Activation and Proliferation of Purified Hematopoietic Precursor Cells from Human Bone Marrow

Abstract

Despite increasing knowledge of the phenotypic and functional heterogeneity of early hematopoietic cells, many questions regarding the biological properties of primitive hematopoietic cells and their regulation remain. Some of these questions are related to the mechanism(s) by which hematopoiesis is maintained throughout the life-span of an individual. Is stem cell self-renewal involved in this process or is there a gradual depletion of an extensive stem cell reserve? The answer to this question is likely to dramatically impact on therapeutic options and strategies. For example, if pluripotent hematopoietic stem cells would have an intrinsic ability to self-renew (as is often assumed) then in vitro conditions could likely be defined that would allow such cells to display this self-renewal potential. This would in turn allow numerical expansion of stem cells ex vivo for transplantation and gene transfer experiments starting with very few (in principle a single) stem cells.