The contribution of marker gene studies to hemopoietic stem cell therapies.

Although the transfer of "therapeutic" genes into hemopoietic stem cells (HSC) offers many opportunities to treat a wide range of human disease, the low efficiency of transfer and limited expression of the transferred gene have so far largely prevented any direct beneficial effect from being obtained. However, gene marker studies in which the transferred genes are used simply to track the individual components of the infused HSC have already shown their utility. Genetic marking may be used to identify cells capable of causing relapse after autologous bone marrow transplantation and to distinguish cells in the graft capable of preventing malignant disease. Marking may also be used to analyze the consequences of ex vivo or in vivo manipulations of the HSC which are intended to accelerate engraftment or augment gene transfer efficiencies. Information obtained from these studies should therefore not only improve the outcome of HSC based therapies, but also aid in the introduction of successful gene therapy protocols.