Hematology: stem cells
Our studies of hematopoietic stem cells (HSCs) focus on molecular genetic mechanisms that regulate differentiation, self-renewal, and aging. Hematopoietic precursors are a useful model for adult stem cells in general for 2 reasons. First, they are essential, producing not only all erythroid, myeloid and lymphoid cells, but natural killer cells and mast cells; and, they produce the macrophages found in liver, lung, bone, brain, and other tissues. Second, they are a well-defined example of self-renewing and differentiating cells that illustrate methods applicable to other stem cell systems. Because differentiated cells turn over continually, constant stem cell proliferation is necessary. In fact, partial proliferative exhaustion can explain losses with age in the many tissues in which repair and function depend on regeneration from adult precursor cells. In general, any impairment of stem cell function with age would reduce health in many biological systems. Conversely, any improvement of stem cell function with age could prolong health in many biological systems.