Every 16 minutes, a person in Germany receives a diagnosis of leukemia. If chemotherapy or radiation is unsuccessful, a stem cell or bone marrow transplant is often the last chance for patients. For about one third of patients, a donation from the family is an option, but often an outside donor is needed, who can be found through a donor file. Read here how you can be typed and learn more about the process and risks of a stem cell donation.
Search for a “genetic twin”
For a leukemia patient to receive a stem cell donation, a “genetic twin” must be found: a donor in whom certain tissue characteristics and surface markers on the white blood cells match those of the patient. If these characteristics are very rare, only one in millions of people may be considered as a donor. This is why the search often takes several months. To facilitate the search, it is important that as many people as possible register in a donor file. The largest and best-known organization in Germany is the DKMS – the German Bone Marrow Donor Center. Since 1991, 3.7 million people have had themselves typed there.
Becoming a donor through typing
Anyone between the ages of 18 and 55 who is physically healthy and weighs over 50 kg can register in a donor file. Whereas in the past a blood sample was necessary for typing, today a swab of the cheek mucosa with a cotton swab is sufficient. You can register online with the DKMS and then have a kit sent to your home. After the swab has been taken, you simply return the cotton swab – free of charge, of course. However, typing costs DKMS 50 euros, which covers the laboratory costs for determining the characteristics. Therefore, the donor files are constantly dependent on donations and funding campaigns. Often, the DKMS or other organizations organize typing events where anyone can obtain information and register directly without registration. There, helpers take the swab and are available to answer questions.
Finding the right donor
After typing, the anonymous donor data is passed on to the Central Bone Marrow Registry Germany (ZKRD), where it is collected and passed on to patients worldwide. Once initial similarities have been established between a leukemia patient and a potential donor, additional tissue characteristics of the donor are verified by a blood sample. If there is also a sufficient match here, the potential donor is thoroughly examined physically. Only when all requirements have been met and a doctor has explained the procedures and all possible side effects does the potential donor make a final decision on whether to donate. If donation does occur, stem cells can be collected by two different methods.
Donate stem cells or bone marrow?
Nowadays, in 80 percent of cases, the so-called peripheral stem cell donation (apheresis) is performed. In this procedure, a hormone-like substance (growth factor C-GSF) is injected under the donor’s skin for five days. This causes the stem cells, which are normally located mainly in the bone marrow, to be stimulated to multiply and float into the blood. Flu-like symptoms may occur during this stimulation phase. After completion of this phase, the so-called apheresis follows, which functions similarly to a blood donation: The blood is drained through a venous access and the stem cells are filtered out; at the same time, the rest of the blood is returned to the donor. This method takes about four hours and is more comfortable for the donor than a bone marrow donation because it is done on an outpatient basis and does not require anesthesia. If not enough cells could be collected, the procedure must be repeated the next day.
Surgery for bone marrow donation
In the conventional method – bone marrow donation – bone marrow along with the life-saving stem cells is collected from the iliac crest under general anesthesia. Bone marrow here is not to be confused with the spinal cord, which is part of the central nervous system and has nothing to do with stem cell donation. The bone marrow is quickly replenished by the body, so there is no deficiency in the donor. As with any surgery, there is a minimal risk of anesthesia and infection, and there may also be wound pain.Usually the donor stays in the hospital for one to two nights. This method has been increasingly replaced by peripheral stem cell donation since 1996 and is now used only in special cases. For example, bone marrow donation is resorted to when the recipient is a child or has a certain form of leukemia for which bone marrow is more effective. Overall, the risks with both methods are low, and usually the donor is fit again after a few days. The donation is usually made at a collection center in the donor’s vicinity, in order to minimize the expense to the donor. All costs incurred are covered by the recipient’s health insurance. After collection, the cells are transported by courier to the patient’s clinic, where they are transplanted the same day.
What do the stem cells do?
In the patient, chemotherapy and other drugs completely destroy the diseased bone marrow during a preparatory phase (conditioning). This is important for two reasons:
- First, the cancer cells that originate from the bone marrow must be destroyed as much as possible.
- Second, the patient’s immune system must be suppressed so that the foreign stem cells are not rejected.
After this phase, the transplantation of the healthy stem cells of the donor takes place, which the recipient receives like a blood transfusion into the veins. From the bloodstream, the cells find their way into the bone marrow of the patient by themselves. There, the stem cells settle and form new, healthy blood cells that kill the remaining cancer cells. Ideally, the donated stem cells thus defeat the leukemia and the patient is cured.
Risks and complications
The success rate of a stem cell transplant is about 40 to 70 percent and depends on many factors, such as the patient’s age and condition and the type of disease. In addition, as with any treatment, complications can occur: Since the patient lives for several weeks completely without an immune system, infections are very common despite extensive hygiene measures. In addition, so-called “graft-versus-host disease” can occur: In this case, the “foreign” immune system created by the donated stem cells attacks the recipient’s body. This manifests itself, for example, as skin and mucous membrane inflammations or problems in the gastrointestinal tract. Last but not least, there is always the possibility that the cancer will return.
Contacting the patient
You don’t get any money for donating stem cells – the reward is the good feeling of possibly having saved someone’s life. The donation is anonymous, but there is a possibility to contact the patient by letter. At the request of both parties, anonymity is lifted after two years and a meeting between donor and patient may occur.