Sclerostin transduced bone marrow mesenchymal stem cells promote fracture healing in rats via the Wnt/ß-catenin signal pathway.

The prognosis of fracture is directly related to several factors. Due to the limitations of existing treatment strategies, there are still many poor fracture healing. Bone marrow mesenchymal stem cells (BMSCs) have the potential to differentiate into osteoblasts and chondrocytes. Therefore, BMSC transplantation is promised as an effective method for treating bone fractures.We aim to explore whether silently expressing Sclerostin gene (SOST) can promote bone formation through sclerostin/Wnt/ß-catenin signal pathway.We isolated rat BMSCs and the target gene(SOST shRNA) was transduced into them for osteogenic induction.The results showed that sclerostin significantly inhibited the proliferation and osteogenic differentiation of BMSCs during osteogenic induction, while silently expressing SOST not only increased the number of surviving BMSCs, but also promoted the expression of osteogenic-related proteins RUNX2, OPG, COL-Ⅰ and BMP-2 during osteogenic induction.The results of imaging examination in rats show that down-regulating the expression of SOST can promote the formation of bony callus and the transformation of cartilage tissue into normal bone tissue, and then accelerate the healing of osteoporotic fracture (OPF). In addition,we also found that the SOST silencing can activate Wnt/ß-catenin pathway to achieve these effects.In conclusion, the SOST silencing can promote the proliferation and osteogenic differentiation of BMSCs in situ, and therefore may enhance the therapeutic efficiency of BMSC transplantation in OPF.

Icariin promotes bone marrow mesenchymal stem cells osteogenic differentiation via the mTOR/autophagy pathway to improve ketogenic diet-associated osteoporosis.

BACKGROUND: Icariin, a traditional Chinese medicine, has demonstrated anti-osteoporotic properties in ovariectomized mice. However, its effectiveness in preventing bone loss induced by ketogenic diet (KD), which mimics osteoporosis in human, remains unexplored. This study aims to investigate icariin's impact on KD-induced bone loss in mice. METHODS: Thirty mice were divided into: sham, KD, and KD + icariin groups. Post a 12-week intervention, evaluation including bone microstructures, serum concentrations of tartrate-resistant acid phosphatase (TRAP) and bone-specific alkaline phosphatase (ALP), and femoral tissue expression levels of osteocalcin (OCN) and TRAP. The expression levels of mammalian target of rapamycin (mTOR), ALP, peroxisome proliferator-activated receptor gamma (PPAR-γ), phosphorylated mTOR (p-mTOR), and the autophagy adaptor protein (p62) were also analyzed. Alizarin granule deposition and cellular ALP levels were measured following the induction of bone marrow mesenchymal stem cells (BMSCs) into osteogenesis. RESULTS: The study found that KD significantly impaired BMSCs' osteogenic differentiation, leading to bone loss. Icariin notably increased bone mass, stimulated osteogenesis, and reduced cancellous bone loss. In the KD + icariin group, measures such as bone tissue density (TMD), bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were significantly higher than in the KD group. Additionally, bone trabecular separation (Tb.Sp) was markedly lower in the KD + icariin group. Moreover, icariin increased OCN and ALP levels while suppressing PPAR-γ, TRAP, p62, and p-mTOR. In cellular studies, icariin encouraged osteogenic development in BMSCs under KD conditions. CONCLUSIONS: Icariin effectively counteracts bone thinning and improves bone microstructure. Its mechanism likely involves stimulating BMSCs osteogenic differentiation and inhibiting bone resorption, potentially through mTOR downregulation. These findings suggest icariin's potential as an alternative treatment for KD-induced bone loss.

Icariin inhibits osteoblast ferroptosis via Nrf2/HO-1 signaling and enhances healing of osteoporotic fractures.

The incidence of osteoporotic fractures is increasing every year because of population aging around the world. The reduced osteoblast activity in osteoporotic fracture has been associated with ferroptosis. A recent study showed that the antioxidant icariin (ICA) reduced iron deposition in the bone marrow of osteoporotic mice, although the underlying regulatory mechanisms were not explored. The objective of present study was to assess the therapeutic effects of ICA in a rat osteoporotic fracture model, with particular focus on its impact on ferroptosis. Primary rat osteoblasts were exposed to the ferroptosis inducer erastin, and then treated with ICA or the ferroptosis inhibitor ferrostatin-1 (Fer-1) as the positive control group. The levels of Nrf2 signaling factors and osteogenesis-related factors were examined by RT-PCR and western blotting. An osteoporotic fracture model was established in rats, and the effect of ICA on bone formation was evaluated by X-ray, Micro CT analysis, histological examination and Safranin O staining. Furthermore, the levels of GPX4, Bax, Nrf2 and Runx2 proteins at the fracture site were examined by immunohistochemistry. ICA significantly reduced ROS levels in the erastin-treated osteoblasts, and downregulated glutathione peroxidase 4 (GPX4) and cystine glutamate antiporter (SLC7A11). Moreover, ICA also upregulated Nrf2, NQO-1, HO-1, Runx2, ALP, OPG and OCN in these cells, which was reversed by inhibitors of the Nrf2 signaling pathway and Nrf2 silencing. X-ray and Micro CT analysis showed that ICA increased the trabecular bone and promoted callus formation in the osteoporotic fracture model, and also enhanced the transition from fibrous to osseous callus. Furthermore, ICA upregulated GPX4, Nrf2 and Runx2 at the fracture site, and significantly reduced the expression of the apoptotic genes of Bax. Taken together, our findings indicate that ICA promotes osteoporotic fracture healing by inhibiting osteoblast ferroptosis via activation of the antioxidant Nrf2/HO-1 signaling pathway.

Icariin Promotes the Osteogenesis of Bone Marrow Mesenchymal Stem Cells through Regulating Sclerostin and Activating the Wnt/ß-Catenin Signaling Pathway.

Osteoporosis (OP) is a metabolic disease characterized by decreased bone mass and increased risk of fragility fractures, which significantly reduces the quality of life. Stem cell-based therapies, especially using bone marrow mesenchymal stem cells (BMSCs), are a promising strategy for treating OP. Nevertheless, the survival and differentiation rates of the transplanted BMSCs are low, which limits their therapeutic efficiency. Icariin (ICA) is a traditional Chinese medicine formulation that is prescribed for tonifying the kidneys. It also promotes the proliferation and osteogenic differentiation of BMSCs, although the specific mechanism remains unclear. Based on our previous research, we hypothesized that ICA promotes bone formation via the sclerostin/Wnt/ß-catenin signaling pathway. We isolated rat BMSCs and transfected them with sclerostin gene (SOST) overexpressing or knockdown constructs and assessed osteogenic induction in the presence or absence of ICA. Sclerostin significantly inhibited BMSC proliferation and osteogenic differentiation, whereas the presence of ICA not only increased the number of viable BMSCs but also enhanced ALP activity and formation of calcium nodules during osteogenic induction. In addition, the osteogenic genes including Runx2, ß-catenin, and c-myc as well as antioxidant factors (Prdx1, Cata, and Nqo1) were downregulated by sclerostin and restored by ICA treatment. Mechanistically, ICA exerted these effects by activating the Wnt/ß-catenin pathway. In conclusion, ICA can promote the proliferation and osteogenic differentiation of BMSCs in situ and therefore may enhance the therapeutic efficiency of BMSC transplantation in OP.