大鼠胚胎干细胞发育潜能的评价及其调控机制的研究

Pluripotency research is one of the most important areas in stem cells and regenerative medicine research, which shows great values in stem cells regulation research and future clinical application. Early studies have demonstrated that embryonic stem cells (ESCs) from different species showed different developmental potentials. Mouse ESCs can support full-term offspring development by tetraploid complementation, rat ESCs can contribute to germline of chimeras by blastocyst-injection, and primate ESCs shown a poor developmental potential. Better understanding the pluripotency regulation mechanism of ESCs in different species can promote the development of ESCs with optimal differentiation potentials in many species including human. In this project, we use rat ESCs as model to assess the developmental potential of rat ESCs from ICM cells derive in vivo, and different periods during cell passaging culture in vitro. By studying the gene expression patterns of ESCs, we tried to find out the key molecular markers of rat ESCs in different developmental potentials. In predictability, it’s the first time to clarify the regulation mechanisms of pluripotency maintenance in different species, which will promote the derivation of ESCs with higher pluripotency in other species including primates.

胚胎干细胞多能性研究对干细胞调控的基础理论及其转化应用均具有重要价值，是干细胞与再生医学领域最重要的科学问题之一。已有研究表明不同物种之间干细胞发育潜能存在差异：小鼠干细胞已能满足多能性评估的最高标准-四倍体补偿，大鼠干细胞能够获得种系嵌合能力，灵长类干细胞仅有低水平的胚胎嵌合能力。了解不同物种之间发育潜能差异的调控机制，将有助于建立包括人在内的其他物种具有发育全能性的干细胞，为干细胞的转化、应用奠定基础。本项目拟以大鼠为模型，追溯大鼠胚胎干细胞建系过程，对不同细胞来源、不同代次的大鼠胚胎干细胞的四倍体补偿能力进行系统评估，分析不同发育等级的大鼠胚胎干细胞的基因表达差异，探索决定大鼠胚胎干细胞最高发育等级的分子标记物。本项目将首次阐释大鼠胚胎干细胞发育全能性获得与维持的调控机制，尝试不同物种间比较干细胞发育潜能调控机制的差异，为人和其它物种具有发育全能性的干细胞的获得提供重要理论基础。

Pluripotency of embryonic stem cells (ESCs) can be functionally assessed according to the developmental potency. Tetraploid complementation, through which an entire organism is produced from the pluripotent donor cells, is taken as the most stringent test for pluripotency. It remains unclear whether ESCs of other species besides mice can pass this test. Here we show that the rat ESCs derived under 2i conditions at very early passages are able to produce fertile offspring by tetraploid complementation. However, they lose this capacity rapidly during culture due to a near completely lost genomic imprinting. Our findings support that the naïve ground state pluripotency can be captured in rat ESCs, but also point to the species-specific differences in its regulation and maintenance, which have implications for the derivation and application of naïve pluripotent stem cells in other species including human.