Use of biodegradable scaffolds as an alternative to engineer new tissues has become an attractive candidate in various transplantation protocols. In particular, small intestinal submucosa (SIS), has shown significant success in bladder regeneration. However, it is a natural matrix and this leads to problems in production, heterogeneity, and limited supply [1]. In this study, we explored formation of synthetic matrix mimicking the characteristics of the SIS. Three dimensional composite structure were developed combining both natural and synthetic polymers. Natural polymers (gelatin/chitosan, etc) have superior biological properties but they degrade slowly and lack physical strength [2]. Synthetic polymers (PLA, PGA, PLGA, etc) have strength, elasticity, and tunable degradation properties but they lack biological activity. However, by forming a three layer (Chitosan – PLGA – Chitosan) composite structure the strengths of each compartment are accentuated while minimizing the weaknesses. The outer chitosan/gelatin layers provide biological activity while the inner PLGA layer provides mechanical strength. Surface microarchitecture, tensile properties, permeability to urea, degradation properties (upto four weeks) and cell colonization of GFP-transfected canine bladder smooth muscle cells (SMC)were evaluated. Formed matrices had sufficient break stress (~4.5MPa), and were largely impermeable to urea. Composites facilitated cell adhesion and colonization and show a potential for tissue regeneration.

1.Raghavan D, Kropp BP, Lin H-K, Zhang Y, Cowan R, Madihally SV. Physical Characteristics Of Small Intestinal Submucosa Scaffolds Are Location-Dependent. J. Biomedical Materials Research-Part A. 73A(1):90-9, 2005

2. Huang Y, Onyeri S, Siewe M, Moshfegian A, Madihally SV. In vitro Characterization of Chitosan-gelatin Scaffolds for Tissue Engineering. Biomaterials. 26(36):7616-27, 2005.