Bone marrow is a spongy substance in the centre of your bones. Your bone marrow contains stem cells, which are a type of cell from which other cells in your body can develop. The stem cells in your bone marrow mature into three types of cells. These are:
The cells are then released into your bloodstream.
Although it's often called a bone marrow transplant, this procedure is really a transplant of your bone marrow stem cells.
If you have a bone marrow transplant, your unhealthy bone marrow will be replaced with healthy stem cells. The healthy stem cells are fed into your blood through a drip and find their way to your bone marrow to make new cells. The stem cells can come from another person (a donor) – this is called an allogeneic transplant. Alternatively the cells can come from your own bone marrow – this is called an autologous treatment. However, this can only happen if the stem cells were removed at a time when they were healthy.
If you have stem cells from another person, they can come from the bone marrow or the blood of the donor. When they come from the blood, this is called peripheral stem cell harvest. If they come from the bone marrow, your donor will usually be a close relative because they are likely to have the best match. After a blood test, your doctor will compare both of your blood cells to see how well they match. This is called tissue typing.
Sometimes, doctors can find a matching donor who isn't related to you through the National Blood Service or a charity, such as the Anthony Nolan Trust.
Stem cells can also come from babies' umbilical cords, although this treatment is only suitable for children and small adults, and is still being tested.
Bone marrow transplantation is used to treat conditions that stop your stem cells working. You may have a bone marrow transplant if:
Doctors usually consider a bone marrow transplant only if other treatments don’t work or aren’t suitable for you.
A bone marrow transplant is a very intensive treatment. Your doctor will take your age and general health into consideration when deciding whether it's right for you. If you’re having a stem cell transplant from a donor, you generally need to be under 55.
Doctors are researching new, alternative treatments to a bone marrow transplant. Mini transplants involve giving a standard dose of chemotherapy because the person isn't fit enough or young enough for a high dose. It's given over five days and then donor stem cells or bone marrow are transplanted. Tandem transplants are when high-dose chemotherapy is given followed by a stem cell transplant, which is then repeated after several weeks or months.
Your doctor and nurse will discuss with you what will happen before, during and after your transplant. This is your opportunity to understand what will happen, and you can help yourself by preparing questions to ask about the risks, benefits and any alternatives to a bone marrow transplant. This will help you to be informed, so you can give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.
You may need to have chemotherapy, and possibly radiotherapy, before a bone marrow transplant if your cancer or leukaemia isn't in remission. This is because the cancer needs to be at the lowest possible level for a bone marrow transplant to work.
The first step is to collect, or 'harvest', the stem cells. The exact process depends on whether the stem cells are coming from a donor or from you.
Peripheral blood stem cell harvest
You or your donor will be given injections of growth factors for around four days. These help the bone marrow to make lots of stem cells for harvesting. Growth factors can also help your stem cells to make blood cells more quickly to help you recover from the transplant.
Harvesting the stem cells from blood takes three to four hours. You or your donor will lie down on a bed and have a drip connected to each arm, or sometimes an arm and a leg. Blood is taken from one arm and goes through a machine called a cell separator. This separates out the stem cells from the other blood cells. It will keep the stem cells and return any other blood cells to the bloodstream through the drip in the other arm or leg. Sometimes the stem cells are cleaned or 'purged' to kill off any last cancer cells, although this is a new treatment and is still being tested.
The stem cells are then frozen until you have had your high dose of chemotherapy.
Harvesting stem cells directly from the bone marrow
Stem cells can also be harvested by taking them out of the bone marrow through a needle inserted into your own or your donor's pelvic bones, or sometimes breast bone. You will have usually have a general anaesthetic or an epidural before this procedure, and will feel sore for a few days afterwards. If you have a general anaesthetic, it means you will be asleep during the procedure.
You will then have a high dose of chemotherapy to completely destroy your own bone marrow and any remaining cancer cells in your body. This treatment may take several days and can make you feel sick or vomit, and generally unwell. Your doctor or nurse will give you medicines to help relieve this.
A day or more after chemotherapy, your own or your donor's stem cells are fed through a drip into your bloodstream. It will take between two and four weeks before there are enough new stem cells in your bone marrow to start making new blood cells.
While your levels of blood cells are low, you will need blood and platelet transfusions. You will also need to take antibiotics to protect you from infection because of a lack of white blood cells. You may need to stay in hospital until your blood cells have gone back up to a safe level.
Autologous treatment usually causes fewer side-effects than a donor (allogeneic) transplant, because your body is less likely to reject stem cells that have come from your own body.
Donor stem cell transplants are physically and emotionally demanding. You may need to stay in hospital for four to six weeks and you will probably feel very ill for some of the time. You will have your own room to help protect you from infections.
Once the levels of your blood cells have returned to a safe level, you will be able to leave the hospital. You will have regular outpatient appointments afterwards. Your doctor will tell you symptoms to look out for, such as fever, which may be a sign of a complication.
As with every procedure, there are some risks associated with bone marrow transplantation. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your doctor or nurse to explain how these risks apply to you.
Side-effects are the unwanted, but mostly temporary, effects you might get after having the procedure. Straight after a bone marrow transplant, the levels of blood cells in your body will be very low. Side-effects of this include:
Complications are when problems occur during or after the procedure.
One possible complication of receiving bone marrow cells from a donor is graft versus host disease. This happens when the white blood cells of the donor attack the tissues of your body. You will be given medicines to prevent this so usually the symptoms are mild, although in some people they may be more serious.
The new stem cells that have been fed into your blood may not produce enough blood cells. If this happens, you will need another stem cell transplant.
Graft versus host disease (GVHD) is a problem that can happen after a bone marrow transplant. In some people it causes minor symptoms and in others it can be very serious or even life-threatening.
If you receive stem cells from a donor, the new cells can sometimes start to attack your body, especially your liver, skin or digestive system. This can sometimes be an advantage because the new cells also attack any remaining cancer cells.
GVHD can be acute (develops within 100 days of your transplant) or chronic (develops more than 100 days after your transplant). Acute GVHD symptoms can be minor or serious, and include:
If you have acute GVHD, you can develop chronic GVHD, or it can develop without acute GVHD. It can cause the symptoms of acute GVHD as well as others including:
Your doctor will monitor you carefully in the weeks and months after having a bone marrow transplant. Your doctor may prescribe medicines to weaken or switch off (suppress) your new immune system.
If GVHD affects your lungs or digestive system, it will do so soon after your transplant. If it affects your skin, it may cause long-term problems. Your skin may become tighter with less elasticity and you may suffer from skin rashes. Your doctor may advise you to stay out of the sun.
Having GVHD doesn't mean that the transplant hasn't worked. In fact, people who have some GVHD are often less likely to have a relapse.
There are two main methods of harvesting stem cells – either from the bone marrow or from the blood.
If stem cells are harvested directly from the bone marrow, your doctor will use a special needle to suck out the stem cells from inside your donor’s hip bones, or occasionally the breastbone. The needle will have to be placed in several different areas to collect enough of these cells. The procedure is done with a general anaesthetic or an epidural.
The area will feel painful and bruised after the procedure and your donor will probably have to stay in hospital overnight to recover. The area will feel sore for a few days afterwards but your donor will be given painkillers.
If stem cells are harvested from your donor’s blood (peripheral blood stem cell harvest), medicine is injected into the blood, which causes stem cells to be released from the bone marrow into the bloodstream. This procedure doesn't need to be done under a general anaesthetic.
More rarely, stem cells from a baby's umbilical cord can be transplanted to a brother or sister. Some hospitals offer parents the chance to collect stem cells from a baby's umbilical cord, which are then stored. Although the number of cord blood cells available is small, it may become a more common procedure in the future. However, at the moment the process is still being tested.
A bone marrow transplant gets your immune system functioning properly again.
The bone marrow is a spongy substance in the centre of your bones. It contains stem cells that mature into different types of blood cells, including white cells. The white blood cells are a major part of your immune system. They are involved in spotting 'foreign' or different cells in the body, such as bacteria or viruses, and co-ordinating the attack against them. This is what helps protect your body from infection.
Certain illnesses can affect your bone marrow and destroy the stem cells. Your body can't replace the blood cells it needs to function properly and you will need a bone marrow (stem cell) transplant to survive. However, not all conditions or diseases that damage the immune system can be treated with a bone marrow transplant.