Myelo-lymphoid lineage restriction occurs in the human haematopoietic stem cell compartment before lymphoid-primed multipotent progenitors

Serena Belluschi,Kendig Yen Chi Sham,Antonella Santoro,Berthold Göttgens,Xiaonan Wang,Elisa Laurenti,Nicole Mende,Emily F Calderbank,Wajid Jawaid,Blanca Pijuan-Sala,Winnie W Y Lau,Evangelia Diamanti,Valerio Ciaurro

doi:10.1038/s41467-018-06442-4

Abstract

Capturing where and how multipotency is lost is crucial to understand how blood formation is controlled. Blood lineage specification is currently thought to occur downstream of multipotent haematopoietic stem cells (HSC). Here we show that, in human, the first lineage restriction events occur within the CD19−CD34+CD38−CD45RA−CD49f+CD90+ (49f+) HSC compartment to generate myelo-lymphoid committed cells with no erythroid differentiation capacity. At single-cell resolution, we observe a continuous but polarised organisation of the 49f+ compartment, where transcriptional programmes and lineage potential progressively change along a gradient of opposing cell surface expression of CLEC9A and CD34. CLEC9AhiCD34lo cells contain long-term repopulating multipotent HSCs with slow quiescence exit kinetics, whereas CLEC9AloCD34hi cells are restricted to myelo-lymphoid differentiation and display infrequent but durable repopulation capacity. We thus propose that human HSCs gradually transition to a discrete lymphoid-primed state, distinct from lymphoid-primed multipotent progenitors, representing the earliest entry point into lymphoid commitment.

Highlights

Capturing where and how multipotency is lost is crucial to understand how blood formation is controlled
We show that within a continuous but highly structured molecular landscape, progression to a CLEC9AloCD34hi phenotype corresponds to the earliest transition of human haematopoietic stem cells (HSC) to a discrete erythroid-null lymphoid-primed cell type characterised by fast quiescent exit kinetics and infrequent but durable repopulation capacity
We included CD117, which levels have been previously shown to mark human HSCs with different repopulation capacities[34], and CLEC9A, a receptor for which the mRNA was expressed at significantly higher levels in 49f+ HSCs (CD19−CD34+CD38−CD45RA−CD90+CD49f+, on average 13.7% of the HSC/multipotent progenitors (MPP) pool) than in 49f− HSCs (CD19−CD34+CD38−CD45RA−CD90−CD49f−, on average 13.4% of the HSC/MPP pool) (Supplementary Fig. 1a)[31,32]

Summary

Introduction

Capturing where and how multipotency is lost is crucial to understand how blood formation is controlled. It is generally understood that whereas cells in the HSC and multipotent progenitors (MPP) compartment are multipotent, the first reported major event of lineage restriction occurs downstream of HSCs/MPPs to separate myelo-lymphoid (My/Ly) and myelo-erythroid (My/Ery) fates. We measure the differentiation potential towards the My, Ery, Meg and Ly lineages of more than 5500 single human HSC/MPP cells and single 49f+ HSCs in vitro Coupling this approach with index-sorting technology and singlecell RNA-seq, we uncover that, in contrast to the accepted model, lineage restriction events towards My/Ly fates already occur within 49f+ HSCs. We show that within a continuous but highly structured molecular landscape, progression to a CLEC9AloCD34hi phenotype corresponds to the earliest transition of human HSCs to a discrete erythroid-null lymphoid-primed cell type characterised by fast quiescent exit kinetics and infrequent but durable repopulation capacity

Methods

Results

Conclusion