Transcriptional heterogeneity and lineage commitment in myeloid progenitors [single cell RNA-seq]

Within the bone marrow, hematopoietic stem cells differentiate and give rise to diverse blood cell types and functions. Currently, hematopoietic progenitors are defined using surface markers combined with functional assays that are not directly linked with the in vivo potential or gene regulatory mechanisms. Here we comprehensively identify myeloid progenitor subpopulations by transcriptional sorting of single cells from the bone marrow. We describe multiple progenitor subgroups showing unexpected transcriptional priming towards seven differentiation fates, but no progenitors with a mixed state. Transcriptional differentiation is correlated with combinations of known and previously undefined transcription factors, suggesting the process is tightly regulated. Histone maps and knockout assays are consistent with the transcriptional states while traditional transplantation experiments are only partially overlapping myeloid transcriptional priming. Our analyses uncover the function of the underlying regulatory mechanisms for several sub groups and establishes a general framework for dissecting hematopoiesis.