What is bone marrow and stem cell transplantation?
Bone marrow and stem cell transplantation replaces the bone marrow of a patient with the new bone marrow that is taken from another “donor” or from the patient himself.
How can one donate bone marrow?
- The donor can donate his or her bone marrow under anesthesia when medium sized needles are used to collect bone marrow from within the bones of the pelvis. This procedure usually takes one hour and involves the collection of about a quarter to half a liter of blood-like material.
- Alternatively, a donor may be hooked up to a special machine resembling one used for dialysis procedures. This machine selects stem cells (which comprise a very small fraction of circulating cells in the blood) and returns the rest to the donor. These stem cells may be used the same way that a bone marrow is used. The BMT specialist will select the more suitable procedure.
What is an autologous transplant?
If bone marrow or stem cells are collected from the patient himself then this is called autologous transplant or high-dose chemotherapy with stem cell rescue. Usually this is done after having received chemotherapy. The collected cells are stored until large doses of chemotherapy are given to eradicate residual malignant cells. The stem cells are then infused to help bone marrow recovery. Autologous transplants are usually done for solid tumors like Ewing sarcoma or neuroblastoma, where the main aim of treatment is to give large doses of chemotherapy.
What is an allogenic transplant?
Here, the bone marrow or stem cells are taken from another person. Later on, the collected cells are infused to the patient to replace of his/her bone marrow. The recipient is given chemotherapy in order to prepare their bone marrow to receive the donor cells. Allogenic transplants are usually performed in cases of leukemia, where the new cells may attack any residual cancer cells. This transplant may also be carried out in cases of bone marrow failure, thalassemia.
Can anyone donate bone marrow?
You have to be HLA-compatible. HLA stands for Human Leukocyte Antigens, which are proteins that are located on the surface of the white blood cells and other tissues in the body. HLA antigens are like blood groups. Not all people can donate blood to each other. Similarly, only compatible individuals can safely receive bone marrow. When two people share the same HLA they are said to be a "match”. For a sibling match between brothers or sisters, the chance of finding a good equivalent is about 25%.
How are bone marrow and stem cells infused?
The procedure is simple. It is similar to a regular blood transfusion that usually lasts less than an hour. Doctors and nurses take this process very seriously, because no mistakes can be tolerated. They thoroughly identify the unit of bone marrow to make sure it is the unit ordered. They will closely monitor the patient during infusion. At times, preservatives in the unit have a very strong smell that you will notice immediately after infusion starts. The odor may linger for a few days before clearing up and urine output may turn a pinkish color.
What is engraftment?
Engraftment is when after a bone marrow or stem cell transplant, the transplanted cells start to produce new cells in the bone marrow. At that time, your old blood cells are gone and you may be on antibiotics. The time it will take for your cell numbers to recover is usually about 2 weeks, more or less depending on the type of transplant. First, the white blood cells come back, then the platelets. You may need months to be completely independent of platelet and blood transfusions. Full recovery of your immune system may take between 6-12 months.
What are the risks of transplantation?
You may have immediate complications, usually as a result of chemotherapy. This includes mouth ulcerations, nausea, vomiting and liver toxicity (called VOD). This last complication can be serious depending on the degree of liver damage. Also, blood stream infections are very common, but are usually controlled with antibiotics until your blood cells recover. In an allogenic transplant, graft versus host disease is another potential complication.
What is graft versus host disease?
Graft versus host disease is the most common complication from an allogenic bone marrow or stem cell transplantation. It is when the transplanted white blood cells identify the body tissue (the host) as "foreign". The transplanted cells then attack the host's body cells. It starts with a skin rash, mild liver problems and diarrhea that can be severe. This may be controlled by giving extra medications including corticosteroids. Sometimes, the process may be prolonged and difficult to control. It may affect virtually any body organ. At KHCC, we have special experts trained in dealing with this problem as well as special machines that help in the treatment of graft versus host disease.