CD34 and myelodysplastic syndrome: However, in a recent study, a reduced ability of MDS bone marrow-derived mesenchymal stromal cells (BMSCs) to support CD34+ hematopoietic stem and progenitor cells (HSPC) was observed in long-term culture-initiating cell assays due to structural, epigenetic, and functional abnormalities in MDS BMSCs [8].