Comparison of morphological and functional restoration between asymmetric bilayer chitosan and bladder acellular matrix graft for bladder augmentation in a rat model

Abstract

Because of the limitations of current scaffolds and unfavorable results of clinical trials, proper scaffolds facilitating bladder reconstruction are highly desirable. The aim of this study was to evaluate a novel asymmetric bilayer chitosan scaffold compared with conventional bladder acellular matrix graft (BAMG) in a rat model of bladder augmentation. Twenty-four 8 week-old male Sprague-Dawley rats were randomly assigned to the chitosan scaffold, BAMG and cystotomy groups. The rats' bladders were sampled for cystography and routine histological examination at 21 and 70 days. Immunofluorescence photometry, conscious cystometry, quantitative real-time polymerase chain reaction, and western blot analyses were performed using bladders at 70 days. Compared with BAMG, the chitosan scaffold consisted of a membrane-like compact layer and a sponge-like porous layer with an excellent combination of mechanical strength and flexibility. The chitosan group showed better performances than the BAMG group in radiographic cystography, smooth muscle regeneration, blood vessel numbers and functional restoration. In contrast to reduced bladder compliance induced by BAMG, bladder augmented by chitosan displayed nearly 1.5-fold increased bladder capacity with comparable compliance to that of the cystotomy group at 70 days. The chitosan group exhibited higher levels of VEGF and VEGFR2, associated with the activation of the hypoxia-related SDF-1α/CXCR4 pathway. These results suggested that the asymmetric bilayer chitosan scaffold is a promising scaffold for bladder reconstruction.