To donate bone marrow, you join a stem cell donor registry, give a cheek swab for tissue typing, and wait to be matched with a patient. If you match, you have a medical check, then donate either peripheral blood stem cells (PBSC) through a vein or liquid marrow from the back of the pelvis under anesthesia. Most donors are back to normal routines within days to a few weeks, and the marrow they give replaces itself.
In this guide I walk through each stage of donating bone marrow, from registration to recovery, so that prospective donors and the clinicians who counsel them know what to expect.
What Is Bone Marrow Donation?
Bone marrow donation means giving hematopoietic stem cells, the parent cells that produce red cells, white cells, and platelets, so they can be transplanted into someone whose own marrow is failing or diseased. Once infused, the donor cells travel to the recipient’s bones, settle in, and start making healthy blood.
Transplants from a donor are called allogeneic transplants. They are used for patients with serious blood disorders such as acute leukemia, myelodysplastic syndromes, some lymphomas, and aplastic anemia. In many of these conditions the bone marrow failure leads to low counts of all three blood cell lines, a picture called pancytopenia, and a transplant may be the only route to a cure.
Who Needs a Donor, and Why Matching Matters
Patients who need a transplant usually have one of several hematological disorders: blood cancers that have relapsed or carry high-risk features, marrow failure syndromes, or inherited conditions such as severe sickle cell disease or thalassemia. Their doctors confirm the need with a complete blood count, a marrow biopsy, and genetic tests on the abnormal cells.
The critical step is finding a donor whose human leukocyte antigen (HLA) type matches the patient’s. HLA proteins sit on the surface of most cells and act as the immune system’s “self” markers. A close match lowers the risk of graft rejection and of graft-versus-host disease (GVHD), in which donor immune cells attack the recipient’s tissues.
A brother or sister who has the same parents has a one-in-four chance of being a full HLA match, because each child inherits one set of HLA genes from each parent. Many patients have no matched sibling, which is why unrelated volunteer registries exist.
How to Donate Bone Marrow: Step by Step
The route from sign-up to donation follows a predictable sequence. Timelines vary between registries, but the stages are broadly the same.
- Join a registry. Sign up with your national donor registry (in the United States, the NMDP registry, formerly Be The Match). Registries set their own age limits and usually favor younger adults, because younger donors are linked to better outcomes for recipients.
- Give a cheek swab. A painless swab of the inside of your cheek provides DNA for HLA typing. Your profile then sits on the registry, sometimes for years.
- Confirmatory testing. If you look like a possible match, you give a blood sample for more detailed HLA typing and infectious disease screening.
- Information session and consent. A coordinator explains both donation methods, the risks, and your right to withdraw. Donors are asked to decide early, because the patient’s conditioning treatment is timed around the donation.
- Medical examination. A physical exam, blood tests, and a review of your health history confirm that donating is safe for you.
- Donation and follow-up. You donate by PBSC collection or marrow harvest, and the registry checks on you afterwards.
Donors are generally not charged for testing, travel, or the procedure itself; the registry or the patient’s transplant program covers these costs.
PBSC Collection vs Bone Marrow Harvest
Most unrelated donations today are PBSC collections. The patient’s transplant doctor requests one method or the other based on the disease being treated and the type of transplant planned.
PBSC collection: for about four to five days beforehand, you receive daily injections of granulocyte colony-stimulating factor (G-CSF), a growth factor that pushes stem cells out of the marrow into the bloodstream. Blood is then drawn from one arm, passed through an apheresis machine that separates out the stem cells, and returned through the other arm. A session takes several hours and sometimes needs a second day.
Bone marrow harvest: this is done in an operating room, usually under general anesthesia. The doctor uses a needle to draw liquid marrow from the posterior iliac crest, the back of the pelvic bone, through small punctures in the skin. Most donors go home the same day or the next morning. You can read more about the technique in our article on bone marrow harvest.
| Feature | PBSC collection | Bone marrow harvest |
|---|---|---|
| Where cells come from | Circulating blood | Pelvic bone marrow |
| Preparation | Daily G-CSF injections for about 4–5 days | Pre-operative assessment |
| Anesthesia | None (local only if a central line is needed) | Usually general |
| Procedure setting | Outpatient apheresis unit | Operating room, often day case |
| Common side effects | Bone aches, headache, tiredness during G-CSF | Lower back soreness, fatigue |
| Typical recovery | A few days | A few days to a few weeks |
Risks, Side Effects, and Recovery
Donation is considered safe for healthy adults, but it is not risk-free. During G-CSF treatment, bone pain, muscle aches, and headaches are common and usually settle with simple pain relief once injections stop. Rarely, the spleen can enlarge, so donors are told to report pain in the upper left abdomen.
After a marrow harvest, soreness over the lower back and hips is expected for several days, along with tiredness. Anesthesia carries its own small risks, which the anesthetist discusses beforehand. Your body replaces the donated marrow on its own, typically within a matter of weeks.
Registries follow donors up after donation, and anyone whose symptoms do not ease should contact their donor center. The procedure is not the same as a diagnostic marrow test; if you are curious about that, see how a bone marrow biopsy is performed.
Key Takeaways
- Donating starts with joining a registry and giving a cheek swab for HLA typing.
- Only a small share of registered donors are ever called, but those who are can offer a patient a potential cure.
- PBSC collection is the most common method; marrow harvest from the pelvis is used when the transplant team requests it.
- Side effects are usually short-lived, and donated marrow regenerates naturally.
- Clinicians counseling donors should explain both methods, the time commitment, and the right to withdraw before the recipient starts conditioning.
For the wider clinical context of transplantation and blood disease, see our overview of haematology from a clinical perspective and the bone marrow guide.
Frequently Asked Questions
Does donating bone marrow hurt?
A marrow harvest is done under anesthesia, so you feel nothing during it, but your lower back is usually sore for several days afterward. PBSC donation involves needles in both arms and often bone aches from the G-CSF injections. Most donors describe the discomfort as manageable with ordinary painkillers.
How long does the whole process take once I am matched?
From the first call to donation usually takes a few weeks to a couple of months, covering confirmatory testing, consent, and the medical exam. The donation itself takes one or two days, plus the preparation days for G-CSF if you give PBSC.
Can I change my mind after joining the registry?
Yes. Donation is voluntary at every stage. The one time to be especially careful is after the patient starts conditioning chemotherapy, because their own marrow has then been destroyed and withdrawing could put their life at risk; this is why coordinators ask for a firm decision before that point.
Will I have less bone marrow after donating?
Only temporarily. The amount removed is a small fraction of your total marrow, and your body replaces it naturally. Donors are not left with a lasting deficit or a weaker immune system.
