Experts At Hematologists' Congress In Vienna Say The Procedure For Donating Stem Cells Is Safe EHA Congress 2007
Donating stem cells is almost free of risk for donors and is often the only chance of survival for many patients with certain severe blood or bone marrow diseases. This was the conclusion arrived at in an observation study conducted by the Medical University of Hanover and just presented at the Congress of the European Hematology Association in Vienna.
Stem cell donors can save lives. The only way to fully cure most types of blood cancer (leukemia) is through the transplantation of what are called hematopoetic stem cells, i.e. by transferring healthy blood-building cells from an appropriate donor. Physicians cannot call on cell donors in good conscience unless this procedure is free of danger. There have been isolated cases of donors reported in the past who themselves came down with leukemia several years after making their life-saving gift. Researchers undertook a number of different studies to determine if there was any connection here.
The Congress of the European Hematology Association (EHA), the leading association of experts on blood and bone-marrow diseases in Europe, is currently being held in Vienna. One of the speakers, Dr. Michael Stadler, senior physician in the Department of Hematology, Hemostaseology and Oncology at the Medical University of Hanover (D), presented the results of a recent study on this subject: "Since March 1994, we have examined nearly 600 donors of bone marrow or peripheral stem cells and determined that the donation of stem cells is a very safe procedure. We have not detected a single case of leukemia to date among our donors and unpleasant side effects occurred for a total of only one percent of these individuals."
The study involved 596 donors aged one to 71 (60% males, 40% females). Both common methods of hematopoetic stem cell transplantation were represented, namely classic bone-marrow transplantation and the modern method of peripheral blood stem cell transplantation.
"Bone marrow can only be extracted under general anesthesia and requires a one to two-day hospital stay," explained Dr. Stadler. "During this procedure, a half to one liter of a mixture of blood and bone marrow is suctioned from around the donor's iliac crest, not from the spinal cord, as is often falsely reported. This mixture is filtered and then transfused into the recipient by way of intravenous infusion. The intervention itself takes about one hour. The bone-marrow cells that are removed are replenished in the donor within about two weeks by subsequent cell growth."
Peripheral blood stem cell transplantation is an even simpler and more comfortable procedure for donors. The reason for the designation is that the stem cells are taken not from bone marrow but from the blood stream at the periphery of the body, e.g. from a vein in the arm. This procedure does require biochemical preparation, however. Dr. Stadler: "For a period of five days beforehand, the donor receives a substance called G-CSF, which stands for Granulocyte-Colony Stimulating Factor. G-CSF is a hormone the body produces itself and is released in the case of inflammations to stimulate the reproduction of white blood corpuscles. If administered as a drug in high doses, it accelerates the overall formation of blood and causes blood stem cells that are not yet fully matured to be detached from their environment in bone marrow, for lack of space you might say. These stem cells make their way to the peripheral blood stream where they can be fished out for the patient using a special separation method called stem cell aphaeresis."
G-CSF stimulation in particular was long suspected of being a possible trigger for leukemia in donors over the long term. In their long-time study, however, Dr. Stadler and his colleagues did not observe a single case of leukemia or a single case of death over a period of more than 12 years. Greater complications arose in a total of only five donors, e.g. persistent pains or a thrombosis. "We did make an interesting finding," said Dr. Michael Stadler. "We had one donor subject to sporadic epileptic attacks, and after each of his two donations, an attack occurred. That raises the question of whether G-CSF could reinforce certain nerve stimuli. This is a mechanism we have to keep our eyes on."
Favorable long-time experience for thousands of donors from various international donor registers was already reported in March 2007 in Lyon at the Congress of the European Group for Blood and Marrow Transplantation (EBMT).
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