Paclitaxel and sirolimus differentially affect growth and motility of endothelial progenitor cells and coronary artery smooth muscle cells

AIMS: EPC and hCASMC play an important role in the pathogenesis of restenosis and stent thrombosis. Drug-coated balloon catheters exert a local, short-term application of antiproliferative agents. This study investigates the time-dependent influence on growth and motility of paclitaxel and sirolimus alone and combined with the coating additive iopromide on EPC and hCASMC. METHODS AND RESULTS: Treatment of cultured human EPC and hCASMC with paclitaxel and sirolimus 1.5 and 15 µM for three seconds, three minutes and 24 hours, alone or combined with iopromide 0.197 M, resulted in a concentration- and time- dependent inhibition of proliferation and of migration. Paclitaxel and sirolimus increase apoptosis in either cell type. However, the effects of paclitaxel and sirolimus differed between the cell types: short-term exposure with paclitaxel leads to stronger inhibition of cell-density and apoptosis of hCASMC compared to EPC. In comparison to paclitaxel, short-term incubation with sirolimus showed a more effective inhibition of cell-density and migration as well as increased apoptosis in EPC in contrast to hCASMC. The effects of paclitaxel and sirolimus were increased in combination with iopromide. Interestingly, the antiproliferative effect of the paclitaxel-iopromide formulation on hCASMC was more potent compared to its effect on EPC. Endothelialisation in a porcine coronary stent model was similar with drug-coated balloons and uncoated controls, whereas it was delayed with drug-eluting stents. CONCLUSION: After short-term application, paclitaxel and sirolimus show differential, cell-specific effects on EPC and hCASMC. Iopromide used as a coating agent intensifies these effects.