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Coulombe JC, Maridas DE, Chow JL, Bouxsein ML. Small animal DXA instrument comparison and validation. Bone 2024; 178:116923. [PMID: 37778596 DOI: 10.1016/j.bone.2023.116923] [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: 08/15/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 10/03/2023]
Abstract
Several new peripheral dual-energy X-ray absorptiometry (DXA) devices designed for assessment of bone and body composition in rodents have been developed. We compared the performance (accuracy and precision) of two of these devices, the InAlyzer and the iNSiGHT, to those of an established device, the PIXImus. We measured total body bone mineral content (BMC), bone mineral density (BMD), and body composition (lean and fat mass) on the three DXA devices in 18 male C57Bl/6 J mice (6 each of ages 8, 14, and 24 weeks, weighing 22 to 33 g). DXA body composition measures were compared to whole-body nuclear magnetic resonance (NMR) outcomes. BMC of the femur was also compared to ex vivo micro-computed tomography (microCT). Total body BMD from the InAlyzer and iNSiGHT devices was strongly correlated to that from PIXImus (R2 = 0.83 and 0.82, respectively), but was ~25 % higher than PIXImus. Total body BMC measures by InAlyzer were strongly associated with those from PIXImus (R2 = 0.86), whereas those from iNSiGHT were only weakly correlated (R2 = 0.29). Femur BMC from InAlyzer was strongly correlated with microCT outcomes, whereas iNSiGHT was only weakly correlated. InAlyzer and iNSiGHT fat mass measures were very strongly correlated with PIXImus and NMR outcomes (R2 = 0.91 to 0.97), with slightly weaker associations for lean mass (R2 = 0.81 to 0.76). Short-term precision of InAlyzer and iNSiGHT measurements were excellent, and akin to those from the PIXImus for both body composition and bone measures, ranging between 0.39 and 3.2 %. With faster scan times, closed X-ray source and excellent precision, the new devices are both satisfactory replacements for the now discontinued PIXImus system. However, given the accuracy of the bone and body composition measures, the InAlyzer may be preferable for studies where musculoskeletal changes are the main interest.
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Affiliation(s)
- Jennifer C Coulombe
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Harvard Medical School, Boston, MA, United States of America
| | | | - Jarred L Chow
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Boston, MA, United States of America
| | - Mary L Bouxsein
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Harvard Medical School, Boston, MA, United States of America.
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Kim SP, Seward AH, Garcia-Diaz J, Alekos N, Gould NR, Aja S, Stains JP, Wolfgang MJ, Riddle RC. Peroxisome proliferator activated receptor-γ in osteoblasts controls bone formation and fat mass by regulating sclerostin expression. iScience 2023; 26:106999. [PMID: 37534168 PMCID: PMC10391670 DOI: 10.1016/j.isci.2023.106999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/01/2023] [Accepted: 05/25/2023] [Indexed: 08/04/2023] Open
Abstract
The nuclear receptor peroxisome proliferator activated receptor-γ (PPARγ) is a key contributor to metabolic function via its adipogenic and insulin-sensitizing functions, but it has negative effects on skeletal homeostasis. Here, we questioned whether the skeletal and metabolic actions of PPARγ are linked. Ablating Pparg expression in osteoblasts and osteocytes produced a high bone mass phenotype, secondary to increased osteoblast activity, and a reduction in subcutaneous fat mass because of reduced fatty acid synthesis and increased fat oxidation. The skeletal and metabolic phenotypes in Pparg mutants proceed from the regulation of sclerostin production by PPARγ. Mutants exhibited reductions in skeletal Sost expression and serum sclerostin levels while increasing production normalized both phenotypes. Importantly, disrupting the production of sclerostin synergized with the insulin-sensitizing actions of a PPARγ agonist while preventing bone loss. These data suggest that modulating sclerostin action may prevent bone loss associated with anti-diabetic therapies and augment their metabolic actions.
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Affiliation(s)
- Soohyun P. Kim
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Avery H. Seward
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jean Garcia-Diaz
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nathalie Alekos
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nicole R. Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Susan Aja
- Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michael J. Wolfgang
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ryan C. Riddle
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Research and Development Service, Baltimore Veterans Administration Medical Center, Baltimore, MD 21201, USA
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Mo C, Guo J, Qin J, Zhang X, Sun Y, Wei H, Cao D, Zhang Y, Zhao C, Xiong Y, Zhang Y, Sun Y, Shen L, Yue R. Single-cell transcriptomics of LepR-positive skeletal cells reveals heterogeneous stress-dependent stem and progenitor pools. EMBO J 2022; 41:e108415. [PMID: 34957577 PMCID: PMC8844986 DOI: 10.15252/embj.2021108415] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 12/31/2022] Open
Abstract
Leptin receptor (LepR)-positive cells are key components of the bone marrow hematopoietic microenvironment, and highly enrich skeletal stem and progenitor cells that maintain homeostasis of the adult skeleton. However, the heterogeneity and lineage hierarchy within this population has been elusive. Using genetic lineage tracing and single-cell RNA sequencing, we found that Lepr-Cre labels most bone marrow stromal cells and osteogenic lineage cells in adult long bones. Integrated analysis of Lepr-Cre-traced cells under homeostatic and stress conditions revealed dynamic changes of the adipogenic, osteogenic, and periosteal lineages. Importantly, we discovered a Notch3+ bone marrow sub-population that is slow-cycling and closely associated with the vasculatures, as well as key transcriptional networks promoting osteo-chondrogenic differentiation. We also identified a Sca-1+ periosteal sub-population with high clonogenic activity but limited osteo-chondrogenic potential. Together, we mapped the transcriptomic landscape of adult LepR+ stem and progenitor cells and uncovered cellular and molecular mechanisms underlying their maintenance and lineage specification.
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Affiliation(s)
- Chunyang Mo
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Jingxin Guo
- MOE Key Laboratory of Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences InstituteZhejiang UniversityHangzhouChina
- Department of Orthopedics Surgery2nd Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhouChina
| | - Jiachen Qin
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Xiaoying Zhang
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Yuxi Sun
- Department of CardiologyShanghai Tenth People's HospitalTongji University School of MedicineShanghaiChina
| | - Hanjing Wei
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Dandan Cao
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Yiying Zhang
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Chengchen Zhao
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Yanhong Xiong
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Yong Zhang
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
| | - Yao Sun
- Department of ImplantologySchool & Hospital of StomatologyShanghai Engineering Research Center of Tooth Restoration and RegenerationTongji UniversityShanghaiChina
| | - Li Shen
- MOE Key Laboratory of Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences InstituteZhejiang UniversityHangzhouChina
- Department of Orthopedics Surgery2nd Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhouChina
- Hangzhou Innovation CenterZhejiang UniversityHangzhouChina
| | - Rui Yue
- Institute for Regenerative MedicineShanghai East HospitalFrontier Science Center for Stem Cell ResearchShanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghaiChina
- Shanghai Institute of Stem Cell Research and Clinical TranslationShanghaiChina
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Abstract
Osteocytes, former osteoblasts encapsulated by mineralized bone matrix, are far from being passive and metabolically inactive bone cells. Instead, osteocytes are multifunctional and dynamic cells capable of integrating hormonal and mechanical signals and transmitting them to effector cells in bone and in distant tissues. Osteocytes are a major source of molecules that regulate bone homeostasis by integrating both mechanical cues and hormonal signals that coordinate the differentiation and function of osteoclasts and osteoblasts. Osteocyte function is altered in both rare and common bone diseases, suggesting that osteocyte dysfunction is directly involved in the pathophysiology of several disorders affecting the skeleton. Advances in osteocyte biology initiated the development of novel therapeutics interfering with osteocyte-secreted molecules. Moreover, osteocytes are targets and key distributors of biological signals mediating the beneficial effects of several bone therapeutics used in the clinic. Here we review the most recent discoveries in osteocyte biology demonstrating that osteocytes regulate bone homeostasis and bone marrow fat via paracrine signaling, influence body composition and energy metabolism via endocrine signaling, and contribute to the damaging effects of diabetes mellitus and hematologic and metastatic cancers in the skeleton.
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Affiliation(s)
- Jesus Delgado-Calle
- 1Department of Physiology and Cell Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas,2Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Teresita Bellido
- 1Department of Physiology and Cell Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas,2Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas,3Central Arkansas Veterans Healthcare System, Little Rock, Arkansas
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Ali D, Tencerova M, Figeac F, Kassem M, Jafari A. The pathophysiology of osteoporosis in obesity and type 2 diabetes in aging women and men: The mechanisms and roles of increased bone marrow adiposity. Front Endocrinol (Lausanne) 2022; 13:981487. [PMID: 36187112 PMCID: PMC9520254 DOI: 10.3389/fendo.2022.981487] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Osteoporosis is defined as a systemic skeletal disease characterized by decreased bone mass and micro-architectural deterioration leading to increased fracture risk. Osteoporosis incidence increases with age in both post-menopausal women and aging men. Among other important contributing factors to bone fragility observed in osteoporosis, that also affect the elderly population, are metabolic disturbances observed in obesity and Type 2 Diabetes (T2D). These metabolic complications are associated with impaired bone homeostasis and a higher fracture risk. Expansion of the Bone Marrow Adipose Tissue (BMAT), at the expense of decreased bone formation, is thought to be one of the key pathogenic mechanisms underlying osteoporosis and bone fragility in obesity and T2D. Our review provides a summary of mechanisms behind increased Bone Marrow Adiposity (BMA) during aging and highlights the pre-clinical and clinical studies connecting obesity and T2D, to BMA and bone fragility in aging osteoporotic women and men.
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Affiliation(s)
- Dalia Ali
- Department of Molecular Endocrinology, KMEB, University of Southern Denmark and Odense University Hospital, Odense, Denmark
- *Correspondence: Dalia Ali, ; Abbas Jafari,
| | - Michaela Tencerova
- Laboratory of Molecular Physiology of Bone, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Florence Figeac
- Department of Molecular Endocrinology, KMEB, University of Southern Denmark and Odense University Hospital, Odense, Denmark
| | - Moustapha Kassem
- Department of Molecular Endocrinology, KMEB, University of Southern Denmark and Odense University Hospital, Odense, Denmark
| | - Abbas Jafari
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Dalia Ali, ; Abbas Jafari,
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Costa S, Fairfield H, Farrell M, Murphy CS, Soucy A, Vary C, Holdsworth G, Reagan MR. Sclerostin antibody increases trabecular bone and bone mechanical properties by increasing osteoblast activity damaged by whole-body irradiation in mice. Bone 2021; 147:115918. [PMID: 33737193 PMCID: PMC8076093 DOI: 10.1016/j.bone.2021.115918] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/22/2021] [Accepted: 03/11/2021] [Indexed: 12/16/2022]
Abstract
Irradiation therapy causes bone deterioration and increased risk for skeletal-related events. Irradiation interferes with trabecular architecture through increased osteoclastic activity, decreased osteoblastic activity, and increased adipocyte expansion in the bone marrow (BM), which further compounds bone-related disease. Neutralizing antibodies to sclerostin (Scl-Ab) increase bone mass and strength by increasing bone formation and reducing bone resorption. We hypothesized that treatment with Scl-Ab would attenuate the adverse effects of irradiation by increasing bone volume and decreasing BM adipose tissue (BMAT), resulting in better quality bone. In this study, 12-week-old female C57BL/6J mice were exposed to 6 Gy whole-body irradiation or were non-irradiated, then administered Scl-Ab (25 mg/kg) or vehicle weekly for 5 weeks. Femoral μCT analysis confirmed that the overall effect of IR significantly decreased trabecular bone volume/total volume (Tb.BV/TV) (2-way ANOVA, p < 0.0001) with a -43.8% loss in Tb.BV/TV in the IR control group. Scl-Ab independently increased Tb.BV/TV by 3.07-fold in non-irradiated and 3.6-fold in irradiated mice (2-way ANOVA, p < 0.0001). Irradiation did not affect cortical parameters, although Scl-Ab increased cortical thickness and area significantly in both irradiated and non-irradiated mice (2-way ANOVA, p < 0.0001). Femoral mechanical testing confirmed Scl-Ab significantly increased bending rigidity and ultimate moment independently of irradiation (2-way ANOVA, p < 0.0001). Static and dynamic histomorphometry of the femoral metaphysis revealed osteoblast vigor, not number, was significantly increased in the irradiated mice treated with Scl-Ab. Systemic alterations were assessed through serum lipidomic analysis, which showed that Scl-Ab normalized lipid profiles in the irradiated group. This data supports the theory of sclerostin as a novel contributor to the regulation of osteoblast activity after irradiation. Overall, our data support the hypothesis that Scl-Ab ameliorates the deleterious effects of whole-body irradiation on bone and adipose tissue in a mouse model. Our findings suggest that future research into localized and systemic therapies after irradiation exposure is warranted.
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Affiliation(s)
- Samantha Costa
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA; Tufts University School of Medicine, Boston, MA, USA
| | - Heather Fairfield
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA; Tufts University School of Medicine, Boston, MA, USA
| | - Mariah Farrell
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA; Tufts University School of Medicine, Boston, MA, USA
| | - Connor S Murphy
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA; Tufts University School of Medicine, Boston, MA, USA
| | - Ashley Soucy
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA
| | - Calvin Vary
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA; Tufts University School of Medicine, Boston, MA, USA
| | | | - Michaela R Reagan
- Maine Medical Center Research Institute, Scarborough, ME, USA; University of Maine Graduate School of Biomedical Science and Engineering, Orono, ME, USA; Tufts University School of Medicine, Boston, MA, USA.
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Reagan MR, Fairfield H, Rosen CJ. Bone Marrow Adipocytes: A Link between Obesity and Bone Cancer. Cancers (Basel) 2021; 13:364. [PMID: 33498240 PMCID: PMC7863952 DOI: 10.3390/cancers13030364] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/24/2020] [Accepted: 01/15/2021] [Indexed: 12/30/2022] Open
Abstract
Cancers that grow in the bone marrow are for most patients scary, painful, and incurable. These cancers are especially hard to treat due to the supportive microenvironment provided by the bone marrow niche in which they reside. New therapies designed to target tumor cells have extended the life expectancy for these patients, but better therapies are needed and new ideas for how to target these cancers are crucial. This need has led researchers to interrogate whether bone marrow adipocytes (BMAds), which increase in number and size during aging and in obesity, contribute to cancer initiation or progression within the bone marrow. Across the globe, the consensus in the field is a unified "yes". However, how to target these adipocytes or the factors they produce and how BMAds interact with different tumor cells are open research questions. Herein, we review this research field, with the goal of accelerating research in the network of laboratories working in this area and attracting bright scientists with new perspectives and ideas to the field in order to bring about better therapies for patients with bone cancers.
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Affiliation(s)
- Michaela R. Reagan
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, ME 04074, USA; (H.F.); (C.J.R.)
- School of Medicine, Tufts University, Boston, MA 02111, USA
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
| | - Heather Fairfield
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, ME 04074, USA; (H.F.); (C.J.R.)
- School of Medicine, Tufts University, Boston, MA 02111, USA
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
| | - Clifford J. Rosen
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, ME 04074, USA; (H.F.); (C.J.R.)
- School of Medicine, Tufts University, Boston, MA 02111, USA
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
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Lee JY, Yang JY, Kim SW. Bone Lining Cells Could Be Sources of Bone Marrow Adipocytes. Front Endocrinol (Lausanne) 2021; 12:766254. [PMID: 34925236 PMCID: PMC8678613 DOI: 10.3389/fendo.2021.766254] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 11/15/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Recently, lineage-tracing studies demonstrated that parathyroid hormone and anti-sclerostin antibody (Scl-Ab) can convert bone lining cells (BLCs) into active osteoblasts. However, BLCs might also be differentiated into other lineages. Here we investigated whether BLCs could differentiate into bone marrow adipocytes (BMAds) and whether Scl-Ab could suppress this process. METHODS Dmp1-CreERt2:mTmG mice were injected with 0.5 mg of 4-hydroxytamoxifen once weekly from postnatal week 4 to week 8. The mice were treated with either vehicle or rosiglitazone for 8 weeks (weeks 12-20). Moreover, they were administered either vehicle or Scl-Ab (50 mg/kg) twice weekly for 4 weeks (weeks 16-20, N = 4-6/group). We chased the GFP+ cells from the endosteal surface to the bone marrow (BM) of the femur. Using immunohistochemical staining, the numbers of perilipin+ or GFP+/perilipin double+ cells in the BM were quantified. In addition, serum N-terminal propeptide of type I procollagen (P1NP) levels were measured at each time point, and bone mass was analyzed at 20 weeks using micro-computed tomography. RESULTS Scl-Ab administration significantly reversed the decreases in bone parameters induced by rosiglitazone. Plump GFP+ cells, presumably active osteoblasts, and extremely flat GFP+ cells, presumably BLCs, were present on the endosteal surface of the femur at 8 and 12 weeks, respectively, in line with prior findings. When we chased the GFP+ cells, rosiglitazone significantly increased the number of GFP/perilipin double+ BMAds compared to the effects of the vehicle (P < 0.001), and overlapping Scl-Ab administration decreased the number of GFP/perilipin double + BMAd compared to rosiglitazone alone (P < 0.001). In addition, we found that osteoblast lineage cells such as BLCs might express PPARγ on immunohistochemical staining. When rosiglitazone was administered to Rip-Cre:mTmG mice, GFP+ cells were not present on the endosteal surface or in the BM of the femur; however, they were present in the pancreas. CONCLUSION BLCs could be sources of BMAds, and rosiglitazone could stimulate the differentiation of osteoblast lineage cells into BMAds. Suppression of the differentiation of osteoblast lineage cells into BMAds might contribute to anabolic effects resulting from the pharmacologic inhibition of sclerostin.
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Affiliation(s)
- Ji Yeon Lee
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
- Department of Research and Experiment, Seoul National University Hospital Biomedical Research Institute, Seoul, South Korea
| | - Jae-Yeon Yang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
- Department of Research and Experiment, Seoul National University Hospital Biomedical Research Institute, Seoul, South Korea
| | - Sang Wan Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
- Division of Endocrinology and Metabolism, Seoul Metropolitan Government Boramae Medical Center, Seoul, South Korea
- *Correspondence: Sang Wan Kim,
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