In vivo liposome-mediated transfection of HLA-DR alpha-chain gene into pig hearts

Scarcity of suitable donor organs remains a major problem for organ transplantation. Transfer of recipient HLA-genes into animal donor-organs during harvest could induce graft-tolerance without suppressing the recipient immune system. Objective: This pilot study aimed to test the feasibility of an in vivo gene transfer into pig hearts by intracoronary infusion of DNA:liposome-complexes and to detect the gene product by immunohistochemistry. Methods: The pcDV1-pL2-vector, containing the basesequence for HLA-DR alpha-chain in plasmids (1.3 kb) was selected. The plasmids were isolated with ethidiumbromide and incubated with lipofectin® in a 1:3-ratio for 10 min. The DNA:lipofectin®-complex was diluted to 10 cc with physiologic saline and delivered into the left anterior descending artery of 6 farm pigs over 10 min. As a control within the same animal, the same amount of lipofectin® alone was infused into the first diagonal branch. Three pigs were sacrificed after 24 h, the other 3 after 48 h. Delivery of DNA:liposome-complexes was detected by oil red 0 staining, expression of HLA- DR alpha-chain-antigen with a monoclonal anti-HLA-DR alpha-antibody. Results: Transfection of the HLA-class-II DR-alpha-chain occurred in endothelial cells. Infiltrating cells around capillaries stained positively for HLA-DR- alpha. These infiltrating cells were negative for the pan B- and the pan T- cell-marker L26 and UCHL-1. There was no transfection and hypercellularity in the myocardium around the first diagonal branch. Conclusions: In vivo intracoronary infusion of the HLA-DR alpha-chain-DNA:lipofectin®-complex leads to expression of the corresponding antigen on pig endothelium for 48h. The infiltrating cells require further characterization.