Poor Potential of Proliferation and Differentiation in Bone Marrow Mesenchymal Stem Cells Derived From Children with Severe Aplastic Anemia.

5081 Introduction Idiopathic severe aplastic anemia (SAA), characterized by failure of hematopoiesis, is rare and potentially life-threatening to children. However, the pathogenesis has not been completely understood, and insufficiency in the hematopoietic microenvironment can be an important factor. Mesenchymal stem cells (MSCs) play an important role in maintaining bone marrow microenvironment. Therefore, we aimed at the intrinsic defects of bone marrow MSCs derived from SAA children. Materials and Methods Bone marrow MSCs were obtained from 5 SAA children and 5 controls. The morphology, immunophenotyping, proliferative capacity and differentiation potential of MSCs from SAA children were determined and compared with those of MSCs from controls. Results In vitro, MSCs of SAA and control group shared a similar spindle-shaped morphology. Both revealed a consistent immunophenotypic profile which was negative for CD45, CD14 and CD34, and positive for CD105, CD73, and CD44. However, SAA MSCs had slower expansion rate and smaller cumulative population doubling from passage 4 to 6 (1.83± 1.21 vs 3.36± 0.87; p = 0.046), indicating lower proliferative capacity. Besides, only 3 of 5 cultures of SAA group retained the ability to continue expansion till 80%-90% confluent cell layer beyond passage 6, suggesting earlier senescence of SAA MSCs. After osteogenic induction, SAA MSCs showed lower alkaline phosphatase activity (1.46± 0.04 vs 2.27± 0.32; p = 0.013), less intense von Kossa staining and lower gene expression of core binding factora1 (0.0015± 0.0005 vs 0.0056± 0.0017; p = 0.013). Following adipogenic induction, SAA MSCs showed less intense Oil red O staining (0.86± 0.22 vs 1.73± 0.42; p = 0.013) and lower lipoproteinlipase expression (0.0105± 0.0074 vs 0.0527± 0.0254; p = 0.013).The results of real time-PCR analysis for the assessment of lineage-specific genes were consistent with the findings of histochemical stains, and both indicated that SAA MSCs had poor osteogenic and adipogenic potential. Conclusions In this study, we demonstrated that bone marrow MSCs from children with SAA had poor potential of proliferation and differentiation. These alterations in MSCs may contribute to the failure of hematopoiesis, and lead to the development of the disease. Further studies are needed to elucidate the relationship between MSCs and SAA. Disclosures No relevant conflicts of interest to declare.