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Osteoporosis (OP) predominantly affects elderly individuals. Stem cells show potential for treating OP. However, animal models with normal immune function can eliminate implanted human cells. This study utilized naturally aging NOD/SCID mice, which exhibit immunodeficiency, to create a human osteoporosis model. This approach helps to minimize the premature immune clearance of transplanted allogeneic or xenogeneic cells in preclinical studies, allowing for a more accurate replication of the clinical pharmacological and pharmacokinetic processes involved in stem cell interventions for osteoporosis. NOD/SCID mice were fed until 12, 32, and 43 weeks of age, respectively, and then euthanized. We harvested lumbar vertebra for Micro-Computed Tomography (Micro-CT) scanning and pathological examination. Additionally, we performed biomechanical testing of lumbar vertebra to assess the severity of osteoporosis. We utilized real-time RT-PCR to assess gene expression changes associated with bone metabolism, aging, inflammation, oxidative stress, and the Tgf-β1/Smad3 signaling pathway. In addition, the protein expression levels of P16, Tgf-β1 and Smad3 were detected using Western Blotting (WB). In comparison to 12-week-old mice, the 32-week-old and 43-week-old mice displayed significantly sparser and fractured trabeculae in their lumbar vertebra, lower bone mineral density (BMD), and changes in bone microstructural parameters (∗∗P < 0.01, ∗∗∗P < 0.001). Additionally, compared to 12-week-old mice, the 32-week-old and 43-week-old mice exhibited decreased expression of osteogenic genes (Alp, Opg, Sp7, Col1a1), increased expression of osteoclastic gene (Rankl), the number of TRAP-positive osteoclasts significantly increased in 32-week-old and 43-week-old mice compared to 12-week-old mice. The expression of genes related to aging and inflammatory (P16, Il-1β, Tnf-α) increases with advancing age (∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001). The expression of oxidative stress-related genes (Sod1, Sod2, Foxo3, Nrf2), as well as Tgf-β1 and Smad3 decreased with age (∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001). As age increases, the levels of P16 protein increase, Tgf-β1 and Smad3 proteins decrease. Our study successfully replicated osteoporosis models in NOD/SCID mice at both 32 and 43 weeks, with the latter exhibiting more severe osteoporosis. This condition seems to be driven by factors such as aging, inflammation, oxidative stress, and the Tgf-β1/Smad3 signaling pathway., Competing Interests: Declaration of competing interest Zhaoxia Ma, Lihua Qiu, Jinyan Li, Zhen Wu, Shu Liang, Yunhui Zhao, Jinmei Yang, Min Hu and Yanjiao Li declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Epithelial stromal interaction 1 (EPSTI1) plays an important role in M1 macrophages, which induce osteoclastogenesis. One recent genome-wide association study (GWAS) involving 426,824 individuals has shown that EPSTI1 is strongly associated with osteoporosis (P < 5E-8). Therefore, we speculate that EPSTI1 participates in the modulation of osteoporosis through osteoclastogenesis. The roles of EPSTI1 in osteoclastogenesis and bone resorption remain unclear., Methods: Femur specimens were collected from osteoporotic patients and control patients. Immunofluorescence staining was used to detect the expression of EPSTI1 and signaling pathways. The osteoclastic potential of RAW264.7 cells with Sh-EPSTI1 lentivirus infection was tested using tartrate-resistant acid phosphatase (TRAP) staining, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Western blotting was also used to examine signaling pathways., Results: In this study, EPSTI1 was found to be significantly increased in tartrate-resistant acid phosphatase positive (ACP5 + ) osteoclasts of bone sections from osteoporotic patients. Next, we identified EPSTI1 as a positive regulator of osteoclastogenesis and osteoclast differentiation capability. Diminished EPSTI1 expression resulted in reduced osteoclastic resorption. Mechanistically, EPSTI1-driven osteoclastogenesis was regulated by NF-κB pathway, which was mediated by the phosphorylation of protein kinase R (p-PKR). Furthermore, EPSTI1 participating in the modulation of osteoporosis via PKR/NF-κB pathway was also verified in the bone samples of osteoporotic patients., Conclusions: Collectively, our findings suggest that EPSTI1 may regulate osteoclast differentiation and bone resorption through PKR/NF-κB pathway and in vivo experiments are needed to further verify EPSTI1 as the therapy target for osteoporosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

An imbalance between the adipogenesis and osteogenesis of bone marrow mesenchymal stem cells (BMSCs) is considered the basic pathogenesis of osteoporosis. Although actin cytoskeleton remodelling plays a crucial role in the differentiation of BMSCs, the role of actin cytoskeleton remodelling in the adipogenesis of BMSCs and postmenopausal osteoporosis (PMOP) has remained elusive. Glia maturation factor-beta (GMFB) has a unique role in remodelling the polymerization/depolymerization cycles of actin. We observed that GMFB expression was increased in bone tissue from both ovariectomized (OVX) rats and PMOP patients. GMFB knockout inhibited the accumulation of bone marrow adipocytes and increased bone mass in the OVX rat model. The inhibition of adipocyte differentiation in GMFB knockout BMSCs was mediated via actin cytoskeleton remodelling and the Ca 2+ -calcineurin-NFATc2 axis. Furthermore, we found that GMFB shRNA treatment in vivo had favourable effects on osteoporosis induced by OVX. Together, these findings suggest a pathological association of the GMFB with PMOP and highlight the potential of the GMFB as a therapeutic target for osteoporosis patients., Competing Interests: Competing interests The authors declare no competing interests. Ethics approval and consent to participate Informed consent was signed by all the patients for the collection of specimens, and the study protocol was approved by the Ethics Committee of Minhang Hospital of Fudan University (Approval Number: K2021-043). The animal care and experiments were approved by the Institutional Animal Care and Use Committee of Fudan University (Approval Number: 2020 Minhang Hospital JS-004). All methods were performed in accordance with the relevant guidelines and regulations., (© 2024. The Author(s).)

Nanotherapeutic techniques are becoming increasingly important in the treatment of bone disorders owing to their targeted drug delivery. This study formulates zein nano coop composites containing chimeric antioxidants (ascorbic acid, luteolin, resveratrol, and coenzyme Q) (AZN) and evaluates its application in bone regeneration using osteoblasts and a Zebrafish osteoporosis model. In vitro experiments with human osteoblast-like MG63 cells showed enhancement of bone mineralization and regeneration. It further exhibited high biocompatibility in Zebrafish larvae, with increased calcium/phosphorus deposition and upregulation of osteogenic genes. The study has unequivocally demonstrated the potential of AZN in bone regeneration and fracture healing in both normal and osteoporosis models, underscoring the significance of this research. Further investigations using higher animal models are warranted to expand on these findings. The impact of this research seems far-reaching, with the possible development of new, effective, and safe treatment options for osteoporosis, addressing the limitations of the currently available treatments.

Osteoporotic bone defects refer to the disruption of bone structural integrity in patients with osteoporosis and pose a substantial challenge to orthopedic surgeons. In this study, we developed a biomimetic hydrogel to improve the osteogenic microenvironment and promote stem cell homing. This hydrogel served as a container for S-nitrosoglutathione and Ca 2+ , promoting the release of bioactive nitric oxide (NO) from bone marrow mesenchymal stem cells (BMSCs) and human vascular endothelial cells and activating the NO/cyclic guanosine monophosphate signaling pathway. These changes promote osteogenic and angiogenic couplings. The hydrogel simultaneously recruited BMSCs by conjugating the stem cell homing peptide SKPPGTSS. Using a rat distal femoral defect model, it was demonstrated that this hydrogel can effectively increase the formation of bone tissue and new blood vessels and has immune-regulating functions. We envision that this hydrogel may be a minimally invasive yet highly effective strategy for expediting the healing of osteoporotic bone defects.

Osteoporosis is a common degenerative skeletal disease among older people, especially postmenopausal women. Bone marrow mesenchymal stem cells (BMSCs), the progenitors of osteoblasts, are essential to the pathophysiology of osteoporosis. Herein, targeting miRNAs with differential expression in dysfunctional BMSCs was accomplished by bioinformatics analysis based on public databases. Target mRNAs were predicted and applied for signaling pathway and function enrichment annotations. In vitro and in vivo effects of selected miRNA on BMSC proliferation and osteogenesis were investigated, the putative binding between selected miRNA and predicted target mRNA was verified, and the co-effects of the miRNA/mRNA axis on BMSCs were determined. miRNA 665 (miR-665) was down-regulated in osteoporotic BMSCs compared with normal BMSCs and elevated in BMSCs experiencing osteogenic differentiation. In BMSCs, miR-665 overexpression promoted cell proliferation and osteogenic differentiation. miR-665 targeted the Wnt signaling inhibitor sclerostin (SOST) and inhibited SOST mRNA and protein expression. SOST overexpression inhibited BMSC cell proliferation and osteogenic differentiation. When co-transduced to BMSCs, SOST knockdown significantly reversed the effects of miR-665 on BMSCs. In ovariectomy (OVX)-induced osteoporosis model mice, OVX remarkably decreased bone mass, whereas miR-665 overexpression partially improved OVX-induced bone mass loss. miR-665 was down-regulated in osteoporotic BMSCs and up-regulated in osteogenically differentiated BMSCs. In conclusion, the miR-665/SOST axis modulates BMSC proliferation, osteogenic differentiation, and OVX-induced osteoporosis in mice, possibly through Wnt signaling., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Osteoporosis is a systemic disease with complex etiology and high prevalence, resulting in a huge economic burden. For a long time, the search for new therapeutic pharmaceuticals has never stopped. Bone loss is related to the imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. In recent years, the role of immunity and inflammation in the development of osteoporosis has studied well. For example, various cytokines, chemokines and endocrine factors regulate osteoclastogenesis via activating different macrophage subtypes, including pro-inflammatory M1 and anti-inflammatory M2. Bilobalide (Bil), an active Ginkgo biloba ingredient, has garnered great interest because of its anti-oxidant and anti-inflammatory activities. In this study, we found that Bil can attenuate osteoclast generation induced by receptor activator of nuclear factor- kappa B ligand (RANKL) through upregulating the sirtuin 3 (SIRT3) and negatively regulating NF-κB signaling. Furthermore, Bil promotes M2 polarization of macrophages in a dose-dependent manner. In vivo studies provided evidence that Bil improves bone density in osteoporosis mice models. Based on the above results, we have reason to believe that Bil has potential therapeutic value in osteoclast-mediated bone loss and offers an effective option for long-term osteoporosis management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: Osteoporosis (OP) is a common cause of morbidity and mortality in older individuals. The importance of Wnt3a in osteogenic activity and bone tissue homeostasis is well known. Here, we explored the possible molecular mechanism by which Wnt3a mediates the LRP6/mTORC1/β-catenin axis to regulate osteoblast differentiation in OP., Methods: OP-related key genes were identified through a bioinformatics analysis. A ROS17/2.8 cell differentiation system for rat osteogenic progenitors and a rat model of senile OP were constructed for in vitro and in vivo mechanism verification., Results: Bioinformatics analysis revealed that LRP6 was poorly expressed in OP and may play a key role in the occurrence of OP by affecting osteoblast differentiation. LRP6 knockdown inhibited osteoblast differentiation in an in vitro model. In addition, Wnt3a promoted osteoblast differentiation by inducing LRP6 phosphorylation. Moreover, LRP6 promoted mTORC1 expression, which indirectly promoted β-catenin expression, thus promoting osteoblast differentiation. Finally, an in vivo assay revealed that LRP6 inhibition improved OP., Conclusion: Our study provides evidence that Wnt3a induces phosphorylation of LRP6 to activate the mTORC1/β-catenin axis, thus promoting osteoblast differentiation and ultimately improving OP in aged rats., (Copyright © 2024. Published by Elsevier Inc.)

Osteoporosis is a widespread chronic condition. Although standard treatments are generally effective, they are frequently constrained by side effects and the risk of developing drug resistance. A promising area of research is the investigation of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, which play a crucial role in bone metabolism. Exosomes, in particular, have shown significant potential in both the diagnosis and treatment of osteoporosis. EVs derived from osteoclasts, osteoblasts, mesenchymal stem cells, and other sources can influence bone metabolism, while exosomes from inflammatory and tumor cells may exacerbate bone loss, highlighting their dual role in osteoporosis pathology. This review offers a comprehensive overview of EV biogenesis, composition, and function in osteoporosis, focusing on their diagnostic and therapeutic potential. We examine the roles of various types of EVs and their cargo-proteins, RNAs, and lipids-in bone metabolism. Additionally, we explore the emerging applications of EVs as biomarkers and therapeutic agents, emphasizing the need for further research to address current challenges and enhance EV-based strategies for managing osteoporosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

The pathogenesis of osteoporosis is driven by several mechanisms including the imbalance between osteoblastic bone formation and osteoclastic bone resorption. Currently, the role of Niacin (NA), also known as vitamin B3, in the regulation of osteoblastic differentiation is not fully understood. Data from the NHANES database were employed to investigate the association of NA intake with the prevalence of osteoporosis. Alterations in mRNA and protein levels of genes and proteins involved in osteogenic differentiation were evaluated via techniques including qRT-PCR, protein immunoblotting, Alkaline Phosphatase (ALP) activity analysis, ALP staining, and Alizarin Red staining. Changes in the mouse skeletal system were investigated by organizational analysis and Micro-CT. The results indicated that NA promoted osteogenic differentiation. Co-immunoprecipitation and chromatin immunoprecipitation were performed to explore the underlying mechanisms. It was observed that NA promoted AREG expression by deacetylating C/EBPβ via SIRT2, thereby activating the PI3K-AKT signaling pathway. It also enhanced the activity of the pivotal glycolytic enzyme, PFKFB3. This cascade amplified osteoblast glycolysis, facilitating osteoblast differentiation. These findings demonstrate that NA modulates glucose metabolism and influences osteogenic differentiation via the SIRT2-C/EBPβ-AREG pathway, suggesting that NA may be a potential therapeutic agent for the management of osteoporosis, and AREG could be a plausible target., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

AMP-activated protein kinase (AMPK), a crucial regulatory kinase, monitors energy levels, conserving ATP and boosting synthesis in low-nutrition, low-energy states. Its sensitivity links microenvironmental changes to cellular responses. As the primary support structure and endocrine organ, the maintenance, and repair of bones are closely associated with the microenvironment. While a series of studies have explored the effects of specific microenvironments on bone, there is lack of angles to comprehensively evaluate the interactions between microenvironment and bone cells, especially for bone marrow mesenchymal stem cells (BMMSCs) which mediate the differentiation of osteogenic lineage. It is noteworthy that accumulating evidence has indicated that AMPK may serve as a hub between BMMSCs and microenvironment factors, thus providing a new perspective for us to understand the biology and pathophysiology of stem cells and bone. In this review, we emphasize AMPK's pivotal role in bone microenvironment modulation via ATP, inflammation, reactive oxygen species (ROS), calcium, and glucose, particularly in BMMSCs. We further explore the use of AMPK-activating drugs in the context of osteoarthritis and osteoporosis. Moreover, building upon the foundation of AMPK, we elucidate a viewpoint that facilitates a comprehensive understanding of the dynamic relationship between the microenvironment and bone homeostasis, offering valuable insights for prospective investigations into stem cell biology and the treatment of bone diseases., (© 2024 Wiley Periodicals LLC.)

To address the adverse side effects associated with systemic high-dose methylprednisolone (MP) therapy for acute spinal cord injury (SCI), we have developed a N-2-hydroxypropyl methacrylamide copolymer-based MP prodrug nanomedicine (Nano-MP). Intravenous Nano-MP selectively targeted to the inflamed SCI lesion and significantly improved neuroprotection and functional recovery after acute SCI. In the present study, we comprehensively assessed the potential adverse side effects associated with the treatment in the SCI rat models, including reduced body weight and food intake, impaired glucose metabolism, and reduced musculoskeletal mass and integrity. In contrast to free MP treatment, intravenous Nano-MP after acute SCI not only offered superior neuroprotection and functional recovery but also significantly mitigated or even eliminated the aforementioned adverse side effects. The superior safety features of Nano-MP observed in this study further confirmed the clinical translational potential of Nano-MP as a highly promising drug candidate for better clinical management of patients with acute SCI., Competing Interests: Declaration of competing interest WZ, ZSJ, YQ, YP, ZC, and CPC have nothing to disclose. WQ, DW, and WAB were coinventors of a patent application (PCT-US20–054559), which covers the development of macromolecular methylprednisolone prodrug nanomedicine (Nano-MP)., (Copyright © 2024. Published by Elsevier Inc.)

The study aimed to explore the role of the irisin receptor (integrin αVβ5) signaling pathway in obesity-induced osteoporosis and its potential mechanism. The integrin αVβ5 gene of bone marrow mesenchymal stem cells (BMSCs) was silenced and overexpressed, and the cells were exposed to irisin treatment and mechanical stretch. Mouse models of obesity were established by feeding mice a high-fat diet, and 8-week caloric restriction/aerobic exercise regimens were implemented. The results showed that after silencing the integrin αVβ5, the osteogenic differentiation of BMSCs was significantly reduced. While overexpression of the integrin αVβ5 increased the osteogenic differentiation of BMSCs. Besides, mechanical stretch promoted the osteogenic differentiation of BMSCs. Obesity did not affect integrin αVβ5 expression in the bone, but it downregulated the expression of irisin and osteogenic factors, upregulated the expression of adipogenic factors, increased bone marrow fat, reduced bone formation, and destroyed the bone microstructure. Caloric restriction, exercise, and a combined regimen reversed these effects and improved obesity-induced osteoporosis, with the combined treatment exhibiting the most potent effect. This study confirms that the irisin receptor signaling pathway has a significant part in transmitting 'mechanical stress' and regulating 'osteogenic/adipogenic differentiation' of BMSCs via recombinant irisin, mechanical stretch, and overexpression/silencing of the integrin αVβ5 gene.

Research at the mesoscale bone trabeculae arrangement yields intriguing results that, due to their clinical resolution, can be applied in clinical field, contributing significantly to the diagnosis of bone-related diseases. While the literature offers quantitative morphometric parameters for a thorough characterization of the mesoscale bone network, there is a gap in understanding relationships among them, particularly in the context of various bone pathologies. This research aims to bridge these gaps by offering a quantitative evaluation of the interplay among morphometric parameters and mechanical response at mesoscale in osteoporotic and non-osteoporotic bones. Bone mechanical response, dependent on trabecular arrangement, is defined by apparent stiffness, computationally calculated using the Gibson-Ashby model. Key findings indicate that: (i) in addition to bone density, measured using X-ray absorptiometry, trabecular connectivity density, trabecular spacing and degree of anisotropy are crucial parameters for characterize osteoporosis state; (ii) apparent stiffness values exhibit strong correlations with bone density and connectivity density; (iii) connectivity density and degree of anisotropy result the best predictors of mechanical response. Despite the inherent heterogeneity in bone structure, suggesting the potential benefit of a larger sample size in the future, this approach presents a valuable method to enhance discrimination between osteoporotic and non-osteoporotic samples., (© 2024. The Author(s).)

Background: Alzheimer's disease and related dementias (ADRD) and osteoporosis (OP) are 2 prevalent diseases of aging with demonstrated epidemiological association, but the underlying molecular mechanisms contributing to this association are unknown., Methods: We used network analysis of bone and brain transcriptomes to discover common molecular mechanisms underlying these 2 diseases. Our study included RNA-sequencing data from the dorsolateral prefrontal cortex tissue of autopsied brains in 629 participants from ROSMAP (Religious Orders Study and the Rush Memory and Aging Project), with a subgroup of 298 meeting criteria for inclusion in 5 ADRD categories, and RNA array data from transiliac bone biopsies in 84 participants from the Oslo study of postmenopausal women. After developing each network within each tissue, we analyzed associations between modules (groups of coexpressed genes) with multiple bone and neurological traits, examined overlap in modules between networks, and performed pathway enrichment analysis to discover conserved mechanisms., Results: We discovered 3 modules in ROSMAP that showed significant associations with ADRD and bone-related traits and 4 modules in Oslo that showed significant associations with multiple bone outcomes. We found significant module overlap between the 2 networks in modules linked to signaling, tissue homeostasis, and development, and Wingless-related integration site (Wnt) signaling was found to be highly enriched in OP and ADRD modules of interest., Conclusions: These results provide translational opportunities in the development of treatments and biomarkers for ADRD and OP., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Pulsatilla koreana Nakai ( P. koreana ) is a perennial herb traditionally used to treat malaria and fever. Although the pharmacological properties of P. koreana have been explored in various contexts, its effects on bone diseases, such as osteoporosis, remain poorly studied. In this study, we investigated the effects of water extracts of P. koreana (WEPK) on osteoclasts, which play a crucial role in bone remodeling, and an ovariectomized (OVX) mouse model, which mimics osteoporosis. Phytochemical profiling of WEPK revealed several compounds that regulate bone or fat metabolism. WEPK suppressed osteoclast differentiation by downregulating the expression of receptor activator of nuclear factor-κB ligand (RANKL), a cytokine that induces osteoclastogenesis. Additionally, WEPK directly inhibited RANKL-induced differentiation of osteoclast precursors by downregulating nuclear factor of activated T cells 1 (NFATc1), the master transcription factor for osteoclastogenesis, by modulating its upstream regulators. In vivo, oral administration of WEPK suppressed bone loss, reduced weight gain, and mitigated fat accumulation in the liver and gonadal tissues of OVX mice. Given its positive impact on bone and fat accumulation under estrogen deficiency, WEPK may serve as a promising alternative therapy for postmenopausal osteoporosis, especially when accompanied by other metabolic disorders, such as obesity and fatty liver.

1,2,3,4,6-penta- O -galloyl-β-D-glucose (PGG) is the main phenolic active ingredient in Paeoniae Radix Alba , which is commonly used for the treatment of osteoporosis (OP). PGG is a potent natural antioxidant, and its effects on OP remain unknown. This study aimed to investigate the effects of PGG on promoting bone formation and explore its estrogen receptor (ER)-related mechanisms. A hydrogen peroxide-induced osteoblast apoptosis model was established in MC3T3-E1 cells. The effects of PGG were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, alkaline phosphatase (ALP) staining, RT-qPCR, and Western blot methods. Furthermore, a prednisolone-induced zebrafish OP model was employed to study the effects in vivo. ER inhibitors and molecular docking methods were used further to investigate the interactions between PGG and ERs. The results showed that PGG significantly enhanced cell viability and decreased cell apoptosis by restoring mitochondrial function, attenuating reactive oxygen species levels, decreasing the mitochondrial membrane potential, and enhancing ATP production. PGG enhanced ALP expression and activity and elevated osteogenic differentiation. PGG also promoted bone formation in the zebrafish model, and these effects were reversed by ICI182780. These results provide evidence that the effects of PGG in alleviating apoptosis and promoting bone formation may depend on ERs. As such, PGG is considered a valuable candidate for treating OP.

Therapeutic efficacy of skeletal diseases is usually limited by unfavorable drug delivery due to incapable bone targeting and low bone affinity of conventional drug carriers, as well as relatively reduced vascularization and dense structure of bone tissues. Due to CXC chemokine receptor 4 (CXCR4)/CXC chemokine ligand 12 (CXCL12) signal axis-guided recruitment, osteoprogenitor cells (OPCs) can actively migrate to bone disease nidus. Here, drugs-loaded nanoliposomes are prepared and decorated onto OPCs by biotin-streptavidin linkage for precise bone disease targeting and effective drug delivery. In mouse models of tibia defect and orthotopic osteosarcoma, superior targeting property of OPCs-based drug delivery systems toward diseased bone niduses is verified. By encapsulating antitumor and antiosteoporosis drugs into nanoliposomes, OPCs-based drug delivery systems effectively inhibit disease development and restore bone destruction in mouse models of orthotopic osteosarcoma and ovariectomized osteoporosis. This study reveals a cell-based drug delivery system for precise bone disease targeting and highly effective drug delivery, which will find great potential as a universal drug delivery platform for targeting treatment of various bone diseases.

Osteoporosis (OP) is a common chronic progressive bone disease that increases fracture risk in postmenopausal women. Research suggests that puerarin (Pue) may be an effective treatment for OP. This study examined the effects and underlying mechanisms of Pue in treating postmenopausal osteoporosis (PMOP) in rats. Sprague-Dawley (SD) rats underwent bilateral ovariectomy to simulate PMOP and were then treated with subcutaneous injections of Pue. Bone mineral density (BMD) was measured using a bone densitometer. Micro-CT scans assessed femur bone structure and various parameters were calculated: bone volume fraction (BV/TV), bone surface density (BS/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and bone surface area-to-bone volume ratio (BS/BV). Hematoxylin-eosin (HE) staining was employed to observe femoral tissue pathology. Serum levels of bone formation metabolism-related markers-osteocalcin (OC), bone alkaline phosphatase (BALP), and procollagen type I N-terminal propeptide (PINP)-were measured via enzyme-linked immunosorbent assay (ELISA). The protein expression levels of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in bone tissue were evaluated using Western blotting assay. The results showed improved bone density and reduced bone loss in rats treated with Pue. There were also significant increases in serum levels of OC and BALP, indicating enhanced osteogenesis. Furthermore, there was a decrease in activation of the JAK2/STAT3 pathway in femoral tissue, suggesting a pathway inhibition. These findings indicate that Pue may combat osteoporosis by promoting osteogenesis and inhibiting activation of the JAK2/STAT3 pathway activation.

Diabetes osteoporosis (DOP) is a chronic metabolic bone disease. This study aimed to identify potential biomarkers of DOP and explore their underlying mechanisms through bioinformatics methods and experimental verification. Bioinformatics methods were used to identify differentially expressed genes (DEGs) for DOP based on GEO data and the GeneCards database. GO and KEGG enrichment analyses were used to search the key pathways. The STRING website was used to construct a protein-protein interaction (PPI) network and identify key genes. Then, 50 mg/mL glucose was used to interveneosteoblasts (OBs).CCK-8 and Alizarin Red staining were used to investigate the proliferation and differentiation changes in OBs. Flowcytometry was used to investigate apoptosis. The membrane protein chip, WB, and RT-PCR were used to verify the expression of key targets or pathways about DOP. Forty-two common genes were screened between DOP-related targets and DEGs. GO and KEGG enrichment analysis showed that DOP was mainly associated with cytokine-cytokine receptor interactions, and apoptosis. PPI network analysis showed that TNF, IL1A, IL6, IL1B, IL2RA, Fas ligand (FASLG), and Fas cell surface death receptor (FAS) were key up-regulated genes in the occurrence of DOP. The experiment results show that 50 mg/mL glucose significantly inhibited OBs proliferation but presented an increase in apoptosis. Membrane protein chip, WB, and RT-PCR-verified a significantly active in the expression of TNF/FASLG/FAS pathway. High glucose activated the TNF-α/FAS/FASLG pathway and induced the inflammatory microenvironment and apoptosis, then impaired osteogenic differentiation of OBs. These may be an important mechanism for the occurrence and development of DOP., (© 2024 Federation of American Societies for Experimental Biology.)

Background: Osteoporosis (OP) has garnered significant attention due to its substantial morbidity and mortality rates, imposing considerable health burdens on societies worldwide. However, the molecular mechanisms underlying osteoporosis pathogenesis remain largely elusive, and the available therapeutic interventions are limited. Therefore, there is an urgent need for innovative strategies in the treatment of osteoporosis., Purpose: The primary objective of this study was to elucidate the molecular mechanisms underlying osteoporosis pathogenesis using single-cell RNA sequencing (scRNA-seq), thereby proposing novel therapeutic agents., Methods: The mice osteoporosis model was established through bilateral ovariectomy. Micro-computed tomography (μCT) and hematoxylin and eosin (H&E) staining were employed to assess the pathogenesis of osteoporosis. scRNA-seq was utilized to identify and analyze distinct molecular mechanisms and sub-clusters. Gradient dilution analysis was used to obtain specific sub-clusters, which were further validated by immunofluorescence staining and flow cytometry analysis. Molecular docking and cellular thermal shift assay (CETSA) were applied for screening potential agents in the TCMSPs database. Alkaline phosphatase (ALP) activity and alizarin red S (ARS) staining were performed to evaluate the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Osteogenic organoids analysis was employed to assess the proliferation and sphere-forming ability of BMSCs. Quantitative real-time PCR (qRT-PCR) and western blot analysis were conducted to investigate signaling pathways. Wound healing assay and tube formation analysis were employed to evaluate the angiogenesis of endothelial cells., Results: The scRNA-seq analysis revealed the crucial role of LEPR + BMSCs in the pathogenesis of osteoporosis, which was confirmed by immunofluorescence staining of the epiphysis. Subsequently, the LEPR + BMSCs were obtained by gradient dilution analysis and identified by immunofluorescence staining and flow cytometry. Accordingly, specnuezhenide (Spe) was screened and identified as a potential compound targeting METTL3 from the TCMSPs database. Spe promoted bone formation as evidenced by μ-CT, and H&E analysis. Additionally, Spe enhanced the osteogenic capacity of LEPR + BMSCs through ALP and ARS assay. Notably, METTL3 pharmacological inhibitors S-Adenosylhomocysteine (SAH) attenuated the aforementioned osteo-protective effects of Spe. Particularly, Spe enhanced the LEPR + BMSCs-dependent angiogenesis through the secretion of SLIT3, which was abolished by SAH in LEPR + BMSCs., Conclusion: Collectively, these findings suggest that Spe could enhance the osteogenic potential of LEPR + BMSCs and promote LEPR + BMSCs-dependent angiogenesis by activating METTL3 in LEPR + BMSCs, indicating its potential as an ideal therapeutic agent for clinical treatment of osteoporosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In the pathophysiology of osteoarthritis and osteoporosis, articular cartilage and bone represent the target tissues, respectively, but muscle is also involved. Since many changes in energy metabolism occur in muscle with aging, the aim of the present work was to investigate the involvement of carnitine palmitoyl transferase 1b (Cpt1b) in the muscle pathophysiology of the two diseases. Healthy subjects (CTR, n = 5), osteoarthritic (OA, n = 10), and osteoporotic (OP, n = 10) patients were enrolled. Gene expression analysis conducted on muscle and myoblasts showed up-regulation of CPT1B in OA patients; this result was confirmed by immunohistochemical and immunofluorescence analyses and enzyme activity assay, which showed increased Cpt1b activity in OA muscle. In addition, CPT1B expression resulted down-regulated in cultured OP myoblasts. Given the potential involvement of Cpt1b in the modulation of oxidative stress, we investigated ROS levels, which were found to be lower in OA myoblasts, and gene expression of nicotinamide adenine dinucleotide phosphate hydrogen oxidase 4 (Nox4), which resulted up-regulated in OA cells. Finally, the immunofluorescence of BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (Bnip3) showed a decreased expression in OP myoblasts, with respect to CTR and OA. Contextually, through an ultrastructural analysis conducted by Transmission Electron Microscopy (TEM), the presence of aberrant mitochondria was observed in OP muscle. This study highlights the potential role of Cpt1b in the regulation of muscle homeostasis in both osteoarthritis and osteoporosis, allowing for the expansion of the current knowledge of what are the molecular biological pathways involved in the regulation of muscle physiology in both diseases.

Background: Arecanut seed is an important traditional medicine in Southeast Asia. It has been presented in a clinical formula to treat osteoporosis (OP) in China. Arecanut seed is abundant in phenols. However, most of current studies mainly focused on estrogen-deficient osteoporosis (OP) model of arecanut seed phenols (ASP), there is still a lack of roundly research about molecular mechanism of ASP therapy on OP and its influence on in drug-induced bone loss., Materials and Methods: To explore potential molecular mechanisms and the effects of ASP on OP, network pharmacology, molecular docking methods and a retinoic acid-induced OP rat model were employed in this study. According to the network pharmacology method, OP related targets and ASP compound related targets were collected from databases to obtain hub targets and top active chemicals in ASP treating OP. The potential therapic pathways were also calculated. Binding capacities of top active chemicals to hub targets were analyzed by molecular dock assay. In the animal experiment, osteocalcin (OCN) levels and alkaline phosphatase (ALP) activity in serum of all the rats were determined. The views of bone section were stained to observe the bone micro-structure of ASP affects. Bone mineral density (BMD), cortical bone thickness (CBT), area ratio of bone cortex (CAR) and area ratio of bone trabecula (TAR) were obtained from micro computed tomography to evaluate the effectiveness of ASP on bone loss., Conclusion: Three hub genes and three top active compounds were screened by network pharmacology analysis and they combined well with each other. ASP had positive effects on alleviating RA-induced bone loss by regulating the expression of the hub genes. Signals in IL-17 pathway were predicted and primarily verified being potential targets in ASP treating OP., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tang, Sun, Song and Chen.)

Chronic kidney disease (CKD) is a significant global health issue and often involves CKD-mineral and bone disorder (MBD) and sarcopenia. Plasminogen activator inhibitor-1 (PAI-1) is an inhibitor of fibrinolysis. PAI-1 has been implicated in the pathogenesis of osteoporosis and muscle wasting induced by inflammatory conditions. However, the roles of PAI-1 in CKD-MBD and sarcopenia remain unknown. Therefore, the present study investigated the roles of PAI-1 in bone loss and muscle wasting induced by adenine in PAI-1-deficient mice. CKD was induced in PAI-1+/+ and PAI-1-/- mice by administration of adenine for ten weeks. Muscle wasting was assessed by grip strength test, quantitative computed tomography (CT) analysis and muscle weight measurement. Osteoporosis was assessed by micro-CT analysis of femoral microstructural parameters. PAI-1 deficiency did not affect adenine-induced decreases in body weight and food intake or renal dysfunction in male or female mice. PAI-1 deficiency also did not affect adenine-induced decreases in grip strength, muscle mass in the lower limbs, or the tissue weights of the gastrocnemius, soleus, and tibialis anterior muscles in male or female mice. PAI-1 deficiency aggravated trabecular bone loss in CKD-induced male mice, but significantly increased trabecular bone in CKD-induced female mice. On the other hand, PAI-1 deficiency did not affect cortical bone loss in CKD-induced mice. In conclusion, PAI-1 is not critical for the pathophysiology of CKD-MBD or CKD-induced sarcopenia in mice. However, PAI-1 may be partly related to bone metabolism in trabecular bone in the CKD state with sex differences., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Mizukami et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Osteoporosis (OP) is a chronic disease characterized by decreased bone mass, loss of skeletal structural integrity and increased susceptibility to fracture. Available studies have shown that the pyruvate dehydrogenase kinase (PDK) family is associated with osteoclastogenesis and bone loss, but the specific role of Pdk3 in bone pathology has not been systematically investigated., Methods: A cell OP model was established in receptor activator for nuclear factor- κ B Ligand (RANKL)-induced bone marrow macrophages (BMMs). Hereafter, the expression levels of Pdk3 and osteoclastogenesis feature genes including nuclear factor of activated T cells 1 ( Nfatc1 ), Cathepsin K ( Ctsk ), osteoclast associated Ig-like receptor ( Oscar ) in BMMs-derived osteoclasts were examined based on real-time quantitative PCR and western blotting methods. Further, the phosphorylation of ERK, P65 and JAK/STAT and their correlation was Pdk3 was gauged. In particular, changes in the activity of these signaling pathways were observed by silencing experiments of the Pdk3 gene (using small interfering RNA). Finally, the effects of Pdk3 gene silencing on signaling pathway activity, osteoclastogenesis, and related inflammatory and apoptotic indicators were observed by transfection with PDK3-specific siRNA., Results: Following RANKL exposure, the levels of Pdk3 and osteoclastogenesis feature genes were all elevated, and a positive correlation between Pdk3 and osteoclastogenesis feature genes was seen. Meanwhile, ERK, P65 and JAK/STAT phosphorylation was increased by RANKL, and Pdk3 was confirmed to be positively correlated with the phosphorylation of ERK, P65 and JAK/STAT. Additionally, in RANKL-exposed osteoclasts, Pdk3 knockdown diminished the phosphorylation of ERK, P65 and JAK/STAT, reduced the expressions of osteoclastogenesis feature genes. Importantly, knockdown of Pdk3 also reduced the expression of inflammatory cytokines and resulted in elevated levels of Bax and Casp3 expression, as well as downregulation of Bcl2 expression., Conclusion: This study reveals for the first time the role of Pdk3 in RANKL-induced osteoclastogenesis and OP. These findings provide a foundation for future studies on the role of Pdk3 in other bone diseases and provide new ideas for the development of OP therapeutics targeting Pdk3., Competing Interests: The authors declare there are no competing interests., (©2024 Zhang et al.)

Osteoporosis, a common bone disease in older individuals, involves the progression influenced by N6-methyladenosine (m6A) modification. This study aimed to elucidate the effects of VDAC3 m6A modification on human bone mesenchymal stromal cell (BMSC) senescence and osteogenic differentiation. BMSCs were treated with etoposide to induce senescence. Senescence was assessed by β-galactosidase staining and quantitative real-time PCR (qPCR), and osteogenic differentiation was evaluated using Western blot, alkaline phosphatase, and alizarin red S staining. VDAC3 and ALKBH5 expression were quantified by qPCR, and their interaction was assessed by RNA immunoprecipitation (RIP) and luciferase reporter assay. m6A methylation was analyzed using the Me-RIP assay. VDAC3 expression was significantly decreased in etoposide-treated BMSCs (1.00 ± 0.13 vs. 0.26 ± 0.06). VDAC3 overexpression reduced etoposide-induced senescence and promoted osteogenic differentiation. ALKBH5 overexpression inhibited VDAC3 m6A modification (1.00 ± 0.095 vs. 0.233 ± 0.177) and its stability. ALKBH5 knockdown decreased etoposide-induced senescence and promoted osteogenic differentiation, effects that were reversed by VDAC3 knockdown. YTHDF1 was identified as the m6A methylation reader, and its overexpression inhibited VDAC3 stability. We demonstrated that ALKBH5 inhibited osteogenic differentiation of etoposide-induced senescent cells through the inhibition of VDAC3 m6A modification, and YTHDF1 acted as the m6A methylation reader. These findings provide a novel theoretical basis for the treatment of osteoporosis., (© 2024. The Author(s).)

Angiogenesis-osteogenesis coupling is critical for proper functioning and maintaining the health of bones. Any disruption in this coupling, associated with aging and disease, might lead to loss of bone mass. Osteoporosis (OP) is a debilitating bone metabolic disorder that affects the microarchitecture of bones, gradually leading to fracture. Computational analysis revealed that normal angiogenesis is disrupted during the progression of OP, especially postmenopausal osteoporosis (PMOP). The genes associated with OP and PMOP were retrieved from the DisGeNET database. Hub gene analysis and molecular pathway enrichment were performed via the Cytoscape plugins STRING, MCODE, CytoHubba, ClueGO and the web-based tool Enrichr. Twenty-eight (28) hub genes were identified, eight of which were transcription factors (HIF1A, JUN, TP53, ESR1, MYC, PPARG, RUNX2 and SOX9). Analysis of SNPs associated with hub genes via the gnomAD, I-Mutant2.0, MUpro, ConSurf and COACH servers revealed the substitution F201L in IL6 as the most deleterious. The IL6 protein was modeled in the SWISS-MODEL server and the substitution was analyzed via the YASARA FoldX plugin. A positive ΔΔG (1.936) of the F201L mutant indicates that the mutated structure is less stable than the wild-type structure is. Thirteen hub genes, including IL6 and the enriched molecular pathways were found to be profoundly involved in angiogenesis/endothelial function and immune signaling. Mechanical loading of bones through weight-bearing exercises can activate osteoblasts via mechanotransduction leading to increased bone formation. The present study suggests proper mechanical loading of bone as a preventive strategy for PMOP, by which angiogenesis and the immune status of the bone can be maintained. This in silico analysis could be used to understand the molecular etiology of OP and to develop novel therapeutic approaches., (© 2024. The Author(s).)

Active vitamin D, known for its role in promoting osteoporosis, has immunomodulatory effects according to the latest evidence. Eldecalcitol (ED-71) is a representative of the third-generation novel active vitamin D analogs, and its specific immunological mechanisms in ameliorating diabetic osteoporosis remain unclear. We herein evaluated the therapeutic effects of ED-71 in the context of type 2 diabetes mellitus (T2DM), delving into its underlying mechanisms. In a T2DM mouse model, ED-71 attenuated bone loss and marrow adiposity. Simultaneously, it rectified imbalanced glucose homeostasis and dyslipidemia, ameliorated pancreatic β-cell damage and hepatic glycolipid metabolism disorder. Subsequently, in mice injected with the Treg cell-depleting agent CD25, we observed that the beneficial effects of ED-71 mentioned earlier were partially contingent on the Treg subsets ratio. Mechanistically, ED-71 promoted the differentiation of CD4 + T cells into Treg subsets, facilitating Ca 2+ influx and the expression of ORAI1 and STIM1, pivotal proteins in store-operated Ca 2+ entry (SOCE). The SOCE inhibitor, 2-APB, partially attenuated the positive effects of ED-71 observed in the above results. Overall, ED-71 regulates SOCE-mediated Treg cell differentiation, accomplishing the dual purpose of simultaneously ameliorating diabetic osteoporosis and glucolipid metabolic disorders, showcasing its potential in osteoimmunity therapy and interventions for diseases involving SOCE., (© 2024. The Author(s).)

Osteoporosis (OP), a systemic skeletal disease, is characterized by low bone mass, bone tissue degradation and bone microarchitecture disturbance. Bazi Bushen, a Chinese patented medicine, has been demonstrated to be effective in attenuating OP, but the pharmacological mechanism remains predominantly unclear. In this study, the senescence-accelerated mouse prone 6 (SAMP6) model was used to explore bone homeostasis and treated intragastrically for 9 weeks with Bazi Bushen. In vivo experiments showed that Bazi Bushen treatment not only upregulated the levels of bone mineral density and bone mineral content but also increased the content of RUNX2 and OSX. Furthermore, the primary culture of bone mesenchymal stem cells (BMSCs) in SAMP6 mice was used to verify the effects of Bazi Bushen on the balance of differentiation between osteoblasts and adipocytes, as well as ROS and aging levels. Finally, the pharmacological mechanism of Bazi Bushen in attenuating OP was investigated through network pharmacology and experimental verification, and we found that Bazi Bushen could significantly orchestrate bone homeostasis and attenuate the progression of OP by stimulating PI3K-Akt and inhibiting apoptosis. In summary, our work sheds light on the first evidence that Bazi Bushen attenuates OP by regulating PI3K-AKT and apoptosis pathways to orchestrate bone homeostasis., (© 2024 The Author(s). Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Weightlessness osteoporosis, which progresses continuously and has limited protective effects, has become one of the major problems that need to be solved in manned spaceflight. Our study aims to investigate the regulatory role of PHF8 in disuse osteoporosis by observing the expression of PHF8 in bone marrow mesenchymal stem cells (BMSCs) under simulated weightlessness conditions. Therefore, we used the model of ground-based microgravity simulated by disuse osteoporosis patients and tail suspension in mice to simulate microgravity in vivo, and measured the expression of PHF8 in bone tissue. Subsequently, we used the 2D gyroscope to simulate the weightless effect on bone marrow mesenchymal stem cells. In the weightless condition, we detected the proliferation, apoptosis, osteogenesis, and osteogenic differentiation functions of BMSCs. We also detected the expression of osteogenic-related transcription factors after knocking down and overexpressing PHF8. Our results show that the weightless effect can inhibit the proliferation, osteogenesis, and osteogenic differentiation functions of BMSCs, while enhancing their apoptosis; and overexpression of PHF8 can partially alleviate the osteoporosis caused by simulated weightlessness, providing new ideas and clues for potential drug targets to prevent weightlessness and disuse osteoporosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Recent evidence suggests an association between age-related osteoporosis and cellular senescence in the bone; however, the specific bone cells that play a critical role in age-related osteoporosis and the mechanism remain unknown. Results revealed that age-related osteoporosis is characterized by the loss of osteoblast Men1. Osteoblast-specific inducible knockout of Men1 caused structural changes in the mice bones, matching the phenotypes in patients with age-related osteoporosis. Histomorphometrically, Men1-knockout mice femurs decreased osteoblastic activity and increased osteoclastic activity, hallmarks of age-related osteoporosis. Loss of Men1 induces cellular senescence via mTORC1 activation and AMPK suppression, rescued by metformin treatment. In bone morphogenetic protein-indued bone model, loss of Men1 leads to accumulation of senescent cells and osteoporotic bone formation, which are ameliorated by metformin. Our results indicate that cellular senescence in osteoblasts plays a critical role in age-related osteoporosis and that osteoblast-specific inducible Men1-knockout mice offer a promising model for developing therapeutics for age-related osteoporosis., (© 2024 The Author(s). Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.)

Mitochondria exhibit heterogeneous shapes and networks within and among cell types and tissues, also in normal or osteoporotic bone tissues with complex cell types. This dynamic characteristic is determined by the high plasticity provided by mitochondrial dynamics and is stemmed from responding to the survival and functional requirements of various bone cells in a specific microenvironments. In contrast, mitochondrial dysfunction, induced by dysregulation of mitochondrial dynamics, may act as a trigger of cell death signals, including common apoptosis and other forms of programmed cell death (PCD). These PCD processes consisting of tightly structured cascade gene expression events, can further influence the bone remodeling by facilitating the death of various bone cells. Mitochondrial dynamics, therefore, drive the bone cells to stand at the crossroads of life and death by integrating external signals and altering metabolism, shape, and signal-response properties of mitochondria. This implies that targeting mitochondrial dynamics displays significant potential in treatment of osteoporosis. Considerable effort has been made in osteoporosis to emphasize the parallel roles of mitochondria in regulating energy metabolism, calcium signal transduction, oxidative stress, inflammation, and cell death. However, the emerging field of mitochondrial dynamics-related PCD is not well understood. Herein, to bridge the gap, we outline the latest knowledge on mitochondrial dynamics regulating bone cell life or death during normal bone remodeling and osteoporosis., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Osteoporosis (OP) is a systemic metabolic bone disease resulting in reduced bone strength and increased susceptibility to fractures, making it a significant public health and economic problem worldwide. The clinical use of anti-osteoporosis agents is limited because of their serious side effects or the high cost of long-term use. The Xianlinggubao (XLGB) formula is an effective traditional Chinese herbal medicine commonly used in orthopedics to treat osteoporosis; however, its mechanism of action remains unclear. In this study, we screened 40 small RNAs derived from XLGB capsules and found that XLGB28-sRNA targeting TNFSF11 exerted a significant anti-osteoporosis effect in vitro and in vivo by simultaneously promoting osteogenesis and inhibiting osteoclastogenesis. Oral administration of bencaosome [16:0 Lyso PA+XLGB28-sRNA] effectively improved bone mineral density and reduced the damage to the bone microstructure in mice. These results suggest that XLGB28-sRNA may be a novel oligonucleotide drug that promotes osteogenesis and inhibits osteoclastogenesis in mice., (© 2024 International Union of Biochemistry and Molecular Biology.)

Cortical bone loss is intricately associated with ageing and coincides with iron accumulation. The precise role of ferroptosis, characterized by iron overload and lipid peroxidation, in senescent osteocytes remains elusive. We found that ferroptosis was a crucial mode of osteocyte death in cortical bone during ageing. Using a single-cell transcriptome analysis, we identified activating transcription factor 3 (ATF3) as a critical driver of osteocyte ferroptosis. Elevated ATF3 expression in senescent osteocytes promotes iron uptake by upregulating transferrin receptor 1 while simultaneously inhibiting solute carrier family 7-member 11-mediated cystine import. This process leads to an iron overload and lipid peroxidation, culminating in ferroptosis. Importantly, ATF3 inhibition in aged mice effectively alleviated ferroptosis in the cortical bone and mitigated cortical bone mass loss. Taken together, our findings establish a pivotal role of ferroptosis in cortical bone loss in older adults, providing promising prevention and treatment strategies for osteoporosis and fractures., (© 2024 The Authors. Cell Proliferation published by Beijing Institute for Stem Cell and Regenerative Medicine and John Wiley & Sons Ltd.)

Radial extracorporeal shockwave (r-ESW) and bone marrow stromal cells (BMSCs) have been reported to alleviate senile osteoporosis (SOP), but its regulatory mechanism remains unclear. In this study, we firstly isolated human BMSCs from bone marrow samples and treated with varying r-ESW doses. And we found that r-ESW could enhance the proliferation of SOP-BMSCs in a dose-dependent manner by EdU assay. Subsequently, the impact of r-ESW on the proliferation, apoptosis and multipotency of BMSCs was assessed. And the outcomes of flow cytometry, Alizarin red S (ARS), and tube formation test demonstrated that the optimal shockwave obviously boosted SOP-BMSCs osteogenesis and angiogenesis but exhibited no significant impact on cell apoptosis. Additionally, the signaling of Piezo1 and CaMKII/CREB was examined by Western blotting, qPCR and immunofluorescence. And the results showed that r-ESW promoted the expression of Piezo1, increased intracellular Ca 2+ and activated the CaMKII/CREB signaling pathway. Then, the application of Piezo1 siRNA hindered the r-ESW-induced enhancement ability of osteogenesis coupling with angiogenesis of SOP-BMSCs. The use of the CaMKII/CREB signaling pathway inhibitor KN93 suppressed the Piezo1-induced increase in osteogenesis and angiogenesis in SOP-BMSCs. Finally, we also found that r-ESW might alleviate SOP in the senescence-accelerated mouse prone 6 (SAMP6) model by activating Piezo1. In conclusion, our research offers experimental evidence and an elucidated underlying molecular mechanism to support the use of r-ESW as a credible rehabilitative treatment for senile osteoporosis., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024. Published by Elsevier Inc.)

Objectives: The mitochondrial deacetylase sirtuin-3 (SIRT3) is necessary for the increased bone resorption and enhanced function of mitochondria in osteoclasts that occur with advancing age; how SIRT3 drives bone resorption remains elusive., Methods: To determine the role of SIRT3 in osteoclast mitochondria, we used mice with conditional loss of Sirt3 in osteoclast lineage and mice with germline deletion of either Sirt3 or its known target Pink1., Results: SIRT3 stimulates mitochondrial quality in osteoclasts in a PINK1-independent manner, promoting mitochondrial activity and osteoclast maturation and function, thereby contributing to bone loss in female but not male mice. Quantitative analyses of global proteomes and acetylomes revealed that deletion of Sirt3 dramatically increased acetylation of osteoclast mitochondrial proteins, particularly ATPase inhibitory factor 1 (ATPIF1), an essential protein for mitophagy. Inhibition of mitophagy via mdivi-1 recapitulated the effect of deletion of Sirt3 or Atpif1 in osteoclast formation and mitochondrial function., Conclusions: Decreasing mitophagic flux in osteoclasts may be a promising pharmacotherapeutic approach to treat osteoporosis in older adults., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Due to bioactive properties, introducing spongin-like collagen (SPG) into the biosilica (BS) extracted from marine sponges would present an enhanced biological material for improving osteoporotic fracture healing by increasing bone formation rate. Our aim was to characterize the morphology of the BS/SPG scaffolds by scanning electron microscopy (SEM), the chemical bonds of the material by Fourier transform infrared spectroscopy (FTIR), and evaluating the orthotopic in vivo response of BS/SPG scaffolds in tibial defects of osteoporotic fractures in rats (histology, histomorphometry, and immunohistochemistry) in two experimental periods (15 and 30 days). SEM showed that scaffolds were porous, showing the spicules of BS and fibrous aspect of SPG. FTIR showed characteristic peaks of BS and SPG. For the in vivo studies, after 30 days, BS and BS/SPG showed a higher amount of newly formed bone compared to the first experimental period, observed both in the periphery and in the central region of the bone defect. For histomorphometry, BS/SPG presented higher %BV/TV compared to the other experimental groups. After 15 days, BS presented higher volumes of collagen type I. After 30 days, all groups demonstrated higher volumes of collagen type III compared to volumes at 15 days. After 30 days, BS/SPG presented higher immunostaining of osteoprotegerin compared to the other experimental groups at the same experimental period. The results showed that BS and BS/SPG scaffolds were able to improve bone healing. Future research should focus on the effects of BS/SPG on longer periods in vivo studies., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

In osteoporosis, bone quality adversely affects the tissue structural competence which increases the risk of a complicated fracture healing. In the present study highly potent scaffold containing natural coral particles was designed and considered for the healing of critical size bone defect in osteoporosis rat model. Scaffold morphological evaluation confirmed the porous nanofibrous structure. Water uptake of about 900 % was obtained for the fabricated scaffold as the result of its composition and three-dimensional structure. Mechanical analysis revealed the compressive modulus of about 50 kPa for the fabricated coral-incorporated nanofibrous structure. In vitro cellular assessments revealed that the designed scaffold induces no toxicity and provides the proper substrate for cell attachment together with increased and prolonged cell proliferation. In vivo experiments demonstrated that implantation of the fabricated scaffold in the femoral defects of osteoporotic rats significantly increased the number of osteocytes and osteoblasts, and enhanced the BTV, and BMP-2 expression compared with the control group. Furthermore, it was observed that seeding the scaffolds with MSCs prior to implantation, resulted in substantial improvements in mRNA expression of the BMP-2 and VEGF genes and considerable enhancement in stereological findings such as significantly higher number of osteoblasts, osteocytes, TVB, and BTV., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Human aging is linked to bone loss, resulting in bone fragility and an increased risk of fractures. This is primarily due to an age-related decline in the function of bone-forming osteoblastic cells and accelerated cellular senescence within the bone microenvironment. Here, we provide a detailed discussion of the hypothesis that age-related defective bone formation is caused by senescence of skeletal stem cells, as they are the main source of bone forming osteoblastic cells and influence the composition of bone microenvironment. Furthermore, this review discusses potential strategies to target cellular senescence as an emerging approach to treat age-related bone loss., Competing Interests: Declaration of Competing Interest All authors have no competing interests to declare., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Age-related osteoporosis is characterized by a marked decrease in the number of osteoblasts, which has been partly attributed to the senescence of cells of the osteoblastic lineage. Epigenetic studies have provided new insights into the mechanisms of current osteoporosis treatments and bone repair pathophysiology. N6-methyladenosine (m6A) is a novel transcript modification that plays a major role in cellular senescence and is essential for skeletal development and internal environmental stability. Bioinformatics analysis revealed that the expression of the m6A reading protein Igf2bp2 was significantly higher in osteoporosis patients. However, the role of Igf2bp2 in osteoblast senescence has not been elucidated. In this study, we found that Igf2bp2 levels are increased in ageing osteoblasts induced by multiple repetition and H 2 O 2 . Increasing Igf2bp2 expression promotes osteoblast senescence by increasing the stability of Slc1a5 mRNA and inhibiting cell cycle progression. Additionally, Mettl3 was identified as Slc1a5 m6A-methylated protein with increased m6A modification. The knockdown of Mettl3 in osteoblasts inhibits the reduction of senescence, whereas the overexpression of Mettl3 promotes the senescence of osteoblasts. We found that administering Cpd-564, a specific inhibitor of Mettl3, induced increased bone mass and decreased bone marrow fat accumulation in aged rats. Notably, in an OVX rat model, Igf2bp2 small interfering RNA delivery also induced an increase in bone mass and decreased fat accumulation in the bone marrow. In conclusion, our study demonstrated that the Mettl3/Igf2bp2-Slc1a5 axis plays a key role in the promotion of osteoblast senescence and age-related bone loss., Competing Interests: Declaration of competing interest No conflicts of interest have been declared by all authors., (Copyright © 2024. Published by Elsevier B.V.)

With the aging of the global demographic, the prevention and treatment of osteoporosis are becoming crucial issues. The gradual loss of self-renewal and osteogenic differentiation capabilities in bone marrow stromal cells (BMSCs) is one of the key factors contributing to osteoporosis. To explore the regulatory mechanisms of BMSCs differentiation, we collected bone marrow cells of femoral heads from patients undergoing total hip arthroplasty for single-cell RNA sequencing analysis. Single-cell RNA sequencing revealed significantly reduced CRIP1 (Cysteine-Rich Intestinal Protein 1) expression and osteogenic capacity in the BMSCs of osteoporosis patients compared to non-osteoporosis group. CRIP1 is a gene that encodes a member of the LIM/double zinc finger protein family, which is involved in the regulation of various cellular processes including cell growth, development, and differentiation. CRIP1 knockdown resulted in decreased alkaline phosphatase activity, mineralization and expression of osteogenic markers, indicating impaired osteogenic differentiation. Conversely, CRIP1 overexpression, both in vitro and in vivo, enhanced osteogenic differentiation and rescued bone mass reduction in ovariectomy-induced osteoporosis mice model. The study further established CRIP1's modulation of osteogenesis through the Wnt signaling pathway, suggesting that targeting CRIP1 could offer a novel approach for osteoporosis treatment by promoting bone formation and preventing bone loss., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Abnormalities in osteoclastic generation or activity disrupt bone homeostasis and are highly involved in many pathologic bone-related diseases, including rheumatoid arthritis, osteopetrosis, and osteoporosis. Control of osteoclast-mediated bone resorption is crucial for treating these bone diseases. However, the mechanisms of control of osteoclastogenesis are incompletely understood. In this study, we identified that inosine 5'-monophosphate dehydrogenase type II (Impdh2) positively regulates bone resorption. By histomorphometric analysis, Impdh2 deletion in mouse myeloid lineage cells (Impdh2 LysM-/- mice) showed a high bone mass due to the reduced osteoclast number. qPCR and western blotting results demonstrated that the expression of osteoclast marker genes, including Nfatc1, Ctsk, Calcr, Acp5, Dcstamp, and Atp6v0d2, was significantly decreased in the Impdh2 LysM-/- mice. Furthermore, the Impdh inhibitor MPA treatment inhibited osteoclast differentiation and induced Impdh2-cytoophidia formation. The ability of osteoclast differentiation was recovered after MPA deprivation. Interestingly, genome-wide analysis revealed that the osteoclastic mitochondrial biogenesis and functions, such as oxidative phosphorylation, were impaired in the Impdh2 LysM-/- mice. Moreover, the deletion of Impdh2 alleviated ovariectomy-induced bone loss. In conclusion, our findings revealed a previously unrecognized function of Impdh2, suggesting that Impdh2-mediated mechanisms represent therapeutic targets for osteolytic diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Regular physical activity is widely recognized for reducing the risk of various disorders, with skeletal muscles playing a key role by releasing biomolecules that benefit multiple organs and tissues. However, many individuals, particularly the elderly and those with clinical conditions, are unable to engage in physical exercise, necessitating alternative strategies to stimulate muscle cells to secrete beneficial biomolecules. Histone acetylation and deacetylation significantly influence exercise-induced gene expression, suggesting that targeting histone deacetylases (HDACs) could mimic some exercise responses. In this study, we explored the effects of the HDAC inhibitor Trichostatin A (TSA) on human skeletal muscle myoblasts (HSMMs). Our findings showed that TSA-induced hyperacetylation enhanced myotube fusion and increased the secretion of extracellular vesicles (EVs) enriched with miR-873-3p. These TSA-EVs promoted osteogenic differentiation in human bone marrow mesenchymal stem cells (hBMSCs) by targeting H2 calponin (CNN2). In vivo, systemic administration of TSA-EVs to osteoporosis mice resulted in significant improvements in bone mass. Moreover, TSA-EVs mimicked the osteogenic benefits of exercise-induced EVs, suggesting that HDAC inhibition can replicate exercise-induced bone health benefits. These results demonstrate the potential of TSA-induced muscle-derived EVs as a therapeutic strategy to enhance bone formation and prevent osteoporosis, particularly for individuals unable to exercise. Given the FDA-approved status of various HDAC inhibitors, this approach holds significant promise for rapid clinical translation in osteoporosis treatment., (© 2024. The Author(s).)

Background: Osteoporosis results from decreased bone mass and disturbed bone structure. Human bone marrow mesenchymal stem cells (hBMSCs) demonstrate robust osteogenic differentiation, a critical process for bone formation. This research was designed to examine the functions of LINC01133 in osteogenic differentiation., Methods: Differentially expressed lncRNAs affecting osteogenic differentiation in hBMSCs were identified from the GEO database. A total of 74 osteoporosis patients and 70 controls were enrolled. hBMSCs were stimulated to undergo osteogenic differentiation using an osteogenic differentiation medium (OM). RT-qPCR was performed to evaluate LINC01133 levels and osteogenesis-related genes such as osteocalcin, osteopontin, and RUNX2. An alkaline phosphates (ALP) activity assay was conducted to assess osteogenic differentiation. Cell apoptosis was detected using flow cytometry. Dual luciferase reporter assay and RIP assay were employed to investigate the association between miR-214-3p and LINC01133 or CTNNB1. Loss or gain of function assays were conducted to elucidate the impact of LINC01133 and miR-214-3p on osteogenic differentiation of hBMSCs., Results: LINC01133 and CTNNB1 expression decreased in osteoporotic patients but increased in OM-cultured hBMSCs, whereas miR-214-3p showed an opposite trend. Depletion of LINC01133 suppressed the expression of genes associated with bone formation and ALP activity triggered by OM in hBMSCs, leading to increased cell apoptosis. Nevertheless, this suppression was partially counteracted by the reduced miR-214-3p levels. Mechanistically, LINC01133 and CTNNB1 were identified as direct targets of miR-214-3p., Conclusions: Our study highlights the role of LINC01133 in positively regulating CTNNB1 expression by inhibiting miR-214-3p, thereby promoting osteogenic differentiation of BMSCs. These findings may provide valuable insights into bone regeneration in osteoporosis., (© 2024. The Author(s).)

Senile osteoporosis (SOP), characterized by significant bone loss, poses a substantial threat to elderly skeletal health, with oxidative stress playing a crucial role in its pathogenesis. Although Tripartite Motif 16 (TRIM16) has been identified as a promoter of antioxidant response and osteogenic differentiation, its regulatory role in SOP remains incompletely understood. This study aims to elucidate the underlying mechanism of TRIM16 in mitigating D-galactose (D-gal)-induced senescent osteoblasts. Initially, we observed diminished bone mineral density (BMD) and impaired bone microstructure in naturally aging (24 months) and D-gal-induced (18 months) aged mice through Dual-energy X-ray absorptiometry (DEXA), micro-CT, hematoxylin and eosin staining, and Masson staining. Immunohistochemistry analysis revealed downregulation of TRIM16 and osteogenic differentiation markers (Collagen-1, Runx-2, osteopontin) in femur samples of aged mice. Furthermore, in D-gal-induced senescent MC3T3-E1 osteoblasts, we observed the suppression of osteogenic differentiation and maturity, along with cytoskeleton impairment via Alkaline phosphatase (ALP), Alizarin Red S, and Rhodamine-phalloidin staining. The protein expression of TRIM16, osteogenic differentiation markers, and antioxidant indicators (Nrf-2, HO-1, SOD1) decreased, while the production of reactive oxygen species (ROS) significantly increased. Knockdown and overexpression of TRIM16 using lentivirus in osteoblasts revealed that the downregulation of TRIM16 inhibited osteogenic differentiation and induced oxidative stress. Notably, TRIM16 overexpression partially attenuated D-gal-induced inhibition of osteogenic differentiation and increased oxidative stress. These findings suggest TRIM16 may mitigate impaired osteogenic differentiation and antioxidant response in D-gal-induced senescent osteoblasts, suggesting its potential as a therapeutic target for SOP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing commercial or associative interests with the work submitted. All of the listed authors have actively participated in this study and approved the submitted manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Age-related osteoporosis is a prevalent bone metabolic disorder distinguished by an aberration in the equilibrium between bone formation and resorption. The reduction in the stemness of Bone Marrow Mesenchymal Stem Cells (BMSCs) plays a pivotal role in the onset of this ailment. Comprehending the molecular pathways that govern BMSCs stemness is imperative for delineating the etiology of age-related osteoporosis and devising efficacious treatment modalities. The study utilized single-cell RNA sequencing and miRNA sequencing to investigate the cellular heterogeneity and stemness of BMSCs. Through dual-luciferase reporter assays and functional experiments, the regulatory effect of miR-183 on CTNNB1 (β-catenin) was confirmed. Overexpression and knockdown studies were conducted to explore the impact of miR-183 and β-catenin on stemness-related transcription factors Oct4, Nanog, and Sox2. Cell proliferation assays and osteogenic differentiation experiments were carried out to validate the influence of miR-183 and β-catenin on the stemness properties of BMSCs. Single-cell analysis revealed that β-catenin is highly expressed in both high stemness clusters and terminal differentiation clusters of BMSCs. Overexpression of β-catenin upregulated stemness transcription factors, while its suppression had the opposite effect, indicating a dual regulatory role of β-catenin in maintaining BMSCs stemness and promoting bone differentiation. Furthermore, the confluence of miRNA sequencing analyses and predictions from online databases revealed miR-183 as a potential modulator of BMSCs stemness and a novel upstream regulator of β-catenin. The overexpression of miR-183 effectively diminished the stemness characteristics of BMSCs by suppressing β-catenin, whereas the inhibition of miR-183 augmented stemness. These outcomes align with the observed alterations in the expression levels and functional assessments of transcription factors associated with stemness. This study provides evidence for the essential involvement of β-catenin in preserving the stemness of BMSCs, as well as elucidating the molecular mechanism through which miR-183 selectively targets β-catenin to modulate stemness. These results underscore the potential of miR-183 and β-catenin as molecular targets for augmenting the stemness of BMSCs. This strategy is anticipated to facilitate the restoration of bone microarchitecture and facilitate bone tissue regeneration by addressing potential cellular dysfunctions, thereby presenting novel targets and perspectives for the management of age-related osteoporosis., (© 2024. The Author(s).)

Heteroplasmic mitochondrial DNA (mtDNA) variants accumulate as humans age, particularly in the stem-cell compartments, and are an important contributor to age-related disease. Mitochondrial dysfunction has been observed in osteoporosis and somatic mtDNA pathogenic variants have been observed in animal models of osteoporosis. However, this has never been assessed in the relevant human tissue. Mesenchymal stem cells (MSCs) are the progenitors to many cells of the musculoskeletal system and are critical to skeletal tissues and bone vitality. Investigating mtDNA in MSCs could provide novel insights into the role of mitochondrial dysfunction in osteoporosis. To determine if this is possible, we investigated the landscape of somatic mtDNA variation in MSCs through a combination of fluorescence-activated cell sorting and single-cell next-generation sequencing. Our data show that somatic heteroplasmic variants are present in individual patient-derived MSCs, can reach high heteroplasmic fractions and have the potential to be pathogenic. The identification of somatic heteroplasmic variants in MSCs of patients highlights the potential for mitochondrial dysfunction to contribute to the pathogenesis of osteoporosis., (© 2024. The Author(s).)

Osteoporosis remains incurable. The most widely used antiresorptive agents, bisphosphonates (BPs), also inhibit bone formation, while the anabolic agent, teriparatide, does not inhibit bone resorption, and thus they have limited efficacy in preventing osteoporotic fractures and cause some side effects. Thus, there is an unmet need to develop dual antiresorptive and anabolic agents to prevent and treat osteoporosis. Hydroxychloroquine (HCQ), which is used to treat rheumatoid arthritis, prevents the lysosomal degradation of TNF receptor-associated factor 3 (TRAF3), an NF-κB adaptor protein that limits bone resorption and maintains bone formation. We attempted to covalently link HCQ to a hydroxyalklyl BP (HABP) with anticipated low antiresorptive activity, to target delivery of HCQ to bone to test if this targeting increases its efficacy to prevent TRAF3 degradation in the bone microenvironment and thus reduce bone resorption and increase bone formation, while reducing its systemic side effects. Unexpectedly, HABP-HCQ was found to exist as a salt in aqueous solution, composed of a protonated HCQ cation and a deprotonated HABP anion. Nevertheless, it inhibited osteoclastogenesis, stimulated osteoblast differentiation, and increased TRAF3 protein levels in vitro. HABP-HCQ significantly inhibited both osteoclast formation and bone marrow fibrosis in mice given multiple daily PTH injections. In contrast, HCQ inhibited marrow fibrosis, but not osteoclast formation, while the HABP alone inhibited osteoclast formation, but not fibrosis, in the mice. HABP-HCQ, but not HCQ, prevented trabecular bone loss following ovariectomy in mice and, importantly, increased bone volume in ovariectomized mice with established bone loss because HABP-HCQ increased bone formation and decreased bone resorption parameters simultaneously. In contrast, HCQ increased bone formation, but did not decrease bone resorption parameters, while HABP also restored the bone lost in ovariectomized mice, but it inhibited parameters of both bone resorption and formation. Our findings suggest that the combination of HABP and HCQ could have dual antiresorptive and anabolic effects to prevent and treat osteoporosis., (© 2024. The Author(s).)

Osteoporotic bone defects are difficult to repair in elderly patients. This study aimed to repair osteoporotic bone defects using a combination of bone tissue engineering (BTE) and drug delivery systems (DDS). Herein, honeycomb granules (HCGs) composed of carbonate apatite microspheres were fabricated as BTE scaffolds. Each HCG possesses hexagonal macropores and abundant interconnected micropores between the microspheres. Owing to these multiscale interconnected pores, HCGs can readily contain antibodies against sclerostin (Scl), which causes imbalances in bone homeostasis. Anti-Scl antibody-loaded HCGs (Scl-Ab-HCGs) regulate the release of Scl-Abs in response to the pH of the osteoporotic environment. In ovariectomized rabbit osteoporotic femurs, HCG monotherapy forms new bone with less osteocyte damage (fewer empty bone lacunae) and fewer osteoclasts than osteoporotic bone; however, it is insufficient to prevent receptor activator of nuclear factor-kappa B ligand (RANKL) overexpression. Consequently, HCG monotherapy restores bone quantity better than no treatment but not to normal levels. In contrast, new bone tissue formed by Scl-Ab-HCG-based DDS predominantly expresses osteocalcin rather than RANKL, similar to normal bone, and shows a similar osteocyte apoptosis level, bone quantity, and osteoclast number as normal bone. Thus, Scl-Ab-HCG-based DDS is a promising approach for osteoporotic bone defect repair.

Rosiglitazone (RSG), as an insulin-sensitizing drug to treat type 2 diabetes mellitus (T2DM) is reported to decrease bone quality and increase bone fracture risk. The multiple off-target effects of Resveratrol (RSV), a natural specific agonist of Sirtuin1 (Sirt1) with pro-osteoblastogenesis and anti-adipogenesis effects, on bone loss in T2DM are still under discussion. In this study, successfully ovariectomized rats were fed with high-fat diet and STZ (HFD/STZ) to induced T2DM mice. RSV alone, RSG alone or co-administration of RSV and RSG were given orally to T2DM rats for 8 weeks to determine whether RSV administration had any prevention effect on T2DM osteoporosis. Bone mesenchymal stem cells (BMSCs) and bone marrow‑derived macrophages (BMMs) were cultured under high glucose condition and were induced to osteoblasts or adipocytes and osteoclasts, respectively. μCT and HE staining showed that in T2DM osteoporotic rats, RSV co-administration prevents RSG induced-bone loss. ELISA results confirmed that RSV suppressed osteoclast activity and promoted osteoblast activity in diabetic osteoporosis rats and RSG-administrated diabetic osteoporosis rats. In vitro study showed that RSV significantly reversed RSG induced inhibition on osteogenesis and promotion on adiopogenesis of BMSC under high glucose (HG). Moreover, RSV significantly reverse RSG induced osteoclast formation and mature under HG. Taken together, these findings uncover a previously unappreciated anti-osteoporosis effect of concomitant treatment with RSV in RSG-administrated diabetic rats, suggesting the clinical use of RSV as an adjuvant in the treatment of T2DM for preventing or reversing RSG administration-associated bone loss., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)