Gene therapy of transplant arteriopathy by liposome-mediated transfection of endothelial nitric oxide synthase

Background: Transplant arteriopathy is the major factor limiting long-term survival after cardiac transplantation. We have previously demonstrated that liposome-mediated gene delivery of endothelial nitric oxide synthase (eNOS) to donor hearts reduces ischemia-reperfusion injury by blocking NF kappaB activation, adhesion molecule expression, and leukocyte infiltration. In this study, we used gene transfer of eNOS in a rabbit carotid transplant model to see whether these same effects would similarly ameliorate transplant arteriopathy. Methods: Liposomes complexed to the gene encoding eNOS were injected into donor carotid arterial segments that were transplanted orthotopically into recipient carotid arteries (n = 10), Controls included transplanted carotids transfected with liposomes complexed to empty plasmids (no functional gene) (n = 4) and transplanted carotids treated with saline (n = 6), Transplanted arteries were harvested for processing at 21 days. Intima/media (I/M) area ratios were calculated by computerized image analysis. Infiltrating T-lymphocytes and macrophages, and expression of VCAM-1 and ICAM-1 were quantified on immunocytochemistry. Results: The I/M ratio was significantly reduced in eNOS-transfected arteries compared with arteries transfected with empty plasmids and saline-treated controls. Compared to transplanted control arteries, eNOS-transfected arteries demonstrated significantly reduced T-cell infiltration into the intima and significantly reduced macrophage infiltration into the media, Cell surface expression of VCAM-1 and ICAM-1 were both reduced in eNOS-transfected arteries. Conclusions: ENOS gene delivery can suppress neointimal lesion formation and T-lymphocyte and macrophage infiltration in transplanted arteries, associated with a reduction in relevant adhesion molecule expression. Thus, gene therapy with eNOS may not only reduce ischemia-reperfusion injury but may also ameliorate transplant arteriopathy in transplanted hearts.