Cloning of murine megakaryocyte progenitor cells in a fibrin clot culture system.

A fibrin clot culture system was applied to the cloning of mouse megakaryocyte colony-forming cells (CFU-Meg). The culture medium in this new method consists of Iscove's minimal essential medium containing fetal bovine serum, bovine fibrinogen, bovine thrombin, and pokeweed mitogen-stimulated mouse spleen cell-conditioned medium (PWM-SCM). CFU-Meg colony frequency with 10% PWM-SCM was maximal on days 5-6 of culture. Plating efficiencies averaged 36.1 +/- 3.9 and 51.9 +/- 6.0 per 1.5 X 10(5) BDF1 bone marrow cells and 1.0 X 10(6) spleen cells, respectively. The addition of bovine serum albumin to the culture medium had no effect on the efficiency of megakaryocyte colony growth in this culture system. This simplified and reproducible culture system supported not only the growth of colonies composed of megakaryocytes in "synchronous maturation," but also so-called "heterogenous" megakaryocyte colonies composed of cells in all stages of maturation.