Myelodysplastic cells in patients re-program mesenchymal stromal cells to establish a transplantable stem cell-niche disease unit.

Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid neoplasms with defects in hematopoietic stem/progenitor cells (HSPCs) and possibly the HSPC niche. Here we show that patient-derived mesenchymal stromal cells (MDS MSCs) display a disturbed differentiation program and are essential for the propagation of MDS-initiating lin-CD34+CD38- stem cells in orthotopic xenografts. Overproduction of niche factors such as N-Cadherin, IGFBP2, VEGFA and LIF is associated with the ability of MDS MSCs to enhance MDS expansion. These factors represent putative therapeutic targets to disrupt critical hematopoietic-stromal interactions in MDS. Finally, healthy MSCs adopt "MDS-MSC like" molecular features when exposed to hematopoietic MDS cells, indicative of an instructive remodeling of their microenvironment. This patient-derived xenograft model therefore provides functional and molecular evidence that MDS is a complex disease involving both the hematopoietic and stromal compartments. The resulting deregulated expression of niche factors may well also be a feature of other hematopoietic malignancies.EGA study EGAS00001000716