Having a bone marrow transplant is a complicated five stage process.
The five stages are:
- a physical examination of your body to assess your general level of health
- obtaining the stem cells that will be used in the transplant (known as harvesting)
- preparing your body for the transplant (known as conditioning)
- transplanting the stem cells
- the recovery period, during which you will be monitored for any complications or side effects
The five stages are described in more detail below.
You will have a thorough physical examination before having a stem cell transplant. Your overall level of health before the transplant will play a big part in how well you recover after the procedure.
As part of the examination, you may have some scans to check the condition of internal organs, such as your liver, heart and lungs.
Some medicines used in the conditioning and recovery process can occasionally cause problems with your organs, so it is important to know how well they are functioning beforehand.
After the transplant, your risk of developing an infection will be increased, so it is vital to ensure you do not have any current underlying infections.
If you have a cancer-related condition, you may need to have a biopsy. This involves removing a small sample of cancerous cells so they can be checked in a laboratory.
The results of a biopsy can show whether your cancer is in remission (under control) and whether there is a high risk of it returning after your transplant.
Obtaining stem cells
When you've had a physical examination, the stem cells will need to be harvested.
The usual method involves removing blood from the body, separating the stem cells from the other cells in the blood and then returning the blood to the body.
Alternatively, the bone marrow itself can be collected by removing stem cells from the hip bone using a special needle and syringe. This may be recommended for certain conditions that require a transplant, or if the donor is a child.
If they are suitable, it may be possible to use your own stem cells. This is known as an autologous transplantation. They can be harvested using either method described above.
Your stem cells may need to be treated with radiation or chemotherapy to ensure that there are no cancerous cells left.
If your bone marrow is being extracted, a needle will be used to remove about a litre of bone marrow. It will usually be removed from your hip bone while you are under general anaesthetic. The procedure is low risk but the area where the needle is inserted may be painful afterwards.
The procedure may need to be carried out several times before enough bone marrow is harvested.
If your own stem cells are not suitable, stem cells will be harvested from a healthy donor. This is known as allogeneic transplantation.
There are currently over 400,000 potential donors on the UK bone marrow register but more are needed, particularly from certain ethnic groups.
There is a particular shortage of donors from African, African-Caribbean, Asian, Jewish, eastern European and Mediterranean communities.
The more people who register, the more chance there is of finding a matching tissue type for someone who needs a transplant. When a suitable donor is found, their identity and location and those of the patient remain confidential. However over time and if both sides want to, NHS Blood and Transplant can facilitate written contact between donor and recipient and this can eventually result in face-to-face contact.
The process of harvesting cells from a healthy donor is similar to the one used for an autologous transplant.
For four days before the transplant, the donor will be given medication to stimulate the production of stem cells in their blood. On the fifth day, they will have a blood test to check they have enough circulating stem cells.
They will then be connected to a cell-separator machine. A general anaesthetic is not needed, which means the harvesting can be done as an outpatient procedure.
Blood is removed through a vein in one arm and passed through a filtering machine to separate the stem cells from other blood cells. It is then returned to the body through a vein in the other arm.
If the number of cells obtained is insufficient, the donor may be asked to return on the sixth day to make another donation. The procedure usually requires about two sessions lasting 2-3 hours on successive days.
Removal of bone marrow from the hip bone is carried out in hospital, under general anaesthetic, using a needle and syringe.
Although it is not a surgical operation, some marks from the needle will be left on the skin. There may also be some discomfort where the needle has been inserted.
As a result, the donor will need to stay in hospital for up to 48 hours and have a period of recovery at home lasting up to five days.
Preparing your body
As part of your conditioning, you will need to be given a range of medicines, so a tube will be inserted into a large vein near your heart. This is known as a central line and will avoid the need for you to have many painful injections.
The conditioning process involves using high doses of chemotherapy and possibly radiation. It is done for three reasons:
- to destroy the existing bone marrow and make room for the transplanted tissue
- to destroy any existing cancer cells
- to stop your immune system working in order to reduce the chance of the transplant being rejected
The conditioning process usually takes four to seven days. You will probably need to stay in hospital throughout the procedure. Side effects from chemotherapy are common and include:
The side effects can last for several weeks after the conditioning has finished, although mouth ulcers and skin rashes should stop once the transplanted tissue begins to produce new blood cells. Hair usually grows back within three to six months.
Two less common side effects of the conditioning process are lung damage and a condition called veno-occlusive disease.
Veno-occlusive disease causes the blood vessels in your liver to swell, stopping it from removing waste products from your body. This can cause abdominal pain, jaundice (yellowing of the skin) and weight gain.
Veno-occlusive disease can be treated with medicines to help prevent blood clots, as well as using blood transfusions and reducing the amount of salt in your diet.
Lung damage or a lung infection can be treated with oxygen, antibiotics and sometimes other treatments. Steroids (strong medication) may also be given to dampen potentially dangerous immune reactions.
Read more about the risks of bone marrow transplants.
It is usually possible to carry out the transplant one to two days after conditioning has finished.
The donated stem cells will be passed into your body through the central line. The process can take from half an hour to several hours to complete, depending on the type of blood cells being used.
The transplant is not painful and you will be awake throughout the procedure.
You may feel weak after the transplant, and you may experience vomiting, diarrhoea and have a loss of appetite.
To prevent malnutrition (a lack of essential nutrients), you will need to have nutritional support, with high-protein fluids taken by mouth or through a tube running through your nose to your stomach.
The first stage of the recovery process involves waiting for the stem cells to reach your bone marrow and start producing new blood cells. This is known as engraftment and it usually occurs 15-30 days after the transplant takes place.
During this period, you will need to have regular blood transfusions because you will have a low number of red blood cells.
You will also be at increased risk of developing an infection because you will have a low number of white blood cells. This means that you will need to stay in hospital in a germ-free environment.
You may be allowed visitors, but it is likely they will have to wear surgical gowns and hats to prevent infection. Antibiotics may also be used to either prevent or treat infections.
Once engraftment has occurred, your bone marrow will begin producing blood cells. However, you will still be very weak due to the effects of the chemotherapy.
You will also still have a high risk of developing an infection because it can take one to two years for your immune system to return to its full strength.
You may also be given medicines that stop your immune system from working (immunosuppressants) to prevent graft versus host disease (GvHD).
Many people are well enough to be discharged from hospital one to three months after having a bone marrow transplant. However, if you develop complications, such as an infection, you may not be able to leave hospital until more than three months after the transplant.