HMGA2 is expressed in HSCs, early progenitors, and erythroid lineage. (A) Overview of hematopoietic cell populations identified in human BM from the Human Cell Atlas data set (integrated data from 8 donors, Uniform Manifold Approximation and Projection [UMAP] reduction, preprocessed data, clusters, and labels adopted from Hay et al²² ). CD34+ HSC cluster is indicated by the black arrow. (B) UMAP plot of HMGA2, CD34, and PCNA expression (MAGIC imputation). (C) Single-cell transcriptomic overview of hematopoietic cell populations identified in human CB cells. Fresh and UM171-expanded CD34⁺ cells (7 days) were integrated and clustered using Seurat 3 (2 samples each condition, 15 921 cells total). Fifteen cell clusters (left) were identified and defined using Seurat (v3) procedure: HSCs, multipotent progenitors (MPP), lymphoid-primed multipotent progenitors (LMPP), granulo-monocytic progenitors (GMP), megakaryocyte-erythroid progenitors (MEP), common lymphoid progenitors (CLP), pre-dendritic cells (pre-DC), plasmacytoid dendritic cells (pDC), myeloid dendritic cells (mDC), monocytes (Mono), neutrophils (Neut), erythroid progenitors (ERP), megakaryocytes (MK), erythrocytes (Ery), and eosinophils/basophils/mast cells(Eo/Bas/Ma). Unsupervised ordering of the HSCs was done with Seurat 3 integrated results as input to build a tree-like differentiation trajectory using the DDRTree algorithm of the Monocle v3 R package (right). (D) UMAP plot of representative stem cell and lineage associated genes compared with HMGA2 expression (integrated data from fresh and UM171-expanded CB cells, MAGIC imputation). (E) UMAP plot of representative stem cell, lineage, and proliferative genes in fresh CD34⁺ CB cells vs UM171 ex vivo expanded cells (MAGIC imputation). Red circle: non-proliferative CD34+ cells, orange circle: proliferative CD34+ FLT3+ progenitors. (F) Irradiated NSG mice were transplanted with CD34⁺ cells infected with short hairpin (sh) RNA green fluorescent protein (GFP) vectors targeting HMGA2 gene or a control locus. Twenty weeks after transplantation, reconstitution was assessed by measuring the percentage of human CD45⁺ GFP⁺ cells in BM (n = 6, median is depicted, Mann-Whitney U test). Gran, granulocytes.