In vitro maturation of immature oocytes from ovarian tissue prior to shipment to a cryobank

Is in vitro maturation of oocytes retrieved ex vivo from ovarian tissue an effective fertility preservation technique in the presence of organic ovarian cysts?

OBJECTIVE(S)

In vitro maturation (IVM) of oocytes retrieved ex vivo from ovarian tissue (OTO-IVM) could be an additional source of mature oocytes with the potential to optimise medical fertility preservation (FP) after oophorectomy. It is often undertaken at the same time as the ovarian tissue cryopreservation (OTC). In the presence of an organic ovarian cyst, OTO-IVM could prove to be the only technique available to permit FP since ovarian stimulation, transvaginal ovarian needle puncture or future ovarian tissue graft are contraindicated. However, the presence of an organic cyst could alter follicular growth and the number of retrievd oocytes. Our study aims to assess the efficiency of OTO-IVM in such situations.

STUDY DESIGN

Retrospective, observational study involving 20 female patients with FP by OTO-IVM between May 2017 and November 2021 at the University Hospital of Toulouse. Oocytes retrieved "ex vivo" were transferred to an IVM medium with HP-hMG, LH and HSA and then vitrified after 24 to 48 h of IVM. Data analysis was performed on the total population and comparatively between patients who had or did not have an organic ovarian cyst.

RESULTS

The indications included 15 oncologic and 5 non-oncologic indications. Ten had an organic ovarian cyst on the retrieved ovary. The number of retrieved oocytes was 17.4+/-12.0 in the absence of cyst vs 4.1+/-6.3 in the presence (p = 0.003). The number of vitrified mature oocytes was 5.8+/-5.3 in the absence vs 1.1+/-2.2 (median = 0) in the presence of a cyst (p = 0.03). Ninety percent of the patients with an organic cyst had less than two vitrified mature oocytes. The mean maturation rate was 34%, not significantly different between the two groups. We found a correlation between serum AMH level and the number of mature oocytes: ρ:0.47 CI95 = [0.02; 0.76]; p = 0.04.

CONCLUSION(S)

OTO-IVM is an additional source of mature oocytes to optimise FP after oophorectomy. However, in the presence of an organic ovarian cyst on the retrieved ovary, the exocrine, paracrine and endocrine functions of the ovary are impaired. As such, the number of immature oocytes obtained is highly impacted and appears to be insufficient to be able to propose systematically this technique in such situations.

Twenty-first century oocyte cryopreservation—in vitro maturation of immature oocytes from ovarian tissue cryopreservation in cancer patients: A systematic review

Objectives:

Our review aimed to consolidate the latest update on the application of in vitro maturation among immature oocyte harvest in combination with ovarian tissue cryopreservation known as ovarian tissue oocyte–in vitro maturation.

Methods:

A thorough search for relevant studies was conducted via PubMed, Google Scholar, EMBASE, and clinical.gov databases up to December 2020. The primary outcome was the oocyte maturation rate, which measured the number of immature oocytes (geminal vesicle stage) that progressed to mature oocytes (meiosis II stage) following in vitro maturation. The secondary outcomes were the fertilization rate following intracytoplasmic sperm injection/in vitro fertilization of these oocytes for the embryo cryopreservation cohort. Our review included pre-pubertal girls and women with cancer who underwent ovarian tissue oocyte–in vitro maturation as fertility preservation.

Results:

The primary search identified 207 studies. Twelve manuscripts were selected for inclusion in our review following duplication assessment, title and abstract screening, and full-text evaluation tailored to our inclusion criteria. All the population belonged to a cancer group and underwent concurrent ovarian tissue oocyte–in vitro maturation. A total of 5724 immature oocytes were obtained following ovarian tissue cryopreservation. Approximately 33.84% of the immature oocytes successfully matured via in vitro maturation, which were cryopreserved as oocytes or fertilized as embryos and subsequently stored for future use.

Conclusion:

Our review proposed the potential application of ovarian tissue oocyte–in vitro maturation in increasing the number of mature oocytes. The acceptable improvement in oocyte maturation rate following in vitro maturation indicates that improving oocyte outcomes is an excellent cost-effective strategy for fertility preservation among women with cancer.

In Vitro Maturation of Oocytes Retrieved from Ovarian Tissue: Outcomes from Current Approaches and Future Perspectives

In vitro maturation (IVM) of transvaginally aspirated immature oocytes is an effective and safe assisted reproductive treatment for predicted or high responder patients. Currently, immature oocytes are also being collected from the contralateral ovary during laparoscopy/laparotomy and even ex vivo from the excised ovary or the spent media during ovarian tissue preparation prior to ovarian cortex cryopreservation. The first live births from in vitro-matured ovarian tissue oocytes (OTO-IVM) were reported after monophasic OTO-IVM, showing the ability to achieve mature OTO-IVM oocytes. However, fertilisations rates and further embryological developmental capacity appeared impaired. The introduction of a biphasic IVM, also called capacitation (CAPA)-IVM, has been a significant improvement of the oocytes maturation protocol. However, evidence on OTO-IVM is still scarce and validation of the first results is of utmost importance to confirm reproducibility, including the follow-up of OTO-IVM children. Differences between IVM and OTO-IVM should be well understood to provide realistic expectations to patients.