p53 gene transfer to the injured rat carotid artery decreases neointimal formation

Purpose: We studied the effect of adenovirus-mediated p53 gene transfer on the injured rat carotid artery to determine its ability to decrease the formation of neointima. Methods: In vivo gene transfer was used in isolated segments of balloon-injured rat carotid arteries. Genetically modified adenovirus containing the gene encoding for wild-type p53 (AdWTp53) was applied in three concentrations: 8 x 10(10), 1.6 x 10(10), and 8 x 10(9) pfu/mL. Control rats received either adenovirus null (AdNull), 8 x 1010 pfu/mL, or Medium-199 solution (vehicle). Expression of p53 was determined 4 days after gene transfer by Western blotting. Neointimal formation was assessed after 14 days by harvesting carotid arteries and determining the intima/media (I/M) ratio based on cross sectional area measurement. Simultaneously, immunohistochemistry was done to detect the presence of p53 on smooth muscle cell nuclei. Results: P53 expression was confirmed by Western blotting. There was a significant reduction in neointimal formation on all treated animals compared with controls. The highest dose of AdWTp53 (8 x 10(10) pfu/ml) resulted in a near-total arrest of neointimal formation (I/M = 0.09 +/- 0.03, mean +/- SEM) with P < .0001 versus vehicle (I/M = 2.23 +/- 0.15) or AdNull (I/M = 2.12 +/- .12). The intermediate dose of AdWTp53 (1.6 x 1010 pfu/ml) resulted in an I/M value of 1.04 +/- 0.18, with P < .001 versus vehicle and P=.001 versus AdNull. The lowest dose (8 x 109 pfu/mL) resulted in an I/M value of 1.12 +/- 0.18, with P<.001 versus vehicle and P<.002 versus AdNull. The immunohistochemistry was positive for the presence of p53 in rats infected with AdWTp53. Conclusions: Adenovirus-mediated gene transfer of p53 protein significantly decreases the formation of neointima in the rat carotid injury model. This map represent a potential therapy for restenosis in humans.