What Is A Bone Marrow Transplant?

What is Bone Marrow?

Bone marrow is the soft spongy tissue that fills the cores of larger bones in humans and other animals.  Unlike the hard, or compact, tissue that forms the outer shells of bones, the marrow has a malleable, sponge-like texture.  It serves an active function in the body by producing all three types of blood cells, as well as lymphocytes, which support the immune system.  Transplants are frequently performed in patients whose own marrow has become diseased.  Additionally, marrow is a major source of stem cells, which can be harvested for certain medical treatments.  Rich in nutrients, bone marrow even makes a highly desirable food source for animals as well as for humans in numerous cultures.

What is a Bone Marrow Transplant?

Bone marrow transplants is a procedure used to treat patients with life-threatening blood, immune system or genetic disorders. This includes leukemia and other blood or bone marrow cancers. A bone marrow transplant replaces the unhealthy blood-forming cells with healthy ones. Healthy bone marrow stem cells are harvested from matching bone marrow donors.

What are the chances for a match?

For siblings, the chances for a compatible bone marrow match is 1 in 4.  Both of William’s brothers, Vince and Marvin, are unfortunately not matches.

The odds are 1 in 20,000 to 1 in a 100,000 in identifying an unrelated compatible marrow donor.  The more possible donor, the better the chances for William and others like him.

When a donor and patient’s bone marrow compatibility is tested, doctors are looking for matching HLA tissue types.  HLA stands for human leukocyte antigen, which is a hereditary protein found on most of the cells in the body.  These proteins act as markers and signify which cells belong in the body and which do not.  Because these markers are hereditary, each person has two sets which include one from each parent.

To evaluate a person’s bone marrow, doctors look at six HLA antigens, but many transplant centers look at eight or ten antigens.  For a successful bone marrow match, at least five antigens must match.  The process used to ensure the best match possible for a donor and recipient is called confirmatory typing.  Bone marrow transplants that use the marrow of another person are called an allogenic bone marrow transplant and are the most popular.

How can I find out if I am a match?

To find out if you are a match, all it takes is to do a buccal swab test (sample from the inside of your cheeks) using a sample kit. To order your buccal swab test kit, please refer to HERE.  If you are a match, your local bone marrow registry will be in touch with you to discuss next steps.

If I am a match, how is the bone marrow transplant done?

Bone Marrow can be collected from a matching donor in 2 possible ways:

  1. Bone Marrow Harvest–This minor surgery is performed under general anesthesia, meaning the donor will be asleep and pain-free during the procedure.  The bone marrow is removed from the back of both hip bones.  The amount of marrow removed depends on the weight of the person who is receiving it.
  2. Leukapheresis–First, the donor is given 5 days of shots to help stem cells move from the bone marrow into the blood.  During leukapheresis, blood is removed from the donor through an IV line in a vein.  The part of white blood cells that contains stem cells is then separated in a machine before being returned to the donor.

Based on William’s USC oncologist, Leukapheresis is the likely process that is needed for his treatment.  This is a minimally invasive procedure for the donor.


  1. wiseGEEK
  2. MedlinePlus