CD34 and acute myeloid leukemia: On the other hand, BM-MSCs ability to support CD34+ cells declines, after getting affected by extracellular vesicles (EVs) containing miR-7977 derived from AML/MDS CD34+ cells. miR-150 EVs target the CXCR4/SDF-1 axis which is fundamental for retention and differentiation of HSPC in BM.