EFFECTS OF POLOXAMER-407 ON TRANSFECTION TIME AND PERCUTANEOUS ADENOVIRUS-MEDIATED GENE-TRANSFER IN NATIVE AND STENTED VESSELS

Reduction in transfection time and the ability to perform gene transfe r in conjunction with endovascular stent implantation constitute two i mportant challenges for percutaneous adenovirus-mediated gene transfer to vessel walls. Studies have suggested that the use of biocompatible polyol poloxamer 407 could be useful. We first evaluated the use of p oloxamer 407 for percutaneous gene transfer in nonstented rabbit iliac arteries. A 200-mu l mixture of Ad-RSV beta gal or Ad-CMVLuc in eithe r phosphate-buffered saline (PBS) or 20% poloxamer was delivered. Afte r 3 days, gene transfection was evaluated by X-Gal staining or measure ment of luciferase activity. Poloxamer use resulted in a 3- to 15-fold increase in the percentage of transfected cells (X-Gal, p = 0.001) an d a 16-fold increase in protein product (luciferase activity, p = 0.03 ), and allowed a decrease in transfection time from 30 to 5 min with m inimal reduction in transfection efficiency. We then evaluated the fea sibility of percutaneous gene transfer, using Ad-RSV beta gal diluted in pure PBS or 20% poloxamer, in conjunction with stent implantation. Gene delivery was performed either immediately before (pre-) or after (post-) stent implantation. When adenoviruses were diluted in PBS, gen e transfer had a low efficiency (prestent, 0.3%; poststent, 0.2%; NS). With poloxamer, the efficacy was much higher (p = 0.0001) and similar ''pre'' (2.2%) or ''post'' (1.7%) stent delivery (NS). Conclusions: ( 1) The use of poloxamer, rather than PBS, as a vehicle increases the e fficacy of percutaneous adenovirus-mediated gene transfer and reduces transfection time; (2) gene transfer performed during stent implantati on with poloxamer is feasible and achieves a significant level of gene expression. Thus percutaneous gene delivery is applicable to conventi onal stents and could present an attractive method by which to achieve local biological effects in a stent environment.