Putting the Brakes on Breaks: Osteoporosis Screening and Fracture Prevention

Untargeted Metabolomics Reveal the Protective Effect of Bone Marrow Mesenchymal Stem Cell Transplantation Against Ovariectomy-Induced Osteoporosis in Mice

Bone marrow mesenchymal stem cell transplantation (BMSCT) is a potential treatment for osteoporosis, capable of contributing to bone tissue repair. BMSCT has demonstrated osteoinductive effects and the ability to regulate microenvironmental metabolism; however, its role and mechanisms in bone loss due to reduced estrogen levels remain unclear. In this study, the effect of BMSCT on ovariectomy (OVX)-induced osteoporosis in mice was assessed, and liquid chromatography–mass spectrometry (LC-MS) metabolomic studies of bone tissue were conducted to identify potential metabolic molecular markers. The results revealed that BMSCT reduces OVX-induced bone loss in mice while improving the mechanical properties of mouse femurs and increasing the expression of osteogenic markers in peripheral blood. In a metabolomic study, 18 metabolites were screened as potential biomarkers of the anti-osteoporotic effect of BMSCT. These metabolites are mainly involved in arachidonic acid metabolism, taurine and hypotaurine metabolism, and pentose and glucuronate interconversions. Collectively, these results illustrate the correlation between metabolites and the underlying mechanisms of osteoporosis development and are important for understanding the role and mechanisms of exogenous bone marrow mesenchymal stem cells (BMSCs) in osteoporosis management. This study lays the foundation for research on BMSCs as a treatment strategy for osteoporosis.

Fracture Risk Assessment: An Update

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Our ability to accurately identify high fracture risk in individuals has improved as the volume of clinical data has expanded and fracture risk assessment tools have been developed.

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Given its accessibility, affordability, and low radiation exposure, dual x-ray absorptiometry (DXA) remains the standard for osteoporosis screening and monitoring response to treatment.

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The trabecular bone score (TBS) is a DXA software add-on that uses lumbar spine DXA imaging to produce an output that correlates with bone microarchitecture. It has been identified as an independent fracture risk factor and may prove useful in further stratifying fracture risk among those with a bone mineral density (BMD) in the osteopenic range (-1.0 to -2.4 standard deviations), in those with low-energy fractures but normal or only mildly low BMD, or in those with conditions known to impair bone microarchitecture.

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Fracture risk assessment tools, including the Fracture Risk Assessment Tool (FRAX), Garvan fracture risk calculator, and QFracture, evaluate the impact of multiple clinical factors on fracture risk, even in the absence of BMD data. Each produces an absolute fracture risk output over a defined interval of time. When used appropriately, these enhance our ability to identify high-risk patients and allow us to differentiate fracture risk among patients who present with similar BMDs.

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For challenging clinical cases, a combined approach is likely to improve accuracy in the identification of high-risk patients who would benefit from the available osteoporosis therapies.

Estrogen promotes lncRNA H19 expression to regulate osteogenic differentiation of BMSCs and reduce osteoporosis via miR-532-3p/SIRT1 axis

Osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) plays an essential role in bone formation. Its imbalance can lead to osteoporosis. Estrogen and long noncoding RNAs (lncRNAs) have been confirmed to participate in osteogenesis. However, the underlying mechanism remains unclear. The purpose of our study was to explore the function of lncRNA H19 in estrogen-induced osteogenic differentiation of BMSCs. The present research demonstrated that the expression levels of lncRNA H19 and SIRT1 were markedly downregulated in postmenopausal osteoporosis (PMOP), while miR-532-3p expression was obviously increased. Moreover, estrogen induced the osteogenic differentiation of BMSCs by upregulating lncRNA H19. Furthermore, our integrated experiments showed that lncRNA H19 caused a decrease in the expression of miR-532-3p, which was verified to target SIRT1 directly. Additionally, estrogen alleviated osteoporosis in OVX rats through lncRNA H19-mediated miR-532-3p/SIRT1 axis. Our findings imply that lncRNA H19 mediates estrogen-regulated osteogenic differentiation in BMSCs via miR-532-3p/SIRT1 signalling and may become a novel target for alleviating PMOP.

Sweroside-mediated mTORC1 hyperactivation in bone marrow mesenchymal stem cells promotes osteogenic differentiation

This paper aims to probe into the effect of sweroside (SOS) in osteoporosis (OP) and explains mechanisms of its molecular. Applying the ovariectomized (OVX) mouse model investigates the preventive effect of SOS against postmenopausal OP after 3 months of SOS treatment (120 mg/kg/day). Using hematoxylin and eosin (HE) staining and micro computed tomography (CT) observed the morphology of OP in each group. Immunohistochemical staining (IHC) was used to examine osteoblast markers. Experiments in vitro, bone marrow mesenchymal stem cells (BMSCs) from C57/BL6 mice were treated with SOS for 14 days. The staining of alizarin red and alkaline phosphatase activity were measured, and the presentation of osteoblast markers was detected by quantitative reverse transcription PCR. BMSCs were also treated with 1 μg/mL SOS with or without rapamycin, the expression of protein S6 (PS6), P-mTOR, runt-related transcription factor 2 (RUNX2), OSX, and osteocalcin (OCN) was detected by Western blotting. Experiments in vivo, HE results show that SOS can alleviate OP, CT results show that there are lower trabecular thickness, bone mineral density, and trabecular number in control OVX mice than those in the OVX + SOS group. IHC results showed that SOS can promote the expression of osteogenic markers and immunofluorescent results show that SOS can promote mTORC1 signal activation. Experiments in vitro revealed that SOS stimulated the activation of the mTORC1 signaling pathway and upregulated RUNX2, OSX, and OCN, rapamycin can reverse it. Our findings demonstrated that differentiated BMSCs into osteoblasts can be promoted by SOS via upregulating the expression of P-mTOR, PS6, RUNX2, OSX, and OCN. SOS effectively prevented OP by hyperactivation of the mTORC1/PS6 signaling pathway.