Dissect the mechanisms underlying interspecies pluripotent stem cell competition

项目总结/摘要 移植器官短缺是最大的未满足的医疗需求之一。研究人员目前正在 研究各种方法来增加可用器官的数量。近年来，生产的前景 通过种间胚泡互补将人类器官移植到动物体内已经引起了人们的重视， 这是一个解决世界范围内捐赠器官短缺问题的创新方法。种间囊胚 互补通过将来自一个物种的供体多能干细胞（PSC）注射到 一个不同物种的器官发生障碍胚泡生长中的宿主胚胎可以提供一个空的 供供体细胞占据的发育器官小生境。然而，尽管有潜力，最近的研究表明， 尽管供体PSC最初可以植入到来自远亲宿主的囊胚内细胞团（ICM）中， 物种，其嵌合贡献早期植入后阶段是低的。这些结果表明， 在进化上遥远的物种之间的胚胎异种障碍。与嵌合体的形成不同， 在同一物种中，多种因素在物种之间可以显著不同，这排除了稳健的嵌合体。 细胞竞争，一种保守的适应性感知过程，在此过程中，适应性较强的细胞会淘汰邻近的适应性较差的细胞， 活细胞，已被提出作为一种监督机制，以确保正常的发展和组织 体内平衡，也被认为是种间嵌合的障碍。在嵌合体时期 当异种供体PSC形成时，异种供体PSC可以作为不合适或异常细胞处理并靶向消除。最 最近，我们开发了一种跨物种PSC共培养策略，并发现了一种以前未知的模式， 物种之间的竞争。PSCs间的种间竞争发生在致敏组而非幼稚组 多能性细胞，以及在进化上遥远的物种之间。通过比较转录组分析，我们发现 与NF-κB和p53信号通路相关的基因在不健康的“失败者”中表达上调。 人体细胞TP 53的遗传失活，其是核心组分（P65，也称为RELA）和上游组分（P65，也称为RELA）。 人PSC中NF-κB复合物的调节剂（MYD 88）可以通过共- 培养的小鼠PSC，从而改善早期小鼠胚胎中人类细胞的存活和嵌合状态。 基于广泛的初步结果，在本提案中，我们将进一步剖析其机制 种间引发的PSC竞争在失败者和赢家细胞。通过抑制种间PSC 竞争，我们的目标是改善嵌合体，并提供跨物种囊胚的概念验证 来自恒河猴（我们的近亲）的供体PSC在远亲小鼠宿主中的互补。

PROJECT SUMMARY/ABSTRACT Shortage of organs for transplantation is one of the largest unmet medical needs. Researchers are currently working on a variety of ways to increase the number of organs available. Recently, the prospect of producing human organs in animals via interspecies blastocyst complementation has raised important attention and may constitute an innovative approach to overcome the worldwide shortage of donor organs. Interspecies blastocyst complementation works by injecting donor pluripotent stem cells (PSCs) from one species into the organogenesis-disabled blastocyst of a different species. The growing host embryo can provide an emptied developmental organ niche for donor cells to occupy. Despite the potential, however, recent work revealed that although donor PSCs can initially engraft to inner cell mass (ICM) of blastocysts from distantly related host species, their chimeric contribution to early post-implantation stages is low. These results suggest the existence of embryonic xenogeneic barriers between evolutionarily distant species. Unlike chimera formation within the same species, a multitude of factors can differ significantly between species, which preclude robust chimerism. Cell competition, a conserved fitness-sensing process during which fitter cells eliminate neighboring less-fit but viable cells, has been proposed as a surveillance mechanism to ensure normal development and tissue homeostasis, and has also been suggested to act as a barrier to interspecies chimerism. During chimera formation, xenogeneic donor PSCs may be treated as unfit or aberrant cells and targeted for elimination. Most recently, we developed an interspecies PSC co-culture strategy and discovered a previously unknown mode of cell competition between species. Interspecies competition between PSCs occurred in primed but not naive pluripotent cells, and between evolutionarily distant species. By comparative transcriptome analysis, we found that genes related to the NF-κB and p53 signaling pathways, among others, were upregulated in less-fit ‘loser’ human cells. Genetic inactivation of TP53, a core component (P65, also known as RELA) and an upstream regulator (MYD88) of the NF-κB complex in human PSCs could overcome their competitive elimination by co- cultured mouse PSCs, thereby improving the survival and chimerism of human cells in early mouse embryos. Based on extensive preliminary results, in this proposal, we will further dissect the mechanisms underlying interspecies primed PSC competition in both loser and winner cells. And, by suppressing interspecies PSC competition, we aim to improve chimerism and provide the proof-of-concept of interspecies blastocyst complementation from donor PSCs of rhesus monkey, our close kin, in distantly related mouse host.