There are two types of bone marrow transplants and donations:

• Autologous bone marrow transplant is when people donate their own bone marrow. "Auto" means self.
• Allogenic bone marrow transplant is when another person donates bone marrow. "Allo" means other.

With an allogenic transplant, the donor's genes must at least partly match the recipient's genes. A brother or sister is most likely to be a good match. Sometimes parents, children, and other relatives are good matches. But only about 30% of people who need a bone marrow transplant can find a matching donor in their own family.

The 70% of people who do not have a relative who is a good match may be able to find one through a bone marrow registry. The largest one is called Be the Match (bethematch.org). It registers people who would be willing to donate bone marrow and stores their information in a database. Doctors can then use the registry to find a matching donor for a person who needs a bone marrow transplant.

How to Join a Bone Marrow Registry

To be listed in a bone marrow donation registry, a person must be:

• Between the ages of 18 and 60
• Healthy and not pregnant

People can register online or at a local donor registry drive. Those who are age 45 to 60 must join online. The local, in-person drives only accept donors who are younger than age 45. Their stem cells are more likely to help patients than stem cells from older people.

People who register must either:

• Use a cotton swab to take a sample of cells from the inside of their cheek
• Give a small blood sample (about 1 tablespoon or 15 milliliters)

The cells or blood is then tested for special proteins, called human leukocytes antigens (HLAs). HLAs help your infection-fighting system (immune system) tell the difference between body tissue and substances that are not from your own body.

Bone marrow transplants work best if the HLAs from the donor and the patient are a close match. If a donor's HLAs match well with a person who needs a transplant, the donor must give a new blood sample to confirm the match. Then, a counselor meets with the donor to discuss the bone marrow donation process.

Donor stem cells can be collected in two ways.

Peripheral blood stem cell collection. Most donor stem cells are collected through a process called leukapheresis.

• First, the donor is given 5 days of shots to help stem cells move from the bone marrow into the blood.
• During the collection, blood is removed from the donor through a line in a vein (IV). The part of white blood cells that contains stem cells is then separated in a machine and removed to be later given to the recipient.
• The red blood cells are returned to the donor through an IV in the other arm.

This procedure takes about 3 hours. Side effects include:

• Headaches
• Sore bones
• Discomfort from needles in the arms

Bone marrow harvest. This minor surgery is done under general anesthesia. This means the donor will be asleep and pain-free during the procedure. The bone marrow is removed from the back of your pelvic bones. The process takes about an hour.

After a bone marrow harvest, the donor stays in the hospital until they're fully awake and can eat and drink. Side effects include:

• Nausea
• Headache
• Fatigue
• Bruising or discomfort in the lower back

You can resume normal activity in about a week.

There are very few risks for the donor and no lasting health effects. Your body will replace the donated bone marrow in about 4 to 6 weeks.

Stem cell transplant - donation; Allogeneic donation; Leukemia - bone marrow donation; Lymphoma - bone marrow donation; Myeloma - bone marrow donation

American Cancer Society website. Stem cell transplant for cancer. www.cancer.org/treatment/treatments-and-side-effects/treatment-types/stem-cell-transplant.html. Accessed October 28, 2022.

Fuchs E. Haploidentical hematopoietic cell transplantation. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds.Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 106.

National Cancer Institute website. Blood-forming stem cell transplants. www.cancer.gov/about-cancer/treatment/types/stem-cell-transplant/stem-cell-fact-sheet. Updated August 12, 2013. Accessed October 28, 2022.

Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.