A bone marrow transplant (BMT) is a process performed to replace either the destroyed or damaged bone marrow with healthy bone marrow. Bone marrow is soft and fatty tissue present inside the bone, producing blood cells.
BMT usually involves taking the cells found in the bone marrow and then giving them back to the patient or another person. BMT aims to transfuse the healthy bone marrow cells into a person after his unhealthy bone marrow has been treated for killing the abnormal cells. Bone marrow is found in your large bones. It produces around 200 billion new blood cells every day, including white blood cells, red blood cells and platelets. But it does not work correctly for people with bone marrow disease, including several types of cancer. A bone marrow transplant increases a person’s chance of survival, and it is the best cure—a bone marrow transplant exchanges unhealthy bone marrow with healthy tissue.
Why is a Bone Marrow Transplant required?
A bone marrow transplant is an essential treatment for some people with a blood cancer like lymphoma, myeloma and leukaemia. After a blood transplant, you can take high doses of chemotherapy and other treatments. The stem cells are taken from the bloodstream or the bone marrow. People have a transplant either using their stem cells (autologous transplant) or stem cells from a matching donor (allogeneic transplant). Different types of diseases may affect the functioning of the bone marrow and may require bone marrow transplants. Some similar conditions are listed below.
Multiple Myeloma is treated with the help of bone marrow transplant. It is a cancer that develops in the white blood cell. A bone marrow transplant can be a practical part of treating multiple Myeloma. Hematopoietic stem cells are located in the bone marrow. They can produce blood cells, such as white blood cells, red blood cells, and platelets. In this procedure, hematopoietic stem cells are collected from the patient or another person.
Amyloidosis is a rare disease. It occurs when amyloid (an abnormal protein, usually formed in the bone marrow) is dumped in any tissue or organ, and it starts interfering with its normal functions. Depending upon the type of amyloidosis, a bone marrow transplant may be recommended.
Acute or chronic Leukemia
It is a blood or bone marrow cancer that may eventually need a bone marrow transplant in specific high-risk subtypes.
Hodgkin’s or Non-Hodgkin’s Lymphoma
Hodgkin’s or Non-Hodgkin’s Lymphoma are the cancer of lymphocytes (type of white blood cell). These lymphocytes are a significant factor for the immune system.
Myelofibrosis is the rarest type of blood cancer where bone marrow is replaced by fibrous scar tissue. Bone marrow transplant is a treatment that might benefit this medical condition.
Germ cell tumors
These are tumors where there is the growth of cells from reproductive cells. They may be cancerous or non-cancerous and are mainly found in the ovaries or the testicles.
These disorders can lead to abnormally low activity or overactivity of the immune system. Overactivity of the immune system causes the body to attack and damage its tissues (autoimmune diseases). Low immune system activity decreases the body’s stamina to fight outsiders, making it vulnerable to infections.
Bone marrow failure
Bone marrow cannot form blood cells. After receiving chemotherapy and radiation therapy for cancer, some patients may need a bone marrow transplant for Aplastic Anaemia or Myelodysplastic syndrome. Some patients after receiving chemotherapy and radiation therapy for cancer, may need a bone marrow transplant.
How to find matching donor cells
To be a donor, your stem cell must be matches with the stem cells of the person you are donating. To confirm this, a blood test is done. This blood test looks at HLA typing or tissue typing. Bone marrow transplantation is a difficult medical procedure and is not recommended for everyone. The healthcare team would evaluate the patient by conducting various medical tests, a complete physical examination and psychosocial evaluations to decide whether that patient is a suitable candidate for bone marrow transplantation.
Conditions required for donating cells
You could become a healthy donor for a bone marrow transplantation if you meet the following conditions:
Age: Healthy individuals between 18 to 60 years could be ideal candidates for a bone marrow transplantation.
Weight: To register as a potential blood stem cell donor, the maximum Body-Mass-Index (BMI) limit is 40 kg/m2. Additionally, if a person is not eligible for donating their blood stem if his weight is below 50 kg.
Health conditions: People with autoimmune diseases, chronic illnesses, such as diabetes or rheumatism, chronic heart diseases, chronic lung diseases, infectious diseases, such as HIV, hepatitis B or hepatitis C, and syphilis cannot be a donor. Blood disorders are not eligible for donating their stem cells. If someone is suffering from the central nervous system or any mental illness, he is not suitable for a blood transplant.
Pregnant women can also donate blood stem cells. But they cannot donate until they fully recover after the delivery—types of transplantation.
There are three different types of bone marrow transplants.
Autologous bone marrow transplant
This is a bone marrow transplant where your cells are used. Before receiving a high dose of radiation or chemotherapy, your cells are removed and stored in the freezer in this treatment. After receiving radiation or chemotherapy treatments, these cells are put back in your body to help in making normal blood cells. This is also known as a rescue transplant.
Allogeneic bone marrow transplant
This is a type of bone marrow transplant where cells are removed from another person (donor). Most times, the genes of the donor must at least partly match your genes. Before initiating the process, some special tests are done to see if a donor is a good match for you. A sibling is most likely to be a good match. However, sometimes children, parents, and other relatives are also suitable matches. In some cases, donors who are not related to you but matches you, are considered.
Umbilical cord blood transplant
This transplant is a type of allogeneic transplant. In this process, cells are removed from a new born baby’s umbilical cord right after birth. These cells are frozen and stored until they are needed for a transplant in the future. Umbilical cord blood cells are quite immature, so there is less of a need for perfect matching. Due to the lesser number of cells, blood counts may take much longer to recover.
Types of bone marrow transplantation donors
Optimal donors: These donors have an identical HLA tissue typing, and are mostly a relative of the recipient, usually a sibling or, in rare cases, a parent or grandparent.
Partially matched donors: These donors have a 50% HLA tissue match (always half matched, or haplo compatible) with the recipient. Biologic parents are always partially matched donors for the recipient.
Alternative donors: These donors are unrelated to the recipient. They are healthy individuals with matching HLA tissue typing with the patient and are willing to donate bone marrow stem cells.
Autologous donors: In this type, the recipients themselves are the donors. Here the stem cells that circulate in the bloodstream are collected and are frozen or stored for later use. The recipient can donate only when his or her body produces enough healthy bone marrow cells.
Donating stem cells or bone marrow to a relative
A brother or sister is most likely to be a match for bone marrow transplant. There is a 1 in 4 chance of your cells matching. This is called a matched related donor (MRD) transplant. Anyone else in the family is unlikely to match. This can be very frustrating for relatives who are keen to help.
Sometimes if your cells are a half (50%) match, you might still be able to donate stem cells or bone marrow to a relative. This is called a haploidentical transplant.
You can’t donate stem cells or bone marrow to your relative if you’re not a match.
It is sometimes possible to get a match from someone outside of the family. This is called a matched unrelated donor. To find a matched unrelated donor, it is usually necessary to search large numbers of people whose tissue type has been tested. So, doctors search national and international registers to try to find a match for your relative.
Even if you can’t donate to your relative, you might be able to become a donor for someone else.