Cryopreservation of Human Ovarian Tissue

Abstract

New and often aggressive treatment schemes allow the successful healing of many young patients with cancer, but the price the young women have to pay is high: many of them lose ovarian function and fertility. Due to the improved long-term survival of adolescents and young women with malignancies undergoing gonadotoxic chemotherapy, preservation of future fertility has been the focus of recent ubiquitarian interest. A feasible solution is the cryopreservation of ovarian tissue. Ovarian tissue, after thawing, can be used in three different ways: 1. grafted into its normal site (orthotopic); 2. grafted into a site other than its normal position (heterotopic), necessitating recourse to in vitro fertilization (IVF); 3. grown and in vitro matured in order to obtain metaphase II oocytes for an IVF program. It is believed that protein supplementation, in cryopreservation solution, is essential for improving ovarian tissue cryopreservation. The aim of this study was to evaluate the ultrastructural appearance of human ovarian tissue cryopreserved in 1.5 M 1,2 propanediol (PROH), 0.2 M sucrose using different protein sources: fetal calf serum (FCS), plasmanate or syntetic serum substitute (SSS). Fresh and frozen/thawed ovarian tissues were compared by transmission electron microscope (TEM), to evaluate the appearance of stromal and follicle cells as affected by different protein sources. Our data indicate that FCS is a better protein support for ovarian tissue cryopreservation when compared to SSS or Plasmanate. In addition the follicles are more resistant to the cryopreservation with respect to stroma.

Impact of freezing and thawing of human ovarian tissue on follicular growth after long-term xenotransplantation

“…Such findings could be due to the deleterious effect of cryopreservation on the ovarian stroma [5,[31][32][33][34][35] and granulosa cells [32,36,37], since these cell populations are directly involved in the formation of the theca layer. During follicular development, granulosa cells stimulate the differentiation of stromal cells into theca cells [38,39] through expression of different factors, such as kit ligand [40] and insulin-like growth factor (IGF)-I and/or -II [41].…”

“…During follicular development, granulosa cells stimulate the differentiation of stromal cells into theca cells [38,39] through expression of different factors, such as kit ligand [40] and insulin-like growth factor (IGF)-I and/or -II [41]. Although the immature oocyte appears to be well maintained after cryopreservation [32,36], different studies have reported that the freezing procedure negatively affects stromal cells [31][32][33][34][35] and granulosa cells [32,36,37]. It might therefore be expected that death of the theca cell precursor population and granulosa cells that express factors involved in the differentiation process could have a detrimental effect on the formation of the theca cell layer.…”

New Approaches of Ovarian Tissue Cryopreservation from Domestic Animal Species

“…Most of authors observed a reduction of normal follicles in frozen/thawed ovarian tissue compared with fresh control when using similar freezing protocols in the mouse (Candy et al, 1997), the goat (Rodrigues et al, 2004), the cow , and the ewe (Demirci et al, 2002). As for the queen, no morphological difference was observed in human follicles before and after cryopreservation (Hovatta et al, 1996;Fabbri et al, 2006) Newton observed similar proportions of "viable" follicles after freezing when using DMSO, ethylene glycol or PROH and xenografting (Newton et al, 1996).…”

Fertility Cryopreservation

“…If samples are thawing slowly, ice crystals can form and/or grow causing more damage; however, if samples are thawed rapidly enough, there is little time for ice nucleation and growth to occur (Fabbri, 2006;Fabbri et al, 2006).…”