Donated stem cells come from the following sources: Bone Marrow Peripheral Blood Stem Cells Umbilical Cord Blood Bone marrow is rich in stem cells and is considered the largest source. Stem cells are also found in the bloodstream, but in smaller numbers. to increase the number of these cells in peripheral blood, donors usually receive a series of injections of a growth factor such as Filgrastim. Umbilical cord blood has been found to be the richest source of stem cells. However, because it is also the smallest volume, typically it is used for stem cell transplantation in pediatric patients.

Fetal circulation is one of the first organ systems to need to be able to function properly in order to sustain the fetus.

Hematopoetic growth factors are called cytokines.

Amgen, based at Thousand Oaks in California, makes a genetically engineered version of erythropoeitin called Epogen for treating anaemia. Sales of this protein generated $3 billion in 1996.