Ureteral reconstruction with reinforced collagen scaffolds in a porcine model.

Repair of long ureteral defects often requires extensive surgical procedures and graft tissue which is associated with various complications, e.g. graft site morbidity or lack of suitable tissue. Tissue engineering might provide an alternative therapeutic approach in these cases. Reinforced tubular collagen-Vicryl scaffolds (l = 5 cm, lumen O = 6 mm, thickness = 3 mm) were developed with or without vascular endothelial growth factor and basic fibroblast growth factor and evaluated in a pre-clinical porcine model. The reinforced scaffolds were successfully implanted in 20 pigs and functional, macroscopic and microscopic evaluation was performed at one and three months. Two animals without scaffold implantation served as control. All animals survived until their predetermined evaluation time point and grafted scaffolds showed urothelial regeneration, smooth muscle cell ingrowth and neovascularization. Loopogram and macroscopic evaluation revealed constriction of the scaffold lumen and hydroureteronephrosis. Enhanced muscle ingrowth was observed in growth factor loaded scaffolds, but this was not significant. We conclude that reinforced collagen-Vicryl scaffolds are mechanically suitable for ureteral repair, but further optimization to prevent strictures is required.