Antisense basic fibroblast growth factor gene transfer reduces neointimal thickening after arterial injury

Purpose: To determine whether synthesis of endogenous basic fibroblast growth factor (bFGF) after arterial injury is critical to the intimal thickening response, intraluminal adenoviral gene transfer of an antisense bFGF (Ad.ASbFGF) transgene was used to inhibit the subsequent synthesis of bFGF protein after injury. Methods: Sprague-Dawley rats underwent balloon catheter carotid artery injury and in vivo gene transfer. Isolated segments of rat common carotid artery were infected with an adenoviral vector encoding an antisense bFGF transcript at concentrations of 2 x 10(9), 1 x 10(10), or 1 x 10(11) pfu/ml. Control rats were treated with either a control adenovirus encoding the beta-galactosidase gene, (Ad.lacZ), at 1 x 10(10), or 1 x 10(11) pfu/ml, or phosphate-buffered saline solution (vehicle). Two weeks after injury the rats were killed and perfusion-fixed. Cross-sectional areas of the carotid arterial intima and media were measured by planimetry, and the intima/media ratio (I/M) was calculated for each vessel. Results: The mean I/M for each Ad.ASbFGF group and controls were compared and the significance assessed by analysis of variance. At two weeks after injury, the highest dose of Ad.ASbFGF, 1 x 10(11) pfu/ml, resulted in a near total inhibition of thickening (I/M = 0.14 +/- 0.04, mean +/- SEM) when compared with phosphate-buffered saline solution alone (I/M = 0.99 +/- 0.07), or Ad.lacZ 1 x 10(10) pfu/ml (I/M = 1.01 +/- 0.10) control treatments (p < 0.01). A tenfold lower dose of Ad.ASbFGF, 1 x 10(10) pfu/ml, also caused significant reduction in intimal thickening (I/M = 0.39 +/- 0.07, p < 0.01). Treatment with 2 x 10(9) pfu/ml Ad.ASbFGF did not significantly limit intimal thickening (I/M = 0.72 +/- 0.12). Conclusions: Inhibition of bFGF synthesis in vivo using an antisense RNA strategy significantly inhibits intimal thickening after arterial balloon injury. This study suggests that continued bFGF synthesis contributes to intimal thickening after arterial injury, and that antisense bFGF may represent an effective strategy in limiting restenosis after angioplasty.