Coronary restenosis and gene therapy

Restenosis continues to limit the efficacy of coronary angioplasty, despite the various mechanical and pharmaceutical interventions that have been employed. The migration, proliferation, and extracellular matrix production by vascular smooth muscle cells are processes integral to restenosis, and sustained local delivery of drugs at high concentration should curtail these vascular responses to balloon angioplasty. Our laboratory and others are exploring the potential of using somatic cell gene therapy to provide such treatment and thereby prevent restenosis. However, conventional methods of gene transfer fail to produce physiologic levels of recombinant protein in vivo. This obstacle might be overcome by using adenoviral vectors to mediate efficient direct gene transfer. Herein we summarize these developments and focus upon our laboratory's progress towards evaluating adenovirus-mediated gene therapy in porcine coronary arteries. Recombinant adenoviruses directing the expression of the beta-galactosidase and luciferase reporter genes were evaluated in cultured coronary vascular smooth muscle cells in vitro and in porcine coronary arteries in vivo. Following percutaneous transluminal gene transfer in vivo, recombinant adenoviruses were shown to produce 70- to 240-fold more reporter protein than that produced by Lipofectin-DNA complexes. Furthermore, the high levels of adenovirus-mediated gene expression were shown to persist for at least 14 days following catheterization. Additional histologic studies will be required to determine the cellular distribution of gene expression and to elucidate potential interactions between adenovirus and the host's immune system, but recombinant adenovirus appears to be a promising vector for evaluating gene therapy against coronary restenosis.