The clonal culture in vitro of multipotential hemopoietic cells: problems and interpretations

The ability to clone mixed hemopoietic colonies in vitro new permits hemopoietic populations to be more effectively assayed for multipotential precursor cells but it is unclear whether all CFU-S are detectable by the culture systems in current use. From the available data, some caution should be used in assuming that the in vitro culture systems give a direct estimate of the repopulating capacity of the population. Although the factors stimulating mixed colony formation have not been purified, it is now possible to analyze the early cellular events during commitment to specific hemopoietic lineages.