Hematopoietic stem cells: clinical requirements and developments in ex-vivo culture.

Ex vivo expansion of hematopoietic stem cells is a promising technology for many potential applications from marrow reconstitution to gene therapy. Considerable progress has been made during the past ten years in understanding the biology of hematopoietic stem cells and its ex vivo expansion; despite this, the cultured cell is still between pre-clinical and phase I clinical trials. This review summarizes recent progress in the ex vivo expansion of hematopoietic stem cells and its requirements for clinical applications. The second section covers hematopoiesis and the bone marrow microenvironment. The third and fourth sections deal with therapeutic applications of stem cells and transplantation requirements, respectively. Biological alteration of expanded stem cells, molecular control of hematopoiesis, characterization of cells, and bioreactors for culture of stem cells and its operational parameters are the subjects of the fifth section. The next section covers pre-clinical and clinical studies on expanded stem cells. Ex vivo expansion of stem cells in three-dimensional culture system is the subject matter for the last section.