ENDOTHELIUM-SPECIFIC IN-VIVO GENE-TRANSFER

Targeted expression of genetic material within the vascular endotheliu m is potentially a powerful tool for the investigation of endothelial cell (EC) biology. We developed, optimized, and characterized an effic ient somatic transgenic model of EC-specific gene transfer. Rat caroti d arteries were infused with adenovirus expressing a beta-galactosidas e (beta-gal) gene. The level and cell-type specificity of recombinant gene expression were measured by assaying beta-gal activity in vessel extracts and by counting transduced cells in histological sections. To xicity was evaluated by counting total ECs (3 days) and by measuring n eointimal formation (14 days). Effects of transduction on the prolifer ation of vascular cells were measured with bromodeoxyuridine and [H-3] thymidine. Maximum recombinant gene expression resulted from infusion of 1x10(10) to 1x10(11) plaque-forming units (pfu) per milliliter; app roximate to 35% of luminal ECs were transduced. A high degree of EC sp ecificity (90% to 98% of total transduced cells) was maintained over t his range of virus concentrations. More highly concentrated virus resu lted in loss of beta-gal expression and a large decrease in luminal EC number (97% decrease, P<.001). Gene transfer at 4x10(10) pfu/mL was e fficient, preserved EC integrity, and caused minimal neointimal format ion. After gene transfer, there were early (3-day) increases in both E C and smooth muscle cell proliferation. At 14 days, only EC proliferat ion remained elevated (18% versus 1.4% in vehicle-infused arteries, P= .005). This animal model permits efficient highly EC-specific gene tra nsfer. Vascular toxicity is minimal, although the EC proliferative ind ex is elevated. This model will be useful in experiments that elucidat e the biological role of EC gene products and define pathways of EC ge ne regulation and signal transduction in vivo.