Hematopoietic stem cell transplantation (often called bone marrow donation) is a medical procedure that treats blood cancers like leukemia and other serious blood disorders. It involves replacing a patient’s diseased blood-forming cells with healthy stem cells from a donor. Successful treatment requires finding a well-matched, healthy donor whose cells will not be rejected by the recipient. The process of becoming a potential donor begins by joining a registry.
General Requirements for All Donors
Becoming a potential donor requires meeting universal health and demographic criteria. Registries focus on recruiting new donors between the ages of 18 and 35, as younger donors generally offer better long-term outcomes for patients. Once registered, individuals remain in the pool of potential donors until they reach age 61.
All donors must be in good general health and free from chronic medical conditions that could pose a risk during the donation procedure or compromise the recipient’s immune system. Disqualifying conditions include HIV, a history of heart disease, or autoimmune disorders such as lupus. Body weight is also screened for donor safety. Most registries require a Body Mass Index (BMI) below 40 for Peripheral Blood Stem Cell (PBSC) donation and often below 35 for the surgical Bone Marrow Harvest procedure.
Specific Medical Considerations for Female Donors
The answer is yes, and female donors are a needed part of the registry. However, unique medical factors are considered during selection. A female donor is temporarily deferred if she is currently pregnant or exclusively breastfeeding. This deferral avoids potential risk to the fetus or infant from necessary pre-donation medications.
A key consideration is the impact of prior pregnancies, known as parity, on the donated cells. During pregnancy, a mother may become “alloimmunized,” meaning her immune system develops antibodies in response to foreign fetal cells. This alloimmunization poses an increased risk for the stem cell transplant recipient.
Grafts from previously pregnant (parous) female donors have been associated with a significantly higher incidence of acute and chronic Graft-versus-Host Disease (GvHD) in the recipient, compared to grafts from male or nulliparous (never pregnant) female donors. This risk is particularly elevated when a female donor with a history of pregnancy is matched with a male recipient. While a history of pregnancy does not automatically disqualify a donor, transplant physicians weigh these factors carefully during the final selection process.
The Two Methods of Donation
Stem cells are collected through one of two distinct medical procedures once a donor is selected. The most common method, accounting for approximately 90% of all donations, is Peripheral Blood Stem Cell (PBSC) donation. This procedure resembles a standard blood platelet donation.
Peripheral Blood Stem Cell (PBSC) Donation
For five days before collection, the donor receives injections of filgrastim, a medication that stimulates the bone marrow to release stem cells into the bloodstream. The donor is then connected to an apheresis machine. This machine draws blood from one arm, separates the stem cells, and returns the remaining blood components through the other arm. Recovery time is typically short, with most donors returning to normal routines within about one week.
Bone Marrow Harvest
The second method is the traditional Bone Marrow Harvest, which requires a surgical procedure performed under general or regional anesthesia. A doctor uses specialized needles to extract liquid marrow directly from the back of the pelvic bone (posterior iliac crest). Since the marrow is a liquid, this is not a spinal procedure and involves no cuts to the spine. Because it is surgical, the median time to full recovery is longer, with most donors feeling completely recovered within 20 days.