Source of Stem Cells
HSCs also exist in small quantities in the peripheral blood.
They can be increased by either administering G-CSF or by giving chemotherapy and waiting for the counts to recover, at which time a number of HSC will be “pushed out” of the marrow and into the blood.
HSCs are harvested (over 2-3 hours) by an apheresis machine. This requires the patient to have a central line but does not need to be done in an operating room.
Almost all autologous HSCTs are done using peripheral blood.
Some allogeneic HSCTs use peripheral blood, particularly in adults. Peripheral blood has the advantage of very early blood count recovery after transplant but the disadvantage (in allogeneic transplants) of much higher rates of chronic GvHD.
Figure: Stem cell harvest from the peripheral blood.