Proliferation and differentiation of murine mast cells in vitro

With advances in micromanipulator techniques, we have been able to observe the proliferation of hemopoietic colonies derived from single cells. In this paper, using clonal culture techniques, we have clarified (i) the origin of murine mast cells, (ii) proliferation mode of mast cells, and (iii) the differentiation and proliferation in culture of mast cell progenitors derived from mast cell-deficient mice of genotype W/W(v). First, we showed that various types of mixed hemopoietic colonies containing mast cells were formed by single blast cells obtained by a micromanipulation technique. This result provides direct evidence that mast cells are derived from pluripotent stem cells and that the differentiation of mast cells appears to occur through a stochastic process. Second, replating studies of mast cells were carried out, and a high incidence of replating was seen. Some of the micromanipulated single cells showed a lag period of more than 48 hrs before proliferation commenced in vitro. Delayed addition of colony-stimulating factor (CSF) to mast cells showed that a progressive fall occurred in the number of colonies with increasing delay before the addition of CSF. These studies showed that CSF does not trigger mast cells into active cell proliferation, but is necessary for continued proliferation of cells. Third, using cell culture assay for hemopoietic progenitors, we examined mast cell progenitors derived from mast cell-deficient mice. These studies demonstrated the normal capacity for differentiation and proliferation in culture of mast cell progenitors from W/W(v) mice. It is suggested that interaction of progenitors with the tissue environment is required for the growth of mast cells in vivo.