Embryonic endothelial evolution towards first hematopoietic stem cells revealed by single-cell transcriptomic and functional analyses
Embryonic endothelial evolution towards first hematopoietic stem cells revealed by single-cell transcriptomic and functional analyses
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单细胞转录组和功能分析揭示胚胎内皮向第一个造血干细胞的进化
DOI：
10.1038/s41422-020-0300-2
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发表时间：
2020-03-20
期刊：
影响因子：
44.1
通讯作者：
Lan, Yu
中科院分区：
文献类型：
--
作者：
Hou, Siyuan;Li, Zongcheng;Lan, Yu
成人造血干细胞（hsc）被认为是由妊娠中期胚胎的造血内皮细胞（hec）产生的。由于罕见和短暂的性质，造血干细胞胜任型hec从未被严格识别和准确捕获，更不用说它们真正的血管前体了。在这里，我们首先使用高精度单细胞转录组学来无偏地检测相关EC群体在胚胎日(E) 9.5至E11.0的连续发育阶段，间隔0.5天。因此，我们通过转录组学鉴定了两个分子上不同的动脉EC群体和假定的hsc引发的HECs，其数量在E10.0时达到峰值，此后急剧下降，位于主动脉-性腺-中肾（AGM）区域的背主动脉。结合计算预测和体内功能验证，我们通过新构建的Neurl3-EGFP报告小鼠模型精确捕获hsc胜任的HECs，并通过结合表面标记(Procr(+)Kit（+)CD44(+), PK44）进一步实现富集。令人惊讶的是，内皮-造血双重电位在单个hec培养中很少但可靠地观察到。值得注意的是，来自E8.0的原始血管内皮细胞经历了两步命运选择，即最初的动脉命运选择和血流命运转换。这一发现解决了先前观察到的几个矛盾。综上所述，全面了解内皮细胞的进化和体内HSC引发HEC规范的分子程序将有助于未来指导体外HSC生产的研究。
Hematopoietic stem cells (HSCs) in adults are believed to be born from hemogenic endothelial cells (HECs) in mid-gestational embryos. Due to the rare and transient nature, the HSC-competent HECs have never been stringently identified and accurately captured, let alone their genuine vascular precursors. Here, we first used high-precision single-cell transcriptomics to unbiasedly examine the relevant EC populations at continuous developmental stages with intervals of 0.5 days from embryonic day (E) 9.5 to E11.0. As a consequence, we transcriptomically identified two molecularly different arterial EC populations and putative HSC-primed HECs, whose number peaked at E10.0 and sharply decreased thereafter, in the dorsal aorta of the aorta-gonad-mesonephros (AGM) region. Combining computational prediction and in vivo functional validation, we precisely captured HSC-competent HECs by the newly constructed Neurl3-EGFP reporter mouse model, and realized the enrichment further by a combination of surface markers (Procr(+)Kit(+)CD44(+), PK44). Surprisingly, the endothelial-hematopoietic dual potential was rarely but reliably witnessed in the cultures of single HECs. Noteworthy, primitive vascular ECs from E8.0 experienced two-step fate choices to become HSC-primed HECs, namely an initial arterial fate choice followed by a hemogenic fate conversion. This finding resolves several previously observed contradictions. Taken together, comprehensive understanding of endothelial evolutions and molecular programs underlying HSC-primed HEC specification in vivo will facilitate future investigations directing HSC production in vitro.