3055 - A Single Cell Haematopoietic Landscape Resolves Eight Lineage Trajectories and Defects in Kit Mutant Mice

Abstract

Haematopoietic stem and progenitor cells play an essential role in maintaining the blood system. The fate decisions in these cells are carefully balanced to produce the correct proportions of mature cell types, yet this balance can be severely disrupted in haematological diseases. To capture gene expression changes across the haematopoietic landscape, we profiled over 44,000 Kit+ mouse bone marrow cells using a droplet based single-cell RNA-Sequencing method. These molecular profiles represent a reference transcriptional landscape revealing entry points to eight different blood lineages (erythroid, megakaryocytic, mast cell, basophil, eosinophil, neutrophil, monocyte and lymphoid). Contrasting single-cell gene expression profiles from a Kit mutant mouse model (W41/W41) revealed qualitative differences in the transcriptional landscape, with a distinct mast cell entry point missing from the mutant mouse bone marrow stem/progenitor cells. Mapping W41/W41 cells to their corresponding wild-type cell types showed a quantitative shift towards more mature erythroid progenitors in the Kit mutant, which we validated using FACS analysis. Differential gene expression between the clusters highlighted potential compensatory processes including downregulation of pro-apoptosis genes in W41/W41 erythroid progenitors, and upregulation of genes in the integrated stress response pathway. We are now working on analysing these data using graph abstraction, which combines clustering analysis with trajectory inference, to better understand gene expression changes throughout the complex haematopoietic differentiation hierarchy. We expect this analysis will identify genes involved in haematopoietic cell fate decisions, and highlight genes with different dynamics in wild-type versus perturbed differentiation.