Types of Transplantation
Blood and bone marrow transplantation involves the replenishing of hematopoietic cells following high dose chemotherapy and radiation. Hematopoietic stem cell, sometimes referred to as blood stem cells, are progenitor cells in the bone marrow that give rise to all blood cell types, including cells of the immune system.
There are several types of blood and bone marrow transplantation depending on who serves as the donor. The source of the hematopoietic cells further defines the type of transplant.
The hematopoietic cells used for transplantation can be collected from the blood or the bone marrow. Hematopoietic cells, sometimes referred to as blood stem cells, are immature cells capable of dividing and developing into any type of mature blood cells.
Autologous – High dose chemotherapy and/or radiation (“high dose therapy”) is given to treat your disease, but requires an infusion of your own hematopoietic cells to restore your body’s ability to make blood cells. Your hematopoietic cells are collected before you receive the high dose therapy, and then frozen. Your hematopoietic cells will be given back to you as an infusion following the high dose therapy. This type of transplant is sometimes referred to as a “stem cell” transplant or rescue.
Allogeneic – An allogeneic approach combines the concepts of high dose therapy with immunotherapy. High dose therapy is administered to treat your disease, followed by an infusion of hematopoietic cells from your donor’s blood or bone marrow. The donor cells provide you with new blood cells and a new immune system. The new immune system helps to eradicate any residual disease, which is immunotherapy. Medications are required to allow your new immune system to function.
Human Leukocyte Antigens (HLA) are genetic markers of our immune system. The donor cells are obtained from a closely or completely HLA matched individual. If the donor is a relative, the transplant is called a related donor BMT. If the donor is an unrelated individual, the transplant is called an unrelated donor (URD) BMT.
Allogeneic transplants can vary based on the intensity of the therapy. A myeloablative allogeneic BMT requires the use of sufficiently high dose chemotherapy and/or radiation to cease the function of your bone marrow and allow for the donor cells to engraft (grow). A nonmyeloablative allogeneic BMT (sometimes referred to as “mini-transplants,” a term we consider misleading) uses lower doses of radiation, immune suppressing drugs and/or chemotherapy. Your bone marrow continues to function until the cells from your donor grow and replace your marrow.
A variety of approaches can be combined with traditional transplantation methods. These include autologous transplantation followed by a non-myeloablative allogeneic BMT, the use of a haploidentical donor, hematopoietic purging techniques, cellular therapy, monoclonal antibodies and vaccinations. If you are considering a transplant your BMT Physician will discuss which options could be most beneficial to you.
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