Human ovarian tissue from cortex surrounding benign cysts: a model to study ovarian tissue cryopreservation

Abstract

Ovarian cortex surrounding ovarian cysts, especially dermoid cysts, could be considered a source of ovarian tissue for future research. In our study, the cryopreservation procedure resulted in high follicular survival assessed by both histological and viability analysis. Nevertheless, further studies of in vivo and in vitro follicular maturation are needed to strengthen this model.

Efficacy of ovarian tissue cryopreservation in a major European center

“…The observed percentages of tissue viability impairment as a result of cryopreservation and thawing are roughly consistent with the 70-80 % follicle survival reported earlier for various slowfreezing protocols. [8,27,29,30,35,38,39] In addition, we observed a 24-27 % reduction in overall tissue viability using the glucose uptake assay. This decreased glucose uptake indicates a reduced metabolism of the tissue during culture as a result of cryodamage.…”

“…Although various large centers for cryopreservation of ovarian tissue exist, [12,13,15,17,18,21,24] to the best of our knowledge, cohort studies in which the impact of currently used cryopreservation/ thawing protocols on both follicle and stromal cell survival in young cancer patients is measured have not been published before. Earlier studies considering the impact of slow freezing techniques other than evaluated here, generally focused on follicle viability only [27][28][29][30][31][32][33][34][35][36][37][38] and often described patient populations without an indication for fertility preservation (e.g. patients applying for a sterilization, cystectomy, or caesarean section) [8, 27-29, 32, 34, 35, 38].…”

“…Although there are studies that quantify the impact of slow-freezing on human ovarian tissue viability, these studies do not per definition focus on the protocols that are currently being used by the major centers. [27][28][29][30][31][32][33][34][35][36][37][38] Moreover, most of these studies did not take the viability of the stromal cell compartment into account. [27][28][29][30][31][32][33][34][35][36][37][38] This compartment, however, is essential for post-autotransplantation neovascularization, follicle survival, and life span of the ovarian graft [39] and is considered to be more sensitive to ischemic and cryoinjury than primordial follicles [8,40].…”

Quality and functionality of human ovarian tissue after cryopreservation using an original slow freezing procedure

“…For each patient, a piece of ovarian cortex overlying the cyst was excised with scissors and without electrocoagulation. The specimens were immediately immersed in the basal "medium A" at 4°C and transported to the laboratory on ice, as previously described [38]. "Medium A" was composed of: NaCl (94.7 mmol/l), KCl (4.8 mmol/ l), MgSO 4 (0.8 mmol/l), NaH 2 PO 4 (1.0 mmol/l), NaHCO 3 (25.0 mmol/l), CaCl 2 (1.8 mmol/l), sodium lactate (21.3 mmol/l), sodium pyruvate (0.3 mmol/l), Dglucose (5.5 mmol/l), L-glutamine (25.0 mmol/l), taurine (0.5 mmol/l), and 0.5 % of human serum albumin (Vitrolife Sweden AB, Sweden).…”

“…The freezing medium, "medium B", consisted of "medium A" without CaCl 2 and supplemented with HEPES (21.8 mmol/l), glycine (50.0 mmol/l), propanediol (3.0 mol/l) and raffinose (0.05 mol/l) [38]. The "medium B" was added in 3 steps to "medium A" which contained ovarian slices, to a final dilution of 1:1 (v/v) under gentle agitation.…”