INDUCTION OF ANGIOGENESIS BY LIDOCAINE AND BASIC FIBROBLAST GROWTH-FACTOR - A MODEL FOR IN-VIVO RETROVIRAL-MEDIATED GENE-THERAPY

A strategy of direct, in vivo retroviral-mediated gene therapy targeti ng capillary endothelial cells must provide an environment of active a ngiogenesis. Both lidocaine and basic fibroblast growth factor (bFGF) promote angiogenesis, but the angiogenic response invoked by these sub stances in normal skeletal muscle has not been fully characterized. We sought to characterize these agents' angiogenic effects in anterior t ibialis muscles of male Sprague-Dawley rats. An injection of either 1% lidocaine with 1:100,000 epinephrine or alternate-day injections of b FGF (0.025 or 0.25 mu g) with or without heparin were tested (n = 6 mu scles/condition). Rats were sacrificed 4, 7, 10, or 12 days later and muscles were evaluated histologically to determine the number of proli ferating cells using 5-bromo-2'-deoxycytidine (BrdC) and evaluated for capillary density using Griffonia simplicifolia I (GSI) lectin. At al l time points, lidocaine produced at least 20-fold greater capillary d ensity and cellular proliferation than PBS control (P < 0.0001). Injec tions of high-dosage bFGF produced more than fivefold greater capillar y density than control injections at 7 and 10 days (P < 0.001), and mo re than twofold greater proliferation at 4, 7, and 12 days (P < 0.001) . Capillary density returned to control levels 12 days following bFGF administration, whereas it remained well above control levels for 12 d ays after lidocaine administration. To confirm that lidocaine can be u tilized in gene therapy strategies targeting vascular endothelium and skeletal muscle fibers, concentrated pLJ retrovirus containing cDNA fo r the heat-stable human placental alkaline phosphatase (hpAP) marker g ene was infused into the rat hindlimb vasculature 4 days post-lidocain e administration. Rats receiving pLJhpAP retrovirus demonstrated signi ficant hpAP transgene expression in endothelial cells and myocytes 21 days after the lidocaine injection (n = 6 muscles). In contrast, contr ols receiving pLJhpAP infusion without prior lidocaine administration failed to demonstrate any hpAP transgene expression. Lidocaine treatme nt evokes a substantially higher proliferative response than bFGF and, importantly, a durable angiogenic response in skeletal muscle. Thus, lidocaine is an ideal agent to induce angiogenesis in preparation for direct in vivo retroviral-mediated gene therapy targeting vascular end othelium. (C) 1997 Academic Press.