Use of stem cell factor to mobilize hematopoietic progenitors

Stem cell factor (SCF) is a multipotent growth factor that plays a role in the growth and development of hematopoietic cells, spermatocytes, melanocytes, and mast cells. SCF alone has little direct stimulatory activity on hematopoietic progenitors but acts synergistically with other colony-stimulating factors to potentiate their effects on colony growth. SCF also potentiates the mobilization of hematopoietic progenitor cells into the peripheral blood in response to granulocyte colony-stimulating factor (G-CSF), with or without chemotherapy. The combination of SCF plus G-CSF appears to be a particularly effective mobilization regimen for patients who have been heavily pretreated. Whether engraftment of peripheral blood progenitor cells mobilized by SCF plus G-CSF is superior to that of cells mobilized by G-CSF alone remains unclear. SCF appears to be a necessary requirement for ex vivo expansion of hematopoietic progenitors in both liquid and bioreactor culture systems and will be an important component of future cellular therapies, such as expansion of placental cord blood progenitors and retroviral-mediated gene transfer into hematopoietic target cells.