BACKGROUND:With aging,the regenerative capacity and differentiation function of bone marrow mesenchymal stem cells progressively decline,reducing bone tissue repair efficacy.Thus,identifying bone marrow mesenchymal stem cell subpopulations with enhanced osteogenic potential is of significant importance for advancing bone tissue engineering.OBJECTIVE:To evaluate the osteogenic differentiation potential differences between STRO-1 positive and negative bone marrow mesenchymal stem cells under osteogenic induction conditions.METHODS:SD rat bone marrow mesenchymal stem cells were isolated and cultured.The expression of CD29,CD45,CD90,and STRO-1 was identified via flow cytometry and immunofluorescence.Immunomagnetic cell sorting was used to separate STRO-1 positive and negative bone marrow mesenchymal stem cells.The cells of two groups were subjected to osteogenic induction for 7 and 14 days.qRT-PCR and western blotting were performed to analyze differences in osteogenesis-related gene expression(Collagen I,Runt-related transcription factor 2,osteoprotegerin,and osteocalcin)and protein levels.Alizarin red staining and alkaline phosphatase staining were used to observe calcium nodule formation.RESULTS AND CONCLUSION:Flow cytometry showed high expression levels of CD29 and CD90 and low expression of CD45,with a positive STRO-1 expression rate of 12.8％.Immunofluorescence results were consistent with those of flow cytometry.After magnetic cell sorting,STRO-1 positive cells demonstrated a higher colony formation rate than STRO-1 negative cells.On day 14,STRO-1 positive cells showed significantly higher osteogenic differentiation potential than on day 7,with significantly elevated osteogenesis-related marker levels compared to STRO-1 negative cells(P＜0.01).The findings indicate that STRO-1 positive bone marrow mesenchymal stem cells exhibit significant advantages in osteogenic potential,providing a theoretical basis for their selection as ideal seed cells in bone tissue engineering.In future applications,they may represent a promising therapeutic approach for bone defect repair.

BACKGROUND:With aging,the regenerative capacity and differentiation function of bone marrow mesenchymal stem cells progressively decline,reducing bone tissue repair efficacy.Thus,identifying bone marrow mesenchymal stem cell subpopulations with enhanced osteogenic potential is of significant importance for advancing bone tissue engineering.OBJECTIVE:To evaluate the osteogenic differentiation potential differences between STRO-1 positive and negative bone marrow mesenchymal stem cells under osteogenic induction conditions.METHODS:SD rat bone marrow mesenchymal stem cells were isolated and cultured.The expression of CD29,CD45,CD90,and STRO-1 was identified via flow cytometry and immunofluorescence.Immunomagnetic cell sorting was used to separate STRO-1 positive and negative bone marrow mesenchymal stem cells.The cells of two groups were subjected to osteogenic induction for 7 and 14 days.qRT-PCR and western blotting were performed to analyze differences in osteogenesis-related gene expression(Collagen I,Runt-related transcription factor 2,osteoprotegerin,and osteocalcin)and protein levels.Alizarin red staining and alkaline phosphatase staining were used to observe calcium nodule formation.RESULTS AND CONCLUSION:Flow cytometry showed high expression levels of CD29 and CD90 and low expression of CD45,with a positive STRO-1 expression rate of 12.8％.Immunofluorescence results were consistent with those of flow cytometry.After magnetic cell sorting,STRO-1 positive cells demonstrated a higher colony formation rate than STRO-1 negative cells.On day 14,STRO-1 positive cells showed significantly higher osteogenic differentiation potential than on day 7,with significantly elevated osteogenesis-related marker levels compared to STRO-1 negative cells(P＜0.01).The findings indicate that STRO-1 positive bone marrow mesenchymal stem cells exhibit significant advantages in osteogenic potential,providing a theoretical basis for their selection as ideal seed cells in bone tissue engineering.In future applications,they may represent a promising therapeutic approach for bone defect repair.

OBJECTIVE To preliminarily investigate the impacts of galangin （Gal） on fracture healing in osteoporosis （OP） model rats by regulating hypoxia-inducible factor-1α （HIF-1α）/vascular endothelial growth factor （VEGF） signaling pathway. METHODS The OP rat model was constructed by using bilateral ovariectomy surgery. The model rats were randomly divided into sham operation group （normal saline）， model group （normal saline）， Gal low-dose， medium-dose and high-dose groups （2.5， 5， 10 mg/kg）， inhibitor group （10 mg/kg Gal+100 mg/kg HIF-1α/VEGF signaling pathway inhibitor PX-478）， with 12 rats in each group. They were given relevant medicine intraperitoneally， once a day， for 90 consecutive days. The microstructure of rat bones was observed， the biomechanical status of rat femurs was evaluated， and the pathological damage and neovascularization of rat callus tissue were observed. The expression of platelet endothelial cell adhesion molecule-1 （PECAM-1） in the femur was detected. The contents of osteocalcin （OCN）， C-terminal telopeptides of type Ⅰ collagen （CTX-Ⅰ） and bone morphogenetic protein 2 （BMP-2） in serum were detected as well as the expressions of alkaline phosphatase （ALP） and HIF-1α/VEGF signaling pathway- related proteins in callus tissue. RESULTS Compared with the sham operation group， the BMD， BV/TV， Tb.N， Tb.Th， maximum load， the number and area of blood vessels， the average fluorescence intensity of PECAM-1， the contents of OCN and BMP-2， and the expression levels of ALP， HIF-1α and VEGF proteins in the model group were reduced significantly （P＜0.05）， while the content of CTX-Ⅰ increased significantly （P＜0.05）. Compared with the model group， the above indexes of rats were reversed significantly in Gal low-dose， medium-dose and high-dose groups （P＜0.05）， in a dose-dependent manner. Compared with the Gal high-dose group， the above indexes of rats were reversed significantly in the inhibitor group （P＜0.05）. CONCLUSIONS Gal can regulate bone metabolism， improve bone density of OP model rats and promote fracture healing， the mechanism of which may be associated with activating the HIF-1α/VEGF signaling pathway and promoting angiogenesis.

Objective: Dendrobium polysaccharide(DOP-1-1) was prepared and its effects on the proliferation, differentiation and mineralization of pre-osteoblast MC3 T3-E1 cells were investigated. Methods : A homogeneous polysaccharide(DOP-1-1) was obtained from Dendrobium officinale polysaccharide(DOP) through systematic separation and purification, and the structure of DOP-1-1 was studied by high-performance gel permeation chromatography, monosaccharide analysis, infrared spectroscopy, methylation analysis, GC-MS and NMR spectroscopy.In vitroexperiments were performed to detect the effects of DOP-1-1 on the proliferation, differentiation and mineralization of MC3 T3-E1 cells by MTT method, ALP activity determination and Alizarin Red S staining. At the same time, Western blot was used to determine the effect of DOP-1-1 on the expression of bone-related proteins(Pin1, BMP2, RUNX2) in MC3 T3-E1 cells. Results : DOP-1-1 was a homogeneous polysaccharide with relative molecular weights of 3 611, which was composed of mannose, glucose and galactose. DOP-1-1 had excellent activity of promoting osteoblast proliferation in a low concentration, and the effects of 2.0 and 4.0 μmol/L of DOP-1-1 were equivalent to Positive Control 17β-estradiol(E2). Compared with the control group, E2 and DOP-1-1(4.0, 8.0 μmol/L) increased the ALP activity and mineralization rate in MC3 T3-E1 cells(P<0.01). In particular, the ALP activity and mineralization rate of DOP-1-1(8.0 μmol/L) were higher than those of the positive control E2(P<0.001). In addition, the expression of Pin1, BMP2, and RUNX2 protein in MC3 T3-E1 cells in the DOP-1-1 group was higher than that in the control group(P<0.05). Conclusion DOP-1-1 can promote the proliferation, differentiation and mineralization of MC3 T3-E1 cells in vitro, and its mechanism is related to the activation of Pin1/BMP2 signaling pathway.