Improving ovarian tissue cryopreservation for oncologic patients Slow freezing versus vitrification effect of different procedures and devices

Capsule:
Vitrification of ovarian tissue employing ethylene glycol and dimethyl sulfoxide in metallic grids preserves morphology of follicles and stroma, and maintains proliferation, viability, and vascularization status similarly to fresh tissue.

Authors:
Sonia Herraiz, Ph.D., Edurne Novella-Maestre, Ph.D., Beatriz Rodríguez, B.Sc., César Díaz-García , M.D., Maria Sánchez-Serrano, M.D., Ph.D., Vicente Mirabet , Ph.D., Antonio Pellicer, M.D., Ph.D.

Volume 101, Issue 3, Pages 775-784.e1, March 2014

Abstract:

Objective:
To compare slow freezing (SF) with four vitrification techniques (VT) for cryopreservation of ovarian tissue (OT) and to evaluate the best protocol for human OT in a xenograft model.

Design:
Experimental study.

Setting:
University hospital.

Patient(s):
Patients undergoing fertility preservation.

Animal(s):
Ovariectomized nude mice.

Intervention(s):
Cryopreservation of bovine OT after SF and four VTs (VT1, VT2, VT3, and VT4) by combining two cryoprotectant vitrification solutions (VS1 and VS2) and two devices (metallic grid and ethyl vinyl acetate bag), after which the cryopreservation of human OT by SF and VT1 and xenograft into nude mice.

Main Outcome Measure(s):
Follicular densities, proliferation, vascularization, fibrosis, apoptosis, tissue viability.

Result(s):
The in vitro study in bovine OT showed a lower percentage of quiescent follicles in the SF group but not in the vitrification groups (VT1–VT4). Apoptosis increased and cell proliferation decreased in all the experimental groups except VT1 (20% ethylene glycol, 20% dimethyl sulfoxide, 0.5 M sucrose, and 20% synthetic serum substitute in HEPES-buffered M199 culture media with Cryotissue metallic grids). Tissue viability was diminished in VT3, and the SF-xenografted human samples showed reduced primordial and secondary densities and unbalanced follicular populations when compared with fresh and VT1 tissue.

Conclusion(s):
VT1 offers similar conditions to fresh tissue for follicular density, proliferation, viability, and cell death and preserves a larger population of quiescent follicles than SF after transplantation, thus ensuring the maintenance of graft potential fertility.

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