P435	Local liposome-mediated gene transfer of C-type natriuretic peptide reduces lumen renarrowing and medial thickening in PTA treated porcine renal arteries.
1A.Kühnl, 2J.Pelisek, 1A.Fuchs, 3S.Nikol
1Paediatric Clinic, Klinikum Grosshadern, Ludwig Maximilian University, Munich; 2Department of Pharmacy, Center of Drug Research, Ludwig Maximilian University, Munich; 3Department of Cardiology and Angiology, University Hospital, Westfaelische Wilhelm University, Muenster.

BACKGROUND: Recent studies demonstrated that restenosis can be significantly reduced by treating balloon injured vessels with local application of CNP peptide, a physiologic proliferation inhibitor of vascular smooth muscle cells, or adenovirus-mediated gene transfer of the CNP gene. In this study, the long-term effect of local, liposome-mediated gene transfer of CNP plasmid on the formation of neointimal hyperplasia and media thickening in porcine renal arteries was investigated. METHODS: Immediately following PTA in porcine renal arteries, CNP peptide, CNP plasmid or β-galactosidase plasmid complexed with cationic lipid DOCSPER were injected into adventitia of balloon-injured renal segments using a needle injection catheter. Transfection and expression of CNP and β-galactosidase were measured by PCR and RT-PCR. Renal arterial lumen narrowing was evaluated by angiographic examinations. Ratio of medial thickness to total arterial diameter and ratio of neointimal area to media area were measured by histomorphometry. RESULTS: Three month after the treatment, computer-assisted morphometric analysis revealed significant reduced ratio of medial thickness to total arterial diameter in CNP plasmid-treated vessels compared with CNP protein-treated vessels and control vessels (CNP plasmid 34.3 +/- 2.04 vs. CNP protein 41.4 +/- 0.28 and control (beta-Gal) 45.0 +/- 2.46 %, p < 0.005). However, no significant changes in the ratio of intimal area to media area were observed (CNP plasmid 1.68 +/- 0.26 versus CNP protein 2.04 +/- 1.30 and control 2.23 +/- 0.63 %, p = NS). The angiographic examination demonstrated slight but non-significant reductions of restenosis in CNP plasmid-treated vessels vs. CNP protein or control transfection using ß-galactosidase gene (CNP plasmid 8.61 +/- 2.56 vs. CNP protein 7.56 +/- 3.12 vs. control 6.28 +/- 2.33 %, p = NS). In addition, transfected DNA and expression of therapeutic and control gene was seen 3 months after transfection. CONCLUSION: Local liposome-mediated gene transfer of CNP using a needle injection catheter in vivo significantly reduced medial thickening due to intimal proliferation of treated renal vessels following PTA.