Fibroblast growth factor 23 regulates hypoxia­induced osteoblast apoptosis through the autophagy­signaling pathway.

Hypoxia can lead to programmed osteoblast death. Prevention of osteoblast apoptosis caused by hypoxia is of great significance in the study of the occurrence and development of bone necrosis. The present study aimed to investigate the effects and mechanism of fibroblast growth factor 23 (FGF23) on hypoxia­induced apoptosis in primary osteoblasts and MC3T3­E1 cells osteoblasts. Cells were transfected with a plasmid carrying the FGF23 gene and a cell model of hypoxia­induced apoptosis was established. FGF23 mRNA levels were measured using reverse transcription­quantitative (RT­q) PCR and western blotting was used to assess protein levels. Apoptosis was analyzed by MTT assay, fluorescein diacetate and ethidium bromide staining, flow cytometry and RT­qPCR and western blotting were used to verify the mRNA and protein levels of apoptosis­ and autophagy­related gene mRNA. The targeted relationship between miR­17­5p and FGF23 was confirmed using the StarBase database, TargetScan database and a luciferase reporter assay. FGF23 decreased cell survival and increased the rate of apoptosis. The mRNA and protein expression of the pro­apoptotic genes Bax and caspases 3 and 9 increased, whereas that of the anti­apoptotic Bcl­2 decreased. The expressions of the autophagy­associated proteins beclin­1, light chain 3­II (LC3­II) and the LC3­II/LC3­I ratio were significantly increased. In addition, a luciferase reporter assay confirmed that FGF23 directly regulated micro RNA (miR)­17­5p. The effects of FGF23 silencing were reversed by miR­17­5p inhibition. FGF23 may regulate hypoxia­induced osteoblast apoptosis by targeting miR­17­5p through the autophagy­signaling pathway. This provides a rationale for FGF23 as a potential therapeutic target for osteonecrosis of the femoral head.

A composite scaffold of Wharton's jelly and chondroitin sulphate loaded with human umbilical cord mesenchymal stem cells repairs articular cartilage defects in rat knee.

To evaluate the performance of a composite scaffold of Wharton's jelly (WJ) and chondroitin sulfate (CS) and the effect of the composite scaffold loaded with human umbilical cord mesenchymal stem cells (hUCMSCs) in repairing articular cartilage defects, two experiments were carried out. The in vitro experiments involved identification of the hUCMSCs, construction of the biomimetic composite scaffolds by the physical and chemical crosslinking of WJ and CS, and testing of the biomechanical properties of both the composite scaffold and the WJ scaffold. In the in vivo experiments, composite scaffolds loaded with hUCMSCs and WJ scaffolds loaded with hUCMSCs were applied to repair articular cartilage defects in the rat knee. Moreover, their repair effects were evaluated by the unaided eye, histological observations, and the immunogenicity of scaffolds and hUCMSCs. We found that in vitro, the Young's modulus of the composite scaffold (WJ-CS) was higher than that of the WJ scaffold. In vivo, the composite scaffold loaded with hUCMSCs repaired rat cartilage defects better than did the WJ scaffold loaded with hUCMSCs. Both the scaffold and hUCMSCs showed low immunogenicity. These results demonstrate that the in vitro construction of a human-derived WJ-CS composite scaffold enhances the biomechanical properties of WJ and that the repair of knee cartilage defects in rats is better with the composite scaffold than with the single WJ scaffold if the scaffold is loaded with hUCMSCs.

Interfering with pak4 Protein Expression Affects Osteosarcoma Cell Proliferation and Migration.

PURPOSE: A number of studies have discovered various roles of PAK4 in human tumors, including osteosarcoma. However, the exact role of PAK4 in osteosarcoma and its mechanism have yet to be determined. Therefore, this study focused on interrogating the PAK4 effect on the proliferation and migration ability of osteosarcoma and its underlying mechanisms. MATERIALS AND METHODS: Western blot and QRT-PCR were utilized to quantify the PAK4 relative protein and mRNA levels. To measure cellular viability and mobility, the MTT and wound-healing assays were preferred. RESULTS: With the adenovirus-mediated overexpression of PAK4, the proliferation and migration of U2-OS and MG-63 osteosarcoma cells were stimulated. Furthermore, a liposome-mediated knockout of PAK4 will inhibit osteosarcoma cells from proliferating. In terms of mechanism, we observed the positive correlation of PAK4 expression with expression of P21, CyclinD1, CyclinE1, CDK2, and CDK6, which drives G0/G1 to the G2/M phase transition. PAK4 can also activate Erk expression in OS cells and induce EMT. CONCLUSION: Interfering with PAK4 protein expression has been shown to affect osteosarcoma proliferation and migration.