In vitro construction of urinary bladder wall using porcine primary cells reseeded on acellularized bladder matrix and small intestinal submucosa

Background: Partial or radical cystectomy requires replacement of the urinary reservoir normally achieved by using small or large bowel segments. Our aim was to establish tissue engineering of an bioartificial bladder wall using primary cultures of porcine urothelial (pUC) and bladder smooth muscle cells (pSMC) to be reseeded on different acellular biological matrices. Methods: Primary porcine cultures of pUC and pSMC were established from open bladder biopsy material 25 mm(2) in size. Acellular matrix was generated either from a) porcine bladder wall segments or b) tubular small intestinal submucosa with the still attached decellularized muscularis layer. Reseeding of these matrices with primary cells was done in a two-dimensional static model and in a three-dimensional rotating bioreactor perfused with cell culture medium for a period of 6 weeks. Results: Prior to reseeding the cultured cells were characterized as pUC and pSMC by immunohistochemical staining with either anti-keratin 7 or anti-alpha actin. For both matrices a reseeded double layer cell system of pUC and pSMC could be identified after incubation in the described systems for 6 weeks. Conclusions: Our results document successful generation of tissue engineered urinary bladder wall, which can be used in further large animal transplantation experiments.