[FABRICATION AND BIOCOMPATIBILITY EVALUATION OF POLYURETHANE- ACELLULAR MATRIX COMPOSITE SCAFFOLD IN VITRO AND IN VIVO].

Objective: To prepare a composite scattold using bladder acellular matrix (BACM) and polyurethane (PU) for bladder repair and regeneration, and to evaluate its mechanical properties and biocompatibility.

Methods: Fresh bladder tissues were obtained from New Zealand rabbits and then treated with 1%SDS and 1%Triton X-100 to obtain BACM. The BACM was combined with PU to fabricate PU-BACM composite scaffold. The tensile strength and elongation at break of BACM and PU-BACM scaffolds were tested. Scaffolds and extracts of scaffolds were prepared to evaluate the biocompatibility. For cell-proliferation analysis, cell counting kit 8 method was used at 1, 3, 5, and 7 days after co-culture of human. bladder smooth muscle cell (HBSMC) and scaffolds. The cell cycle was tested by flow cytometry after HBSMC co-cultured with extracts of scaffolds and DMEM culture medium (control group) for 24 hours. Finally, 12 New Zealand rabbits were used to establish the model of bladder repair and regeneration. Incision of 5 mm was made on the bladder, and PU-BACM scaffold was sutured with the incision. The rabbits were sacrificed at 10, 20, 40, and 60 days after surgery to observe the inflammatory cell infiltration, new tissues formation, and regeneration of epithelium by HE staining.

Results: The tensile strength of BACM and PU-BACM composite scaffold was (5.78 ± 0.85) N and (11.88 ± 3.21) N, and elongation at break was 14.46% ± 3.21% and 23.14% ± 1.32% respectively, all showing significant diffeence (t = 3.182, P = 0.034; t = 4.332, P = 0.012). The cell-proliferation rates of controls, PU, BACM, and PU-BACM were 36.78% ± 1.21%, 30.49% ± 0.89%, 18.92% ± 0.84%, and 22.42% ± 1.55%, it was significantly higher in PU-BACM than BACM (P < 0.05). In the bladder repair and regeneration experiment, inflammatory cell infiltration was observed at 10 days after operation, and reduced at 20 days after implantation. In the meanwhile, the degradation of scaffolds was observed in vivo. The regeneration of epithelium could be observed after 40 days of implantation. At 60 days after implantation, in situ bladder tissue formed.

Conclusion: PU-BACM composite scaffold has higher mechanical properties and better biocompatibility than BACM scaffold. PU-BACM composite scaffold will not lead to strong immune response, and new bladder tissue can form in the in vivo rabbit bladder repair experiment. These results can provide research basis and theoretical data for further study.