Hematopoietic stem cells, overview and pathways implied on their self-renewal mechanisms

Abstract

Blood tissue is composed approximately in45% by cells and its derivatives, with a life spanof around 120 days for erythrocytes and 3 yearsfor certain type of lymphocytes. This lost is compensatedwith the hematopoietic system activityand the presence of an immature primitive cellpopulation known as Hematopoietic Stem Cells(HSCs) which perform the hematopoiesis, a processthat is active from the beginning of the fetallife and produces near to 2 x 1011 eritrocytes and1010 white blood cells per day (1). HematopoieticStem Cells are capable of both self-renewal and differentiation into multiple lineages, are locatedin a particular niche and are identified by theirown cell surface markers, as the CD34 antigen.Recently it has been possible to advance in theunderstanding of self-renewal, differentiation andproliferation processes and in the involvementof the signaling pathways Hedgehog, Notch andWnt. Studying the influence of these mechanismson in vivo and in vitro behavior and the basicbiology of HSCs, has given valuable tools for thegeneration of alternative therapies for hematologicdisorders as leukemias.

Keywords

• Hematopoietic Stem Cells
• quiescence
• self-renewing
• notch
• wnt
• hedgehog