植入失败是限制人类体外受精胚胎种植率的关键问题。已知胎盘特异性抗原8（PLAC8）是参与调控哺乳动物胚胎发育和植入的重要分子，但其在人类胚胎植入中的作用尚不清楚。申请人前期工作发现PLAC8在人类早期胚胎中表达，且在人类囊胚体外植入过程中的表达及定位变化与胚胎植入状态相关。本项目拟在前期工作基础上，利用所建立的人胚胎-子宫内膜基质细胞共培养模型，通过在临床废弃人早期胚胎上干扰和过表达PLAC8，明确PLAC8对人类早期胚胎发育及囊胚体外植入过程的影响；进一步采用单细胞转录组测序技术检测拟进行植入前遗传学筛查的人类囊胚滋养层细胞，分析PLAC8表达与胚胎体内移植后妊娠率的相关性；同时比较胚胎移植后妊娠成功与否的PLAC8相关转录组差异，寻找PLAC8上下游分子，初步探讨PLAC8参与调控人类胚胎种植的可能机制。项目将为阐明人类早期胚胎着床种植机理、寻找有效标志胚胎着床潜能的关键分子提供依据。

Implantation failure is the primary cause for in vitro fertilization (IVF) failure. Placenta-specific 8 (PLAC8) was shown to be a key molecule in early mammalian embryonic development and in the process of embryonic implantation, however, little is known about PLAC8 expression in human embryos and embryonic implantation. The applicant preliminary work suggests the presence of PLAC8 protein in the cytoplasm of all human oocytes and embryos preceding implantation, and after the blastocysts implanting and invading endometrial stromal cells, PLAC8 protein was located in the nucleolus, relating to the state of embryonic implantation. Using embryo-endometrial stromal cell co-culture models, this project is planed to clear the effect of PLAC8 on human early embryo development and blastocyst implantation process in vitro, and to explore its possible molecular mechanisms by interference and overexpression PLAC8 molecules of human abnormal fertilized embryo. Furthermore, we plan to use human blastocyst trophoblastic single-cell transcriptome sequencing and difference transcriptome analysis to observe the correlation of PLAC8 expression and pregnancy rate, to preliminary find the upstream and downstream molecules of PLAC8, and to explore PLAC8 role in the human early embryo development and implantation process. The knowledge of our study will provide important experimental basis on the development and implantation mechanism of human embryo, and will be benefit for looking for a new biological marker indicating potential of embryonic implantation.