Notch-Hes pathway mediates the impaired osteogenic differentiation of bone marrow mesenchymal stromal cells from myelodysplastic syndromes patients through the down-regulation of Runx2.

Previous studies have demonstrated that bone marrow mesenchymal stromal cells (BMMSCs) from patients with myelodysplastic syndromes (MDS) display defective proliferative potential and impaired osteogenic differentiation ability. However, the underlying mechanisms are unclear. In the present study, the impaired osteogenic differentiation potential of BMMSCs was found in cases with RARS (83.3%), RCMD (75.0%), RAEB I (44.4%), RAEB II (40%). We also observed that MDS-BMMSCs with impaired osteogenic differentiation potential exhibited accelerate senescence and decreased hematopoietic supporting function. Further, we found that an abnormal activation of Notch-Hes signaling pathway in MDS-BMMSCs. By overexpression of Notch intracellular domain (NICD) in BMMSCs from healthy donors, we confirmed that Notch signaling pathway negatively regulated BMMSCs osteogenesis through inhibition of Runx2 transcriptional activity. Importantly, treatment with DAPT, a γ-secretase inhibitor of Notch signaling reversed the osteogenic differentiation in MDS-BMMSCs. Collectively, we provide evidence that activation of Notch-Hes signaling pathway is involved in the impaired osteogenic differentiation of MDS-BMMSCs and support the concept of a primary BMMSCs defect that might have a contributory effect in MDS pathogenesis.