Preparing for stem cell transplant
When doctors are considering stem cell transplant as a treatment option, they do an assessment to find out if the person with cancer (recipient) is a suitable candidate for the procedure. Doctors may do several examinations and diagnostic tests to determine if candidates are physically and mentally prepared for the procedure. The recipient may also need other procedures to prepare for the stem cell transplant.
The doctor may do the following tests to determine if a person is a suitable candidate for stem cell transplant:
- complete medical history and physical examination
- routine blood tests, such as complete blood count (CBC) and blood chemistry tests
- tests for certain viruses, such as hepatitis, herpes and HIV
- bone marrow biopsy
- human leukocyte antigen (HLA)human leukocyte antigen (HLA)A protein found on the surface of all cells, including white blood cells (leukocytes) and platelets, that plays a role in the immune system’s response to foreign substances. typing
- CT scan or MRI
- electrocardiogram (ECG), echocardiogram (Echo) or multigated acquisition (MUGA) scan to check heart function
- chest x-ray and pulmonary function test (PFT)pulmonary function test (PFT)A test used to measure how well the lungs are working, including how much air the lungs can hold, how quickly air moves in and out of the lungs, how much oxygen is taken in and how much carbon dioxide is given off. to check lung function
Members of the healthcare team teach the person with cancer and the family about the procedure and what to expect. They discuss the risks and benefits of stem cell transplants. They will also arrange:
- dental care – There is a higher risk for oral and dental problems after stem cell transplant.
- nutritional assessment – A dietitian can help make sure the recipient is eating as well as possible.
- social work assessment – A social worker can help identify social support needs, find available resources and provide support throughout the transplant experience.
- psychological and emotional evaluation – This assessment determines the person’s strengths and coping strategies.
- fertility counselling – Infertility is usually a side effect of high-dose chemotherapy or radiation therapy.
- For men, the testicles might stop making sperm after high-dose therapy. It may be possible to freeze and store sperm before treatment so that they can be used later.
- For women, high-dose therapy can affect the ovaries and stop menstrual periods. It may be possible to freeze and store fertilized eggs (embryos) so they can be used later.
- Some recipients cannot have these fertility procedures because they have already received significant doses of chemotherapy, radiation therapy or both. It may also not be possible to have these procedures if the transplant must be done quickly.
Once recipients have been fully informed about all procedures and agree to have a stem cell transplant, they sign a consent form (informed consentinformed consentThe process by which a person learns the important facts about a procedure, treatment, clinical trial or test before deciding to participate.).
A central venous catheter (CVC) is a thin, flexible tube. It is placed into the large vein above the heart, usually through a vein in the neck, chest or arm. It is also called central venous line or central line.
- A local or general anesthetic is given before the doctor places the CVC.
- One end of the catheter stays outside the body. It is used to:
- take blood samples
- give medicines and fluids
- give the stem cells
- The catheter is put in at the time of stem cell harvest or before the high-dose therapy is given. It stays in place until it is no longer needed.
For allogeneic stem cell transplants, the recipient’s transplant doctor identifies potential matches and arranges donor testing.
To increase the chance of a successful transplant and to reduce complications, the transplanted stem cells must match the recipient’s as closely as possible. Most matches are between close family members (related donor), so the search for a donor starts with the recipient’s brothers and sisters. The closest match is an identical twin because identical twins have the same HLAs.
- HLA typing is usually done by a special blood test.
- A match of 6–10 specific antigens is thought to be important.
- A transplant is sometimes done with a match that is slightly less than perfect.
- There is a 1 in 4 (25%) chance that a sibling will be a match.
- The more siblings a person has, the higher the chance of finding a match.
If a sibling match is not found, parents or extended family members, such as aunts, uncles and cousins, may be tested. Parents and children of recipients are unlikely to be perfect matches because they pass on or receive only 3 of the 6 genes needed for a perfect match. According to Canadian Blood Services, less than 30% of people have an HLA-matched donor in their family.
If a match is not found within the family (and often only brothers and sisters are tested), the search starts for an unrelated donor in the general public through the OneMatch Stem Cell and Marrow Network. This registry has access to over 10 million volunteers worldwide.
Donors are checked to make sure that they are in good health and physically able to donate stem cells. Tests may include:
- complete history and physical examination
- additional blood and urine tests
- electrocardiogram (ECG)
- chest x-ray
- bone marrow aspiration and biopsy
Once donors are informed about the donation process and agree to proceed, they sign a consent form (informed consent).
When children are matched donors
When children are stem cell donors, a social worker or child-life specialist may be able to help them cope with the medical procedure. Donors who give bone marrow or stem cells to help their brother or sister often feel a lot of pressure. They are often told that they are helping save their brother’s or sister’s life. If the transplant does not go well, they may feel responsible, guilty and depressed. If other siblings in the family are not chosen as the donor, make sure they understand that a tissue match is random and not a measure of how important they are in the family.
The process of collecting the stem cells is called harvesting. Harvesting differs based on where the stem cells are collected from. Stem cells may be collected from bone marrow, peripheral blood or umbilical cord blood.
Stem cells may be harvested or treated differently for different types of stem cell transplants (allogeneic, syngeneic or autologous stem cell transplants).
- For autologous transplants, the stem cells are usually harvested when the person is in remissionremissionA decrease in or the disappearance of signs and symptoms of a disease (such as cancer). and has recovered from other treatments.
- Occasionally, the stem cells are specially treated to destroy any remaining cancer cells. This process is called purging.
- It is not yet known what the best method of purging is or whether purging is beneficial in reducing the risk of cancer coming back.
- For allogeneic transplants with stem cells from an unrelated donor, the stem cells may be specially treated to remove T cells. T cells are white blood cells that help control immune response (the immune system’s reaction to the presence of foreign substances in the body), fight infection and destroy abnormal cells. The process of removing T cells is called T-cell depletion. It is done to lower the chance of graft-versus-host disease (GVHD).
For some allogeneic and syngeneic transplants, the stem cells may be given to the recipient within several hours of being harvested from the donor. In other transplants, stem cells are harvested and mixed with a preservative so that they can be stored by a special freezing process. This is called cryopreservation. This process helps keep stem cells alive until it is time for the transplant.
Stem cells may be collected from the umbilical cord shortly after a baby is born. They are processed from the cord blood, frozen and stored until they are needed.