Hemopoietic stem cell growth and microdiffusion

Abstract Extensive experiments carried out to study the kinetics of stem cell growth in the spleen of irradiated mice are reported here and the methods used are elaborated. The temporal and spatial features of the growth of the hypernetted, interacting system of stem cell chains in the spleen may be understood on the basis of a random distribution of source cells and of a microdiffusing stimulus for stem cell renewal along the cell chains. To test the validity of these assumptions, the growth kinetics are studied after administering various doses of colchicine to stem cells during different stages of growth. The behavior of the various phases of the recovery curves lends support to the theory of microdiffusion. Using the number of stem cells at saturation, the diffusion coefficient of the stimulus for renewal is approximately 10 -7 cm 2 sec -1 .