In the absence of international guidelines indicating the usage of vitrification rather than slow-freezing, the study aim was to analyze a large cohort of slow-frozen/thawed embryos to produce a rationale supporting the standardization of IVF cryopreservation policy. This retrospective analysis included 4779 cleavage stage embryos cryopreserved by slow-freezing/thawing from September 2009 to April 2017 at a single Center. Biological and clinical outcomes of three different commercial kits adopted sequentially, i.e. Vitrolife Cleave Kit® from Vitrolife (kit 1) vs. K-SICS-5000 Kit® and K-SITS-5000 Kit® from Cook Medical (kit 2) and Freeze/Thaw 1™ Kit® from Vitrolife (kit 3) were collected and compared in the light of cryoprotectants composition. Kit 3 compared to kit 1 and kit 2 showed significantly (P < 0.001) higher embryo survival (79.9% vs. 75.6 and 68.1%, respectively) and frozen embryo replacement (91.5% vs. 86.5 and 83.3%, respectively) rates, and significantly (P < 0.001) lower blastomere degeneration rate (41.5% vs. 43.6 and 52.4%, respectively). No significant difference for clinical outcomes was observed among kits. Only a slight positive trend was observed for kit 3 vs. kit 1 and kit 2 on delivery rate per thawing cycle (7.12% vs. 4.19 and 4.51%, respectively; P < 0.058) and live birth rate (3.07% vs. 2.59 and 1.93%, respectively, P < 0.069). Thawing solutions of kit 3 were similar to those of any warming protocol. A defined concentration of extracellular cryoprotectants in thawing/warming solutions had a beneficial effect on the embryo cryosurvival rate. Results could provide the rationale for the adoption of a single standardized warming protocol.

中文翻译：

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卵裂期胚胎未冷冻溶液中细胞外冷冻保护剂功效的单中心分析

由于缺乏国际指南表明使用玻璃化而不是缓慢冷冻，该研究的目的是分析大量缓慢冷冻/解冻的胚胎，以提供支持 IVF 冷冻保存政策标准化的理由。这项回顾性分析包括 2009 年 9 月至 2017 年 4 月在单个中心通过缓慢冷冻/解冻冷冻保存的 4779 个卵裂期胚胎。依次采用的三种不同商业试剂盒的生物学和临床结果，即 Vitrolife Cleave Kit®（试剂盒 1）与来自 Cook Medical（试剂盒 2）的 K-SICS-5000 Kit® 和 K-SITS-5000 Kit® 以及 Freeze/收集 Vitrolife 的 Thaw 1™ Kit®（套件 3）并根据冷冻保护剂成分进行比较。与试剂盒 1 和试剂盒 2 相比，试剂盒 3 的胚胎存活率（分别为 79.9% vs. 75.6 和 68.1%）和冷冻胚胎替换率（分别为 91.5% vs. 86.5 和 83.3%）显着更高（P < 0.001），并且显着（P < 0.001）降低卵裂球退化率（分别为 41.5% vs. 43.6 和 52.4%）。试剂盒之间的临床结果没有观察到显着差异。与套件 1 和套件 2 相比，套件 3 在每个解冻周期的分娩率（分别为 7.12% vs. 4.19 和 4.51%；P < 0.058）和活产率（3.07% vs. 2.59 和 4.51%）方面仅观察到轻微的积极趋势。分别为 1.93%，P < 0.069）。套件 3 的解冻溶液与任何加温方案的解冻溶液相似。解冻/加温溶液中规定浓度的细胞外冷冻保护剂对胚胎冷冻存活率具有有益影响。结果可以为采用单一标准化变暖协议提供依据。