Microvesicles from mesenchymal stromal cells are involved in HPC-microenvironment crosstalk in myelodysplastic patients

Exosomes/microvesicles (MVs) provide a mechanism of intercellular communication. Our hypothesis was that mesenchymal stromal cells (MSC) from myelodysplastic syndrome (MDS) patients could modify CD34 cells properties by MVs. They were isolated from MSC from MDS patients and healthy donors (HD). MVs from 30 low-risk MDS patients and 27 HD were purified by ExoQuick-TCor ultracentrifugation and identified by transmission electron microscopy, flow cytometry (FC) and western blot for CD63. Incorporation of MVs into CD34 cells was analyzed by FC, and confocal and fluorescence microscopy. Changes in hematopoietic progenitor cell (HPC) properties were assessed from modifications in micro- RNAs and gene expression in CD34 cells as well as viability and clonogenic assays of CD34 cells after MVs incorporation. Some microRNAs were overexpressed in MVs from patients MSC and two of them, miR-10a and miR-15a, were confirmed by RT-PCR. These microRNAs were transferred to CD34 cells, modifying the expression of MDM2 and P53 genes, which was evaluated by RT-PCR and western blot. Finally, examining CD34 cells properties after incorporation, higher cell viability (p = 0.025) and clonogenic capacity (p = 0.037) were observed when MVs from MDS patients were incorporated. In summary, we show that BM-MSC release MVs with a different cargo in MDS patients compared with HD. These structures are incorporated into HPC and modify their properties.Gerencia Regional de Salud de Castilla y León (GRS 873/A/13) MCC, Fondo de Investigaciones Sanitarias (PS09/01530) MCC, Ministerio de Ciencia e Innovación, Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica, 2008-2011 (CEI10-1-0010) MCC. A fellowship from the Portuguese Fundação para a Ciência e Tecnologia (SFRH/BD/86451/2012) TLR.Peer Reviewe