The process of stem cell donation provides a potentially curative treatment for people facing life-threatening blood cancers and disorders. Hematopoietic stem cells are the blood-forming cells found primarily in the bone marrow, responsible for generating all other blood cell types, including white cells, red cells, and platelets. When a patient’s own cells are damaged by disease, such as leukemia, lymphoma, or sickle cell disease, an infusion of healthy donor stem cells can rebuild a new and functioning blood and immune system. This life-saving procedure, often called a stem cell transplant, relies entirely on the generosity and commitment of volunteer donors.
Joining the Donor Registry
The first step in becoming a potential donor is to voluntarily join a national or international registry. Individuals must generally be between the ages of 18 and 60 and meet certain health guidelines to be eligible. Younger donors (18 to 35) are often preferred because clinical outcomes for patients tend to be better.
Registration involves filling out a consent form and a comprehensive health questionnaire to determine basic medical eligibility. Joining the registry requires a simple cheek swab, often provided in a mailed kit. The swabs collect cells from the inside of the mouth, and the sample is sent to a laboratory for initial genetic testing. By submitting this sample, the individual commits to being available should they be identified as a match for a patient, a commitment that can last for many years.
The Matching and Health Screening Phases
The genetic information obtained from the cheek swab is used to analyze the donor’s Human Leukocyte Antigens (HLA). HLA are proteins found on most cells in the body that play a direct role in regulating the immune system. A successful transplant depends on a close match between the donor’s and the patient’s HLA markers to minimize the risk of rejection.
If a patient is found to have a preliminary match, the potential donor is contacted and asked to complete further, more detailed testing. This confirmation involves drawing blood samples for high-resolution HLA typing, which checks for a greater number of genetic markers to ensure the specificity of the match. Most people on the registry are never contacted, but those who are must undergo a thorough physical examination and health screening. This medical evaluation confirms that the donor is in excellent health and cleared to safely proceed with the donation.
Understanding the Two Donation Procedures
Once a donor is medically approved, the collection method is determined based on the patient’s disease and the physician’s preference. There are two primary methods for collecting stem cells: Peripheral Blood Stem Cell (PBSC) donation and bone marrow donation.
Peripheral Blood Stem Cell (PBSC) Donation
PBSC donation is the most common method, accounting for approximately 90% of all procedures. It is a non-surgical, outpatient procedure similar to donating platelets or plasma. The process, called apheresis, involves drawing the donor’s blood from one arm and passing it through a machine. This specialized equipment separates and collects the stem cells before returning the remaining blood components to the donor through a needle in the other arm. The procedure typically takes between four and eight hours and is often completed in a single session.
Bone Marrow Donation
The second method is traditional bone marrow donation, a surgical procedure performed in a hospital setting. The donor receives general or regional anesthesia to ensure there is no pain during the collection. Doctors use hollow needles to aspirate liquid marrow directly from the back of the pelvic bone (posterior iliac crest). This collection takes approximately one to two hours, and the amount of marrow removed is a small fraction of the donor’s total supply.
Donor Preparation and Post-Procedure Recovery
Preparation for a PBSC donation requires the donor to receive daily injections of Filgrastim (G-CSF) for four to five days leading up to the procedure. G-CSF is a synthetic hormone that signals the bone marrow to produce extra stem cells. The medication mobilizes these cells from the bone marrow into the circulating bloodstream so they can be collected via apheresis.
The most common temporary side effects of G-CSF injections are flu-like symptoms, including headaches and mild bone or muscle pain, often felt in the lower back and pelvis. These aches are caused by the rapid expansion of blood cell production within the bones and are managed with over-the-counter pain relievers. For PBSC donors, recovery is very fast, with most individuals returning to normal activities within one to seven days after the collection.
Recovery from a surgical bone marrow donation takes longer due to the use of anesthesia and the collection site. Donors often feel tenderness, bruising, or soreness at the lower back incision site for several days. Most bone marrow donors leave the hospital the same day or the next morning and can resume full activities within one week. In both procedures, the donated stem cells naturally regenerate within the donor’s body in a matter of weeks.