[Effect of growth and differentiation factor 5 gene transferred by adenovirus on hBMSCs osteogenic differentiation].

OBJECTIVE: To introduce growth and differentiation factor 5 (GDF-5) gene into hBMSCs using recombinant adenovirus vector and to investigate the effect of GDF-5 gene expression on hBMSCs osteogenic differentiation.

METHODS: Recombinant adenovirus GDF-5 (Ad-GDF-5) containing green fluorescent protein (GFP) and Ad-GFP were amplified and titered. hBMSCs at passage 3 were infected with two viruses at different titers. At 2 days after intervention, GFP expression was observed using fluorescence microscope, and GDF-5 expression in hBMSCs was detected by RT-PCR. Adherent hBMSCs at passage 3 were randomly divided into 4 groups: experimental group (GDF-5 gene transfection), osteogenic induction group, Ad-GFP infection group, and control group. Cell differentiation was detected by inverted phase contrast microscope observation, fluorescence microscope observation, reverse transcription fluorescence quantitative PCR, immunofluorescence staining, and von Kossa staining at different time points after intervention.

RESULTS: The titer of Ad-GDF-5 and Ad-GFP was 1.0 x 10(9) pfu/mL and 1.2 x 10(9) pfu/mL, respectively, hBMSCs was efficiently infected by Ad-GDF-5 and Ad-GFP, and expressed target gene and GFP gene. At 1-7 days after intervention, morphology and growth pattern of the hBMSCs in the experimental group and the osteogenic induction group were transformed into osteoblast-like cells, whereas the cells in the other two groups were still maintained their original morphology and growth pattern. Reverse transcription fluorescence quantitative PCR detection: at 4 days after intervention, GDF-5 expression in the experimental group was obviously higher than that of other groups (P < 0.05); ALP, Col I, and OC gene expression in the experimental and the osteogenic induction group were superior to those of the Ad-GFP infection and the control group (P < 0.05); Col I gene expression in the osteogenic induction group was greater than that of the experimental group (P < 0.05). Immunofluorescence staining: at 4 days after intervention, the cells in the osteogenic induction group and the experimental group expressed and secreted Col I, and no expression of Col I was evident in the other two groups. At 10 days after intervention, the cells in the osteogenic induction and the experimental group were positive for von Kossa staining, and the results of the other two groups were negative.

CONCLUSION: GDF-5 gene can be transferred into hBMSCs via adenovirus vector and be expressed stably. It can facilitate the osteogenic differentiation of the hBMSCs and lay a foundation for the further study of this kind of gene transferred hBMSCs effect on bone tissue repair.