Ovarian Tissue Oocyte-In Vitro Maturation for Fertility Preservation

Summary

Presented here is ovarian tissue oocyte-in vitro maturation (OTO-IVM), an accessible technique within a medical assisted reproduction (MAR) laboratory offering realistic additional fertility preservation options to patients who need ovarian tissue cryopreservation.

Abstract

Mature oocyte vitrification is the standard of care to preserve fertility in women at risk of infertility. However, ovarian tissue cryopreservation (OTC) is still the only option to preserve fertility in women who need to start gonadotoxic treatment urgently or in prepubertal children. During ovarian cortex preparation for cryopreservation, medullar tissue is removed. Growing antral follicles reside at the border of the cortex-medullar interface of the ovary and are broken during this process, releasing their cumulus-oocyte complex (COC). By thoroughly inspecting the medium and fragmented medullar tissue, these immature cumulus-oocyte complexes can be identified without interfering with the OTC procedure. The ovarian tissue-derived immature oocytes can be successfully matured in vitro, creating an additional source of gametes for fertility preservation. If OTC is performed within or near a medical assisted reproduction laboratory, all necessary in vitro maturation (IVM) and oocyte vitrification tools can be at hand. Furthermore, upon remission and child wish, the patient has multiple options for fertility restoration: ovarian tissue transplantation or embryo transfer after the insemination of vitrified/warmed oocytes. Hence, ovarian tissue oocyte-in vitro maturation (OTO-IVM) can be a valuable adjunct fertility preservation technique.

Introduction

Fertility preservation (FP) options for women planned for gonadotoxic treatment, sex-reassignment therapy, or women who have a genetic predisposition for premature ovarian failure, depend on the health and age of the patient, available timeframe, type of treatment, patient's preference, and FP procedures available at the fertility center of choice. Vitrification of mature oocytes obtained after ovarian stimulation with gonadotropins and oocyte retrieval in a medical assisted reproduction (MAR) laboratory cycle is considered the preferred option for FP^1,2. However, for prepubertal girls, women in whom the u....

Protocol

The present study on OTO-IVM has been approved by the local Ethical Committee of UZ-Brussels (addendum of project 2008/068 and project 2022/303). All patients signed written informed consent. Each patient was individually assessed by a reproductive medicine specialist physician, navigator nurse, and the referring oncologist to compose the optimal FP treatment plan, taking into account the patient's preferences¹⁴. In short, patients eligible for OTC are in urgent need of FP and are less than 36 years of age¹⁴. To combine OTC with OTO-IVM, chemo- or radiotherapy cannot have been administered in the 6 months preceding O....

Results

Over the past decade, 98 patients undergoing oophorectomy or ovarian biopsy for OTC were also offered OTO-IVM. The results presented here are an update of the clinical program as published before^7,13. Immature oocytes obtained during ovarian tissue processing were matured in vitro predominantly for 30 h. However, a more flexible maturation time was allowed for practical reasons or because of low maturation, ranging from 28-42 h. Patients opted predominan.......

Discussion

The priority of the FP procedure is always to manipulate and freeze the ovarian cortex according to the standard operating protocol that has been validated in the clinic. A drawback in FP is the absence of a standard protocol available in the published literature regarding OTC and OTO-IVM. It is difficult to assess the efficiency and validity of the techniques and adaptations since there is a large time gap between freezing/vitrification and thawing/warming in a clinical setting. If changes to the OTC protocol are made t.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1000 µL filter tips	Eppendorf/VWR International	613-6780	COC search
Benchtop Cooler	Fisher Scientific	15-350-54	Benchtop Cooler lid is used to prepare the tissue, Benchtop Cooler tube holder to keep cryovials with freezing medium cooled
Corning Cell culture dish, non-treated, 100 mm	Corning/VWR International	430591	Dish for ovarian tissue preparation
CryoSure-DMSO	WAK Chemicals	0482	Cryoprotectant for ovarian tissue cryopreservation
Cumulase	Origio/CooperSurgical	16125000A	recombinant human hyaluronidase enzyme for cumulus cell removal after IVM
Decontamination spray: Suprox	Medipure LTD	MP016	Desinfectant solution for aseptic handling with bactericide and sporicide action
Disposable scalpels	Swann-Morton	0511	Ovarian tissue preparation
Falcon 14 mL Round Bottom Polystyrene Test Tube, with Snap Cap, Sterile	Falcon/VWR International	BDAA352057	Medium container
Falcon Cell strainer 70 µm	Falcon/VWR International	352350	Filter for elimination of red blood cell contamination and COC search
Freeze control Ampoule Cryochamber and Temperature Controller	Cryologic	CL-8800i   CC60AS	Slow freezing machine
FSH: Menopur 75 IU	Ferring	BE197504	Follicle Stimulating Hormone : Supplement for IVM medium
Handling pipette 290-310 µm	Vitrolife	15538	COC search: gentle transfer of COC without damaging oocyte-cumulus cell connectivity
hCG: Brevactid 5000 IE	Ferring	5008001036	Human Chorionic Gonadotropin : Supplement for IVM medium
High security tube	CryoBioSystem	022252	cryovial, heat-sealed for safe cryostorage
HSA-solution	Vitrolife	10064	Human serum Albumin: supplement for IVM medium
Leibovitz's L-15 medium	Life Technologies Europe	31415-029	Handling medium for ovarian tissue preparation
MediCult IVM system	Origio/CooperSurgical	82214010	medium for IVM containing both LAG and IVM medium. IVM medium needs to be supplemented as detailed in the protocol
METZENBAUM fino scissors 140 mm	Chirurgical Maintenance	VIZ08280314	Medium size scissors for initial medulla removal
Nunc 4-well dishes for IVF	Nunc/VWR International	144444	COC collection during COC search and IVM culture
Nunc Invitro fertilization Petri Dish with Vented Lid, 60 mm, Non-Pyrogenic, Sterile	Thermo Scientific/VWR	NUNC150270	Dish for COC search
Oocyte handling medium : Flushing Medium with heparin	Origio/CooperSurgical	10765060	Search medium for COC search
Ovoil	Vitrolife	10029	oil for IVM culture
Penicillin/Streptomicin mix	Life Technologies Europe	15140-148	Supplement for OTC handling medium
Scissors, curved, 150 mm long, 20 mm blade	Chirurgical Maintenance	VIREBST999-SC	Small size scissors for residual medulla removal