A Bioactive defined biomatrix for Bladder Wall Regeneration

Abstract

PURPOSE Bladder augmentation through tissue engineering currently involves autologous tissue transplantation, e.g. insertion of small intestinal tissue. We evaluated four acellular collagen biomatrices for bladder wall regeneration in a rabbit model. MATERIAL AND METHODS Rabbits underwent bladder wall augmentation with a circular biochemically defined single (SL) or dual layer (DL) collagen biomatrix. The SL or DL matrices were composed of collagen (COL) + heparin (HEP) or COL + HEP + Growth Factors (GF). The following GF were used: Epithelial Growth Factor (EGF), Vascular Epithelial Growth Factor (VEGF) and b-Fibroblast Growth Factor (b-FGF). The regenerated bladder walls were harvested at 2, 4 and 12 weeks after implantation. Tissue regeneration was evaluated using routine histology. RESULTS Biomatrix encrustation was observed in 30/48 (63%) of animals. All biomatrices showed considerable influx of inflammatory cells in the first 4 weeks, gradual decreasing in time. At all time points, we found collagen remnants in the regenerated bladder. The SL-HEP-GF, DL-HEP and DL-HEP-GF matrices showed earlier epithelialization and neovascularization in comparison with the SL-HEP biomatrix at 2weeks. In the biomatrices with growth factors, only single muscle cells were present at the peripheral area of the regenerated graft material at 12 weeks. CONCLUSIONS Tissue regeneration velocity was higher with the use of dual layer or Growth Factors-modified biomatrices. This clearly shows that bioactive modifications with the use of special coatings and growth factors improves bladder wall regeneration for tissue engineering. The dual-layer biomatrix containing heparin and growth factors have a high capacity for bladder regeneration.