Study question Could the exclusion of multinucleated cells from an embryo be a mechanism to dispose of cells with aberrant genetic content? Summary answer Exclusion of multinucleated cells could be a self-correction mechanism that would allow some embryos to exclude aneuploid cells. What is known already Multinucleation represents a poor prognosis morphologic trait related to low blastocyst formation rates and implantation rates. Moreover, it has been correlated with an increased rate of aneuploidies and chromosomal abnormalities, thus increasing misscarriage rates. Traditional morphokinetics ensure that excluding blastomeres during the compaction, the embryo could reduce its potential to achieve an euploid blastocyst. According to our previous studies multinucleated embryos excluding multinucleated cells during the blastocyst formation increase their reproductive potential. These studies assessed the clinical outcomes based on the morphokinetics of multinucleated blastomeres, without taking into account the chromosomal status of these embryos. Study design, size, duration Retrospective cohort study involving data from 157 PGT-cycles, performed between 2017 and 2019, with at least one multinucleated embryo. This trial included 678 embryos cultured until blastocyst stage using one-step culture media in time-lapse incubators (Embryoscope, Vitrolife) up to D + 5/6 when PGT-A was performed by trophectoderm biopsy using the NGS analysis technique in good quality embryos (≥3BB) according to the Gardner Score. Chi-square test for a contingency table was performed to compare all groups. Participants/materials, setting, methods Two main groups were considered: Control Group (CG; n = 474), embryos without multinucleation and Multinucleation Group (MNC; n = 204), embryos with at least one blastomere multinucleated on D + 2/3. Multinucleation Group was subdivided in three groups according to the multinucleation cell location using time-lapse technology to track them. MNC-1 (N = 87), no cells excluded; MNC-2 (N = 31), mononucleated cells excluded; MNC-3 (N = 41), multinucleated cells excluded. We had to exclude from the study 45 embryos that could not be follow up. Main results and the role of chance We observed multinucleation in the 20.33% of the embryos. MNC-3 (43.9%) achieved the higher euploidy rate, equivalent to the CG (43.9%); p = 0.998. MNC-1 (26.4%) and MNC-2 (22.6%) had lower euploidy rates than Groups MNC-3 and GC; p < 0.05. Regarding to the aneuploidy rates, MNC-2 (77.4%) showed a higher rate than of the other groups (MNC-1=52.9%; MNC-3=41.5%; CG = 42.0%), being significant compared to the CG and MNC-3; p < 0.05. The mosaicism rate of the MNC-1 (20.7%) is significantly higher than that of the CG (14.0%); p < 0.05. Limitations, reasons for caution Limitations include the retrospective analysis of data, the wide difference on sample size between MNC and CG groups and the amount of embryos excluded due to the impossibility to be monitored. Wider implications of the findings These results prove that embryos excluding multinucleated cells reach equivalent euploidy values than embryos without multinucleation. This outcome, together with previous studies, suggest a self-correction capacity that would allow some embryos to detect and expel cells with aneuploid genetic content, thus improving the global chromosomal status of the embryo. Trial registration number not applicable

中文翻译：

---

P-151 通过排除多核细胞进行胚胎自我校正提高整倍体率

研究问题 从胚胎中排除多核细胞是否可以作为处理具有异常遗传内容的细胞的一种机制？总结答案 排除多核细胞可能是一种自我校正机制，允许某些胚胎排除非整倍体细胞。已知的多核代表与低囊胚形成率和植入率相关的不良预后形态特征。此外，它与非整倍体和染色体异常率的增加有关，从而增加了流产率。传统的形态动力学确保在压实过程中排除卵裂球，胚胎可以降低其获得整倍体囊胚的潜力。根据我们之前的研究，在囊胚形成过程中不包括多核细胞的多核胚胎增加了它们的繁殖潜力。这些研究基于多核卵裂球的形态动力学评估临床结果，而不考虑这些胚胎的染色体状态。研究设计、规模、持续时间回顾性队列研究涉及 157 个 PGT 周期的数据，在 2017 年至 2019 年间进行，至少有一个多核胚胎。该试验包括 678 个胚胎，在延时培养箱（Embryoscope，Vitrolife）中使用一步培养基培养至囊胚阶段，直至 D + 5/6，当 PGT-A 使用 NGS 分析技术在优质胚胎中进行滋养外胚层活检时(≥3BB) 根据加德纳评分。对列联表进行卡方检验以比较所有组。参与者/材料、设置、方法考虑了两个主要组：对照组（CG；n = 474），无多核胚胎和多核组（MNC；n = 204），在 D + 2/3 上具有至少一个卵裂球多核的胚胎. 多核组根据多核细胞位置细分为三组，使用延时技术对其进行跟踪。MNC-1 (N = 87)，不排除任何细胞；MNC-2 (N = 31)，排除单核细胞；MNC-3 (N = 41)，排除多核细胞。我们不得不从研究中排除 45 个无法跟进的胚胎。主要结果和机会的作用 我们在 20.33% 的胚胎中观察到多核。MNC-3（43.9%）达到了更高的整倍体率，与CG（43.9%）相当；p = 0.998。MNC-1 (26. 4%) 和 MNC-2 (22.6%) 的整倍体率低于 MNC-3 和 GC 组；p＜0.05。关于非整倍体率，MNC-2（77.4%）的比率高于其他组（MNC-1=52.9%；MNC-3=41.5%；CG=42.0%），与 CG 和跨国公司-3；p＜0.05。MNC-1的嵌合率（20.7%）明显高于CG（14.0%）；p＜0.05。局限性、谨慎的原因 局限性包括数据的回顾性分析、MNC 和 CG 组之间样本量的巨大差异以及由于无法监测而排除的胚胎数量。研究结果的更广泛意义 这些结果证明，不包括多核细胞的胚胎达到与没有多核细胞的胚胎相当的整倍性值。这一结果与以前的研究一起，提出了一种自我校正能力，使一些胚胎能够检测和排出具有非整倍体遗传内容的细胞，从而改善胚胎的整体染色体状态。试用注册号不适用