Vitrification of in vitro matured oocytes collected from surplus ovarian medulla tissue resulting from fertility preservation of ovarian cortex tissue

Abstract

Purpose The aim of the study was to investigate the maturation rate of immature oocytes collected from ovarian medulla tissue normally discarded during preparation of ovarian cortical tissue for fertility preservation. Further we evaluated survival of derived MII oocytes following vitrification and warming. Methods 36 patients aged from 8 to 41 years who had one ovary excised for fertility preservation were included. Oocytes were collected from the medulla tissue and matured in vitro 44-48 h followed by vitrification. Number of oocytes collected, the rates of maturation and post-warming survival were assessed. Results On average, 11 immature oocytes were collected per patient. The overall maturation rate was 29 % irrespective of whether the ovary was transported 4-5 h on ice or obtained immediately after oophorectomy. The maturation rate in patients below 20 years of age (55 %) was significantly higher than that of patients aged 20-30 years (29 %) and above 30 years (26 %). The post-warming survival rate was 64 %. No significant relationship was observed between the number of collected oocytes and the age of patients.Conclusions Approximately three MII oocytes were obtained per patient following in vitro maturation (IVM) of immature oocytes collected from medulla tissue, of which two survived vitrification and warming. This approach represents an add-on method to potentially augment the fertility opportunity for cancer patients, especially in young women with cancer where transplantation of cortical tissue may pose a risk of relapse, but the IVM approach is currently too inefficient to be the only method used for fertility preservation.

In vitro maturation of human immature oocytes for fertility preservation and research material

“…In recent years, patients with breast cancer, blood cancer, brain cancer, gynecological cancer etc. have been provided with FP . In particular, breast cancer is the most common cancer in women and one‐third of cases affect women of reproductive age.…”

Oocyte collection and in vitro maturation after train transportation of human follicular fluid aspirated from resected non‐stimulated ovaries of patients with endometrial adenocarcinoma

“…A, Correlation between the number of collected oocytes and age in the 14 patients in this study. B, Correlation between the number of collected oocytes and age in 22 patients: 14 from this study and 6 from our previous research . Black circles indicate the patients in our previous report.…”

“…There have also been reports on the transportation of human follicular fluid (HFF) and ovaries . Prior to two decades ago, only a few institutions performed intra‐cytoplasmic sperm injection (ICSI), and therefore, HFF aspirated from stimulated ovaries was transported by car and airplane from satellite clinics to in vitro fertilization centers; this transportation occurred at distances of 90‐500 km at temperatures of 37°C with no 5% CO 2 chamber .…”

“…In the field of oncofertility, however, it is common at present to transport resected ovarian tissue (ROT) on ice or at 4°C . In past reports, the maturation rate of immature human oocytes collected from non‐stimulated ROT was about 30%‐40% . For clinical and research purposes, it would be beneficial if we could obtain immature human oocytes from transported HFF that was aspirated from resected ovaries at a satellite hospital, and then acquire mature oocytes by IVM.…”

In vitro maturation and cryopreservation of oocytes retrieved from intra-operative aspiration during second enucleation for ovarian tumor: A case report

“…It is known that oncofertility treatment requires about 20 matured oocytes (meiosis II stage) for one child (Yin et al, 2016), so the number of oocytes collected in this case was insufficient. Intra-operative retrieval of oocytes may be considered in addition to postoperative oocyte retrieval.…”