Discovery Opens New Options for Improving Transfusions

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    ScienceDaily (July 15, 2011) — Donated red blood cells lose a key feature
    that diminishes their lifesaving power the longer they have been stored,
    according to researchers at Duke University Medical Center.

    The finding, published in the journal Critical Care Medicine, details how
    banked blood undergoes a change during storage that decreases its
    ability to transport oxygen.

    Slowing that process could offer a way to boost the longevity and
    vitality of stored blood -- more than 14 million units of which are used
    each year in the United States to treat cancer, acute heart syndromes,
    trauma and other criticalillnesses.

    "Studies have indicated that older red blood cells appear to be inferior
    for some patients," said Timothy J. McMahon, M.D., PhD, associate
    professor of medicine at Duke and senior author of the study.

    "With the supply and demand balance for red blood cells very, very tight,
    it's important to find ways to optimize the benefit of transfusions and ex-
    tend the shelf life of stored blood," McMahon said.

    Doctors have long noted complications among some critically ill patients who
    have undergone transfusions for anemia, and researchers have been working to
    ease these problems by identifying and correcting the shortcomings of stored

    One finding reported previously by Duke scientists focused on nitric oxide, a
    chemical that helps keep blood vessels open. Banked blood quickly begins losing
    nitric oxide, making it difficult for it to speed through the body and deliver

    The current Duke team's finding offers an additional insight. Stored red blood
    cells also lose the ability to release a key molecule called adenosine-5'-
    triphosphate (ATP), which works as a sort of anti-adhesive.

    As their ability to release ATP diminishes the longer they're stored, red
    blood cells develop a sticky quality. When transfused, these older cells tend to
    adhere to the blood vessels in the lungs instead of transporting their oxygen
    payload throughout the body.

    When that happens, patients may be at risk for heart attacks, respiratory
    failure and other complications that have been associated with transfusions.

    "We show that the export of ATP is important to prevent red blood cells from
    sticking to the inner lining of blood vessel walls," McMahon said. "Whereas pre-
    vious reports had shown increasing adhesion as a function of storage time,
    there were very few studies on the mechanism of that adhesion."

    McMahon said the researchers are now exploring whether they can ease the
    problem, perhaps by fortifying stored red blood cells with additional ATP or
    with an agent that stimulates ATP release.

    In addition to McMahon, study authors include: Hongmei Zhu; Rahima Zennadi;
    Bruce X. Xu; Jerry P. Eu; Jordan A. Torok; and Marilyn J. Telen.

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