Ureteral gene transfer to porcine induced strictures using endourologic delivery of an adenoviral vector

Purpose: Direct gene transfer to the ureter is an attractive approach to prevent restenosis after endourologic management of ureteral strictures. We therefore assessed the rationale for adenovirus-mediated gene transfer in the ureter in vitro and in vivo using a porcine model. Materials and Methods: Primary cultures of porcine ureteral epithelial and stromal cells were infected with an adenoviral solution carrying a nucleus-targeted P-Galactosidase (p-Gal) reporter gene (6.5 10(8) pfu/ml.), In addition, in order to mimic the human clinical situation, we have devised a model of thermally-induced stricture in porcine ureter which produced tight fibrotic stenosis within 8 days. Using a purposely designed channelled balloon catheter prototype, these strictures were endoscopically dilated and then instilled with the same P-Gal adenoviral construction. Results: Application of recombinant adenovirus harboring a nucleus-targeted P-Gal reporter gene to cultured porcine urothelial and stromal cells resulted in high transduction efficiency of up to 99% and 84% respectively. Seven days after infection, X-Gal staining of the strictured ureters demonstrated transfection up to 2 mm, depth within the fibrosis, confirmed by polymerase chain reaction (PCR) analysis. Adjacent and distal spread of the virus was excluded by histochemistry (X-Gal staining) and PCR. Conclusion: This data represents the first report of adenovirus-mediated gene transfer to the ureter. It remained site specific by endourologic retrograde clinically applicable techniques.