14 - Growth factors and the regulation of haemopoietic stem cells

Abstract

This chapter focuses on growth factors and the regulation of hemopoietic stem cells. The proliferation and development of hemopoietic stem cells in vivo is promoted by contact with bone marrow stromal cells and the surrounding extracellular matrix (ECM). While there is some ability of soluble cytokines or growth factors to promote survival and proliferation of stem cells and their progeny in the absence of a stromal cell matrix, the primitive hemopoietic stem cell can only be maintained, in the long term, when co-cultured with the appropriate stromal cell environment. The data on the specific molecular interactions that are involved in the association between hemopoietic cells, stromal cells, and ECM have been obtained using a number of different approaches. Purification procedures to isolate populations of primitive hemopoietic cells have been devised such that the short-term response to specific cytokines can be gauged. This chapter describes some of the recent work describing cell purification, molecular characterization of cytokines and their receptors, and in vivo studies with growth factors which have provided the background for informed debate on the response of stem cells to growth factors. It explains concepts related to purification of hemopoietic stem cells. It also describes receptors types found on primitive cells.