Seet V Y K, Al-Samerria S, Wong J, Stanger J, Yovich J L, Almahbobi G
School of Biomedical Sciences, Western Australian Biomedical Research Institute, Curtin Health Innovation Research Institute, Curtin University, Kent St, Bentley, Perth, WA 6102, Australia.
Reprod Fertil Dev. 2013;25(6):918-26. doi: 10.1071/RD12136.
Oocyte vitrification is a clinical practice that allows preservation of fertility potential in women. Vitrification involves quick cooling using high concentrations of cryoprotectants to minimise freezing injuries. However, high concentrations of cryoprotectants have detrimental effects on oocyte quality and eventually the offspring. In addition, current assessment of oocyte quality after vitrification is commonly based only on the morphological appearance of the oocyte, raising concerns regarding its efficiency. Using both morphological and functional assessments, the present study investigated whether combinations of cryoprotectants at lower individual concentrations result in better cryosurvival rates than single cryoprotectants at higher concentrations. Surplus oocytes from IVF patients were vitrified within 24h after retrieval using the Cryotop method with several cryoprotectants, either individually or in combination. The morphological and functional quality of the vitrified oocytes was investigated using light microscopy and computer-based quantification of mitochondrial integrity, respectively. Oocyte quality was significantly higher using a combination of cryoprotectants than vitrification with individual cryoprotectants. In addition, the quality of vitrified oocyte varied depending on the cryoprotectants and type of combination used. The results of the present study indicate that observations based purely on the morphological appearance of the oocyte to assess the cryosurvival rate are insufficient and sometimes misleading. The outcome will have a significant implication in the area of human oocyte cryopreservation as an important approach for fertility preservation.
卵母细胞玻璃化冷冻是一种可保留女性生育潜能的临床实践。玻璃化冷冻涉及使用高浓度冷冻保护剂进行快速降温，以尽量减少冷冻损伤。然而，高浓度的冷冻保护剂会对卵母细胞质量乃至后代产生不利影响。此外，目前对玻璃化冷冻后卵母细胞质量的评估通常仅基于卵母细胞的形态外观，这引发了对其评估效率的担忧。本研究采用形态学和功能评估方法，探究较低个体浓度的冷冻保护剂组合是否比高浓度单一冷冻保护剂具有更高的冷冻存活率。体外受精（IVF）患者的多余卵母细胞在采集后24小时内，使用Cryotop方法，分别单独或组合使用几种冷冻保护剂进行玻璃化冷冻。分别使用光学显微镜和基于计算机的线粒体完整性定量分析方法，对玻璃化冷冻卵母细胞的形态和功能质量进行研究。与使用单一冷冻保护剂进行玻璃化冷冻相比，使用冷冻保护剂组合时卵母细胞质量显著更高。此外，玻璃化冷冻卵母细胞的质量因冷冻保护剂及其组合类型而异。本研究结果表明，单纯基于卵母细胞形态外观来评估冷冻存活率是不够的，有时甚至会产生误导。这一结果对于人类卵母细胞冷冻保存这一重要的生育力保存方法领域具有重要意义。
