Isolated Organ Support of a Sheep's Gravid Uterus

The placenta is essential to animal development, yet its function is understudied. Existing placental support models study the organ in isolation without the uterus and fetus. We report our early experience with a novel extracorporeal placental support model that perfuses the intact gravid sheep uterus.

A gravid hysterectomy was performed after cannulation of the uterine vessels, and the explanted uterus was maintained in a warm crystalloid tank. Oxygenation, electrolytes, and glucose were provided through an extracorporeal membrane oxygenation circuit. The objectives were to establish the feasibility of the model, confirm the ability to transition the organ to ex vivo support, and measure the duration of fetal survival after explantation.

Across 51 surgeries, 76% of uteri achieved initial successful transition to ex vivo support. Growing experience throughout the study period was associated with technical adaptations and longer survival up to 16 h. Uteri with a singleton fetus had longer median survival times than twins (130 min [interquartile range 67-270] versus 47 [interquartile range 42-160]; P = 0.039). Anemia, acidosis, and coagulopathy were common, and most uteri developed substantial clot formation around the placentomes by the end of the experiment.

This novel extracorporeal placental support model demonstrates the feasibility of sustaining a gravid sheep uterus ex vivo. Fetal survival under the model was associated with progressive lactic acidosis and coagulopathy, identifying specific targets for future iterations. The platform is a potential tool for studying fetoplacental physiology and mechanisms that are not accessible in traditional in vivo systems.