In vitro cloning of hemopoietic cells.

Semisolid cloning systems are now available to detect the specific progenitor cells of neutrophilmacrophages, eosinophils, megakaryocytes and erythroid cells. Colony proliferation in vitro with the production of mature progeny requires stimulation by glycoprotein regulators specific for each hemopoietic class. Two of these, erythropoietin and GM-CSF have been purified. A new cloning system has been developed using spleen conditioned medium that detects multipotential hemopoietic cells in the mouse.