胚胎造血干细胞发育全程线粒体动态特征及功能研究

Dynamic changes and function of mitochondria in development of em⁃bryonic hematopoietic stem cells

目的:描绘线粒体在小鼠胚胎造血干细胞发育全程的动态特征并探究线粒体在此过程中的功能。方法:分析小鼠胚胎造血干细胞发育动态连续群体的单细胞转录组数据,描绘线粒体及能量代谢相关基因的动态变化特征;利用荧光探针染色结合流式细胞术对上述各个阶段细胞内线粒体的数量及膜电位进行检测,探究造血干细胞发育过程中线粒体数量和活性的动态变化特征;在共孵育诱导体系中加入抑制线粒体合成及能量代谢的小分子抑制剂,并结合造血集落形成实验评价抑制线粒体功能后对于体外造血诱导的影响。结果:(1)单细胞转录组数据分析显示,相较于糖酵解相关基因,线粒体合成及氧化磷酸化相关基因在生血内皮细胞和I型造血干细胞前体阶段呈现显著高表达,并且这部分基因能够显著区分连续动态发育群体。(2)荧光染色及流式细胞术结果显示,线粒体数量和膜电位在从生血内皮细胞到造血干细胞前体的连续发育过程中呈现不断上升的趋势,在II型造血干细胞前体阶段达到最高,而在胎肝造血干细胞中有所下降。(3)体外共孵育及造血集落培养结果显示,与对照组相比,抑制线粒体呼吸链I和V能够显著减少胚胎主动脉-性腺-中肾区CD31+细胞诱导产生的造血集落数量(P<0.05)。结论:(1)线粒体合成及氧化磷酸化相关基因在生血内皮细胞和I型造血干细胞前体中显著高表达,并能区分连续发育群体;(2)线粒体数量和膜电位在造血干细胞连续发育过程中不断上升,在II型造血干细胞前体中达到最高;(3)体外抑制线粒体呼吸链I和V能够显著降低造血产物生成。

AIM:To describe the dynamic characteristics of mitochondria in the development of mouse embryonic hematopoietic stem cells,and to explore the function of mitochondria in this process.METHODS:Single-cell transcrip-tomic data of continuous developmental hematopoietic stem cell-related populations were analyzed to describe the dynamic changes of genes related to mitochondrial synthesis and energy metabolism.To explore the dynamic changes in the number and activity of mitochondria during the development of hematopoietic stem cells,we detected the mitochondrial number and mitochondrial membrane potential of the cells in each stage of hematopoietic stem cell development by fluorescent probe staining combined with flow cytometry.We added small molecule inhibitors of mitochondrial synthesis and energy metabolism and used hematopoietic cell colony formation assay to detect the effect of mitochondrial function inhibition on the induction of hematopoietic products in vitro.RESULTS:(1)Single-cell transcriptome analysis showed that genes in-volved in mitochondrial synthesis and oxidative phosphorylation were significantly up-regulated in endothelial cell and type I pre-hematopoietic stem cell compared with those involved in glycolysis,and these genes could significantly distinguish continuous dynamic populations.(2)The results of fluorescence staining and flow cytometry analysis showed that mito-chondrial number and mitochondrial membrane potential had an increasing trend during the continuous development of he-matopoietic stem cell,reaching the highest level in the precursor stage of type 2 pre-hematopoietic stem cell,and decreasing in the mature hematopoietic stem cell of fetal liver.(3)Compared with control group,inhibition of mitochondrial respirato-ry chain I and V significantly reduced the number of hematopoietic colonies(P<0.05).CONCLUSION:(1)Genes re-lated to mitochondrial synthesis and oxidative phosphorylation are highly expressed in hemogenic endothelial cells and type I pre-hematopoietic stem cells,and can be used to distinguish continuous developing populations.(2)The mitochondrial number and mitochondrial membrane potential increased continuously during hematopoietic stem cell development and reached the highest level in type 2 pre-hematopoietic stem cells.(3)Inhibition of mitochondrial respiratory chain I and V significantly reduced the production of hematopoietic products in vitro.