Tears, Sweat, and Blood
The growing thirst for hemoglobin stand-ins
It was frustrating enough that Edward Lee, a retired mechanic with cirrhosis of the liver, waited a year to get to the top of the transplant list. But even worse, halfway into the 80-mile trip to the hospital from his home in rural Varnville, S.C., Lee answered his cellphone and heard the grim news: "They told me, `Turn around and go back home. We've got a liver but we don't have enough blood to do the operation.' "
Unhappy scenarios like this played out numerous times last year, as scores of operations were postponed because the blood supply dipped to critical lows--including a record low last fall. The situation hasn't gotten much better. This month, according to the American Red Cross, the blood supply is seriously hurting. Nearly half of its stations have less than a one-day inventory of blood. And it is only expected to get worse. In the coming years, the need for blood should soar with aging baby boomers facing more health problems. At the same time, the donor pool is shrinking with new restrictions to protect the supply from the human version of mad cow disease. To stave off a crisis, this spring the Red Cross announced the launching of an aggressive grass-roots campaign to recruit donors. "We can't afford to allow the situation to continue," says Bernadine Healy, president of the American Red Cross. "We literally won't have any blood."
One drop. But just as blood banks are trying to beef up the supply, a legion of industry scientists are working on the problem from an entirely different perspective: designing an artificial blood substitute. This April in fact, these scientists tasted their first drop of triumph. South Africa, whose blood supply has dried up because of an AIDS-riddled donor population, became the first country to approve a human blood substitute for use in surgery.
Biotech researchers don't claim to be in pursuit of a total replacement for blood, a complicated stew of plasma, platelets, and blood cells. Indeed, the need for human blood donations will never entirely disappear. But scientists are rushing to breed stand-ins for the most commonly transfused element of blood, red blood cells. Packed inside these red blood cells is hemoglobin, the body's prized protein that ferries oxygen to its tissues.
Scientists are employing a variety of tactics to mimic this molecule. One company has extracted hemoglobin from bovine blood and chemically treated it to make it more stable and palatable to the human body. Others are inserting human hemoglobin genes into bacteria that will multiply and spew out the protein in massive quantities. And still another group is concocting a milky-white synthetic substance called perfluorocarbon that looks nothing like hemoglobin but has similar function.
These hemoglobin understudies can tote oxygen around just as well as or even better than normal hemoglobin, but they do not last as long. The body clears these modified proteins after a few days, whereas donor blood cells circulate for 42 days. So, the thinking goes, if doctors could infuse patients with at least some units of hemoglobin substitute during emergencies or elective surgeries, they wouldn't have to use as many real-blood packets from hospital storage. Researchers for Alliance Pharmaceutical Corp. in San Diego estimate from their clinical trials that for every 1,000 patients undergoing major surgery, their substitute could save 600 units of blood.
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