Ahmad Reza Rahnemoon
Hematopoietic stem cells (HSCs) were first identified in 1961 by Till and McCulloch which less than 0.01% in the Bone Marrow (BM) cells. We know these are multi-potent stem cells defined by their ability to self-renewal, differentiation and maintenance of all blood cell types in hematological system during the entire life time of the organism. In fact, adult Hematopoietic Stem Cells (HSCs) are thecells capable of self-renewal and remain component in the process of hematopoiesis which, together with the cells that makeup the bone marrow stromal environment and other factors ,which means there is a balance between processes such as self-renewal, proliferation and differentiation of the cells versus apoptosis and cell cycle arrest in HSCs.