Abstract
Cryopreservation of ovarian tissue followed by transplantation represents a strategy to restore ovarian function and fertility. Stress from cryopreservation-thawing processes can lead to alterations and/or damage to mitochondrial structure and functionality. High resolution respirometry and histological analysis were used to evaluate the effect of cryopreservation and transplantation on ovarian tissue. Four different conditions were performed: Fresh non-transplanted tissue, Fresh transplanted tissue, Cryopreserved non-transplanted tissue and Cryopreserved transplanted tissue. All groups were able to respond to the substrates-uncoupler-inhibitor protocol. We found a dramatic decrease in general oxygen consumption in hemi-ovaries submitted to cryopreservation and/or transplantation. The effect of cryopreservation on mitochondrial metabolism was less intense than effect of transplantation, since the transplantation affected all of the mitochondrial states. A total of 2644 follicles were analyzed. Of these, 2198 were classified as morphologically normal. The percentage of morphologically normal follicles was significantly lower in the Cryopreserved transplanted group when compared to the Cryopreserved non-transplanted group and the Fresh transplanted group (p-value < 0.05). Despite decreased follicular viability and mitochondrial activity, the cryopreservation followed by transplantation of ovarian tissue proved feasible for attempts to restore ovarian function.
Highlights
Cryopreservation of ovarian tissue followed by transplantation represents a strategy to restore ovarian function and fertility
Using high-resolution respirometry (HRR), we assessed the effect of the cryopreservation and transplantation on the O2 consumption rates (OCR) in homogenates of hemi-ovaries
This protocol allowed us to determine the: basal OCR; oxygen consumption linked to Complex II (Leak-supported by succinate); OXPHOS; Oligo; ETS
Summary
Cryopreservation of ovarian tissue followed by transplantation represents a strategy to restore ovarian function and fertility. Studies report that stress arising from cryopreservation-thawing processes can lead to alterations and/or damage to mitochondrial structure and functionality, contributing, for example, to reactive oxygen substance (ROS) generation[5,11,12]. Since oxidative stress determines important cellular processes, such as apoptosis, senescence and cellular signalization[5], it is relevant to analyse the mitochondrial activity, as one strategy to measure the efficacy of cryopreservation and thawing, followed by transplantation. In this scenario, the development of new techniques to improve the efficacy of cryopreserved tissue transplantation can positively impact the process. Analysis of metabolic parameters in cryopreserved/transplanted tissues, such as measuring mitochondrial oxygen consumption, can provide essential data to better understand cellular metabolism[5,11,13]
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