Bone marrow transplants and stem cell transplants are both terms used to describe the same process. The process involves:
- Collecting healthy stem cells from a patient or donor
- Giving the patient chemotherapy and/or radiation therapy to treat diseased cells
- Infusing the healthy stem cells back into the patient so they can create a new population of healthy blood-forming stem cells.
The terms are often used interchangeably, however technically speaking:
Bone Marrow Transplants: uses stem cells collected directly from the bone marrow
Peripheral blood stem cell transplant: uses blood stem cells collected from the blood stream.
The stem cells collected in the bone marrow or from the blood are the same.
What are bone marrow and stem cells?
Bone marrow is the tissue that fills the cavities in your bones and is where most of your blood cells are made.
Stem cells are cells found in your bone marrow that can divide and form all different types of blood cells. They are cells that have not yet decided what they will be yet and can mature into red or white blood cells or platelets
Normal blood cells have a life-span and are continually replaced; therefore, bone marrow tissue is active throughout your whole life and stem cells continually divide to produce new blood components.
What is treated with a Bone marrow or stem cell transplant?
Stem cell transplants are used to treat haematalogical (blood) cancers and a range of other blood disorders.
Not all patients with blood cancer will need a stem cell transplant. Stem cell transplants may be required if a patients disease worsens during other treatment, the disease is not entirely gone after other treatment or the disease type is known to reoccur after treatment.
Some diseases that may be treated with a stem cell transplant include:
- Acute and chronic leukaemia
- Aplastic anaemia
- Some immune system disorders
How does a bone marrow or stem cell transplant work?
High dose chemotherapy and radiotherapy are given in order to kill disease. Unfortunately these treatments can not target only the diseased cells and in the process it can also kill the important stem cells in the bone marrow.
For other blood disorders that are not blood cancer, stem cells may be defective.
Regardless of whether the transplant is used to treat blood cancer or another blood disorder, the stem cells will need to be replaced. These transplanted cells will be used to rebuild the body's blood and immune system.
The word transplant can be misleading. The procedure is not a surgical one and the healthy stem cells are given intravenously through the vein, much like a blood transfusion.
Types of bone marrow and stem cell transplants
The type of stem cell transplant you have will depend on the type of disease you have, your age and health, the condition of your bone marrow and whether or not stem cells can be collected from you or a donor collection is necessary and available. Your doctor will discuss with you the best options for you. There are two different types of transplants:
- Autologous Transplants
- Allogeneic Transplants (allografts)
In an autologous transplant a patients own stem cells are taken in advance when their disease is in remission and returned to them after high dose chemotherapy or radiation therapy. Most commonly people have one autologous transplant, although some patients might have two or more transplants. This is called 'staged autologous transplantation' and usually occurs over a few months and is used to help decrease the chance of the disease relapsing.
At Peter Mac Autologous stem cell collection usually occurs in the apheresis unit of Day therapy as an outpatient, however you may also have stem cells collected as an inpatient. Transplantation occurs as an inpatient in the specialised Haematology ward on level 5.
Find out more about our myeloma and autologous stem cell transplantation service.
In allogeneic transplants (also referred to as allografts) the stem cells are taken from a compatible donor.
The most common donors are siblings of the patient. If a compatible sibling is unavailable another compatible family member can also be used. Sometimes stem cells can be used from a donor whose tissue type is slightly mismatched to the patients. This is called a mismatched transplant.
If a compatible family member is not found or unable to donate, the next option is a volunteer unrelated donor (VUD) transplant. This donor may be unrelated to the patient but with similarly matched tissue.
The choice of donor is determined by ensuring the donors cells are the best possible match to the patient. This is done by a blood test. Tissue type and blood type are not the same and a donors tissue may be compatible even if their blood type is not.
At Peter Mac donations for allogeneic transplants are taken in Day Therapy as an outpatient procuedure. Transplants are performed in the specialised ward 7B at the Royal Melbourne Hospital as part of the Parkville Integrated Haematology Service.
Find out more about our allogeneic transplantation service.
This content was adapted from the Leukaemia Foundation's Guides for Patient and Families.