Single-cell transcriptome of erythroid cell–enriched bone marrow. (A) The experimental design used to enrich erythroid marrow precursors and label surface proteins for quantification during scRNAseq. (B) Uniform manifold approximation and projection (UMAP) visualization of all bone marrow mononuclear cells identified based on cell lineage and type of sample. The majority of the cells were erythroid precursors, as expected. (C) Dot plot of gene expression level and frequency showing the 6 highest expressed globally distinguishing genes in each cell lineage cluster. (D) Individual UMAP visualizations of all bone marrow mononuclear cells identified based on cell lineage for cells analyzed after 0, 3, or 6 days of culture. The small number of cells in the latest stages of erythroid differentiation, as identified based on their relatively low diversity of transcripts (ie, orthochromatic erythroblasts or reticulocytes) that persisted from day 0 to day 3 were almost completely absent on culture day 6. Thus the 6-day culture amplifies the numbers of early precursors that were present at a very low frequency in day-0 marrow. Ex vivo (day 0) marrow predominately consists of terminal stage precursors. (E) Dot plot showing the changes in the distinguishing genes expression level and frequency over time in culture for each cell lineage. Bc, B cell; CLP, common lymphoid progenitor; Ctrl, control; Dc, dendritic cell; Ery, erythroid; Mac, macrophage; Meg, megakaryocyte; MPP, multipotent progenitor; Neu, neutrophile; NK, natural killer; Tc, T cell.