STEM-CELL FACTOR

Stem cell factor (SCF) is the ligand for the tyrosine kinase receptor c-Kit, which is expressed on both primitive and mature hematopoietic p rogenitor cells, In vitro, SCF synergizes with other growth factors, s uch as granulocyte colony-stimulating factor (G-CSF), granulocyte macr ophage-colony-stimulating factor, and interleukin-3 to stimulate the p roliferation and differentiation of cells of the lymphoid, myeloid, er ythroid, and megakaryocytic lineages. In vivo, SCF also synergizes wit h other growth factors and has been shown to enhance the mobilization of peripheral blood progenitor cells in combination with G-CSF, In pha se I/II clinical studies administration of the combination of SCF and G-CSF resulted in a two- to threefold increase in cells that express t he CD34 antigen compared with G-CSF alone, Other potential clinical us es include ex vivo expansion protocols and in vitro culture for gene t herapy.