What is a Stem Cell Transplant?
- A stem cell transplant is used to increase the chance of a cure or remission for various cancers and blood disorders.
- A stem cell transplant may be necessary if your bone marrow stops working and doesn't produce enough healthy stem cells.
- A transplant may occasionally be required to suppress an overactive immune system
- A stem cell transplant also may be performed if high-dose chemotherapy or radiation therapy is given in the treatment of blood disorders such as leukaemia, lymphoma or multiple myeloma.
- The treatment requires close nursing and medical care for a number of weeks. It is an intensive treatment and there are risks involved in undergoing this therapy.
What is the bone marrow, and what are stem cells and blood cells?
Blood cells are made in the bone marrow, by stem cells. Bone marrow is the soft sponge-like material in the centre of bones. Large flat bones such as the breastbone (sternum) and pelvis contain the most bone marrow. To make blood cells constantly you need a healthy bone marrow. You also need nutrients from your diet, including iron and some vitamins.
Stem cells are early (immature) cells. Stem cells constantly divide and produce new cells. Some new cells remain as stem cells, whilst others go through a series of maturing stages (precursor or blast cells) before forming into mature blood cells.
Mature (fully formed) blood cells are released from the bone marrow into the bloodstream.
Mature blood cells are:
- Red cells (erythrocytes) - These make blood a red colour. One drop of blood contains about five million red cells. Red cells contain a chemical called haemoglobin which binds to oxygen and takes oxygen from the lungs to all parts of the body.
- White cells (leukocytes) - The different types of white cells are called neutrophils, lymphocytes, eosinophils, monocytes, and basophils. They are part of the immune system and their main role is to defend the body against infection.
- Platelets - These are tiny cells and help the blood to clot if we cut or injure ourselves.
The bone marrow is very active, and stem cells rapidly multiply to make billions of blood cells each day. Because chemotherapy drugs work by killing rapidly dividing cells (such as cancer cells), the bone marrow cells are more easily killed by chemotherapy than most other cells in the body. Stem cells are relatively resistant to chemotherapy; however high doses given during preparation for transplant will kill most stem cells.
Where are stem cells obtained from?
An Autologous Transplant
This means that the stem cells used for the transplant come from your own body. They are usually collected when you are free of any sign of disease (when you are in remission) following conventional chemotherapy or other treatments. The stem cells can be used soon after being collected, but most often are frozen, stored and used in the future. An autologous stem cell transplant is also called stem cell support, as the stem cells come from your own body.
An Allogeneic Transplant
This means the stem cells used for the transplant come from someone else - a donor. All people (except identical twins) are different, and tests are required to see if you are similar enough to the donor to allow the transplant to take place. You may be aware of your blood group (and indeed we will test this as well), but more importantly, we are looking at the major HUMAN LEUKOCYTE ANTIGEN (HLA) system or tissue typing. This is similar to blood group but involves all the tissues and organs of your body. It is possible to have a full match, a partial match (mismatch or half match) or not a match at all. Each full brother or sister has a 25% of being a full match, and a 50% chance of being a half (haplo) match. Each parent or child is usually a half match for the recipient.
Stem cells can be collected:
- From the bone marrow. This involves a small operation to collect some marrow from the pelvic bone. This method is much less common currently than harvest from the blood.
- From the blood. Some stem cells occur in the blood, but most are in the bone marrow. Drugs are given for a few days before this procedure to stimulate the body to make more stem cells in the bone marrow, which then spill out into the blood. The stem cells in the blood can be collected (harvested) by a machine called a cell separator. The blood flow is diverted from a vein in the arm to pass through the machine which separates out the stem cells. The procedure takes about 4-6 hours.
- From blood taken from the umbilical cord of a new born baby; this is usually only used in children, and rarely in adults.
A stem cell transplant poses many risks or complications, some of which are potentially fatal. The risk can depend on many factors, including the type of blood disorder, the type of transplant, and the age and health of the person. Although some people experience few problems with a transplant, others may develop complications that may require treatment or prolonged hospitalisation. Some complications could even be life-threatening.
Complications that can arise with a stem cell transplant include:
- Infections are the main risk.
Following the intensive chemotherapy, and before the time your bone marrow is working again, you have very low immunity. During this time, you are at risk of serious and life-threatening infections. This is why antibiotics are given and you will be nursed away from other people until your bone marrow recovers. However, even though your bone marrow function appears to recover, you will be at long term risk for increased infections.
- Nausea, vomiting and diarrhoea
- Mouth sores or ulcers
- Hair loss
- Infertility or sterility (the inability to produce children)
- Reduced libido and sexual potency (may be short-term or long-term)
- Glandular dysfunction
- Bleeding problems from the low level of platelets after the chemotherapy
- Stem cell (graft) failure
- Organ injury to the liver, kidneys, lungs and/or heart.
- Cataracts(clouding of the lens of the eye, which causes loss of vision), particularly if radiotherapy is given
- New cancers
- Graft-versus-host disease:
A potential risk when stem cells come from donors: If you're undergoing a transplant that will use stem cells from a donor (allogeneic stem cell transplant), you may be at risk of graft-versus-host disease. This condition occurs when a donor's transplanted stem cells attack your body. Graft-versus-host disease can be mild or severe. This complication can develop within a few weeks of the transplant (acute GVHD) or much later (chronic GVHD). To prevent this complication, then you may receive medications that suppresses the immune system. Graft-versus-host disease can affect any organ, commonly the skin (rash, often like sunburn), gut (mouth sores, abdominal pain, diarrhoea, nausea or vomiting), liver (jaundice or yellowing of the skin), lungs (blocked airways) or eyes (irritation and light sensitivity). It can lead to chronic disability due to organ injury or infections and can be life-threatening. Your doctor will monitor you closely for signs and symptoms of graft-versus-host disease.
Pre-transplant tests and procedures
Finding a donor (for allogeneic transplant):
Samples of blood will be drawn from a vein in your arm and will be sent for testing (usually in the Tissue Typing Laboratory NHLS in Cape Town, but occasionally also sent to the SANBS [blood bank] or specialised laboratories in Europe).
Samples of your blood will also be frozen at this lab, for use in further testing (avoiding the need except in exceptional circumstances to repeat the blood draw) or monitoring in post-transplant testing should you undergo a successful transplant. Testing usually takes a few weeks; however, the whole process may take a lot longer depending on:
- You provide us with all the names and contact numbers of your brothers, sisters and other potential family members to test, and that they agree to be tested.
- If no fully matched donor is found, the options such as an unrelated donor (on either the local South African donor registry – SABMR, or international donor registries) or haplo-identical (half- matched family donor) will be considered. The decision is based on your illness for which you require the transplant, the funding options from your medical aid / insurance, your general condition and the possible donor options.
- Unrelated donor search can take considerable period of time to complete.
- Some people who need an allogeneic (donor transplant) may never find a suitable donor.
Once a donor is found, and the transplant is scheduled, you'll undergo a series of tests and procedures to assess your health and the status of your condition, and to ensure that you're physically prepared for the transplant.
Samples of blood will be drawn from a vein in your arm and the following laboratory tests will be performed:
- FBC-full blood count
- CMP-comprehensive metabolic panel
- Pregnancy test (all females)
- Bleeding times
- ABO blood type
- Infectious disease tests — *human immunodeficiency virus (HIV), cytomegalovirus (CMV), toxoplasmosis, hepatitis, Epstein-Barr virus (EBV), herpes, malaria and syphilis
*Informed consent and discussion done separately
In addition, a surgeon may implant a long thin tube (intravenous catheter) in your chest near your neck. Alternatively, a large drip can be placed in the chest or neck in the ward by one of the doctors. The catheter, often called a central line, usually remains in place for the duration of your treatment. Your doctors will use the central line to infuse the transplanted stem cells and other medications and blood products into your body.
The conditioning process
After you complete your pre-transplant tests and procedures, you begin a process known as conditioning. During conditioning, you'll undergo chemotherapy and possibly radiation to:
- Destroy cancer cells
- Suppress your immune system so that your body doesn't reject the transplanted stem cells
The type of conditioning process you'll be given depends on a number of factors, including your disease, overall health and the type of transplant planned. You may have both chemotherapy and radiation or just one of these treatments as part of your conditioning treatment.
Side effects of the conditioning process can include: mouth sores, nausea, vomiting, be unable to eat, lose your hair, and have lung or breathing problems.
You may be able to take medications or other measures to reduce such side effects.
'Mini' stem cell transplants
A mini stem cell transplant, also called reduced-intensity conditioning or a non-myeloablative transplant is a type of allogeneic transplant that involves a less intense conditioning option.
Reduced-intensity conditioning, which includes lower doses of chemotherapy and radiation, kills some cancer cells and somewhat suppresses your immune system. Then, the donor's cells are infused into your body. Donor cells replace cells in your bone marrow over time and immune factors in the donor cells may then fight your cancer cells.
A less intense conditioning regimen may seem attractive because it involves less intense chemotherapy and radiation. However, this kind of transplant isn't appropriate for all situations.
What you can expect during your stem cell transplant
Stem cell transplantation involves infusing, or injecting, donor stem cells through a drip into your body after completion of several days of chemotherapy, radiation therapy or both. The infusion usually takes one to a few hours.
The transplanted stem cells make their way to your bone marrow, where they begin creating new blood cells. It can take a few weeks for new blood cells to be produced and for your blood counts to begin recovering.
Bone marrow or blood stem cells that have been frozen and thawed contain a preservative that protects the cells. Just before the transplant, you may receive medications to reduce the side effects the preservative may cause. You'll also likely be given IV fluids (hydration) before and after your transplant to help rid your body of the preservative. Side effects of the preservative may include nausea, fever, diarrhoea, chills, hives, red urine.
Not everyone experiences side effects from the preservative, and for some people those side effects are minimal. Supportive management during the immediate transplant period will be provided in a protected environment at the transplant centre where you are being treated. You will most likely receive blood transfusions, antibiotics as indicated for infection prevention and treatment.
After your stem cell transplant
- In the days and weeks after your stem cell transplant, you'll have blood tests and other tests to monitor your condition.
- You may need medicine to manage complications, such as nausea and diarrhoea.
- After your stem cell transplant, you'll need to remain under close medical care.
- If you're experiencing infections or other complications, you may need to remain in the hospital for several days or weeks. Depending on the type of transplant and the risk of complications, you'll need to remain nearby for several weeks to months to allow close monitoring.
- You may also need periodic transfusions of red blood cells and platelets until your bone marrow begins producing enough of those cells on its own.
- Due to the risk of infection and immune system dysfunction during the years following transplant, it is essential that you attend the clinic for regular follow-up as well as be compliant with your home medication.
- You may be at greater risk of infections or other complications for months to years after your transplant.
- Photopheresis or extracorporeal photoimmune therapy is a procedure that might be recommended by your doctor to prevent or to treat graft versus host disease (GvHD). This procedure offers another way to try to suppress the donor lymphocytes (type of white blood cells) that stimulate immune reactions and aid in the development of GvHD. A few patients might experience a slight drop in blood pressure during the procedure. This is easily corrected by receiving intravenous fluids. You must avoid sunlight, even if it's indirect sunlight, for 24 hours after each procedure since you will be more sensitive to the sun. If you go outside, please apply sunscreen with at least SPF 15. Please wear UVA protective sunglasses in a "wraparound" style to protect the sides of your eyes.
- Patients who have received a stem cell transplant from a related or unrelated donor could still experience a relapse of their underlying disease/cancer. A donor leukocyte infusion (DLI) is a possible strategy for managing a patient in relapse. In this procedure, the patient receives a boost of immune cells from the original donor's blood. In certain circumstances, it may be extremely effective in controlling recurrent cancer in a patient.
A stem cell transplant can cure some diseases and put others into remission. Goals of a stem cell transplant depend on your individual situation but usually include controlling or curing your blood disorder, extending your life, and improving your quality of life. Some people complete stem cell transplantation with few side effects and complications. Others experience numerous challenging problems, both short and long term. The severity of side effects and the success of the transplant vary from person to person and sometimes can be difficult to predict before the transplant.
It can be discouraging if significant challenges arise during the transplant process. However, it is sometimes helpful to remember that there are many survivors who also experienced some very difficult days during the transplant process but ultimately had successful transplants and have returned to normal activities with a good quality of life.