The Quest for Artificial Blood: Synthetic Substitutes Now Being Tested May Be Safer, More Practical and Save Even More Lives
Underwood, Anne, Newsweek
Byline: Anne Underwood
Edna Fodor was enjoying a lazy summer evening at her son's cottage in Canada when the bonfire she was tending flared suddenly, searing her body from the waist up. Emergency rescue teams choppered her to Hamilton General Hospital in Ontario, where doctors would normally have cut away the burned skin to prevent infections, then grafted healthy skin to replace it. But such surgery involves extensive bleeding--and Fodor is a Jehovah's Witness, a member of a religious group that refuses blood transfusions. "We faced two deadly alternatives," says Dr. Brian Egier, director of the intensive-care unit. "We could either perform the surgery and have her bleed to death or let her die from the infections." Fortunately for Fodor, Egier was able to suggest a third option--so-called bloodless surgery using an experimental blood substitute called Hemolink. Although the product is not yet approved, Egier obtained an exemption for Fodor. Two years later she is happy, healthy and "lucky to be alive," she admits.
Hemolink is just one of a half-dozen blood substitutes that are nearing the market after decades of research. Known technically as "oxygen therapeutics," they aim to replace only oxygen-bearing red cells rather than whole blood with its additional plasma, platelets and infection-fighting white cells. Red cells are the most frequently transfused component of blood--tallying more than 12 million units a year--and the one that faces periodic shortfalls. Replacements could not only alleviate shortages, but also offer important advantages, including longer shelf life and compatibility with any blood type. "The minute they get approved, I'm going to be all over them," says Dr. Bruce Speiss, vice chair of anesthesiology at the Medical College of Virginia.
The history of transfusions has come a long way since the early 1800s, when Dr. James Blundell in England lost as many patients as he rescued with transfusions, since blood typing had not yet been discovered. "In the last century, transfusions have saved more lives than any therapy except antibiotics," says Dr. Harvey Klein, chief of transfusion medicine at the National Institutes of Health. But they have sometimes proved a mixed blessing. Two devastating bloodborne diseases--AIDS and hepatitis C--were unwittingly spread to tens of thousands of people by donor blood before the pathogens were identified. And although the U.S. blood supply is very safe today, says Karen Shoos Lipton, CEO of the American Association of Blood Banks, "we can only screen for diseases we know about."
Oxygen therapeutics could reduce the risks. These blood substitutes fall into two general types. The first is a synthetic chemical called a perfluorocarbon, or PFC, which would not risk contamination by bloodborne pathogens. The second type is based on actual hemoglobin extracted from discarded human or cow blood. The four companies in clinical trials with these products use stringent multistep processes to extract hemoglobin from red cells, then purify and stabilize it, so only hemoglobin is left. …