Background: Defects of male urogenital structures subsequent to major trauma are associated with severely reduced function and quality-of-life. As of recent, penis transplantation represents an exciting avenue for restoration of male urogenitalia. However, little is currently known about the immunological features of these grafts. To fill this void, we established a new animal model and clinical & histological rejection classification.

Methods: In male BN & Lewis rats the penis was dissected to design a penile graft including prepuce skin. A non-suture cuff technique was employed for the anastomosis of the graft vessels to the recipient inferior epigastric vessels. 30 syngeneic and allogeneic transplants were performed. Grafts were followed clinically and histologically at post-operative days(POD) 3,5,7,9,11,13,14,16 and 18.

Results: The graft design using anastomosis of the dorsal penile vein and the internal pudendal artery yields optimal perfusion of all graft tissues. The non-suture cuff technique allows for successful anastomosis by a single surgeon in an average of 2.5 hours (91% surgical success rate). Long-term graft survival (>POD 45) was observed in syngeneic transplants. Graft rejection follows a 4-stage clinical progression, with all untreated allografts fully rejected by POD 16. Histological analysis allowed for the development of a specific 4-grade rejection classification in analogy to the 2007 BANFF criteria for hand transplantation. Of note, graft skin and urethral lining tissue are first targets of rejection, which follows a distal to proximal pattern.

Conclusion: We established a robust and reproducible murine model to study the immunobiology of urogenital tissue in the context of transplantation. The graft design ensures vascular perfusion of all penile tissues and allows for standardized visual monitoring of graft viability. We propose a novel 4-grade histological rejection scale based on graft skin and urethral lining as the main targets of rejection.

CITATION INFORMATION: Fidder S., Furtmüller G., Simons B., Kern B., Lough D., Oh B., Chicco M., Brayton C., Lee W., Cooney D., Redett R., Brandacher G. Functional Reconstruction of Urogenital Tissue Defects Using VCA: A Novel Microsurgical Penis Transplant Model and Clinical & Histological Rejection Classification Am J Transplant. 2017;17 (suppl 3).

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