Hematopoietic stem cells are very primitive cells localized in the bone marrow (BM). They are pluripotent cells, having capacity for self-renewal and differentiation to produce all kinds of blood cells (e.g. T cells, B cells, natural killer cells, granulocytes, monocytes, erythrocytes and platelets) to perform different functional roles in the human body.^1,2  The mature blood cells have a limited lifespan (several days to many years); thus, hematopoietic stem cells produce a large number of bloods cell every day to replace the dying cells and ultimately sustain the hematopoietic system of individuals throughout their lives (Figure 2.1)....