Victor Seid, Flavio Galvao, Daniel Waisberg, Andre Lee, Raoni Galvao, Eleazar Chaib, Luiz D'Albuquerque

Department of Gastroenterology, University of Sao Paulo Medical School, Sao Paulo, Brazil

Introduction: Anorectal transplantation is a potential proposal for severe anorectal dysfunction. The lacking of experimental models hampers the development of this technique.

Objective: To evaluate anorectal function in a model of autologous anorectal transplantation in rats.

Methods: Sixty male Wistar rats were divided in 4 groups (n=15): autologous ortothopic anorectal transplantation, autologous heterothopic transplantation, sham and normal rat. Body weight measurement, clinical evaluation and manometry were performed pre-operatively and on 2nd, 7th and 14th post-operative day (POD). Material for histopathological analysis was collected following sacrifice on 14th POD.

Results: Surgical procedure period was around 40 minutes. Ortothopic and heterothopic groups showed satisfactory evolution; however, animals from group I achieved faster recovery, higher body mass gain, normalization of clinical parameters on 7th POD and higher survival rate (86.7%). In group II animals, scores were numerically higher until study end point, with 66.6% survival rate [Final body mass: 319.5 ± 40.7g (ortothopic); 292.7 ± 38.3g (heterothopic); 317.8 ± 36.6g (sham); 322.9 ± 34.1g (control); p<0.01. Final behavior scores: 0.3 ± 0.5 (ortothopic); 0.6 ± 0.7 (heterothopic); 0.2 ± 0.4 (sham); 0.1 ± 0.3 (control); p<0.01. Final stool scores: 0.1 ± 0.4 (ortothopic); 0.3 ± 0.5 (heterothopic); 0.0 ± 0.0 (sham and control); p=0.01. Final stoma scores: 0.0 ±0.0 (ortothopic. sham and control); 0.7 ± 1.0 (heterothopic); p<0.01]. All surviving animals showed adequate sphincter structure in histopathological analysis. Manometry on study end point, ortothopic and sham groups showed numerically similar values compared to pre-operative data and statistically similar values to control group (ortothopic 25,4±18,2, sham 25,3±4,2, control 30,4±18,2 cmH20, p>0.05). Heterothopic group showed final values lower than their pre-operative data or control group (10,5±10,5 cmH20, p=0,01).

Conclusion: We described a feasible model of autologous anorectal transplantation in rats to study anorectal function recovery. Ortothopic group showed better clinical and eletromanometrical evolution than heterothopic group.