Liposome-mediated gene transfection of endothelial nitric oxide synthase reduces endothelial activation and leukocyte infiltration in transplanted hearts

Background-During cardiac ischemia-reperfusion injury, neutrophilic infiltr ation of the myocardium is mediated by adhesion molecule expression on acti vated coronary endothelium. Nitric oxide inhibits neutrophil adhesion to en dothelium in vitro by blocking the nuclear factor (NF)-kappaB-dependent tra nscription of adhesion molecules. We investigated whether intraoperative ge ne delivery of endothelial nitric oxide synthase (eNOS) into donor hearts b efore transplantation would have a similar effect on an entire organ. Methods and Results-In an allogeneic rabbit heart transplant model, liposom es complexed to the gene encoding eNOS were infused into the donor coronary circulation before transplantation. By 24 hours after transplantation, cal cium-dependent nitrite production was significantly higher in eNOS-transfec ted donor hearts than in the 3 control groups: donor hearts transfected wit h empty plasmids alone, donor hearts treated with diluent only, and untrans planted native hearts. Intramyocardial neutrophil and T-lymphocyte populati ons were halved in eNOS-transfected hearts compared with control donor hear ts (P < 0.05). Moreover, the prevalence of NF-kappaB activation in microvas cular endothelial cells and surrounding cardiac myocytes as well as endothe lial vascular cell adhesion molecule-1 and intracellular adhesion molecule- 1 expression were all significantly reduced in eNOS-transfected hearts comp ared with control donor hearts (P < 0.01). Without immunosuppression, eNOS- transfected hearts survived longer than controls. Conclusions-Intraoperative liposome-mediated gene delivery of eNOS to donor hearts can result in early gene expression sufficient to reduce ischemia-r eperfusion injury by inhibiting NF-kappaB activation, adhesion molecule exp ression, and the early infiltration of leukocytes, all of which may improve graft survival.