Bone Marrow Transplants

Donors who give the gift of life – amazing heroes.

Last week a dear friend was in the hospital waiting for a cure, when the doctors decided to go to the next option – a bone marrow, aka a hematopoietic stem cell, transplant.  People who love her, friends and family were obvious, willing donors – but as is so often the case, the best match was a perfect stranger.  What an amazing thing that a volunteer was willing to save a life of someone they’d never met.  I had no idea that people are registered to be stem cell donors and that they are willing to donate to save strangers, so I began to look into this further.  I know this is kind of technical, and I have NO medical training – but I appreciate what doctors and donors can do.

For patients with life threatening conditions such as leukemia, lymphoma, aplastic anemia, and dozens of other diseases – a stem cell or bone marrow transplant is a potential cure.  There is a nonprofit National Marrow Donor Program which operates the Be The Match Registry.  They have 22 million potential donors and have already provided Hematopoietic (HLA) stem cells for more than 100,000 transplants. The odds of a patient finding a good donor match are more than 20,000 to 1, so the registry is most useful if it has a large number of possible donors.

I have seen fictional, dramatic, ‘last resort’ searches for a donor in TV dramas and movies.  I have learned that the reality of Hematopoietic stem cell transplant is reassuringly less painful and dangerous than the procedure I had envisioned.

Who is eligible to be a donor?

Most of the time, donors are between 18 and 44 because people in that age range have produced the best outcomes for patients with the lowest risk to donors.  The best match for a patient often comes from a donor with a similar ethnic background, and many ethnic groups are underrepresented in the registry.

The procedure to become a donor is quick and painless – it is a cheek swab that allows the doctors to see your HLA protein type. It is important to know that joining the registry does not mean you have to donate even if you are a match. If you are notified that you are a match, there may be more than one match. The local transplant center will walk the potential donor through the donation procedure, and you will have multiple opportunities to decide if donation makes sense for you at that time. My daughter has been registered for nearly a decade and has not received a match notification.

My friend is getting healthy and may not need the transplant  – but that does not diminish the heroism of the young stranger who agreed to be her donor – or my awe at what doctors are able to do.  Since I am not in the donor age group, I am going to send a donation to support the donors who are willing to save lives.   Be The Match – Save A Life

Part 2:

My daughter Robyn D. knows a lot about Hematopoietic stem cells and for those of you with more technical interests – here are her insights.

bone marrow transplants

© 2007 Terese Winslow
U.S. Govt. has certain rights

Transplanted ‘Hematopoietic cells’ can become the three types of blood cells: red blood cells, white blood cells and platelets.  While each of these components is crucial, white blood cells are perhaps the most critical as they are the backbone of any person’s immune system. Hematopoietic cells have a remarkable ‘homing’ ability, meaning that no matter where in the body you infuse them, they will travel through the patient’s veins and find their way to the bones, attach themselves (engraft) and begin growing.

Hematopoietic cells used to be transplanted from a donor to patient by extracting bone marrow from the donor’s pelvic bone in a surgical procedure and infusing them into a patient, just like a blood infusion.  These days almost 80% of donated Hematopoietic cells come from a process which is similar to donating plasma.  For five days before the procedure, the donor is injected with a drug which increases the number of Hematopoietic cells in the donor’s blood stream. The actual donation procedure is to insert a needle in one arm of the donor, filter the blood through a machine to remove the important cells, then return the rest of the donor blood through a needle into the other arm. This process called ‘apheresis’ is essentially the same as dialysis, and just as painless.

For the 20% or so of donors who go through the surgical harvesting procedure, they receive anesthesia, and a needle is inserted in the back of their pelvic bone to withdraw bone marrow.  In both cases, donors’ bodies replace their stem cells to 100% in 4-6 weeks.

Another source of these Hematopoietic stem cells is ‘cord blood’ or the blood in the umbilical cord after the birth of the child.  It is discarded most of the time, but now it can be frozen and banked to provide a Hematopoietic stem cells for transplant. For treating a child, blood from a single cord is typically sufficient, but for an adult you often need at least two cords to get enough cells. There are ‘cord banks’ that can help with the matching of the second cord, and as more and more people opt to store their cords, this has become a more viable option. Banking cord blood for yourself can be expensive, but there are also options to donate the cord at no cost to you – essentially salvaging a cord that would otherwise be thrown out and could provide someone else critical cells. Many countries have instituted public cord banks to try and store as many of these cords as possible as a public resource, though the US tends more heavily towards private banking.

It is worth noting that everything in this article is focused on ‘allogeneic’ transplants, or transplants from a donor other than oneself. HCT can also be ‘autologous’, meaning for some conditions the doctor will take your own bone marrow as described above, and then infuse it back into you, usually after a major treatment like chemotherapy that they worry will harm your own bone marrow in the process of killing the cancer. These are easier transplants as they don’t need any matching, but can still be complicated procedures. Many doctors hope that in the future, we might be able to harvest a patient’s own bone marrow, manipulate it in a lab to cure whatever the disease is, and re-infuse the cells to avoid matching all together. However, this ‘personalized’ approach is still many years off, and may never be financially viable, so it is critical that we maintain large databases to get the best matches for patients now.

All cells, including those transplanted during hematopoietic cell transplant (or “HCT” as it is often referred to) have little proteins on the outside of the cells called human leukocyte antigen or HLA proteins. These proteins allow the body to tell “self from not-self” so the body can fight off foreign invaders like bacteria. These HLA proteins are what doctors are “matching” when they look at donor HCT cells. If the donor cells have HLA proteins too distant from the recipient, the donor cells will either attack the person’s healthy cells – a disease called “graft vs host disease”(GVHD) – or the cells will fail to take hold and start growing in the recipient. In many cases doctors will recommend a transplant even if there isn’t a perfect match as GVHD is much more manageable than the underlying disease. This is, however, a trade off no physician or patient wants to make. Generally, the better the match, the better the outcome.

Due to the incredible complexity found in HLA proteins, only ~30% of patients who need a Hematopoietic cell transplant find a match in their families, the rest rely on volunteer donors who have registered in the Be The Match Registry or elsewhere.