Login to Access Video or Poster Abstract: MP36-01
Sources of Funding: Viscofan, BioEngineering, Weinheim, Germany

Introduction

Regarding urethral reconstruction of urethral stricures we demonstrated in a previous short-term pilot study that human urothelial cells (HUC) seeded on a bovine collagen cell carrier (CCC), used as a xenograft in minipigs is technically feasible for urethral reconstruction. The aim of this following study was to evaluate the use of CCC in a long-term animal model and to compare it with primary surgical reconstruction without CCC of the porcine urethra.

Methods

Twelve male Göttingen minipigs with immunosuppression (cyclosporine A) were used for this study. Eight weeks after urethral stricture induction and protective vesicostomy animals were subdivided in a short-term group (4 pigs with HUC seeded CCC) and a long-term group (2 pigs with static HUC seeded CCC, 2 pigs with CCC-only, 2 pigs with bioreactor cultivated dynamic HUC seeded CCC). As a control-group SHAM operated animals were selected (2 pigs without CCC and primary urethral reconstruction). HUC obtained from human benign ureteral tissue were stained by PKH26 before seeding on CCC. Follow-up timeframe was 2 and 4 weeks in the short-term group, 2 weeks in the sham operated group and 3 months in the long-term group. Hereafter animals were euthanized. Urethrography, histological assessment and immunofluorescence were performed.

Results

Surgery was well tolerated and technically feasible in all 12 mini-pigs. In the final urethrography no remaining significant stricture could be detected in the long-term group. In contrast both SHAM operated pigs showed a persistent urographic urethral stricture in the final examination. A radiological extravasation was only found in short-term (3/4) and SHAM (1/2) animals but not in the long-term group. The final histological examination showed the CCC close to the previously suture-tagged operating area (range 0.5-1.2 mm). In case of HUC seeded CCC near porcine urothelium PKH26 positive areas were found even if partially detached from CCC. However, porcine urethra revealed intact urothelium in the long-term group expressing CK20, E-Cadherin and ZO-1 whereas 1 of 2 SHAM animals had a histologically discontinuous urethra.

Conclusions

Compared to the control-group with primary urethral reconstruction CCC with or without HUC seems to increase the stability of the reconstructed urethra and supports survival and growth of seeded urothelial cells leading to an intact regeneration of the urothelial tissue. Finally, this study demonstrates that CCC in minipigs is technically feasible showing promising results for further studies.

Funding

Viscofan, BioEngineering, Weinheim, Germany