Objective: Previous studies showed potential role of tissue factor pathway inhibitor (TFPI) on attenuating restenosis, we investigated the effect of TFPI gene transfer on vascular smooth muscle cells (VSMCs) apoptosis.
Methods: Human TFPI recombinant adenovirus or LacZ recombinant adenovirus or PBS were transferred to rat aortic VSMCs respectively in vitro. RT-PCR was used to detect the expression of exogenous TFPI gene. VSMCs were examined by cell counting and MTT. Apoptosis of VSMCs was detected by flow cytometry, TUNEL and electron microscope at different time after gene transfer.
Results: mRNA expression of TFPI was detected in VSMCs at the 3rd day after gene transfer. Cell numbers and absorbance value in Ad-TFPI group were similar as those in Ad-LacZ and PBS groups at the 1st, 3rd and 5th day but significantly lower at the 7th day (P<0.05) after gene transfer. The apoptosis rates in Ad-TFPI group tested by flow cytometry were all significant higher than those in Ad-lacZ groups at each time point. The positive rates in Ad-TFPI group determined by TUNEL were significant higher than those in Ad-LacZ groups at 3rd (10.82% +/- 1.57% vs. 3.46% +/- 0.93%), 5th and 7th (16.95% +/- 2.01% vs. 5.11% +/- 1.29%, all P<0.05) day post gene transfer. Electron microscope evidenced cell contracting, cytoplasm condensing, lightly swelled mitochondria, nucleus pyknosis and apoptotic body formation after gene transfer in Ad-TFPI group which were not shown in cells of LacZ and PBS groups.
Conclusion: TFPI gene transfer could induce apoptosis in rat VSMCs which might be one of the mechanisms responsible for its beneficial effect on restenosis inhibition after angioplasty.