OBJECTIVETo assess the biocompatibility of a urethral acellular matrix graft (UAMG) and evaluate its effect in repairing urethral defect in rabbit models.

METHODSThe UAMG was prepared and its structural features were observed using optical and electron microscopy. In vitro cultured rabbit bladder smooth muscle cells were seeded on UAMG and the cell proliferation was observed. The cytotoxicity of the aqueous extract of the UAMG against the cells was evaluated by MTT assay, and its biocompatibility was assessed by implanting the grafts subcutaneously on the back of the rabbits. In 24 male rabbits, a 2-cm urethral defect was induced and repaired with UAMG (experimental group, n=12) or left untreated (control group, n=12). In both groups, the rabbits were sacrificed 2, 4, 8 and 12 weeks after the operation for histological and immunohistochemical examination of the tissue regeneration.

RESULTSThe UAMG had a reticular fibrous structure without cell residues. The bladder smooth muscle cells showed normal proliferation on UAMG with normal cell morphology. The rabbits receiving the implants showed no abnormal response, and the UAMGs gradually degraded in vivo with grade 0 or 1 cytotoxcity showing satisfactory cytocompatibility. In the experimental group, new urethral tissues that were histologically compatible with normal urethral tissues were regenerated in the defect area 12 weeks after UAMG implantation.

CONCLUSIONAs a tissue engineered scaffold material for urethral reconstruction, the UAMG possesses good biocompatibility and can induce the regeneration of urethral epithelial cells and smooth muscle cells.