Abstract
Purpose:
To investigate the long-term effect of local, liposome-mediated gene transfer of C-type natriuretic peptide (CNP) plasmid versus CNP protein on restenosis in porcine renal arteries following balloon angioplasty.
Methods:
The renal arteries of 15 pigs were dilated and the adventitia at the site of balloon injury injected with CNP protein, pCR3.1 plasmid encoding CNP, or the β-galactosidase gene (control) via a needle injection catheter. Five animals receiving the CNP and control genes in dilated arteries were sacrificed after 3 weeks to analyze re-endothelialization, proliferation, and early CNP expression. Ten animals designated for the long-term experiments (3 months) were treated with the CNP gene versus CNP protein (n=3), the CNP gene versus the control gene (n=3), and the CNP protein versus the control gene (n=3). One animal served as a dilated non-treated control. Transfection and expression of CNP and β-galactosidase were measured by polymerase chain reaction (PCR) and reverse transcription PCR. Renal arterial lumen narrowing was measured with angiography and histology. Endothelialization was assessed using Evans blue stain; vWF, CD31, factor VIII, and Ki67 were markers for immunohistochemical analysis.
Results:
An intact endothelial layer was seen at 3 weeks following angioplasty in all transfected arteries. Three months following treatment, computer-assisted morphometric analysis revealed significant enlargement of the arterial cross-sectional areas in CNP plasmid-treated vessels compared to dilated but untreated arteries (CNP plasmid +34.8%±13.9% versus CNP protein −1.75%±19.9% versus β-galactosidase −47.0%±13.9%, p < 0.01). Angiographic analysis showed significant enlargement of the arterial diameter compared to dilated, untreated arteries (CNP plasmid +20.8%±6.8% versus CNP protein +5.7%±6.0% versus β-galactosidase −24.5%±10.2%, p < 0.01).
Conclusions:
Local application of CNP plasmid proved superior to CNP protein in producing rapid re-endothelialization and significantly enlarging the renal arterial lumen following dilation.