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Nitric Oxide May Improve Blood Transfusions
Researchers at Case Western Reserve University School of Medicine have developed a new approach to restore nitric oxide (NO) to donated blood, which could dramatically reduce harmful effects from transfusions.
In an article published in the Proceedings of the National Academy of Sciences of the United States of America, Jonathan Stamler, MD, and his colleagues report that restoring blood levels of NO in animals prior to transfusion improved their tissue blood flow, oxygen delivery, and kidney function.
Increasingly, medical research publications associate transfusions with harmful consequences, including heart attacks, renal failure, and death. A compelling explanation put forward in the literature is that the quantity of NO declines rapidly after donation because it has a short lifespan. Normally, NO dilates blood vessels and allows red blood cells to access tissue and deliver oxygen.
In the blood, NO exists in a bioactive form called S-nitrosohemoglobin (SNO-Hb). According to Stamler and his team, the new process they developed to restore SNO-Hb — so-called renitrosylation therapy — could have significant benefits for millions of patients.
The researchers hypothesized that the loss of NO compromises the ability of blood vessels to dilate and thereby deliver oxygen to tissues, which is critical for survival. Red blood cells lacking NO instead would plug small blood vessels and cause heart attacks and kidney failure. In contrast, restoration of NO would ensure oxygen delivery.
Their study, funded by the National Heart Lung and Blood Institute (NHLBI), found that mice, rats, and sheep transfused with untreated banked blood had decreased oxygen levels in skeletal muscle and other tissues — exactly the opposite of what would have been predicted. By contrast, in animals transfused with renitrosylated (NO-repleted) red blood cells, tissue oxygenation improved. In addition, researchers applied the same treatment to anemic animals and found improved blood flow, tissue oxygenation, and kidney function.
The FDA considers a transfusion successful if 75% of the banked red blood cells are circulating in the body of the recipient 24 hours after administration.
“Based on our findings, the criteria might need to be revised to include measures of red blood cell function — namely the ability of banked blood to deliver oxygen,” Stamler said.
Source: Case Western Reserve University; June 25, 2013.