Reprinted from Wired Magazine Strange Blood
Cataclysmic shortages. Tainted supplies. There is a solution: artificial blood.
By Wil McCarthy
Hemopure is also less viscous than blood, and because it's made up of small molecules, it not only
travels past obstructions that would block a red cell, but also, in a wholly novel way, carries
oxygen directly into the tissues. And that - not the bloodstream itself - is where the oxygen
ultimately needs to go. Blood gas is irrelevant - if successful, HBOC drugs could well drive the
adoption of a "tissue oximeter" (instead of the standard pulse oximeter) as the final measure of a
patient's respiration. And once you accept this tissue-ox concept, a whole host of other HBOC
applications will begin to suggest themselves, from the reversal of carbon-monoxide poisoning to the
travel-packing of live organs for transplant.
Perhaps the most important difference between Hemopure and ordinary blood is the way Hemopure
interacts with the body's red cell gas transport systems. "Since blood plasma is normally a barrier
to oxygen transfer," Levien says, "red cells can release oxygen only when they're in direct contact
with the capillary membrane. With hemoglobin dissolved directly into the bloodstream, on the other
hand, the red cells can suddenly exchange oxygen with the plasma itself. It's the difference between
a truck that has to stop at your front door and one that can hand its cargo off to pedestrians in
the street who will carry it the rest of the way."
Even at very low doses, when the HBOC molecules are moving a tiny fraction of total blood oxygen,
they serve this unloading function, allowing oxygen to penetrate tissues more efficiently. A similar
effect is observed in racehorses and greyhounds and extreme human athletes when red cells rupture
under distress, spilling hemoglobin directly into the bloodstream. "We used to think this condition
was pathological," Levien observes with a hint of a smile, "but now I'm not so sure. It's bad for
the kidneys, yes, but it would be a handy adaptation to extreme exercise. The body's own HBOC."
Does this effect make Hemopure an appealing - if illegal - performance enhancer? "Unfortunately,
yes," Levien says. "The potential for abuse is enormous." Already, Biopure's veterinary product,
Oxyglobin, is being used by cyclists, many of whom are accustomed to taking some very scary stuff.
HBOC, it turns out, is sneakier than erythropoietin, the scandalous star of the 1998 Tour de France.
The latter increases red cell count - a warning flag to race committees everywhere. Hemopure, on the
other hand, doesn't reveal this increase till days after the race, while its oxygen-transport
improvements are immediate and undetectable. Guess what the next major sports scandal will be? The
purple-eyed winners can tell you.
In a running- and biking-obsessed country such as South Africa, it isn't at all difficult to meet a
guy who knows a guy who knows a guy. I'm cautiously put in touch with a bicyclist I'll call Chris,
who seems nervous about discussing the issue and yet bursting with the need to. "I've used Oxyglobin
in competition," he tells me. "I get some abdominal cramps and occasional flushing, which I don't
like. But it improves my peak performance considerably."
"That's not surprising," says Biopure's head of corporate communications, Douglas Sayles. "We have
anecdotal reports of its use in animal racing as well. The company does not condone that,
obviously."
Although the clinical use of HBOC has just begun - about 100 South African patients have been
infused since the product was approved in the country - demand there is expected to surge to about
100 units a day by next year. In anticipation of US approval, perhaps as early as 2003, and next a
greenlight in Europe, Biopure has upgraded its Cambridge plant for an annual capacity of 100,000
units and is breaking ground on a 500,000-unit facility in South Carolina.
For now, Biopure is providing Hemopure to South Africans like Cappy free of charge, in exchange for
the "education" the patients provide to the medical community. Eventually, the product will be
priced at $150 per unit, comparable to the cost of blood. Commercial similarities end there though.
The inherent waste and logistical headaches of blood banking mean that red cell units are often sold
at a loss, with the profits being made on other components. If the handling of red blood cells could
be replaced with easy movement of a room temperature-storable product promising a shelf life of
years rather than weeks, the dollar savings could be enormous. As Biopure's CEO Carl Rausch says of
the Red Cross, "They have to type test, cross test, viral check - every two weeks! This changes the
paradigm of managing blood." Plus, as other blood components are increasingly replaced with
recombinant vat product, banks are losing an important source of revenue, which could force an
increase in the cost of red cells.
In addition, artificial blood has the potential to provide an entirely new service: transfusion in
forward areas, from battlefields to ambulances, from rural clinics to cruise ships and oil rigs. The
Netcare paramedics I talk to are thrilled by the prospect. "At our level, the response level," one
tells me, "medicine fundamentally hasn't changed since the defibrillator. Once the patient arrests
we still have 98 percent mortality, yah. Anything we can do in the golden hour to improve oxygen
levels is bound to have an effect on survival."
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<b>Ben Morris</b>
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