The role of polymer nanosurface roughness and submicron pores in improving bladderurothelial cell density and inhibiting calcium oxalate stone formation

Abstract

Synthetic polymers have been proposed for replacing resected cancerous bladder tissue.However, conventional (or nanosmooth) polymers used in such applications (such aspoly(ether) urethane (PU) and poly-lactic-co-glycolic acid (PLGA)) often fail clinically dueto poor bladder tissue regeneration, low cytocompatibility properties, and excessive calciumstone formation. For the successful reconstruction of bladder tissue, polymer surfacesshould be modified to combat these common problems. Along these lines, implementingnanoscale surface features that mimic the natural roughness of bladder tissue on polymersurfaces can promote appropriate cell growth, accelerate bladder tissue regeneration andinhibit bladder calcium stone formation. To test this hypothesis, in this study,the cytocompatibility properties of both a non-biodegradable polymer (PU) anda biodegradable polymer (PLGA) were investigated after etching in chemicals(HNO3 and NaOH, respectively) to create nanoscale surface features. After chemical etching, PUpossessed submicron sized pores and numerous nanometer surface features while PLGApossessed few pores and large amounts of nanometer surface roughness. Results from thisstudy strongly supported the assertion that nanometer scale surface roughness produced onPU and PLGA promoted the density of urothelial cells (cells that line the interior of thebladder), with the greatest urothelial cell densities observed on nanorough PLGA. Inaddition, compared to respective conventional polymers, the results providedevidence that nanorough PU and PLGA inhibited calcium oxalate stone formation;submicron pored nanorough PU inhibited calcium oxalate stone formation themost. Thus, results from the present study suggest the importance of nanometertopographical cues for designing better materials for bladder tissue engineeringapplications.