Bone Marrow Donation: Treatment, Effects & Risks

Currently, the German Bone Marrow Donor Institute (DKMS) is eagerly recruiting new bone marrow donors. No wonder, a bone marrow donation represents the only chance of a cure for many people affected by leukemia and other blood diseases. With its more than 6 million registered donors, many lives have already been saved or prolonged.

What is bone marrow donation?

There are two different application methods to harvest stem cells from bone marrow to a donor, by collecting stem cells from peripheral blood or by puncturing the pelvis. Bone marrow donation is most often defined by the disease that the very donation is intended to fight: Leukemia, sporadically referred to as blood cancer. Leukemia is a very dangerous blood disease in which the new formation of white blood cells, leukocytes, which are part of the immune system, is disturbed. Like a production plant that has been given the wrong blueprint, the diseased bone marrow ceaselessly produces defective leukocytes that attack all other blood cells instead of foreign bodies. In Germany, around 10,000 people contract leukemia every year, including many children and young people. About one fifth of all cases are fatal. A donation of healthy bone marrow is still the best chance of a cure. When looking for the right donor, it is important that the HLA tissue characteristics (human leukocyte antigens) of the sick person and those of the donor are as identical as possible. HLA characteristics are surface features of body cells, certain structures by which the immune system distinguishes the body’s own cells from those of other organisms. There are many different HLA characteristics, and each chromosome has two of them, one from the father and one from the mother. In addition to the more than 100 expressions that each HLA trait can have, this leads to more than 10,000 combinations of different overall HLA patterns. Therefore, there are only a few matching donors for each person. And only one third of all affected people find donors within their own family. This is why donors from other countries are needed, who can be quickly found with the help of the DKMS network. But still one fifth of all patients do not find a donor.

Function, effect and goals

Today, there are two different application procedures for taking stem cells from the bone marrow of a donor, the first of which is much less invasive: it is the collection of stem cells from the peripheral blood. In this procedure, it is first necessary to ensure that stem cells are detached from the bone marrow and enter the bloodstream. This is accomplished with the drug G-CSF, which is injected under the donor’s skin twice a day during a four-day pretreatment. The actual collection then begins, during which blood is drained from the donor and filtered in a cell separator – a centrifuge that separates the blood cells according to their mass – before it is returned to the body. A second method of bone marrow donation, rarely used today, is pelvic puncture. Here, the marrow is aspirated directly from the bone, which takes about an hour and is always done under general anesthesia. The pelvis is usually used for this purpose because, firstly, it is a very large bone in the human body that can provide and regenerate enough marrow. And secondly, the bone lies directly under the skin at the sides, which is why it is not necessary to cut deeply to reach the pelvis. Nevertheless, this puncture is considerably more aggressive than the peripheral collection of stem cells from the blood, which is why the donor may suffer a blood loss of more than one liter during this procedure. This is compensated for by collecting the donor’s own blood three weeks prior to donation. During these weeks, sufficient blood is replenished, and at the time of the donation itself, the stored blood can then be returned to the body. So basically it is a delayed autotransfusion. The bone marrow itself regenerates in the donor’s own pelvic bone within just a few weeks, so the donor experiences no permanent disadvantage.

Risks, side effects, and hazards

Both methods of stem cell collection carry certain risks and side effects, albeit minor: In peripheral donation, symptoms such as bone, head, or muscle pain may occur as a result of G-CSF treatment, similar to the flu.Allergic reactions may occur, but only in very rare cases. Any long-term effects or permanent side effects of this treatment in the donor are not known. Surgical bone marrow aspiration always carries a very small residual risk due to its general anesthesia, as is the case with all operations. Bruising and pain may occur at the donor site on the bone and skin. However, even these unpleasant effects usually heal in the course of only a few days. It can therefore be summarized that the only side effects with this method of bone marrow donation have nothing to do with the loss of the marrow itself, but with the surgical procedure and the necessarily accepted injury to the skin and the pelvic bone. In connection with possible risks and side effects of bone marrow donation, it should also be mentioned that donors naturally have the right to withdraw from the donation without giving reasons if they are too unsure. However, they are only allowed to do so as long as the recipient’s preparation has not yet begun. This is because during this process, his remaining diseased spinal cord is killed with chemotherapy and/or radiation to ensure smooth subsequent settlement of the fresh donor bone marrow. Therefore, it should be understandable why withdrawing from the bone marrow donation while the patient is already being prepared can put the same in acute danger of death.