All about Bone marrow transplantation
Bone Marrow Transplant(BMT) or Stem Cell Transplantation (SCT) is a procedure in which healthy bone marrow stem cells or peripheral blood stem cells replace your diseased or damaged bone marrow. BMT/ SCT is sometimes the only option if you have issues with your existing bone marrow. These issues could be due to conditions like leukemia, lymphoma, myeloma, other blood disorders like thalassemia, etc. You may have these issues due to some diseases
What is bone marrow?
Bone marrow is the soft, spongy, and fatty tissues that you have inside your bones. There are stem cells in these bone marrow tissues, which produce blood cells.
In a healthy body, the stem cells in the bone marrow produce more than 3.5 million blood cells and platelets every second. These stem cells develop into
- Red blood cells or erythrocytes, which carry oxygen and nutrients to the tissues in your body
- White blood cells or leukocytes, which fights infection and aids your immune system
- Platelets, which helps in the clotting of your blood
Healthy bone marrow and blood cells are essential for you to survive and be healthy. When the bone marrow is damaged or destroyed, it can no longer produce the stem cells. It results in anemia, weakness, infections, excessive bleeding, and sometimes even death.
Why do you need a bone marrow transplant?
A BMT or SCT can cure many diseases, mainly a few types of cancers. It helps to
- Replace damaged or diseased bone marrow due to diseases like sickle cell anemia and leukemia, affecting your bone marrow.
- Improve your immune system so that it can kill any cancer cells in your body
- Replace the damaged bone marrow due to treatments like chemotherapy and radiation
It thus helps in direct treatments, preventing further occurrences of cancer and recovery after other treatment methods.
Which are the conditions that BMT or SCT treats?
A bone marrow transplant is an ideal treatment option for many diseases. In some cases, it is the only option. Some of the conditions which can be treated by BMT are
- Aplastic anemia - A rare but serious condition where your body stops producing new blood cells.
- Multiple myeloma - A type of cancer that affects the plasma cells in your blood.
- Leukemias - A group of blood cancers that affects the white blood cells
- Lymphomas - Another kind of blood cancers that starts in your lymph nodes
- MDS - It is a group of blood disorders that disrupts the production of new blood cells in your body
- Neuroblastoma- It is a type of cancer that develops mainly in your adrenal glands
- Plasma cell disorders - They begin when your plasma cells start to multiply uncontrollably
- Sickle cell anemia - It is an inherited blood disorder affecting the red blood cells in your body
- Thalassemia - It is another inherited blood disorder in which your body does not make enough of hemoglobin
- Congenital neutropenia - It is a condition which makes you prone to repeated infections
What are the types of bone marrow transplants?
There are two types of bone marrow transplants, which are
- Autologous bone marrow transplant
- Allogenic bone marrow transplant
The disease for which you need the treatment determines the type of transplant.
What is an autologous bone marrow transplant?
In an autologous stem cell transplant, the healthy bone marrow will be taken from your own body to replace the damaged cells. It is an option in those cases where your body produces healthy bone marrow.
It is most often the treatment choice for the following diseases like
- Lymphomas - Hodgkin's and Non-Hodgkin's
- Plasma cell disorders
In these cases, you will have BMT after chemotherapy or radiation treatments. These treatments will destroy or damage your bone marrow. So, the doctors will first harvest your healthy bone marrow cells before these treatments. They will be frozen and stored for use in the transplant after the completion of chemotherapy or radiation treatment.This type is a relatively safe one as there are no risks with donor matching for transplant.
What is an allogeneic bone marrow transplant?
An allogeneic transplant uses bone marrow cells from a healthy donor to replace your bone marrow. The donor may be from your sibling(which is ideal), parents, or someone not related to you.
The doctors will collect healthy stem cells or bone marrow cells from the donor's blood or bone marrow. It can also be from a donated umbilical cord. The donor can be a sibling, other related, or unrelated individual.
An allogeneic transplant is the main choice for cases like
- Aplastic anemia
- Blood cancers like leukemias, lymphomas
- Multiple myeloma
- Sickle cell anemia
In all these cases, you will have chemotherapy or other treatments like radiation to kill the cancer cells. You will have the BMT procedure as the second phase of your treatment.
Who does the bone marrow transplant procedure?
BMT is a total team effort in any hospital. It takes a team of doctors, nurses, technicians, and others for a successful BMT procedure. It includes a team of experts like
- Medical Oncologist
- Trained transplant nurses
- Microbiologist or infection control specialists
The team will first do an extensive evaluation of you and the donor (where applicable) to ensure that both are ready for the transplant.
How do you prepare for the bone marrow transplant?
The team of doctors will do a detailed evaluation and check your medical history. They will ask for blood tests and organ function tests to check the function of your heart, lungs, kidney, and liver. These tests are important for the doctors to assess your condition and readiness for the BMT.
In the case of allogeneic transplants, your donor will also need to go for few tests. These tests are to check the general health, resistance to infections, and any exposure to viruses.
Donor matching process
A donor can be within your family or from outside. It is best to have a donor from your immediate family and that too a sibling where possible. The donor's tissue type should match with your type. This process is HLA matching.
HLA stands for human leukocyte antigen, a protein marker that helps your immune system distinguish between your own body cells and cells from foreign bodies like viruses.
There are antigens on the surface of these white blood cells, which helps in HLA matching. These HLAs reside on chromosome6 in your body.
While there are more than 100 antigens, only a few major ones affect the matching. The more the number of matches, the better it will be for the success of the BMT.
As we inherit one copy of chromosome 6 from each parent, a sibling has the best chance of having matched HLA type. In fact, there is a 25% chance of having the best match with your brother or sister.
Stem cell collection process
There are two main ways of collecting stem cells
1. Peripheral blood stem cells: In this, the stem cells will be from the donor's blood cells. The doctor will insert two needles in the veins of both arms of the donor. These needles will have a connection to a separator machine. Apheresis is the name of this process.
Blood flows out of the donor through one needle in one of the arms to the machine. The machine then separates the stem cells from the blood. The remaining blood gets back to the donor through the needle on the other arm.
There may be many such sessions to collect the needed amount of stem cells.
2. Bone marrow harvesting: It involves collecting stem cells from the donor's bone marrow using a needle. The hip bones are the most common location for collecting bone marrows. The donor will be under anesthesia during the process and so will not feel any pain.
You will need to be in the hospital a few days before the transplant for the pre-transplant workup. The days before the procedure are for the tests and evaluations.
During this time, the doctor will implant a tube (IV catheter) into a large vein near the chest or neck area. This tube (also known as the central line) will be there during the procedure. The doctors will use this central line to infuse the healthy stem cells into your body.
What happens after BMT?
The infused healthy stem cells travel through your blood to your bone marrow. They will have to start producing new blood cells for the transplant to be successful. This process, known as engraftment, may take 15-30 days. You may need blood transfusions until this time.
You will have blood tests during this period. It helps to monitor your condition and to check for any infections.
If you had stem cells from a donor, you need to have medicines. It is to
- Prevent graft-versus-host disease
- Reduce the reaction of your immune system to the foreign blood cells
- Prevent infections as your immune system will be weak and so will be a high risk for infections
Apart from these medicines, you will also have to make some changes to your diet and lifestyle. The advice from the doctors and the dieticians include steps such as to
- Limit salt intake
- Limit alcohol consumption
- Stop smoking
- Eat healthy food like vegetables, fish, and fruits
- Control your weight
- Activities to increase your stamina, strengthen your bones
What are the risks of bone marrow transplant?
A BMT is a procedure that has some risks with it. While some people will not experience any problems, others can have issues that can even be life-threatening.
Some of the common problems after BMT are
- Graft-versus-host disease (GVHD). It happens when the donor stem cells in your body start attacking the tissues in your body, assuming it to be foreign tissues.
- Damages to organs such as kidney, lungs, heart, and liver
- Infections- As the immune system is weak, the risk of infections is higher
- Infertility - BMT can affect fertility. So, you should be aware of this and plan accordingly.
What is the prognosis of the bone marrow transplant?
A BMT can be a very good cure for many diseases. The prognosis depends on many factors like
- Your age - younger the age, better are the chances
- Type of transplant - autologous transplants are safer and successful
- Nature and stage of the disease - BMT in early stages are definitely better
- Your overall health - It is a major factor as it controls the infections
- Your tolerance to medicines
The results of BMT can vary from person to person. One needs to have follow-up care after transplant for the best results