Stem cell transplantation can lead to a cure for blood-forming disorders, such as leukemia. This treatment is also known as a bone marrow transplant. The bone marrow is where the various blood cells are produced. The principle behind the therapy is to first remove the diseased cells and replace them with healthy ones. Ideally, this allows the body to produce healthy blood again.
Here you will find further information as well as a selection of specialists and centers for stem cell transplants.
What is a stem cell transplant?
Many patients suffering from leukemia or another blood disorder place great hope in stem cell transplantation.
In this procedure, a donor’s blood stem cells are transplanted into the patient. By “resetting” the disrupted blood-forming process, a complete cure is possible in the best-case scenario. The challenge with stem cell transplantation is finding a compatible bone marrow donor.
Stem cell transplantation is also called a bone marrow transplant.
What are stem cells?
The human body consists of individual cells that, working together, form the various organs. Each cell must perform a different function: A skin cell on the nose must be different from a cell in the large intestine or in bone. After all, you can’t use a molar in the heart muscle.
Thanks to the blueprints encoded in the genetic material, the body knows which cells it needs and where. It needs stem cells to produce the correct cells for each specific task. Stem cells are the starting point for the entire structure of the human body.
Numerous specialized cell types are also found in the blood, such as
- red and white blood cells with their subtypes, and
- many other components that make blood what it is.
Blood cells do not live very long and are therefore constantly being produced anew in the bone marrow. There, special stem cells are responsible exclusively for the production of various blood cells. If, due to diseases (e.g., leukemia), there is overproduction or the production of abnormal cells, this can have life-threatening consequences.
Ideally, a stem cell transplant restores healthy blood production © Henrie | AdobeStock
What happens during a stem cell transplant?
When doctors diagnose such a disease, they must decide on an appropriate treatment. This can vary greatly from person to person. The choice of treatment depends on the type of disease. The umbrella term “leukemia” encompasses a wide variety of different forms, all of which require a specific approach.
Lymphomas (malignant diseases of the lymphatic system) and certain diseases of the immune system can also respond to a stem cell transplant.
The idea behind the treatment is similar to resetting a computer’s operating system: The abnormal and defective production of blood cells is first stopped. Then, blood production is “restarted” using healthy stem cells.
First, the immune system and bone marrow are treated with radiation therapy and/or chemotherapy. Ideally, this should destroy all diseased cells. This first step is called conditioning.
Afterward, doctors transfuse healthy bone marrow into the patient through a vein. The blood stem cells contained in the stem cell donation settle in the marrow cavities of the patient’s bones. Within a few weeks, they should have completely replaced the original bone marrow.
However, because the body’s immune system is suppressed during this time, the patient faces a significantly increased risk of infection. In addition, rejection reactions to the donor material—which is foreign to the body—may occur.
What is the difference between a stem cell transplant and a bone marrow transplant?
Most people simply refer to it as a bone marrow transplant. However, this is not the only way to transfer blood stem cells.
In the past, bone marrow was generally harvested from the donor under general anesthesia. To do this, a relatively large needle was inserted into the iliac crest (near the hip), and an appropriate amount of bone marrow was extracted. This material was then processed in the laboratory, and the stem cells were administered to the recipient in the same way as a blood transfusion.
The risk to the donor is very low—aside from the general anesthesia and the usual risks and side effects associated with it. The puncture site may still be sore for a few days.
However, the term “bone marrow transplant” often leads to misunderstandings among the general public. This deters many people from registering as donors in the first place. Many people confuse bone marrow with the spinal cord. But bone marrow transplantation has nothing to do with the spinal cord. Therefore, there is clearly no risk of paralysis or other complications that would be expected from a procedure involving the spinal cord.
That is why medical professionals today prefer to use the term “stem cell transplant.”
However, there is now another procedure for transferring blood stem cells: peripheral blood stem cell collection. In this procedure, the necessary blood stem cells can be obtained directly from the donor’s blood. This procedure is possible in about 80 percent of all cases.
For this procedure, the donor receives various medications prior to collection that promote the release of stem cells into the bloodstream. The cells obtained in this way are then centrifuged and processed in the laboratory so that they can be administered to the patient.
A successful transplant typically requires six to eight rounds of this procedure, known as leukapheresis.
General anesthesia is not necessary for the donor in this case, and the entire collection can be performed on an outpatient basis.
This procedure also appears to have therapeutic advantages: In many recipients, blood cell production resumes more quickly than with traditional bone marrow transplantation. However, for about 20 percent of donors, only a direct bone marrow donation is possible.
A donor is not always required
For the treatment to be successful, the new stem cells must be as compatible as possible with the patient. This is why it is so difficult to find a suitable donor. The goal is to identify a genetic twin.
If no donor can be found or if an allogeneic transplant is not an option, an autologous transplant may be attempted. This involves the patient donating their own blood stem cells.
To do this, the patient’s own blood stem cells are first collected during remission (a phase of low disease activity). These can be reinfused later. However, there is always a risk that diseased cells will also re-enter the body in this way.
This form of treatment is most commonly used for lymphomas and, less frequently, for acute and chronic leukemia.
Stem cell transplantation is often the only hope
Although all of this is quite taxing for the patient and carries a high risk of infection, many patients have no other choice. After all, in many cases, the procedure offers relatively good prospects for a cure, though this always depends on the individual case. Most patients therefore accept the risks and side effects.
For the donor, the procedure involves relatively little effort and risk. Finding a suitable stem cell donor, however, remains the greatest challenge in the fight against leukemia and other blood disorders.