cHSPC subsets show differential migratory propensities toward extramedullary organs. (A) Heat map showing the scaled organ-specific module scores (top-20 DE genes, rows) evaluated for each PB-HSPC cluster (columns). (B) Heat map showing the scaled expression levels of TSP1 genes (rows) across MLPs (columns, clusters 4). Cells were clustered into K = 3 groups by K-means clustering algorithm. The table below displays the proportion of TSP1-high MLP in BM and PB. (C) Histograms showing the relative frequencies of the lymphoid cellular outputs of BM- and PB-MLPs detected at the end of the T-cell differentiation assay. The histogram above displays the proportions of CD4/CD8 double-negative (DN), CD4/CD8 double positive (DP), CD4 single-positive (CD4⁺ SP), and CD8 single-positive (CD8⁺ SP) cells detected within CD3⁺ cell compartment. The histogram below shows the proportions of T-cell precursors within the CD3^– CD56^– CD19^– cell fraction. Data are shown as mean ± SEM. (D) UMAP embedding of the integrated scRNAseq data set, coloring cells by source: BM (red), PB (blue), and thymus (violet). (E) Density plots, showing cell classification as TSP1, TSP2, or ETP. (F) UMAP embedding, showing Monocle3 estimated pseudotime. (G) Percentages of TSP1 genes expressed (UMI > 0) by lymphoid–circulating CD34⁺ cells selected from a published peripheral blood mononuclear cells (PBMC) scRNAseq data set of healthy individuals from distinct ranges of age.⁴⁷ The significance of the 1-way analysis of variance test across age classes revealed differences in the percentage of expressed TSP1 genes (P < .0001). These differences were then assessed through pairwise t test. Multiple hypotheses testing issue was accounted for adjusting the P values through the Benjamini-Hochberg method.