Objective To investigate the role of micro RNA-451 (miRNA-451) in promoting the osteogenesis of mesenchymal stem cells (MSCs) by targeting regulatory calcium binding protein 39 (CAB39). Methods pMIR-report and pRL-TK vectors were selected to identify the relationship between miRNA-451 and CAB39 by using dual-luciferase reporter assay. pre-miRNA-451 (group A), anti-miRNA-451 (group C), pre-miRNA negative control (group B), and anti-miRNA negative control (group D) were transfected into the C3H10T1/2 cells, respectively. Then, the cells were collected after osteogenic induction for 7 and 14 days. At 7 and 14 days, the real-time fluorescent quantitative PCR and Western blot assays were performed to detect the related osteogenetic biomarkers [Runx2 and alkaline phosphatase (ALP) mRNA] and expressions of CAB39 protein. At 14 days, the extracellular calcium deposition during the osteogenesis of MSCs was tested by Alizarin red staining method. Results CAB39 was the target gene of miRNA-451. At 7 and 14 days after osteogenic induction, the mRNA expressions of Runx2 and ALP in group A were significantly higher than those in group B (P lt; 0.05), and the expressions in group C was significantly lower than those in group D (P lt; 0.05). Furthermore, at 14 days after osteogenic induction, the protein expression of CAB39 in group A (0.55 ± 0.05) was significantly lower than that in group B (1.00 ± 0.07), and the protein expression in group C (1.21 ± 0.05) was significantly higher than that in group D (1.00 ± 0.04), all showing significant difference (P lt; 0.05). Finally, at 14 days after osteogenic induction, the extracellular calcium deposition in group A was obviously more than that in group B, and group C was downregulated when compared with group D. Conclusion miRNA-451 can promote the osteogenesis process of MSCs by downregulating the CAB39.
ObjectiveBased on the cell-extracellular matrix adhesion theory in selective cell retention (SCR) technology, demineralized bone matrix (DBM) modified by simplified polypeptide surface was designed to promote both bone regeneration and angiogenesis.MethodsFunctional peptide of α4 chains of laminin protein (LNα4), cyclic RGDfK (cRGD), and collagen-binding domain (CBD) peptides were selected. CBD-LNα4-cRGD peptide was synthesized in solid phase and modified on DBM to construct DBM/CBD-LNα4-cRGD scaffold (DBM/LN). Firstly, scanning electron microscope and laser scanning confocal microscope were used to examine the characteristics and stability of the modified scaffold. Then, the adhesion, proliferation, and tube formation properties of CBD-LNα4-cRGD peptide on endothelial progenitor cells (EPCs) were detected, respectively. Western blot method was used to verify the molecular mechanism affecting EPCs. Finally, 24 10-week-old male C57 mice were used to establish a 2-mm-length defect of femoral bone model. DBM/LN and DBM scaffolds after SCR treatment were used to repair bone defects in DBM/LN group (n=12) and DBM group (n=12), respectively. At 8 weeks after operation, the angiogenesis and bone regeneration ability of DBM/LN scaffolds were evaluated by X-ray film, Micro-CT, angiography, histology, and immunofluorescence staining [CD31, endomucin (Emcn), Ki67].ResultsMaterial related tests showed that the surface of DBM/LN scaffold was rougher than DBM scaffold, but the pore diameter did not change significantly (t=0.218, P=0.835). After SCR treatment, DBM/LN scaffold was still stable and effective. Compared with DBM scaffold, DBM/LN scaffold could adhere to more EPCs after the surface modification of CBD-LNα4-cRGD (P<0.05), and the proliferation rate and tube formation ability increased. Western blot analysis showed that the relative expressions of VEGF, phosphorylated FAK (p-FAK), and phosphorylated ERK1/2 (p-ERK1/2) proteins were higher in DBM/LN than in DBM (P<0.05). In the femoral bone defect model of mice, it was found that mice implanted with DBM/LN scaffold had stronger angiogenesis and bone regeneration capacity (P<0.05), and the number of CD31hiEmcnhi cells increased significantly (P<0.05).ConclusionDBM/LN scaffold can promote the adhesion of EPCs. Importantly, it can significantly promote the generation of H-type vessels and realize the effective coupling between angiogenesis and bone regeneration in bone defect repair.