Objective     To observe the role of TGF-β1 in promoting transformation of endothelial cells into interstitial cells and study the source of myofibroblasts and the mechanism underlying fibrosis.     Methods    Endothelial cells were isolated from human umbilical vein and cultured with different concentrations of TGF-β1 (0

10

25 and 50 ng/ml) for 72 h. Then

changes of cell morphology were observed under an inverted phase contrast microscope. Expression of factor Ⅷ related antigen and α-Smooth muscle actin (α-SMA) was detected by immunofluorescence assay. Expression of VE-Cadherin

α-SMA and type 1 collagen was detected by RT-PCR.     Results    A paving stone-like growth and a spindle-like growth of endothelial cells was observed in control group and TGF-β1 stimulating group

respectively. Immunofluorescence assay showed a small number of factor Ⅷ and α-SMA positive cells in control group. The number of factor Ⅷ and α-SMA positive cells was significantly greater in TGF-β1 group than in control group (P0.05) and increased with the concentration of TGF-β1. RT-PCR showed that the expression level of VE-Cadherin significantly decreased with the concentration of TGF-β1 (P0.05) while the expression level of α-SMA and type 1 collagen significantly increased with concentration of TGF-β1 (P0.05).      Conclusion    TGF-β1 promotes the transformation of endothelial cells into interstitial cells in a concentration-dependent manner.