In vivo characterization of metabolic activity and oxidative stress in grafted human ovarian tissue using microdialysis.

OBJECTIVE: To characterize oxidative stress and metabolic activity in xenografted human ovarian tissue using microdialysis.

DESIGN: Prospective experimental study.

SETTING: Gynecology research unit at a university hospital.

PATIENT(S): Cryopreserved ovarian cortex from five women 27-35 years of age.

INTERVENTION(S): Frozen-thawed human ovarian tissue fragments were xenografted to the back muscle of ten nude mice. Before grafting, a microdialysis probe was placed inside each fragment.

MAIN OUTCOME MEASURE(S): Daily reactive oxygen species (ROS), lactate, and glucose levels were collected by means of microdialysis. Follicle loss (hematoxylin and eosin), murine and human vascularization, and vessel stability (CD31, von Willebrand factor, and α-smooth muscle actin triple immunofluorescence) were analyzed on post-grafting days 10 and 21.

RESULT(S): Lactate levels were significantly higher than glucose levels until day 10, after which time the lactate-glucose ratio stabilized at ∼1:1. Regarding ROS generation, there were two peaks on post-grafting days 10 and 17. Total vascularization increased significantly up to day 10 and remained similar up to day 21. However, murine vessel area and stabilization significantly increased up to day 21. Major follicle loss occurred in the first 10 days after transplantation.

CONCLUSION(S): Our data validated microdialysis as a tool to characterize metabolic behavior and oxidative stress in grafted ovarian tissue. Three different post-grafting periods were identified according to the metabolic activity of grafted tissue, showing a long progression from anaerobic to aerobic metabolism and a protracted period of ROS generation. Oxidative stress was observed relatively late, after the most critical period of follicle loss, and lasted until the tissue vasculature stabilized.