Cryopreservation of human embryos and oocytes for fertility preservation in cancer and non cancer patients: a mini review

Abstract

The term ‘cryopreservation’ illustrates the process of freezing cells and storing at very low temperature in liquid nitrogen (–196 °C). Cooling is not a physiological condition for human cells especially due to the high concentration of water in the living matter, whose conversion to ice crystals may be associated with cell death. Human oocytes are particularly sensitive to the freezing process, primarily because of their large size and the presence of the meiotic spindle, which at low temperature can degenerate. In the last decade, the cryopreservation technology has become highly important as an option for fertility preservation (FP) in women with cancer. Anticancer therapy might promote premature ovarian failure and negatively affects the reproductive outcome. Over the years, scientists have proposed different cryopreservation strategies in the effort to maintain the physiological functions of oocytes and embryo. However, despite the first success obtained in the 1980s with frozen oocytes, it was not until recently that a new approach has been proposed: the ‘Vitrification’ which allowed a breakthrough in this procedure. FP is a major determinant for cancer survivor women in the reproductive age. This article describes the FP options currently available, focusing mainly on oocyte and embryo cryopreservation.

摘要

术语“低温保存”说明了将细胞冷冻并在非常低的温度下(-196°C)储存在液氮中的过程。对人类细胞来说, 冷冻不是一种生理状态, 特别是因为生物体内的水浓度很高, 生物转化为冰晶可能与细胞死亡有关。人类卵母细胞对冷冻过程特别敏感, 主要是因为它们的大小和减数分裂纺锤体的存在, 这种纺锤体在低温下可能退化。在过去的十年里, 冷冻保存技术已经成为癌症女性生育能力保存(FP)的一种非常重要的选择。抗癌治疗可能会促进卵巢早衰, 并对生殖结局产生负面影响。多年来, 为了维持卵母细胞和胚胎的生理功能, 科学家们提出了不同的冷冻保存策略。然而, 尽管冷冻卵母细胞在20世纪80年代获得了第一次成功, 但直到最近才提出了一种新的方法：“玻璃化冷冻”, 这使得这一过程取得了突破。FP是癌症幸存者育龄妇女的主要决定因素。这篇文章介绍了目前可用的FP方案, 主要集中在卵母细胞和胚胎的冷冻保存上。

The Chinese abstracts are translated by Prof. Dr. Xiangyan Ruan and her team: Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.

Keywords:

• In vitro fertilization
• cancer patients
• oocyte and embryo cryopreservation
• fertility preservation
• vitrification

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and with the 1964 Helsinki declaration and its later amendments. For this type of study, formal consent is not required.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

This work was supported by Edinburgh Reproductive Endocrine Center, RIE, Edinburgh, UK.