Effect Of Paclitaxel And All-trans Retinoic Acid On The Growth Of S-D Rat Aorta Endothelial Cells

Background and Objective:Coronary heart disease (CHD) is one of clinic familiar diseases, and PCI is an efficient way to treat CHD at present. However, restenosis has already affected PCI on the middle and long-term curative effect. In stent era, the major mechanism of restenosis may be that neointimal is excess thick, which is aroused by smooth muscle cells' (SMC) migration, proliferation and secretion extral cellular matrix triggered by the injury of endothelial cells. The invention of drug-eluting stent is used to reduce the rate of restenosis in the aspect of reducing the growth of neointimal aroused by SMC's migration, proliferation and secretion. Nowadays, there are two kinds of drug-eluting stents widely applied: sirolimus-eluting stent (Cypher and Firebird) and paclitaxel-eluting stent (TAXUS). Clinic study shows that the use of Cypher has a lower restenosis rate than that of TAXUS. The possible mechanism is that paclitaxel inhibits the proliferation of SMC as well as endothelial cells, and enhances the injury of endothelial cells. Research investigates that paclitaxel inhibits the proliferation of not only SMC but also endothelial cells in the condition of high concentration, but it only inhibits proliferation of SMC in low concentration. Another report is said that all-trans retinoic acid can protect endothelial cells, quicken the recovery of endothelial cells function, and reduce neointimal hyperplasia. In addition, many researches show that ATRA can inhibit the proliferation of SMC. It is assumed that certain concentration of paclitaxel and ATRA be used together in appropriate proportion not only to inhibit proliferation of SMC, but also to protect endothelial cells to reduce restenosis rate. This study is designed to investigate the effect and mechanism of paclitaxel and all-trans retinoic acid on the growth of S-D rat aorta endothelial cells cultured on gelatin-coated dishes. Materials and Methods: Experimental animals S-D rats were 6-8 months, weighted 180g-250g, without thinking about sex, and were provided by the center of experimental animals of Dalian medical university. S-D rat aorta endothelial cells were obtained through collagenase digestion culture and identified with platelet factor â…§ relative antigen. Using MTT method and flow cytometry, the action of paclitaxel and all-trans retinoic acid (ATRA) on the cell cycle and proliferation in phase-synchronized S-D rat aorta endothelial cells was observed. There were control groups and experimental groups, which included 1nmol/L, 10 nmol/L, 100 nmol/L, and 1000 nmol/L subgroups of paclitaxel and ATRA respectively, as well as subgroups of ATRA (100 nmol/L) along with paclitaxel in a concentration of 1 nmol/L, 10 nmol/L, 100 nmol/L, and 1000 nmol/L respectively. Result: (1) Paclitaxel in concentration from 1 nmol/L to 1000nmol/L diminished the proliferative activity of cultured S-D rat aorta endothelial cells. Paclitaxel began to inhibit the proliferation of S-D rat aorta endothelial cells in the concentration of 1nmol/L, but there was no evidence vs. control's (n=6, P=0.06), and the inhibition action was in a concentration-dependent manner between 10 nmol/L and 1000nmol/L (n=6, P=0.000). In the concentration of 1000nmo/L, paclitaxel inhibited theproliferation activity of S-D rat aorta endothelial cells by 54.9%. Furthermore, the G2/M-phase cell phase blockade was detectable in phase-synchronized cells subjected to treatment of paclitaxel (100nmol/L). (2) ATRA promoted the proliferation activity of S-D rat aorta endothelial cells between 1nmol/L and 100nmol/L in a concentration-dependent manner (n=6, P=0.000). And in the concentration of 100nmol/L, the proliferation rate was as high as 41.4%. However, in higher concentration (1000nmol/L), ATRA showed slight inhibition activity to S-D rat aorta endothelial cells. (3) ATRA (100nmol/L) along with paclitaxel in the concentration of 1nmol/L or 10nmol/L promoted the proliferation activity of S-D rat aorta endothelial cells, with the proliferation rate of 41.9% and 41.1% respectively (n=6, P=0.082).