Investigating the causes and remedies for oocyte injury in fertility preservation for cancer patients.

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K18205
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 56040:Obstetrics and gynecology-related
• Research Institution: St. Marianna University School of Medicine
• Principal Investigator: Suzuki Yuki 聖マリアンナ医科大学, 医学研究科, 助教 (00836992)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 妊孕性温存療法 / 卵子凍結 / ミトコンドリア

Outline of Final Research Achievements

MII oocytes acquired from ICR mice were divided into fresh and frozen-thawed oocyte groups for evaluation. The evaluation of internal structural changes by scanning electron microscopy showed a decrease in mitochondrial density and mitochondrial swelling in the freeze-thawed oocyte group compared to the fresh oocyte group, and after fluorescent staining with Mito-Tracker Green (MTG) and TMRE, the mitochondria were analyzed by confocal laser scanning microscopy. The analysis and evaluation of the cluster distribution and its area showed a significant difference in the number of clusters between the two groups. Quantitative PCR and digital PCR evaluation of mitochondrial DNA copy number showed no significant difference between the two groups. Frozen oocyte damage was found not to be a cell death-inducing disorder.

Free Research Field

卵子凍結

Academic Significance and Societal Importance of the Research Achievements

若年がん患者における妊孕性温存療法の一つとして卵子凍結が注目を浴びている中、本研究は卵子凍結における低出生率について着目した。今回の検討では卵子の凍結融解におけるダメージを検討した。顕微鏡下観察による形態的評価では新鮮卵子同様全く異常のない凍結融解卵子であっても、卵子の凍結融解ストレスによるミトコンドリア障害が生じていることを明らかにした。卵子凍結では卵子の細胞死を誘導するほどのダメージではないが、ミトコンドリアをはじめとしたオルガネラの障害が生じることが示唆された。本研究により凍結融解障害が凍結卵子における妊娠率低下の原因となる可能性が示唆された。