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Overview
Best Pract Res Clin Haematol, 2010:
Should double cord blood transplants be the preferred choice when a sibling donor is unavailable?
"Umbilical cord blood transplant is an important alternative stem cell source for both children and adults with hematologic malignancies. Umbilical cord blood units are rapidly available and have less stringent human leukocyte antigen (HLA) matching requirements.
Mismatch at two antigens actually improves the risk of relapse for umbilical cord blood transplant recipients with relatively low risk of severe acute or chronic graft vs host disease. However, umbilical cord blood transplant is associated with an inferior neutrophil recovery rate when compared to other stem cell sources.
It is for this reason that we have explored ‘double unit umbilical cord blood transplants,’ not only as a platform for evaluating the safety and effectiveness of new methods of ex vivo expansion or methods of enhanced homing, but also as an approach itself to remedy the problem of limited cell dose, particularly for adults.
A stem cell transplant* may sometimes be medically necessary for patients with lymphomas.
With a stem cell transplant, the stem cells** obtained from bone marrow, peripheral blood, or umbilical cord blood are given back to the patient following high dose treatment, which can damage or ablate (kill off) these vital cells. The engrafted stem cells can then restore bone marrow function** impaired or destroyed by the high dose conditioning therapy.
A stem cell transplant is sometimes called a bone marrow transplant.
*The terms stem cell transplant, infusion, rescue, engraftment, or support may be used interchangeably and essentially have the same meaning.
** Stem cells are "immature cells known as hematopoietic or blood-forming stem cells. Hematopoietic stem cells divide to form more blood-forming stem cells, or they mature into one of three types of blood cells: white blood cells, which fight infection; red blood cells, which carry oxygen; and platelets, which help the blood to clot. Most hematopoietic stem cells are found in the bone marrow, but some cells, called peripheral blood stem cells (PBSCs), are found in the bloodstream. Blood in the umbilical cord also contains hematopoietic stem cells. Cells from any of these sources can be used in transplants" [in order to restore bone marrow function.] - cancer.gov
The different types of stem cell transplants are named from the
origin of the stem cells:
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allogeneic - stem cells harvested from donor (following reduced for full intensity therapy)
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autologous - stem cells harvested from self
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syngeneic - stem cells harvested from identical twin
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cord blood - stem cells from saved cord blood, from self or donor
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Cord blood is now being investigated as a source of stem cells for patients receiving high dose treatment for lymphoma and other cancers.
Q&A: How does a cord blood transplant compare with other types?
"Cord Blood Cord blood transplants are a "type" of allogeneic transplant. The reason they are different is that the stem cells found in the cord blood are more immunologically naive than the stem cells from marrow. As a result, they are more "forgiving" when it comes to inducing graft versus host disease (GVHD). This is when the donor cells start attacking the host (or recipient) of the transplant as if it were an infection.
GVHD is one of the more feared complications of allogeneic transplantation. The biggest problem is that "some" GVHD is helpful in that it helps to control the leukemia. This "beneficial" part is termed graft versus leukemia (GVL) effect. You need some of the GVL, and can tolerate some GVHD, but you do not want too much as it can be lethal.
Cord blood, because it is less developed immunologically is thought to cause less GVHD. We do not yet know if it the less GVHD results in less GVL and less effectiveness in controlling the disease. "
~ Rick Furman, MD (Sept 2008)
Also see: How are umbilical cord stem cells obtained for transplantation? Cancer.gov
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