161932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/08/2023] [Indexed: 10/25/2023] Open
Abstract
Osteocytes express parathyroid hormone (PTH)/PTH-related protein (PTHrP) receptors and respond to the PTHrP analog abaloparatide (ABL) and to the PTH 1-34 fragment teriparatide (TPTD), which are used to treat osteoporosis. Several studies indicate overlapping but distinct skeletal responses to ABL or TPTD, but their effects on cortical bone may differ. Little is known about their differential effects on osteocytes. We compared cortical osteocyte and skeletal responses to ABL and TPTD in sham-operated and ovariectomized mice. Administered 7 weeks after ovariectomy for 4 weeks at a dose of 40 μg/kg/d, TPTD and ABL had similar effects on trabecular bone, but ABL showed stronger effects in cortical bone. In cortical osteocytes, both treatments decreased lacunar area, reflecting altered peri-lacunar remodeling favoring matrix accumulation. Osteocyte RNA-Seq revealed that several genes and pathways were altered by ovariectomy and affected similarly by TPTD and ABL. Notwithstanding, several signaling pathways were uniquely regulated by ABL. Thus, in mice, TPTD and ABL induced a positive osteocyte peri-lacunar remodeling balance, but ABL induced stronger cortical responses and affected the osteocyte transcriptome differently. We concluded that ABL affected the cortical osteocyte transcriptome in a manner subtly different from TPTD, resulting in more beneficial remodeling/modeling changes and homeostasis of the cortex.
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Affiliation(s)
- Zhengtao Lv
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Jiaming Zhang
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Shuang Liang
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Chenhe Zhou
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Dorothy Hu
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Daniel J. Brooks
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Mary L. Bouxsein
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
- Harvard Medical School and Massachusetts General Hospital (MGH) Endocrine Unit, Boston, Massachusetts, USA
| | | | | | - Francesca Gori
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Roland Baron
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
- Harvard Medical School and Massachusetts General Hospital (MGH) Endocrine Unit, Boston, Massachusetts, USA
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4
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Root SH, Vrhovac Madunic I, Kronenberg MS, Cao Y, Novak S, Kalajzic I. Lineage Tracing of RGS5-CreER-Labeled Cells in Long Bones During Homeostasis and Injury. Stem Cells 2023; 41:493-504. [PMID: 36888549 PMCID: PMC10183968 DOI: 10.1093/stmcls/sxad020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 02/21/2023] [Indexed: 03/09/2023]
Abstract
Regulator of G protein signaling 5 (RGS5) is a GTPase activator for heterotrimeric G-protein α-subunits, shown to be a marker of pericytes. Bone marrow stromal cell population (BMSCs) is heterogeneous. Populations of mesenchymal progenitors, cells supportive of hematopoiesis, and stromal cells regulating bone remodeling have been recently identified. Periosteal and bone marrow mesenchymal stem cells (MSCs) are participating in fracture healing, but it is difficult to distinguish the source of cells within the callus. Considering that perivascular cells exert osteoprogenitor potential, we generated an RGS5 transgenic mouse model (Rgs5-CreER) which when crossed with Ai9 reporter animals (Rgs5/Tomato), is suitable for lineage tracing during growth and post-injury. Flow cytometry analysis and histology confirmed the presence of Rgs5/Tomato+ cells within CD31+ endothelial, CD45+ hematopoietic, and CD31-CD45- mesenchymal/perivascular cells. A tamoxifen chase showed expansion of Rgs5/Tomato+ cells expressing osterix within the trabeculae positioned between mineralized matrix and vasculature. Long-term chase showed proportion of Rgs5/Tomato+ cells contributes to mature osteoblasts expressing osteocalcin. Following femoral fracture, Rgs5/Tomato+ cells are observed around newly formed bone within the BM cavity and expressed osterix and osteocalcin, while contribution within periosteum was low and limited to fibroblastic callus with very few positive chondrocytes. In addition, BM injury model confirmed that RGS5-Cre labels population of BMSCs expands during injury and participates in osteogenesis. Under homeostatic conditions, lineage-traced RGS5 cells within the trabecular area demonstrate osteoprogenitor capacity that in an injury model contributes to new bone formation primarily within the BM niche.
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Affiliation(s)
- Sierra H Root
- Center for Regenerative Medicine and Skeletal Development, UConn Health, Farmington, CT, USA
| | - Ivana Vrhovac Madunic
- Center for Regenerative Medicine and Skeletal Development, UConn Health, Farmington, CT, USA
| | - Mark S Kronenberg
- Center for Regenerative Medicine and Skeletal Development, UConn Health, Farmington, CT, USA
| | - Ye Cao
- Center for Regenerative Medicine and Skeletal Development, UConn Health, Farmington, CT, USA
| | - Sanja Novak
- Center for Regenerative Medicine and Skeletal Development, UConn Health, Farmington, CT, USA
| | - Ivo Kalajzic
- Center for Regenerative Medicine and Skeletal Development, UConn Health, Farmington, CT, USA
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Monahan GE, Schiavi-Tritz J, Britton M, Vaughan TJ. Longitudinal alterations in bone morphometry, mechanical integrity and composition in Type-2 diabetes in a Zucker diabetic fatty (ZDF) rat. Bone 2023; 170:116672. [PMID: 36646266 DOI: 10.1016/j.bone.2023.116672] [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: 11/04/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 01/15/2023]
Abstract
Individuals with Type-2 Diabetes (T2D) have an increased risk of bone fracture, without a reduction in bone mineral density. It is hypothesised that the hyperglycaemic state caused by T2D forms an excess of Advanced Glycated End-products (AGEs) in the organic matrix of bone, which are thought to stiffen the collagen network and lead to impaired mechanical properties. However, the mechanisms are not well understood. This study aimed to investigate the geometrical, structural and material properties of diabetic cortical bone during the development and progression of T2D in ZDF (fa/fa) rats at 12-, 26- and 46-weeks of age. Longitudinal bone growth was impaired as early as 12-weeks of age and by 46-weeks bone size was significantly reduced in ZDF (fa/fa) rats versus controls (fa/+). Diabetic rats had significant structural deficits, such as bending rigidity, ultimate moment and energy-to-failure measured via three-point bend testing. Tissue material properties, measured by taking bone geometry into account, were altered as the disease progressed, with significant reductions in yield and ultimate strength for ZDF (fa/fa) rats at 46-weeks. FTIR analysis on cortical bone powder demonstrated that the tissue material deficits coincided with changes in tissue composition, in ZDF (fa/fa) rats with long-term diabetes having a reduced carbonate:phosphate ratio and increased acid phosphate content when compared to age-matched controls, indicative of an altered bone turnover process. AGE accumulation, measured via fluorescent assays, was higher in the skin of ZDF (fa/fa) rats with long-term T2D, bone AGEs did not differ between strains and neither AGEs correlated with bone strength. In conclusion, bone fragility in the diabetic ZDF (fa/fa) rats likely occurs through a multifactorial mechanism influenced initially by impaired bone growth and development and proceeding to an altered bone turnover process that reduces bone quality and impairs biomechanical properties as the disease progresses.
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Affiliation(s)
- Genna E Monahan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, College of Science and Engineering, University of Galway, Galway, Ireland
| | - Jessica Schiavi-Tritz
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, College of Science and Engineering, University of Galway, Galway, Ireland; Laboratoire Réactions et Génie des Procédés, Université de Lorraine, CNRS UMR, 7274 Nancy, France
| | - Marissa Britton
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, College of Science and Engineering, University of Galway, Galway, Ireland
| | - Ted J Vaughan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, College of Science and Engineering, University of Galway, Galway, Ireland.
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6
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Yoshimoto T, Kittaka M, Doan AAP, Urata R, Prideaux M, Rojas RE, Harding CV, Henry Boom W, Bonewald LF, Greenfield EM, Ueki Y. Osteocytes directly regulate osteolysis via MYD88 signaling in bacterial bone infection. Nat Commun 2022; 13:6648. [PMID: 36333322 PMCID: PMC9636212 DOI: 10.1038/s41467-022-34352-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022] Open
Abstract
The impact of bone cell activation on bacterially-induced osteolysis remains elusive. Here, we show that matrix-embedded osteocytes stimulated with bacterial pathogen-associated molecular patterns (PAMPs) directly drive bone resorption through an MYD88-regulated signaling pathway. Mice lacking MYD88, primarily in osteocytes, protect against osteolysis caused by calvarial injections of bacterial PAMPs and resist alveolar bone resorption induced by oral Porphyromonas gingivalis (Pg) infection. In contrast, mice with targeted MYD88 restoration in osteocytes exhibit osteolysis with inflammatory cell infiltration. In vitro, bacterial PAMPs induce significantly higher expression of the cytokine RANKL in osteocytes than osteoblasts. Mechanistically, activation of the osteocyte MYD88 pathway up-regulates RANKL by increasing binding of the transcription factors CREB and STAT3 to Rankl enhancers and by suppressing K48-ubiquitination of CREB/CREB binding protein and STAT3. Systemic administration of an MYD88 inhibitor prevents jawbone loss in Pg-driven periodontitis. These findings reveal that osteocytes directly regulate inflammatory osteolysis in bone infection, suggesting that MYD88 and downstream RANKL regulators in osteocytes are therapeutic targets for osteolysis in periodontitis and osteomyelitis.
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Affiliation(s)
- Tetsuya Yoshimoto
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202-5126, USA
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Mizuho Kittaka
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202-5126, USA
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Andrew Anh Phuong Doan
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202-5126, USA
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Rina Urata
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202-5126, USA
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Matthew Prideaux
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | | | - Clifford V Harding
- Department of Pathology, Case Western Reserve University & University Hospitals Cleveland Medical Center, Cleveland, OH, 44106-4960, USA
| | - W Henry Boom
- Department of Pathology, Case Western Reserve University & University Hospitals Cleveland Medical Center, Cleveland, OH, 44106-4960, USA
- Department of Medicine, Case Western Reserve University & University Hospitals Cleveland Medical Center, Cleveland, OH, 44106-4960, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University & University Hospitals Cleveland Medical Center, Cleveland, OH, 44106-4960, USA
| | - Lynda F Bonewald
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Edward M Greenfield
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Yasuyoshi Ueki
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202-5126, USA.
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA.
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7
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Isojima T, Walker EC, Poulton IJ, McGregor NE, Wicks IP, Gooi JH, Martin TJ, Sims NA. G-CSF Receptor Deletion Amplifies Cortical Bone Dysfunction in Mice With STAT3 Hyperactivation in Osteocytes. J Bone Miner Res 2022; 37:1876-1890. [PMID: 35856245 DOI: 10.1002/jbmr.4654] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 06/27/2022] [Accepted: 07/16/2022] [Indexed: 11/09/2022]
Abstract
Bone strength is determined by the structure and composition of its thickened outer shell (cortical bone), yet the mechanisms controlling cortical consolidation are poorly understood. Cortical bone maturation depends on SOCS3-mediated suppression of IL-6 cytokine-induced STAT3 phosphorylation in osteocytes, the cellular network embedded in bone matrix. Because SOCS3 also suppresses granulocyte-colony-stimulating factor receptor (G-CSFR) signaling, we here tested whether global G-CSFR (Csf3r) ablation altereed bone structure in male and female mice lacking SOCS3 in osteocytes, (Dmp1Cre :Socs3f/f mice). Dmp1Cre :Socs3f/f :Csf3r-/- mice were generated by crossing Dmp1Cre :Socs3f/f mice with Csf3r-/- mice. Although G-CSFR is not expressed in osteocytes, Csf3r deletion further delayed cortical consolidation in Dmp1Cre :Socs3f/f mice. Micro-CT images revealed extensive, highly porous low-density bone, with little true cortex in the diaphysis, even at 26 weeks of age; including more low-density bone and less high-density bone in Dmp1Cre :Socs3f/f :Csf3r-/- mice than controls. By histology, the area where cortical bone would normally be found contained immature compressed trabecular bone in Dmp1Cre :Socs3f/f :Csf3r-/- mice and greater than normal levels of intracortical osteoclasts, extensive new woven bone formation, and the presence of more intracortical blood vessels than the already high levels observed in Dmp1Cre :Socs3f/f controls. qRT-PCR of cortical bone from Dmp1Cre :Socs3f/f :Csf3r-/- mice also showed more than a doubling of mRNA levels for osteoclasts, osteoblasts, RANKL, and angiogenesis markers. The further delay in cortical bone maturation was associated with significantly more phospho-STAT1 and phospho-STAT3-positive osteocytes, and a threefold increase in STAT1 and STAT3 target gene mRNA levels, suggesting G-CSFR deletion further increases STAT signaling beyond that of Dmp1Cre :Socs3f/f bone. G-CSFR deficiency therefore promotes STAT1/3 signaling in osteocytes, and when SOCS3 negative feedback is absent, elevated local angiogenesis, bone resorption, and bone formation delays cortical bone consolidation. This points to a critical role of G-CSF in replacing condensed trabecular bone with lamellar bone during cortical bone formation. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Tsuyoshi Isojima
- St. Vincent's Institute of Medical Research, Fitzroy, Australia.,Department of Pediatrics, Teikyo University School of Medicine, Tokyo, Japan
| | - Emma C Walker
- St. Vincent's Institute of Medical Research, Fitzroy, Australia
| | | | | | - Ian P Wicks
- Walter and Eliza Hall Institute, Parkville, Australia
| | - Jonathan H Gooi
- St. Vincent's Institute of Medical Research, Fitzroy, Australia.,Bio21 Molecular Science and Biotechnology Institute, Parkville, Australia
| | - T John Martin
- St. Vincent's Institute of Medical Research, Fitzroy, Australia.,The University of Melbourne, Department of Medicine at St. Vincent's Hospital, Fitzroy, Australia
| | - Natalie A Sims
- St. Vincent's Institute of Medical Research, Fitzroy, Australia.,The University of Melbourne, Department of Medicine at St. Vincent's Hospital, Fitzroy, Australia
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Maruoka H, Yamamoto T, Zhao S, Hongo H, Abe M, Ishizu H, Yoshino H, Luiz de Freitas PH, Li M, Hasegawa T. Histological functions of parathyroid hormone on bone formation and bone blood vessels. J Oral Biosci 2022; 64:279-286. [PMID: 35977651 DOI: 10.1016/j.job.2022.08.002] [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: 07/24/2022] [Revised: 08/05/2022] [Accepted: 07/26/2022] [Indexed: 10/15/2022]
Abstract
BACKGROUND The intermittent administration of parathyroid hormone (PTH) has been prescribed to osteoporotic patients due to its bone anabolic effects. In addition to its actions on bone cells, PTH appears to affect bone-specific blood vessels. These blood vessels are derived from bone marrow sinusoids, which express EphB4, a hallmark of veinous vascular endothelial cells. Given the presence of osteo-vascular interactions, it is important to elucidate the effects of PTH on bone cells and blood vessels in murine models. HIGHLIGHTS PTH stimulates preosteoblastic proliferation and osteoblastic bone formation. The former appears to be directly affected by PTH, whereas the latter requires osteoclast-mediated coupling. The administration of PTH through high-frequency dosage schemes accelerates bone turnover featuring remodeling-based bone formation, whereas low-frequency schemes cause mainly remodeling-based and partly modeling-based bone formation. Normally, many blood vessels lack alpha smooth muscle actin (αSMA)-immunoreactive vascular muscle cells surrounding basement membranes, indicating them being capillaries. However, PTH administration increases the number of blood vessels surrounded by αSMA-positive cells. These αSMA-positive cells spread out of blood vessels and express alkaline phosphatase and c-kit, suggesting their potential to differentiate into osteogenic and vascular endothelial/perivascular cells. Unlike bone cells, αSMA-positive cells did not appear in the periphery of blood vessels in the kidney and liver, and the thickness of the tunica media did not change regardless of PTH administration. CONCLUSION Based on the results of the study and presence of osseous-vascular interactions, PTH appears to influence not only osteoblastic cells, but also blood vessels in bone.
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Affiliation(s)
- Haruhi Maruoka
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine
| | - Tomomaya Yamamoto
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine; Northern Army Medical Unit, Camp Makomanai, Japan Ground Self-Defense Forces, Sapporo, Japan
| | - Shen Zhao
- Department of Endodontics & Conservative Dentistry, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hiromi Hongo
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine
| | - Miki Abe
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine
| | - Hotaka Ishizu
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine; Orthopedic Surgery, Graduate School of Medicine, And Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Hirona Yoshino
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine
| | | | - Minqi Li
- Shandong Provincial Key Laboratory of Oral Biomedicine, The School of Stomatology, Shandong University, Jinan, China
| | - Tomoka Hasegawa
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, And Faculty of Dental Medicine.
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9
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Chen R, Baron R, Gori F. Sfrp4 and the Biology of Cortical Bone. Curr Osteoporos Rep 2022; 20:153-161. [PMID: 35182301 PMCID: PMC9098678 DOI: 10.1007/s11914-022-00727-w] [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] [Accepted: 12/03/2021] [Indexed: 11/03/2022]
Abstract
PURPOSE OF REVIEW Periosteal apposition and endosteal remodeling regulate cortical bone expansion and thickness, both critical determinants of bone strength. Yet, the cellular characteristics and local or paracrine factors that regulate the periosteum and endosteum remain largely elusive. Here we discuss novel insights in cortical bone growth, expansion, and homeostasis, provided by the study of Secreted Frizzled Receptor Protein 4 (Sfrp4), a decoy receptor for Wnt ligands. RECENT FINDINGS SFRP4 loss-of function mutations cause Pyle disease, a rare skeletal disorder characterized by cortical bone thinning and increased fragility fractures despite increased trabecular bone density. On the endosteal surface, Sfrp4-mediated repression of non-canonical Wnt signaling regulates endosteal resorption. On the periosteum, Sfrp4 identifies as a critical functional mediator of periosteal stem cell/progenitor expansion and differentiation. Analysis of signaling pathways regulating skeletal stem cells/progenitors provides an opportunity to advance our understanding of the mechanisms involved in cortical bone biology.
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Affiliation(s)
- Ruiying Chen
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
| | - Roland Baron
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital and Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Francesca Gori
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.
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10
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Buettmann EG, Yoneda S, Hu P, McKenzie JA, Silva MJ. Postnatal Osterix but not DMP1 lineage cells significantly contribute to intramembranous ossification in three preclinical models of bone injury. Front Physiol 2022; 13:1083301. [PMID: 36685200 PMCID: PMC9846510 DOI: 10.3389/fphys.2022.1083301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/02/2022] [Indexed: 01/06/2023] Open
Abstract
Murine models of long-bone fracture, stress fracture, and cortical defect are used to discern the cellular and molecular mediators of intramembranous and endochondral bone healing. Previous work has shown that Osterix (Osx+) and Dentin Matrix Protein-1 (DMP1+) lineage cells and their progeny contribute to injury-induced woven bone formation during femoral fracture, ulnar stress fracture, and tibial cortical defect repair. However, the contribution of pre-existing versus newly-derived Osx+ and DMP1+ lineage cells in these murine models of bone injury is unclear. We addressed this knowledge gap by using male and female 12-week-old, tamoxifen-inducible Osx Cre_ERT2 and DMP1 Cre_ERT2 mice harboring the Ai9 TdTomato reporter allele. To trace pre-existing Osx+ and DMP1+ lineage cells, tamoxifen (TMX: 100 mg/kg gavage) was given in a pulse manner (three doses, 4 weeks before injury), while to label pre-existing and newly-derived lineage Osx+ and DMP1+ cells, TMX was first given 2 weeks before injury and continuously (twice weekly) throughout healing. TdTomato positive (TdT+) cell area and cell fraction were quantified from frozen histological sections of injured and uninjured contralateral samples at times corresponding with active woven bone formation in each model. We found that in uninjured cortical bone tissue, Osx Cre_ERT2 was more efficient than DMP1 Cre_ERT2 at labeling the periosteal and endosteal surfaces, as well as intracortical osteocytes. Pulse-labeling revealed that pre-existing Osx+ lineage and their progeny, but not pre-existing DMP1+ lineage cells and their progeny, significantly contributed to woven bone formation in all three injury models. In particular, these pre-existing Osx+ lineage cells mainly lined new woven bone surfaces and became embedded as osteocytes. In contrast, with continuous dosing, both Osx+ and DMP1+ lineage cells and their progeny contributed to intramembranous woven bone formation, with higher TdT+ tissue area and cell fraction in Osx+ lineage versus DMP1+ lineage calluses (femoral fracture and ulnar stress fracture). Similarly, Osx+ and DMP1+ lineage cells and their progeny significantly contributed to endochondral callus regions with continuous dosing only, with higher TdT+ chondrocyte fraction in Osx+ versus DMP1+ cell lineages. In summary, pre-existing Osx+ but not DMP1+ lineage cells and their progeny make up a significant amount of woven bone cells (particularly osteocytes) across three preclinical models of bone injury. Therefore, Osx+ cell lineage modulation may prove to be an effective therapy to enhance bone regeneration.
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Affiliation(s)
- Evan G Buettmann
- Department of Orthopaedic Surgery, Washington University in St. Louis School of Medicine, St. Louis, MO, United States.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States.,Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - Susumu Yoneda
- Department of Orthopaedic Surgery, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
| | - Pei Hu
- Department of Orthopaedic Surgery, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
| | - Jennifer A McKenzie
- Department of Orthopaedic Surgery, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
| | - Matthew J Silva
- Department of Orthopaedic Surgery, Washington University in St. Louis School of Medicine, St. Louis, MO, United States.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
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11
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Wee NK, Sims NA, Morello R. The Osteocyte Transcriptome: Discovering Messages Buried Within Bone. Curr Osteoporos Rep 2021; 19:604-615. [PMID: 34757588 PMCID: PMC8720072 DOI: 10.1007/s11914-021-00708-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/24/2021] [Indexed: 12/16/2022]
Abstract
PURPOSE OF THE REVIEW Osteocytes are cells embedded within the bone matrix, but their function and specific patterns of gene expression remain only partially defined; this is beginning to change with recent studies using transcriptomics. This unbiased approach can generate large amounts of data and is now being used to identify novel genes and signalling pathways within osteocytes both at baseline conditions and in response to stimuli. This review outlines the methods used to isolate cell populations containing osteocytes, and key recent transcriptomic studies that used osteocyte-containing preparations from bone tissue. RECENT FINDINGS Three common methods are used to prepare samples to examine osteocyte gene expression: digestion followed by sorting, laser capture microscopy, and the isolation of cortical bone shafts. All these methods present challenges in interpreting the data generated. Genes previously not known to be expressed by osteocytes have been identified and variations in osteocyte gene expression have been reported with age, sex, anatomical location, mechanical loading, and defects in bone strength. A substantial proportion of newly identified transcripts in osteocytes remain functionally undefined but several have been cross-referenced with functional data. Future work and improved methods (e.g. scRNAseq) likely provide useful resources for the study of osteocytes and important new information on the identity and functions of this unique cell type within the skeleton.
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Affiliation(s)
- Natalie Ky Wee
- Bone Cell Biology and Disease Unit, St Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, 3065, Australia
| | - Natalie A Sims
- Bone Cell Biology and Disease Unit, St Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, 3065, Australia
- Department of Medicine, The University of Melbourne, St. Vincent's Hospital, Melbourne, 3065, Australia
| | - Roy Morello
- Department of Physiology & Cell Biology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
- Division of Genetics, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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12
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Isojima T, Sims NA. Cortical bone development, maintenance and porosity: genetic alterations in humans and mice influencing chondrocytes, osteoclasts, osteoblasts and osteocytes. Cell Mol Life Sci 2021; 78:5755-5773. [PMID: 34196732 PMCID: PMC11073036 DOI: 10.1007/s00018-021-03884-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/06/2021] [Accepted: 06/21/2021] [Indexed: 12/13/2022]
Abstract
Cortical bone structure is a crucial determinant of bone strength, yet for many years studies of novel genes and cell signalling pathways regulating bone strength have focused on the control of trabecular bone mass. Here we focus on mechanisms responsible for cortical bone development, growth, and degeneration, and describe some recently described genetic-driven modifications in humans and mice that reveal how these processes may be controlled. We start with embryonic osteogenesis of preliminary bone structures preceding the cortex and describe how this structure consolidates then matures to a dense, vascularised cortex containing an increasing proportion of lamellar bone. These processes include modelling-induced, and load-dependent, asymmetric cortical expansion, which enables the cortex's transition from a highly porous woven structure to a consolidated and thickened highly mineralised lamellar bone structure, infiltrated by vascular channels. Sex-specific differences emerge during this process. With aging, the process of consolidation reverses: cortical pores enlarge, leading to greater cortical porosity, trabecularisation and loss of bone strength. Each process requires co-ordination between bone formation, bone mineralisation, vascularisation, and bone resorption, with a need for locational-, spatial- and cell-specific signalling pathways to mediate this co-ordination. We will discuss these processes, and a number of cell-signalling pathways identified in both murine and human genetic studies to regulate cortical bone mass, including signalling through gp130, STAT3, PTHR1, WNT16, NOTCH, NOTUM and sFRP4.
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Affiliation(s)
- Tsuyoshi Isojima
- St. Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, VIC, 3122, Australia
- Department of Pediatrics, Teikyo University School of Medicine, Tokyo, Japan
| | - Natalie A Sims
- St. Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, VIC, 3122, Australia.
- Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, VIC, Australia.
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13
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Mizoguchi T, Ono N. The diverse origin of bone-forming osteoblasts. J Bone Miner Res 2021; 36:1432-1447. [PMID: 34213032 PMCID: PMC8338797 DOI: 10.1002/jbmr.4410] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 06/29/2021] [Accepted: 06/29/2021] [Indexed: 12/17/2022]
Abstract
Osteoblasts are the only cells that can give rise to bones in vertebrates. Thus, one of the most important functions of these metabolically active cells is mineralized matrix production. Because osteoblasts have a limited lifespan, they must be constantly replenished by preosteoblasts, their immediate precursors. Because disruption of the regulation of bone-forming osteoblasts results in a variety of bone diseases, a better understanding of the origin of these cells by defining the mechanisms of bone development, remodeling, and regeneration is central to the development of novel therapeutic approaches. In recent years, substantial new insights into the origin of osteoblasts-largely owing to rapid technological advances in murine lineage-tracing approaches and other single-cell technologies-have been obtained. Collectively, these findings indicate that osteoblasts involved in bone formation under various physiological, pathological, and therapeutic conditions can be obtained from numerous sources. The origins of osteoblasts include, but are not limited to, chondrocytes in the growth plate, stromal cells in the bone marrow, quiescent bone-lining cells on the bone surface, and specialized fibroblasts in the craniofacial structures, such as sutures and periodontal ligaments. Because osteoblasts can be generated from local cellular sources, bones can flexibly respond to regenerative and anabolic cues. However, whether osteoblasts derived from different cellular sources have distinct functions remains to be investigated. Currently, we are at the initial stage to aptly unravel the incredible diversity of the origins of bone-forming osteoblasts. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
| | - Noriaki Ono
- University of Texas Health Science Center at Houston School of Dentistry, Houston, TX, USA
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Acid Dentin Lysate Failed to Modulate Bone Formation in Rat Calvaria Defects. BIOLOGY 2021; 10:biology10030196. [PMID: 33807565 PMCID: PMC7999213 DOI: 10.3390/biology10030196] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 12/19/2022]
Abstract
Autogenous tooth roots are increasingly applied as a grafting material in alveolar bone augmentation. Since tooth roots undergo creeping substitution similar to bone grafts, it can be hypothesized that osteoclasts release the growth factors stored in the dentin thereby influencing bone formation. To test this hypothesis, collagen membranes were either soaked in acid dentin lysates (ADL) from extracted porcine teeth or serum-free medium followed by lyophilization. Thereafter, these membranes covered standardized 5-mm-diameter critical-size defects in calvarial bone on rats. After four weeks of healing, micro-computed tomography and histological analyses using undecalcified thin ground sections were performed. Micro-computed tomography of the inner 4.5 mm calvaria defects revealed a median bone defect coverage of 91% (CI: 87-95) in the ADL group and 94% (CI: 65-100) in the control group, without significant differences between the groups (intergroup p > 0.05). Furthermore, bone volume (BV) was similar between ADL group (5.7 mm3, CI: 3.4-7.1) and control group (5.7 mm3, CI: 2.9-9.7). Histomorphometry of the defect area confirmed these findings with bone area values amounting to 2.1 mm2 (CI: 1.2-2.6) in the ADL group and 2.0 mm2 (CI: 1.1-3.0) in the control group. Together, these data suggest that acid dentin lysate lyophilized onto collagen membranes failed to modulate the robust bone formation when placed onto calvarial defects.
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Zhao S, Hasegawa T, Hongo H, Yamamoto T, Abe M, Yoshida T, Haraguchi M, de Freitas PHL, Li M, Tei K, Amizuka N. Intermittent PTH Administration Increases Bone-Specific Blood Vessels and Surrounding Stromal Cells in Murine Long Bones. Calcif Tissue Int 2021; 108:391-406. [PMID: 33170307 DOI: 10.1007/s00223-020-00776-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/29/2020] [Indexed: 12/28/2022]
Abstract
To verify whether PTH acts on bone-specific blood vessels and on cells surrounding these blood vessels, 6-week-old male mice were subjected to vehicle (control group) or hPTH [1-34] (20 µg/kg/day, PTH group) injections for 2 weeks. Femoral metaphyses were used for histochemical and immunohistochemical studies. In control metaphyses, endomucin-positive blood vessels were abundant, but αSMA-reactive blood vessels were scarce. In the PTH-administered mice, the lumen of endomucin-positive blood vessels was markedly enlarged. Moreover, many αSMA-positive cells were evident near the blood vessels, and seemed to derive from those vessels. These αSMA-positive cells neighboring the blood vessels showed features of mesenchymal stromal cells, such as immunopositivity for c-kit and tissue nonspecific alkaline phosphatase (TNALP). Thus, PTH administration increased the population of perivascular/stromal cells positive for αSMA and c-kit, which were likely committed to the osteoblastic lineage. To understand the cellular events that led to increased numbers and size of bone-specific blood vessels, we performed immunohistochemical studies for PTH/PTHrP receptor and VEGF. After PTH administration, PTH/PTHrP receptor, VEGF and its receptor flk-1 were consistently identified in both osteoblasts and blood vessels (endothelial cells and surrounding perivascular cells). Our findings suggest that exogenous PTH increases the number and size of bone-specific blood vessels while fostering perivascular/stromal cells positive for αSMA/TNALP/c-kit.
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Affiliation(s)
- Shen Zhao
- National Clinical Research Center of Stomatology, Department of Endodontics, School of Medicine, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Ninth People's Hospital, Shanghai Jiaotong University, Shanghai, China
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan
- Oral and Maxillofacial Surgery, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Tomoka Hasegawa
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan.
| | - Hiromi Hongo
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan
| | - Tomomaya Yamamoto
- Section of Dentistry, Camp Asaka, Japan Ground Self-Defense Forces, Tokyo, Japan
| | - Miki Abe
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan
| | - Taiji Yoshida
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan
| | - Mai Haraguchi
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan
| | | | - Minqi Li
- Shandong Provincial Key Laboratory of Oral Biomedicine, The School of Stomatology, Shandong University, Jinan, China
| | - Kanchu Tei
- Oral and Maxillofacial Surgery, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Norio Amizuka
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan
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16
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Cao Y, Buckels EJ, Matthews BG. Markers for Identification of Postnatal Skeletal Stem Cells In Vivo. Curr Osteoporos Rep 2020; 18:655-665. [PMID: 33034805 DOI: 10.1007/s11914-020-00622-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW The adult skeleton contains stem cells involved in growth, homeostasis, and healing. Mesenchymal or skeletal stem cells are proposed to provide precursors to osteoblasts, chondrocytes, marrow adipocytes, and stromal cells. We review the evidence for existence and functionality of different skeletal stem cell pools, and the tools available for identifying or targeting these populations in mouse and human tissues. RECENT FINDINGS Lineage tracing and single cell-based techniques in mouse models indicate that multiple pools of stem cells exist in postnatal bone. These include growth plate stem cells, stem and progenitor cells in the diaphysis, reticular cells that only form bone in response to injury, and injury-responsive periosteal stem cells. New staining protocols have also been described for prospective isolation of human skeletal stem cells. Several populations of postnatal skeletal stem and progenitor cells have been identified in mice, and we have an increasing array of tools to target these cells. Most Cre models lack a high degree of specificity to define single populations. Human studies are less advanced and require further efforts to refine methods for identifying stem and progenitor cells in adult bone.
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Affiliation(s)
- Ye Cao
- Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92-019, Auckland, 1142, New Zealand
| | - Emma J Buckels
- Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92-019, Auckland, 1142, New Zealand
| | - Brya G Matthews
- Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92-019, Auckland, 1142, New Zealand.
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Influence of the TGF-β Superfamily on Osteoclasts/Osteoblasts Balance in Physiological and Pathological Bone Conditions. Int J Mol Sci 2020; 21:ijms21207597. [PMID: 33066607 PMCID: PMC7589189 DOI: 10.3390/ijms21207597] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/09/2020] [Accepted: 10/10/2020] [Indexed: 12/19/2022] Open
Abstract
The balance between bone forming cells (osteoblasts/osteocytes) and bone resorbing cells (osteoclasts) plays a crucial role in tissue homeostasis and bone repair. Several hormones, cytokines, and growth factors-in particular the members of the TGF-β superfamily such as the bone morphogenetic proteins-not only regulate the proliferation, differentiation, and functioning of these cells, but also coordinate the communication between them to ensure an appropriate response. Therefore, this review focuses on TGF-β superfamily and its influence on bone formation and repair, through the regulation of osteoclastogenesis, osteogenic differentiation of stem cells, and osteoblasts/osteoclasts balance. After introducing the main types of bone cells, their differentiation and cooperation during bone remodeling and fracture healing processes are discussed. Then, the TGF-β superfamily, its signaling via canonical and non-canonical pathways, as well as its regulation by Wnt/Notch or microRNAs are described and discussed. Its important role in bone homeostasis, repair, or disease is also highlighted. Finally, the clinical therapeutic uses of members of the TGF-β superfamily and their associated complications are debated.
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18
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Lukač N, Katavić V, Novak S, Šućur A, Filipović M, Kalajzić I, Grčević D, Kovačić N. What do we know about bone morphogenetic proteins and osteochondroprogenitors in inflammatory conditions? Bone 2020; 137:115403. [PMID: 32371019 DOI: 10.1016/j.bone.2020.115403] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 04/10/2020] [Accepted: 04/28/2020] [Indexed: 02/07/2023]
Abstract
Osteochondroprogenitors are crucial for embryonic bone development and postnatal processes such as bone repair in response to fracture injury, and their dysfunction may contribute to insufficient repair of structural damage in inflammatory arthritides. In the fracture healing, the early inflammatory phase is crucial for normal callus development and new bone formation. This process involves a complex interplay of many molecules and cell types, responsible for recruitment, expansion and differentiation of osteochondroprogenitor populations. In inflammatory arthritides, inflammation induces bone resorption and causes insufficient bone formation, which leads to local and systemic bone loss. While bone loss is a predominant feature in rheumatoid arthritis, inflammation also induces pathologic bone formation at enthesial sites in seronegative spondyloarthropathies. Bone morphogenetic proteins (BMP) are involved in cell proliferation, differentiation and apoptosis, and have fundamental roles in maintenance of postnatal bone homeostasis. They are crucial regulators of the osteochondroprogenitor pool and drive their proliferation, differentiation, and lifespan during bone regeneration. In this review, we summarize the effects of inflammation on osteochondroprogenitor populations during fracture repair and in inflammatory arthritides, with special focus on inflammation-mediated modulation of BMP signaling. We also present data in which we describe a population of murine synovial osteochondroprogenitor cells, which are reduced in arthritis, and characterize their expression of genes involved in regulation of bone homeostasis, emphasizing the up-regulation of BMP pathways in early progenitor subset. Based on the presented data, it may be concluded that during an inflammatory response, innate immune cells induce osteochondroprogenitors by providing signals for their recruitment, by producing BMPs and other osteogenic factors for paracrine effects, and by secreting inflammatory cytokines that may positively regulate osteogenic pathways. On the other hand, inflammatory cells may secrete cytokines that interfere with osteogenic pathways, proapoptotic factors that reduce the pool of osteochondroprogenitor cells, as well as BMP and Wnt antagonists. The net effect is strongly context-dependent and influenced by the local milieu of cells, cytokines, and growth factors. Further elucidation of the interplay between inflammatory signals and BMP-mediated bone formation may provide valuable tools for therapeutic targeting.
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Affiliation(s)
- Nina Lukač
- Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Anatomy, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Vedran Katavić
- Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Anatomy, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Sanja Novak
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT, USA
| | - Alan Šućur
- Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Physiology and Immunology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Maša Filipović
- Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Physiology and Immunology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Ivo Kalajzić
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT, USA
| | - Danka Grčević
- Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Physiology and Immunology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Nataša Kovačić
- Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Anatomy, University of Zagreb School of Medicine, Zagreb, Croatia.
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