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Mesenchymal stromal cells (MSC) may exert their functions by the release of extracellular vesicles (EV). Our aim was to analyze changes induced in CD34 + cells after the incorporation of MSC-EV. MSC-EV were characterized by flow cytometry (FC), Western blot, electron microscopy, and nanoparticle tracking analysis. EV incorporation into CD34 + cells was confirmed by FC and confocal microscopy, and then reverse transcription polymerase chain reaction and arrays were performed in modified CD34 + cells. Apoptosis and cell cycle were also evaluated by FC, phosphorylation of signal activator of transcription 5 (STAT5) by WES Simple, and clonal growth by clonogenic assays. Human engraftment was analyzed 4 weeks after CD34 + cell transplantation in nonobese diabetic/severe combined immunodeficient mice. Our results showed that MSC-EV incorporation induced a downregulation of proapoptotic genes, an overexpression of genes involved in colony formation, and an activation of the Janus kinase (JAK)-STAT pathway in CD34 + cells. A significant decrease in apoptosis and an increased CD44 expression were confirmed by FC, and increased levels of phospho-STAT5 were confirmed by WES Simple in CD34 + cells with MSC-EV. In addition, these cells displayed a higher colony-forming unit granulocyte/macrophage clonogenic potential. Finally, the in vivo bone marrow lodging ability of human CD34 + cells with MSC-EV was significantly increased in the injected femurs. In summary, the incorporation of MSC-EV induces genomic and functional changes in CD34 + cells, increasing their clonogenic capacity and their bone marrow lodging ability. Stem Cells 2019;37:1357-1368., (©2019 The Authors. Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press 2019.)