Differential affinity of vitronectin versus collagen for synthetic biodegradable scaffolds for urethroplastic applications

Cell-seeded synthetic polymer scaffolds constitute an emerging technology for urethroplastic applications. The study goal was to identify urethral proteins appropriate for cell attachment and optimize their adsorption onto two types of scaffolds: porous poly(ester urethane) with a poly(caprolactone) soft segment (PEU-PCL) and poly-(96% L/4% D)-lactic acid (P96L/4DLA). Specimens from eight men undergoing urethral reconstruction for stricture diseases were subjected to immunohistochemical analysis. Type I collagen, type IV collagen and vitronectin were detected at the interface between the epithelium and its basement membrane. Electrophoresis confirmed that polypeptide chains in the starting material were also present in fractions eluted from adsorbed scaffolds. Over a 4 week incubation assay, only vitronectin exhibited 100% retention levels for all scaffolds. The saturation point for each protein on each scaffold type was determined by titration and ELISA. The collective evidence indicates the concept that vitronectin > type IV collagen > type I collagen are preferred adsorption proteins for PEU-PCL and P96L/4DLA.