Hydrogel contained valproic acid accelerates bone-defect repair via activating Notch signaling pathway in ovariectomized rats

The purpose was to observe whether valproic acid (VPA) has a positive effect on bone-defect repair via activating the Notch signaling pathway in an OVX rat model. The MC3T3-E1 cells were cocultured with VPA and induced to osteogenesis, and the osteogenic activity was observed by alkaline phosphatase (ALP) staining, Alizarin Red (RES) staining and Western blotting (WB). Then the hydrogel-containing VPA was implanted into the femoral epiphysis bone-defect model of ovariectomized (OVX) rats for 12 weeks. Micro-CT, biomechanical testing, histology, immunofluorescence, RT-qPCR, and WB analysis were used to observe the therapeutic effect and explore the possible mechanism. ALP and ARS staining and WB results show that the cell mineralization, osteogenic activity, and protein expression of ALP, OPN, RUNX-2, OC, Notch 1, HES1, HEY1, and JAG1 of VPA group is significantly higher than the control group. Micro-CT, biomechanical testing, histology, immunofluorescence, and RT-qPCR evaluation show that group VPA presented the stronger effect on bone strength, bone regeneration, bone mineralization, higher expression of VEGFA, BMP-2, ALP, OPN, RUNX-2, OC, Notch 1, HES1, HEY1, and JAG1 of VPA when compared with OVX group. Our current study demonstrated that local treatment with VPA could stimulate repair of femoral condyle defects, and these effects may be achieved by activating Notch signaling pathway and acceleration of blood vessel and bone formation.

miR-196a-5p Promoted the Osteogenic Differentiation and Calvarial Bone Defect Repair of Wharton’s Jelly Umbilical Cord Stem Cells

Background: To investigate the effect of miR‐196a-5p on the osteogenic differentiation and defected bone repair of Wharton’s jelly umbilical cord stem cells (WJCMSCs). Methods: miR‐196a-5p mimic or inhibitor was applied to overexpress or silence miR‐196a-5p expression in WJCMSCs. The alkaline phosphatase (ALP) activity, mineralization ability, and osteogenic markers expression were used to test WJCMSCs osteogenic potential in vitro. Calvarial bone defect model of rat was used to evaluate WJCMSCs bone regeneration ability in vivo. mRNA microarray was used to reveal the underling mechanisms that miR‐196a-5p regulated bone repair.Results: miR-196a-5p inhibition reduced the ALP activity, mineralization ability, and level of osteogenic markers OCN, DSPP, DMP1 and BSP, while miR-196a-5p overexpression enhanced the ALP activity, mineralization ability, and level of OCN, DSPP, DMP1 and BSP of WJCMSCs in vitro. Next, the micro-CT and histopathology results showed miR-196a-5p-overexpressed-WJCMSCs obviously promoted the new bone tissue regeneration and calvarial bone defect repair after MSCs transplanted for 12 weeks. Further, mRNA microarray of miR-196a-5p-overexpressed-WJCMSCs revealed totally 959 significantly differentially expressed genes (DEGs), among which 34 upregulated and 925 downregulated. Also, 241 miR-196a-5p targeted genes were predicted by using miRNA targeted websites and only 19 predicted genes were consistent with microarray results. On this basis, one significantly downregulated gene SERPINB2 was selected and revealed that SERPINB2 deletion obviously enhanced the ALP activity and mineralization ability of WJCMSCs in vitro.Conclusions: miR-196a-5p promoted the osteogenic differentiation potential and calvarial bone defect repair ability of WJCMSCs. And SERPINB2 acted as one key downstream gene to participate in the miR-196a-5p promoted MSCs osteogenic differentiation.