Extracellular vesicles from bone marrow mesenchymal stromal cells of severe aplastic anemia patients attenuate hematopoietic functions of CD34+ hematopoietic stem and progenitor cells

Mesenchymal stromal cells (MSC) regulate hematopoiesis in the bone marrow (BM) niche and extracellular vesicles (EVs) released by BM‐MSC are important mediators of the cross‐talk between BM‐MSC and hematopoietic stem and progenitor cells (HSPC). We have previously demonstrated that BM‐MSC of severe aplastic anemia (SAA) patients have an altered expression of hematopoiesis regulatory molecules. In the present study, we observed that CD34+ HSPC when cocultured with BM‐MSC EVs from aplastic anemia patients exhibited a significant reduction in colony‐forming units (p = .001), cell proliferation (p = .002), and increased apoptosis (p > .001) when compared to coculture with BM‐MSC EVs from controls. Collectively, our results highlight that EVs derived from the BM‐MSC of SAA patients impair the hematopoiesis supporting function of HSPC.