Enhanced external counterpulsation inhibits endothelial apoptosis via modulation of BIRC2 and Apaf-1 genes in porcine hypercholesterolemia

Abstract Objectives Enhanced external counterpulsation (EECP) could improve endothelium-dependent vasodilatation of carotid artery and restore imbalance of nitric oxide and endothein-1 in patients with coronary artery disease. Our study was designed to test the hypothesis that long-term EECP may protect vascular endothelial cells from apoptosis by modifying apoptosis-related gene expression. Methods Eighteen male Yorkshire pigs were randomly assigned to three groups: usual diet (Normal), high cholesterol diet (HC) and high cholesterol diet plus EECP (HC + EECP). Vascular endothelial cells were isolated from the aortic endothelium and identified by CD31 staining and DiI-Ac-LDL reaction. Morphological changes were observed by both scanning and transmission electronic microscopes. TUNEL technique was applied to detect the apoptotic index of vascular endothelial cells. Two genes, Apaf-1 and BIRC2, were chosen for exploring the potential mechanisms of action at the molecular level. Results EECP brought a certain degree of alleviation from ultrastructural changes such as shrinking and blebbing of cytomembrane, marginalization, degeneration, and fragmentation of the nucleus. EECP also significantly reduced apoptotic indices while compared with that of control (177 ± 12‰ vs. 237 ± 23‰, P < 0.05). The Apaf-1 expression at both protein and mRNA level in pigs of HC + EECP group was significantly decreased than those of the HC group ( P < 0.05), whereas the BIRC2 expression was significantly enhanced after EECP treatment, documented by immunostaining and semi-quantitative RT-PCR analysis, respectively ( P < 0.05). Conclusions EECP could protect vascular endothelial cells from apoptosis, thereby delaying the progression of early atherosclerotic lesions possibly through transcriptional down-regulation of pro-apoptotic gene Apaf-1, and up-regulation of anti-apoptotic gene BIRC2.