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[Effects of daphnetin combined with insulin-like growth factor 1 on chondrogenic differentiation of adipose-derived mesenchymal stem cells in rats].

Objective
To investigate the effect of daphnetin (DAP) combined with insulin-like growth factor 1 (IGF-1) gene transfection on chondrogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) in rats.


Methods
Rat ADSCs were isolated and amplified by enzymatic digestion. The third generation ADSCs were treated with IGF-1 gene transfection as experimental group and normal ADSCs as control group. The cells of the two groups were treated with different concentrations of DAP (0, 30, 60, 90 μg/mL), respectively. Cell proliferation was detected by cell counting kit 8 (CCK-8) after cultured for 72 hours. After 14 days, real-time fluorescence quantitative PCR and Western blot were used to detect the mRNA and protein expressions of chondrocyte markers (collagen type Ⅱ and Aggrecan) in each group; and toluidine blue staining and collagen type Ⅱ immunohistochemical staining were performed.


Results
CCK-8 assay showed that with the increase of DAP concentration, the cell absorbance ( A) value of the control group and the experimental group increased gradually ( P<0.05). At the same DAP concentration, the cell A value of the experimental group was significantly higher than that of the control group ( P<0.05). Real-time fluorescence quantitative PCR and Western blot showed that with the increase of DAP concentration, the relative mRNA and protein expressions of collagen type Ⅱ and Aggrecan in the control group did not change significantly, and there was no significant difference among the different concentration groups ( P>0.05). But the mRNA and protein expressions of collagen type Ⅱ and Aggrecan in the experimental group increased gradually, and the 60 and 90 μg/mL DAP concentration groups were significantly higher than 0 μg/mL DAP concentration group ( P<0.05). At the same DAP concentration, the relative mRNA and protein expressions of collagen type Ⅱ and Aggrecan were significantly higher in the experimental group than in the control group ( P<0.05). Toluidine blue staining showed that with the increase of DAP concentration, there was no significant difference in cell staining between the control group and the experimental group. At the same DAP concentration, the cells in the experimental group were slightly darker than those in the control group. Immunohistochemical staining of collagen type Ⅱ showed that with the increase of DAP concentration, there was no significant difference in the cytoplasmic brown-yellow coloring of the cells in the control group. The cytoplasmic brown-yellow coloring of the cells in the experimental group gradually deepened, with 60 and 90 μg/mL DAP concentration groups significantly deeper than 0 μg/mL DAP concentration group. At the same DAP concentration, the color of the cells in the experimental group was significantly deeper than that in the control group.


Conclusion
DAP can promote the proliferation of ADSCs in rats. The differentiation of ADSCs into chondrocytes induced by DAP alone was slightly, but DAP combined with IGF-1 gene transfection has obvious synergistic effect to promote chondrogenic differentiation of ADSCs.