Chapter category: Stem Cells
Clinical Applications of Hematopoietic Stem Cells
Chapter authors:
Ian McNiece
The bone marrow is the principal site for blood cell formation in humans. In normal adults the body produces about 2.5 billion red blood cells (RBC), 2.5 billion platelets and 10 billion granulocytes per kilogram of body weight per day.1 The production of mature blood cells is a continual process that is the result of proliferation and differentiation of stem cells, committed progenitor cells and differentiated cells. Within these three stages, extensive expansion of cell numbers occurs through cell division. A single stem cell has been proposed to be capable of more than 50 cell divisions or doublings and has the capacity to generate up to 1015 cells, or sufficient cells for up to 60 years.2 The proliferation and differentiation of cells is controlled by a group of proteins called hematopoietic growth factors (HGFs). The major clinical application for hematopoietic cells (HC) has been as a cellular source to support cancer patients undergoing high dose chemotherapy (HDC) with hematologic malignancies and solid organ diseases [for more details visit the website of the National Marrow Donor Program – www.marrow.org]. Bone marrow (BM) was the first source of hematopoietic cells used for transplantation.3 Since then other sources including mobilized peripheral blood progenitor cells (PBPC)4 and cord blood cells5 have been utilized in different clinical settings. An optimal hematopoietic graft contains a mixture of cells including; i) committed progenitor cells that provide rapid recovery of neutrophils and platelets, and ii) hematopoietic stem cells (HSC) that provide long term durable engraftment.
