Ovarian Stem Cells (OSCs) from the Cryopreserved Ovarian Cortex: A Potential for Neo-Oogenesis in Women with Cancer-Treatment Related Infertility: A Case Report and a Review of Literature

Abstract

Cancer treatment related infertility (CTRI) affects more than one third of young women undergoing anti-cancer protocols, inducing a premature exhaustion of the ovarian reserve. In addition to ovarian suppression by GnRHa, oocyte and cortex cryopreservation has gained interest in patients with estrogen-sensitive tumors for whom the hormonal burst to prompt the multiple follicular growth could provide a further pro-life tumor pulsing. On the other hand, cortex reimplantation implies a few drawbacks due to the unknown consistency of the follicles to be reimplanted or the risk of reintroducing malignant cells. The capability of ovarian stem cells (OCSs) from fresh ovarian cortex fragments to differentiate in vitro to mature oocytes provides a tool to overcome these drawbacks. In fact, since ovarian cortex sampling and cryopreservation is practicable before gonadotoxic treatments, the recruitment of OSCs from defrosted fragments could provide a novel opportunity to verify their suitability to be expanded in vitro as oocyte like cells (OLCs). Here, we describe in very preliminary experiments the consistency of an OSC population from a single cryopreserved ovarian cortex after thawing as well as both their viability and their suitability to be further explored in their property to differentiate in OLCs, thus reinforcing interest in stemness studies in the treatment of female CTRI.

Keywords: cancer treatment related infertility (CTRI); cryopreserved ovarian cortex; oocyte like cells (OLCs); ovarian stem cells (OSCs); stem cell differentiation.

Figure 1

Schematic representation of two procedures of ovarian cortex cryopreservation by laparoscopic retrieval.

Figure 2

Flowcytometry analysis of ovarian stem cells (OSCs) isolated from a thawed ovarian cortex sample. After isolating the cell suspension by Ficoll density gradient, the cell population incubated with FITC-conjugated anti-Ddx4 oogonial marker included a large consistency of positive cells (A), which were then analyzed in their vitality using the PC5-conjugated 7-AAD viability marker. As shown, almost the full population, namely 95.7% of Ddx4-positiive cells were found viable in contrast with a minority equal to 4.3% of dead cells (B,C). This result suggested that the cryopreservation of ovarian cortex fragments in liquid nitrogen is almost indolent on the OSC viability and that probably other functions including their capability to differentiate in oocytes in vitro is also restored after their thawing. (Values are percentage of positive cells measured on 10,000 events).