Liposome-Mediated Gene Transfection of Endothelial Nitric Oxide Synthase Reduces Endothelial Activation and Leukocyte Infiltration in Transplanted Hearts

Abstract

Background —During cardiac ischemia-reperfusion injury, neutrophilic infiltration of the myocardium is mediated by adhesion molecule expression on activated coronary endothelium. Nitric oxide inhibits neutrophil adhesion to endothelium in vitro by blocking the nuclear factor (NF)-κB–dependent transcription of adhesion molecules. We investigated whether intraoperative gene delivery of endothelial nitric oxide synthase (eNOS) into donor hearts before transplantation would have a similar effect on an entire organ. Methods and Results —In an allogeneic rabbit heart transplant model, liposomes complexed to the gene encoding eNOS were infused into the donor coronary circulation before transplantation. By 24 hours after transplantation, calcium-dependent nitrite production was significantly higher in eNOS-transfected donor hearts than in the 3 control groups: donor hearts transfected with empty plasmids alone, donor hearts treated with diluent only, and untransplanted native hearts. Intramyocardial neutrophil and T-lymphocyte populations were halved in eNOS-transfected hearts compared with control donor hearts ( P <0.05). Moreover, the prevalence of NF-κB activation in microvascular endothelial cells and surrounding cardiac myocytes as well as endothelial vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 expression were all significantly reduced in eNOS-transfected hearts compared 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-reperfusion injury by inhibiting NF-κB activation, adhesion molecule expression, and the early infiltration of leukocytes, all of which may improve graft survival.