Background and ObjectivesAplastic anemia is a syndrome of bone marrow (BM) failure characterized by peripheral pancytopenia and marrow hypoplasia. Its etiology has been attributed to medications, chemicals, and environmental factors. However, the exact mechanism by which these factors cause BM aplasia is still not clear. Mesenchymal stem cells (MSCs) play an important role in providing the specialized BM microenvironment for hematopoietic stem cells (HSCs) survival and differentiation. Therefore, MSCs dysfunction may result in impairment of hematopoiesis. In this study, we compare the basic properties of BM-MSCs derived from patients with aplastic anemia and that of controls in order to study the potential role of MSCs in the pathogenesis of aplastic anemia. Design and Methods:MSCs were isolated from BM aspirate collected from 10 newly diagnosed patients with aplastic anemia and 10 age and sex matched controls. MSCs were characterized by morphology and immunophenotyping. Their viability, proliferative capacity and adipogenic as well as osteogenic differentiation were assessed.Results:MSCs from aplastic anemia patients and controls shared similar spindle shaped morphology and surface marker expression. MSCs derived from patients with aplastic anemia showed slower expansion rate as indicated by; smaller number of harvested cells, smaller population doubling and smaller cumulative population doubling from passages 1 to 4 (0.70±0.22 vs 2.34±0.84; p=0.009). Besides, aplastic anemia MSCs had poor capacity to differentiate into adipocytic and osteocytic lineages.ConclusionsAccording to our results, BM MSCs derived from children with aplastic anemia had poor potential of proliferation and differentiation. These alterations may be important in the pathogenesis of the disease.