Effect of short pulsed nonablative infrared laser irradiation on vascular cells in vitro and neointimal hyperplasia in a rabbit balloon injury model

Background-Neointimal hyperplasia after PTCA is an important component of r estenosis. Methods and Results-Cultures of rabbit endothelial cells and smooth muscle cells (SMCs) were irradiated with different doses of nonablative infrared ( 1064-nm) radiation. Normalized viability index detected with nondestructive Alamar Blue assay and direct cell count were studied. Our experiments demo nstrated dose-dependent cytostatic or cytotoxic effects of laser irradiatio n. We also evaluated the Ion-term effect of endoluminal nonablative infrare d laser irradiation on neointimal hyperplasia in a rabbit balloon injury mo del. PTCA of both iliac arteries of 23 New Zealand White rabbits was perfor med. One iliac artery was subjected to intra-arterial subablative infrared irradiation via a diffuse tip fiber. The contralateral vessel served as con trol. The diet was supplemented With 0.25% cholesterol and 2% peanut oil fo r 10 days before and 60 days after PTCA. Morphometry after 60 days showed t hat intimal areas were 0.76 +/-0.18 and 1.85 +/-0.30 mm(2) in the laser and control arteries, respectively (P=21.22X10(-11)). Conchisions-We conclude that nonablative infrared laser inhibited neointima l hyperplasia after PTCA in cholesterol-fed rabbits for up to 60 days.