Transplantation of the uterus in sheep: methodology and early reperfusion events

Uterine transplantation is developing into a clinical treatment for uterine factor infertility. An animal model with a similar uterus size and vessels to humans and with pregnancy extending over several months would be beneficial for research on uterine transplantation. The aim of this study was to develop and evaluate autotransplantation of the sheep uterus to an orthotopic position in the pelvis.

Female sheep (n=7) were subjected to laparotomy with the uterus and its vascular supply and drainage being surgically isolated. The excised uterus was kept ex vivo at +4 degrees C for 60 min and then autotransplanted with vascular end-to-side anastomoses to the external iliac vessels. The effects of uterine blood-reperfusion were assessed by measurements of pCO(2), pO(2), lactate and pH in uterine venous blood. Uterine contractility and histology was assessed after 3 h of reperfusion.

Reperfusion of blood was observed in five out of seven transplanted uteri. The pCO(2)/pO(2)-ratio and the lactate level were initially elevated but decreased and became normal after 60 min. After 3 h of reperfusion there was a visible tissue blood flow and spontaneous uterine contractions were seen. Histological analysis revealed a mild inflammation, but no edema or stasis.

This study demonstrates that the sheep uterus can successfully be autotransplanted to an orthotopic position with novel vascular connections. This model is suitable for future experiments studying long-term results concerning uterine viability and pregnancy using a transplanted uterus of similar size to the human uterus.