Ex Vivo Expansion of HSPCs

Abstract

Transplantation of hematopoietic stem cells (HSCs, the cells that can give rise to all blood and most immune cell types) is a life-saving procedure for patients with hematopoietic malignancies, marrow failure syndromes, and hereditary immunodeficiency disorders. However, the wide application of this procedure is always limited either by availability of suitably HLA-matched adult donors or obtaining enough stem cell for a successful transplant. Over the past years, the results of ex vivo stem/progenitor cell expansion have been promising, numerous studies have described the effects of combinations of a variety hematopoietic growth factors on hematopoietic stem and progenitor cells (HSPCs) expansion in vitro. Most experimental evidence indicated that a combination of several cytokines such as stem cell factor (SCF), FLT-3/FLK-2 Ligand (Flt3-ligand), thrombopoietin (TPO) seems to be essential for progenitor amplification. Among these growth factors, SCF is unanimously agreed to be indispensable for stem and progenitor expansion and even shows to be a key factor for hematopoietic progenitor cell survival. With this cytokine cocktail, CD34+ cells can be expanded ex vivo about 10–1000-fold over pre-expanded values [1–3]. These kinds of expansion protocol provided sufficient numbers of hematopoietic progenitor cells to rapidly restore blood formation in patients undergoing high-dose chemotherapy or/and irradiation treatment. The development of ex vivo culture systems that facilitate the expansion of HSCs is crucial to stem cell research and clinical application. In this chapter, we describe the protocols to expand HSPCs ex vivo and analyze their population ability. This information is beneficial for successful use of stem cells in therapeutic studies.