[Effect of growth differentiation factor 7 on tenogenic differentiation of bone marrow mesenchymal stem cells of rat in vitro].

OBJECTIVE: To investigate the effect of growth differentiation factor 7 (GDF-7) on the tenogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro, to provide evidence for improving the efficacy of BMSCs on tendon repair.

METHODS: BMSCs were isolated from bone marrow tissue of green fluorescent protein rats by density gradient centrifugation method. Chondrogenic, osteogenic, and adipogenic differentiation assays were used to demonstrate the multi-differentiation potential of the BMSCs. BMSCs at passage 3 were cultured and divided into 4 groups according to different concentrations of GDF-7 (0, 12.5, 25.0, and 50.0 ng/mL): group A, B, C, and D, respectively. After cultured for 2 weeks in vitro, the mRNA expressions of scleraxis, tenomodulin, tenascin C, and collagen type I were detected by real-time fluorescent quantitative PCR method, the protein expressions of tenomodulin, tenascin C, and collagen type I by immunocytochemistry staining in 4 groups, and the protein expressions of tenomodulin by Western blot in groups A and C.

RESULTS: BMSCs had osteogenic, chondrogenic, and adipogenic differentiation potentials. The mRNA expressions of tenomodulin in groups B, C, and D were 2.85, 3.41, and 3.07 times higher than that in group A, respectively; the mRNA expressions of scleraxis in groups B, C, and D were 2.13, 1.50, and 2.56 times higher than that in group A, respectively; and the mRNA expressions of tenascin C in groups B, C, and D were 2.45, 2.86, and 1.88 times higher than that in group A, respectively. There were significant differences between groups B, C, D and group A (P < 0.05), while there was no significant difference among groups B, C, and D (P > 0.05). The mRNA expressions of collagen type I in groups B and C were 1.92 and 2.45 times higher than that in group A, showing significant differences between groups B, C and group A (P < 0.05), but no significant difference between groups A and D (P > 0.05). Immunocytochemistry staining showed that the protein expressions of tenomodulin, tenascin C, and collagen type I were detected in groups B, C, and D but not in group A. The results were further confirmed by Western blot results which showed higher protein expression of tenomodulin in group C than in group A.

CONCLUSION: GDF-7 can be used to promote tenogenic differentiation of rat BMSCs in vitro.