660 ELECTROSPUN-ACELLULAR MATRIX COMPOSITE SCAFFOLD FOR BLADDER RECONSTRUCTION

Abstract

INTRODUCTION AND OBJECTIVES: Tissue engineering aims to provide alternatives to bladder reconstruction to overcome the significant limitations associated with enterocystoplasty such as metabolic disturbance, urolithiasis, infections and even malignant diseases. As the scaffold is an important determining factor for the success of tissue engineering we have developed a composite scaffold mimicking morphological and functional characteristics of the bladder wall. A two layered construct, consistent of bladder acellular matrix (BAM) and electrospun poly(lactide-co-glycolide) (PLGA) microfibers seeded with autologous smooth muscle cells (SMCs) was developed and evaluated in a cystoplasty model in rats. METHODS: The composite scaffold was manufactured by direct electrospinning of randomly oriented PLGA fibers onto bladder acellular matrix. To assess the capability to support cell attachment, proliferation and migration autologous bladder SMCs were cultured, expanded and seeded on the polymer fibers of the composite scaffold. Electron microscopy, histological examinations and biochemical assays for cell proliferation (MTT assay) were performed. In 16 Lewis rats, partial cystectomy ( 50%) was performed, followed by augmentation cystoplasty with seeded or unseeded (control) scaffolds. Histological studies were performed after 4 and 8 weeks. RESULTS: Direct electrospinning of PLGA microfibers onto bladder acellular matrix resulted in composite scaffold with randomly oriented microstructures and remained stable in aqueous medium over prolonged time period. SEM analysis showed single fiber diameter ranging from 4–5 im. Composite scaffolds provided good support for cell attachment, proliferation and migration, and eventually developed into a bladder wall-like structure in vivo. Histological evaluation of the implanted biomaterial revealed a normally structured urothelial lining, a collagen rich compartment with early revascularisation, early smooth muscle cell infiltration and regeneration of the lamina muscularis mucosae. Immuno-histochemical analyses confirmed the urothelial and muscle cell phenotype and showed the presence of blood vessels and smooth muscle cells. CONCLUSIONS: We were able to demonstrate that a biomaterial system consisting of two completely different materials is capable to promote cell growth and proliferation in vitro and generation of bladder wall structures in vivo. This scaffold may be useful in patients requiring bladder reconstruction.