Bone Marrow Transplant or Stem Cell Transplant
Bone marrow is soft, gelatinous tissue that fills the medullary cavities, the centers of bones. The two types of bone marrow are red bone marrow, known as myeloid tissue, and yellow bone marrow, or fatty tissue
Both types of bone marrow are enriched with blood vessels and capillaries.
Bone marrow makes more than 200 billion new blood cells every day. Most blood cells in the body develop from cells in the bone marrow.
Bone marrow stem cells
The bone marrow contains two types of stem cells, mesenchymal and hematopoietic.
Red bone marrow consists of a delicate, highly vascular fibrous tissue containing hematopoietic stem cells. These are blood-forming stem cells.
Yellow bone marrow contains mesenchymal stem cells, also known as marrow stromal cells. These produce fat, cartilage, and bone.4
Stem cells are immature cells that can turn into a number of different types of cell.
Hematopoietic stem cells in the bone marrow give rise to two main types of cells: myeloid and lymphoid lineages. These include monocytes, macrophages, neutrophils, basophils, eosinophils, erythrocytes, dendritic cells, and megakaryocytes or platelets, as well as T cells, B cells, and natural killer cells.
The different types of hematopoietic stem cells vary in their regenerative capacity and potency.
Some are multipotent, oligopotent or unipotent as determined by how many types of cell they can create.
Pluripotent hematopoietic stem cells have the following properties:
- Renewal: They can reproduce another cell identical to themselves.
- Differentiation: They can generate one or more subsets of more mature cells.
The process of development of different blood cells from these pluripotent stem cells is known as hematopoiesis.
It is these stem cells that are needed in bone marrow transplant.
Stem cells constantly divide and produce new cells. Some new cells remain as stem cells and others go through a series of maturing stages, as precursor or blast cells, before becoming formed, or mature, blood cells. Stem cells rapidly multiply to make millions of blood cells each day.
Blood cells have a limited life span. This is around 100-120 days for red blood cells. They are constantly being replaced. The production of healthy stem cells is vital.
The blood vessels act as a barrier to prevent immature blood cells from leaving the bone marrow.
Only mature blood cells contain the membrane proteins required to attach to and pass through the blood vessel endothelium. Hematopoietic stem cells can cross the bone marrow barrier, however. These may be harvested from peripheral, or circulating, blood.
The blood-forming stem cells in red bone marrow can multiply and mature into three significant types of blood cells, each with their own job:
- Red blood cells (erythrocytes) transport oxygen around the body
- White blood cells (leukocytes) help fight infection and disease. White blood cells include lymphocytes - the cornerstone of the immune system - and myeloid cells which include granulocytes: neutrophils, monocytes, eosinophils, and basophils
- Platelets (thrombocytes) help with clotting after injury. Platelets are fragments of the cytoplasm of megakaryocytes, another bone marrow cell.
Once mature, these blood cells move from the marrow into the bloodstream, where they perform important functions required to keep the body alive and healthy.
Mesenchymal stem cells are found in the bone marrow cavity. They differentiate into a number of stromal lineages, such as:
- chondrocytes (cartilage generation)
- osteoblasts (bone formation)
- adipocytes (adipose tissue)
- myocytes (muscle)
- endothelial cells
Types of Bone Marrow Transplant
There are two major types of bone marrow transplants. The type used will depend on the reason you need a transplant.
Autologous transplants involve the use of a person’s own stem cells. They typically involve harvesting your cells before beginning a damaging therapy to cells like chemotherapy or radiation. After the treatment is done, your own cells are returned to your body.
This type of transplant isn’t always available. It can only be used if you have a healthy bone marrow. However, it reduces the risk of some serious complications, including GVHD.
Allogeneic transplants involve the use of cells from a donor. The donor must be a close genetic match. Often, a compatible relative is the best choice, but genetic matches can also be found from a donor registry.
Allogeneic transplants are necessary if you have a condition that has damaged your bone marrow cells. However, they have a higher risk of certain complications, such as GVHD. You’ll also probably need to be put on medications to suppress your immune system so that your body doesn’t attack the new cells. This can leave you susceptible to illness.
The success of an allogeneic transplant depends on how closely the donor cells match your own.
Symptoms of Bone Marrow Transplant
The side effects of a stem cell or bone marrow transplant are caused by high dose chemotherapy.
You might have extra side effects if you also have whole body radiotherapy as part of the treatment. Whole body radiotherapy is also called total body irradiation or TBI.
All the side effects are at their worst when you have just had your high dose treatment and for a few weeks afterwards. When your blood counts start to rise (engraftment) you will start to feel better. Let your team know if you have any side effects. They can do a lot to help you.
In the longer term, these treatments often cause infertility, although some people who have had a transplant do go on to have children.
Risk of infection
You have a low white blood cell count after your intensive treatment. So you are at more risk of getting an infection. This can be from normally harmless bacteria that we have in our digestive system and on our skin.
To try and stop this from happening you might have:
- anti-fungal medicines
You need to have a shower every day to reduce the risk of infection. If you are finding it hard to shower, let your nurse know and they can help. Your room is cleaned and your bedsheets are changed every day.
Your visitors should wash their hands before they come into your room. They might need to wear gloves and aprons like the nurses and doctors. They shouldn't visit if they have coughs or colds.
You are also at risk of infection from some foods. The rules about what you can eat are different in different hospitals. While you are an inpatient and if you need it, you have meals that are less likely to cause an infection. Talk to your nurse and dietitian about getting a good balance between what you fancy eating and what might cause an infection.
When first back at home you might need to take some precautions. For example:
- heat all hot meals thoroughly and eat them fresh
- wash and peel all fruit
- carefully wash all salad leaves
- avoid lightly cooked eggs
- avoid soft cheese
Check with your medical teams if you need to follow a special diet at home and how long this should be for.
Even with these precautions you are very likely to get an infection at some point. You will need antibiotics to treat the infection.
After a transplant you lose immunity to diseases you were vaccinated against as a child. Your transplant team will let you know which vaccinations you need to have again after your treatment. It's important that all your family have the flu vaccine and any children in your close family have their childhood immunisations.
Low red blood cell count (anaemia)
Your red blood cell count will fall after treatment. Your transplant team will check your red blood cell count every day. If it gets too low you might feel:
- lacking in energy
You might need a blood transfusion to top up your red blood cells. This will make you feel better almost straight away.
Sometimes people have an allergic reaction to a blood transfusion. Let your nurse or doctor know as soon as possible if you feel hot and shivery, or itchy. You will have medicines to stop the reaction. Your nurse may also slow down the transfusion rate.
More rarely, some people have:
- chest or kidney pain (pain in your back or side)
- a flushed face
- burning along the vein that your drip goes into
Tell your doctor or nurse straight away if you have any of the above. Your nurse will need to treat your reaction and might stop the infusion.
Risk of bleeding
Your platelet level will fall after your treatment. Platelets help the blood to clot. A low platelet level means you are at risk of bleeding. You might find you are bruising more easily than normal.
Tell your nurse or doctor straight away if you notice:
- bleeding gums when you clean your teeth
- very heavy periods
- blood in your urine or poo
- bruises or small dark red spots on your skin
Your treatment team will arrange for you to have a platelet transfusion. You have the platelets as a drip into your vein. It takes about half an hour.
Sometimes people have a reaction to platelets. This is uncomfortable at the time but soon passes. Let your nurse or doctor know as soon as possible if you feel:
Your platelet count can take a while to get back to normal after a stem cell or bone marrow transplant. It might take longer to recover if you have had your own stem cells (rather than a donor's stem cells).
Sickness and diarrhea
You might feel sick after your chemotherapy and radiotherapy. But you should start to feel better after a couple weeks. Unfortunately other treatments you have can make you feel sick, such as antibiotics. You can have anti sickness medicines for as long as you need them.
You might have diarrhoea as a reaction to the radiotherapy or chemotherapy. You might also have it due to an infection or because you have developed another side effects called graft versus host disease. Tell your nurse or doctor if the diarrhoea is severe. They will give you medicine that will help. You will also need treatment for the underlying cause of the diarrhoea.