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 tha t liposome-mediated gene delivery of endothelial nitric oxide synthase (eNO S) to donor hearts reduces ischemia-reperfusion injury by blocking NF kappa B activation, adhesion molecule expression, and leukocyte infiltration. In this study, we used gene transfer of eNOS in a rabbit carotid transplant mo del to see whether these same effects would similarly ameliorate transplant arteriopathy. Methods: Liposomes complexed to the gene encoding eNOS were injected into d onor carotid arterial segments that were transplanted orthotopically into r ecipient 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), Transplant ed arteries were harvested for processing at 21 days. Intima/media (I/M) ar ea ratios were calculated by computerized image analysis. Infiltrating T-ly mphocytes and macrophages, and expression of VCAM-1 and ICAM-1 were quantif ied on immunocytochemistry. Results: The I/M ratio was significantly reduced in eNOS-transfected arteri es compared with arteries transfected with empty plasmids and saline-treate d controls. Compared to transplanted control arteries, eNOS-transfected art eries demonstrated significantly reduced T-cell infiltration into the intim a and significantly reduced macrophage infiltration into the media, Cell su rface expression of VCAM-1 and ICAM-1 were both reduced in eNOS-transfected arteries. Conclusions: ENOS gene delivery can suppress neointimal lesion formation an d T-lymphocyte and macrophage infiltration in transplanted arteries, associ ated with a reduction in relevant adhesion molecule expression. Thus, gene therapy with eNOS may not only reduce ischemia-reperfusion injury but may a lso ameliorate transplant arteriopathy in transplanted hearts.