23 October 2009
John Higgins
Department of Systems Biology
Harvard Medical School
250 billion new red blood cells (RBCs) move from the bone marrow into the peripheral circulation every day in the typical healthy human adult. Each RBC then circulates for about 100 days before being cleared. We know that the physiologic processes ensuring homeostasis of this circulating population of RBCs are quite robust in the face of mild perturbations to production (eg: thalassemia minor, iron deficiency), loss (eg: chronic intestinal bleeding), and destruction (eg: G6PD-enzyme deficiency, auto-immune hemolytic anemia). We do not understand the dynamics of these processes. I will describe a preliminary effort to derive a master equation for some characteristics of the circulating population of human red blood cells. I will present initial results suggesting that this model of RBC population dynamics reflects important qualitative features of normal physiology and suggests how these processes may compensate for mild pathologic situations such as thalassemia minor and iron deficiency.