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The types of stem cell transplants are based on who the stem cells come from. There are 3 basic types:
An allogeneic transplant is also called an allograft. Stem cells are taken (harvested) from one person (donor) and given to another (recipient).
An allogeneic transplant has higher complication rates than an autologous transplant. One of the most important risks is graft-versus-host disease (GVHD). GVHD is when the donated stem cells have an immune reaction against the donor’s cells. The donated cells see the recipient’s cells as foreign and start to destroy them.
At the same time, allogeneic transplant is associated with the beneficial graft-versus-tumour (or graft-versus-leukemia) effect. In the graft-versus-tumour effect, the donor’s stem cells attack any cancer cells that are still in the recipient’s body. As a result, cancer is less likely to return after treatment.
A newer method for allogeneic transplant involves using stem cells collected from umbilical cord blood. This method is used mostly in transplants for children and small adults.
Compared to a standard allogeneic transplant, reduced-intensity transplant uses lower-dose chemotherapy, radiation therapy or both before the stem cell transplant. This approach kills some cancer cells and some bone marrow cells. This approach weakens the recipient’s immune system enough to allow donor cells to destroy any remaining cancer cells (graft-versus-tumour effect).
Reduced-intensity allogeneic transplant may also be called non-myeloablative transplant or mini-transplant.
Syngeneic transplant is an allogeneic transplant between identical twins. Stem cells are taken from one identical twin and given to the other.
An autologous transplant uses the recipient’s own stem cells. It is also called an autotransplant or autograft.
There is no risk of graft-versus-host disease (GVHD) with autologous transplant. There is a higher chance of relapse with this type of transplant.
A tandem transplant means that 2 autologous transplants are given in a row. The recipient is given 2 courses of high-dose chemotherapy. Each dose is followed by a stem cell transplant.
Researchers are still trying to determine the best use of this type of transplant. It has been used for some people with multiple myeloma, Hodgkin lymphoma and non-Hodgkin lymphoma.
Stem cells can be taken (harvested) from bone marrow, peripheral blood or umbilical cord blood.
Bone marrow stem cells can be used for all types of transplants. Stem cells are collected from the bone marrow during a procedure called harvesting.
Peripheral blood stem cells can be used for all types of transplants. Stem cells are collected from the circulating (peripheral) blood.
Stem cells from umbilical cord blood are mostly used for transplants in children because there usually aren’t enough stem cells for adults.
Using stem cells from umbilical cord blood offers some benefits. Stem cells from cord blood rarely contain harmful viruses and infections. There is also a lower risk of graft-versus-host-disease (GVHD) when cord blood stem cells are used.
On the other hand, engraftment (when new stem cells start to appear) happens more slowly with stem cells from cord blood than with stem cells from bone marrow or adult blood. Cord blood stem cells may carry undetected genetic or congenital diseases.
Researchers are still studying cord blood to find out how long stem cells can be stored before they lose their effectiveness. They are also studying the long-term success rate of transplants using umbilical cord blood.
The Canadian Cancer Society’s peer support program is a telephone support service that matches cancer patients and their caregivers with specially trained volunteers.