Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita University, Akita, Japan.
PLoS One. 2019 Jan 16;14(1):e0210992. doi: 10.1371/journal.pone.0210992. eCollection 2019.
Recent studies reported morphokinetic indices for optimal selection of embryos in assisted reproductive technology (ART). The morphokinetics in blastocyst stage include the collapse and re-expansion rates after thawing. However, evaluation methods using these morphokinetics have not been established, mainly because the underlying molecular mechanisms remain unclarified. In this study, we focused on the relationship between these morphokinetic observation of the blastocyst behaviour and the number of cells constituting the blastocyst. We evaluated 38 surplus human frozen-thawed blastocysts using time-lapse cinematography and recorded their expansion, contraction, and hatching. A total of 28 blastocysts expanded in culture (cross-sectional area ≥ 5,000 π μm2). In comparison to the ones that did not, the expanded group presented significantly more number of inner cell mass (ICM) and trophectoderm (TE) cells, which eventually develop into the fetus and placenta, respectively (ICM: Expanded 10.2 ± 6.3 vs. Non-Expanded 6.0 ± 12.3, p < 0.05; TE: Expanded 165.7 ± 74.8 vs. Non-Expanded 57.0 ± 29.4, p < 0.05). Moreover, a positive correlation was found between the expansion rate (up to 4 h) and the number of TE cells (r = 0.558, p = 0.0021). Additionally, blastocysts that hatched had a significantly higher number of TE cells than those that did not (hatching 225.2 ± 61.2 vs. no hatching 121.1 ± 48.6, p < 0.0001). The number of TE cells per unit of cross-sectional area correlated negatively with the contraction time (r = -0.601, p = 0.0007). No correlation between the number of ICM cells and these morphokinetics was detected. In conclusion, our study demonstrates that different morphokinetics of frozen-thawed blastocysts reflect the number of TE cells. The differentiation of blastocysts containing sufficient TE cells would be beneficial for implantation and prognosis of a subsequent pregnancy. Thus, evaluation of these morphokinetics can be an effective method to screen good embryos for ART.
最近的研究报告了辅助生殖技术（ART）中胚胎最佳选择的形态动力学指标。囊胚阶段的形态动力学包括解冻后的塌陷和再扩张率。然而，由于潜在的分子机制尚不清楚，因此尚未建立使用这些形态动力学的评估方法。在这项研究中，我们专注于囊胚行为的这些形态动力学观察与构成囊胚的细胞数量之间的关系。我们使用延时电影法评估了 38 个人类冷冻解冻囊胚的扩张、收缩和孵化情况，并记录了它们的扩张、收缩和孵化情况。共有 28 个囊胚在培养中扩张（横截面积≥5000πμm2）。与未扩张的囊胚相比，扩张组的内细胞团（ICM）和滋养外胚层（TE）细胞数量明显更多，这些细胞最终分别发育成胎儿和胎盘（ICM：扩张组 10.2±6.3 比非扩张组 6.0±12.3，p<0.05；TE：扩张组 165.7±74.8 比非扩张组 57.0±29.4，p<0.05）。此外，扩张率（长达 4 小时）与 TE 细胞数量之间存在正相关关系（r=0.558，p=0.0021）。此外，孵化的囊胚的 TE 细胞数量明显高于未孵化的囊胚（孵化 225.2±61.2 比未孵化 121.1±48.6，p<0.0001）。单位横截面积的 TE 细胞数量与收缩时间呈负相关（r=-0.601，p=0.0007）。未发现 ICM 细胞数量与这些形态动力学之间存在相关性。总之，我们的研究表明，冷冻解冻囊胚的不同形态动力学反映了 TE 细胞的数量。含有足够 TE 细胞的囊胚的分化将有利于后续妊娠的着床和预后。因此，评估这些形态动力学可以成为筛选 ART 中优质胚胎的有效方法。
