Transcriptome of cord blood derived subsets of human haematopoietic stem cells, LMPP and MLP myelo-lymphoid restricted progenitors [49f+ Subset2, Subset2, LMPPs, MLPs]

Integration of index sorting and single cell functional assays allowed identification of novel haematopoietic stem cell (HSC) and multiprogenitor subsets (MPP) that differ in their lineage differentiation potential in vitro and in vivo, cell cycle properties and long-term repopulation capacity in the NSG xenograft model. Here we report single cell transcriptomes of CD49f+ HSCs as well as those of CD49f+ Subset1 (CD19- CD38- CD45RA- CD90+ CD49f+ CD34lo CLEC9Ahi, Myelo-erythroid-skewed in vitro but Lymphoid-competent) and CD49f+ Subset2 cells (CD19- CD38- CD45RA- CD90+ CD49f+ CD34hi CLEC9Alo, Myelo-Lymphoid competent but Erythroid-deficient). We also report bulk transcriptomes of pools of 20 cells from HSC/MPP Subset1 (CD19- CD38- CD45RA- CD34lo CLEC9Ahi) and HSC/MPP Subset2 (CD19- CD38- CD45RA- CD34hi CLEC9Alo). Altogether these data show a diffuse transcriptional landscape of the CD49f+ HSC compartment, which is polarised along an axis that separates Myelo-Erythroid and Myelo-Lymphoid lineage-priming. Consistently with their differentiation capacity in vitro, CD49f+ Subset1 cells cluster at the Myelo-Erythroid end of the landscape, while CD49f+ Subset2 cells cluster at the Myelo-Lymphoid end. In addtion, these lineage-priming signatures were found to be more marked in HSC/MPP Subset1 and HSC/MPP Subset2, than in the equivalent CD49f+ subsets. In conclusion, 49f+ Subset1 and 49f+ Subset2 populations have activated distinct transcriptional lineage-priming programmes corresponding to the phenotypic lineage-skewing observed in vitro, that then become reinforced within the broader HSC/MPP pool. Altogether our data shows that lineage-priming and lineage-restriction programmes are initially established within the CD49f+ HSC subset in humans.

通过整合索引分选与单细胞功能测定技术，本研究成功鉴定出全新的造血干细胞（hematopoietic stem cell, HSC）与多祖细胞亚群（multiprogenitor subsets, MPP）；这些亚群在体外与体内的谱系分化潜能、细胞周期特性，以及NSG异种移植模型中的长期重构建能力均存在差异。
本研究报道了CD49f阳性造血干细胞（HSC）的单细胞转录组数据，同时涵盖CD49f阳性亚群1（CD19⁻ CD38⁻ CD45RA⁻ CD90⁺ CD49f⁺ CD34^lo CLEC9A^hi，体外呈髓系-红系偏倚但具备淋巴系分化能力）与CD49f阳性亚群2细胞的单细胞转录组数据（CD19⁻ CD38⁻ CD45RA⁻ CD90⁺ CD49f⁺ CD34^hi CLEC9A^lo，具备髓系-淋巴系分化能力但存在红系缺陷）。
本研究同时报道了来自造血干细胞/多祖细胞亚群1（CD19⁻ CD38⁻ CD45RA⁻ CD34^lo CLEC9A^hi）与亚群2（CD19⁻ CD38⁻ CD45RA⁻ CD34^hi CLEC9A^lo）的20个细胞混合样本的批量转录组数据。
综合上述数据可见，CD49f阳性造血干细胞群存在弥散的转录组图谱，并沿区分髓系-红系与髓系-淋巴系谱系预致敏的轴线呈现极化分布特征。
与体外分化能力的观测结果一致，CD49f阳性亚群1细胞聚集于该转录组图谱的髓系-红系端，而CD49f阳性亚群2细胞则聚集于髓系-淋巴系端。
此外，相较于对应的CD49f阳性亚群，上述谱系预致敏特征在造血干细胞/多祖细胞亚群1与亚群2中的表达更为显著。
综上，CD49f阳性亚群1与亚群2已激活独特的转录谱系预致敏程序，该程序与体外观测到的表型性谱系偏倚相对应，并在更广泛的造血干细胞/多祖细胞库中得到强化。
综合本研究全部数据可见，人类CD49f阳性造血干细胞亚群中，谱系预致敏与谱系限制程序最初即已建立。