Overexpression of a Constitutively Active Protein Kinase G Mutant Reduces Neointima Formation and In-Stent Restenosis

Abstract

Background — Neointima formation after arterial injury is associated with reduced vascular cyclic guanosine monophosphate (cGMP) and cGMP-dependent protein kinase (PKG), a major cGMP effector in vascular smooth muscle. We tested the effect of PKG overexpression on the neointimal response to vascular injury. Methods and Results — Infection of cultured rat aortic smooth muscle cells (RASMCs) with an adenoviral vector specifying a cGMP-independent, constitutively active PKG mutant (AdPKGcat) reduced serum-induced migration by 33% and increased serum-deprivation–induced apoptosis 2-fold ( P <0.05 for both). Infection with wild-type PKG (AdPKG), in the absence of cGMP, did not affect migration or apoptosis. Two weeks after balloon-injured rat carotid arteries were infected with 1× 10 10 pfu AdPKGcat (n=12), AdPKG (n=8), or a control adenovirus (n=8), intima-to-media ratio was less in AdPKGcat-infected arteries than in AdPKG- or control adenovirus–infected vessels (0.26±0.06 versus 0.61±0.12 and 0.70±0.12, respectively, P <0.05 for both). Two weeks after intramural administration of 1.75×10 10 pfu AdPKGcat (n=8) or a control adenovirus (n=8) into porcine coronary arteries with in-stent restenosis, luminal diameter was greater in AdPKGcat-infected arteries than in control adenovirus-infected vessels (2.32±0.16 versus 1.81±0.13 mm, P =0.028), associated with reduced neointimal area (3.30±0.24 versus 4.15±0.13 mm 2 , P =0.008), neointima-to-vessel area ratio (0.42±0.05 versus 0.58±0.04, P <0.05), and percent stenosis (45±6% versus 70±4%, P <0.05). Conclusions — Expression of a constitutively active PKG reduces neointima formation after balloon injury in rats and reduces coronary in-stent restenosis in pigs. PKGcat gene transfer may be a promising strategy for vasculoproliferative disorders.