Peripheral blood stem cells (PBSCs) are collected from the blood. These stem cells are similar to the cells in the bone marrow, except that the numbers are far fewer in the blood circulation.
In order to increase the numbers of stem cells in the blood, the donor (who could be the patient or another individual) is injected with drugs that increase the number of stem cells released into the bloodstream. This takes place from 4 to 5 days prior to the collection procedure.
Once the stem cells in blood have reached a certain concentration, the donor is called in for collection. The collection procedure is called ‘apheresis’ or ‘leukapheresis.’ A needle is inserted in the vein and connected to a set of tubes and a collection machine. Over a period of 4 to 6 hours the blood passes through the collection machine. The stem cells are filtered out while the rest of the blood passes back into the body.
The stem cells that remain are then mixed with preservatives and stored in freezing conditions (cryopreserved). This allows them to be used later.
To find out what happens to the collected stem cells, read the article - How are stem cells received by the patient?
Source: Clinical Bone Marrow and Blood Stem Cell Transplantation. Author: Kerry Atkinson and colleagues. Published by Cambridge University Press, 2003.
