At any given time, U.S. blood banks may be just 36 hours away from going broke. And it’s no wonder: How do you match an unpredictable supply with an unpredictable demand?
To help resolve that problem, in recent years universal blood substitutes have been developed. The synthetic blood has worked well enough in trials, except it doesn’t last long in the body. Now, however, assistant professor of chemical engineering Andre Palmer believes he’s found a way to extend the blood substitute’s viability.
As blood flows through the circulatory system, the cells get knocked around. These “shear forces” tear away at the blood substitute, turning it into debris to be cleared away, Palmer explains. Red blood cells normally have a circulation lifetime of 120 days before they are flushed away; blood substitutes last only a day or two, and therefore are only an emergency stopgap requiring more transfusions.
Using sophisticated emulsion techniques Palmer hopes to create a “mechanically strengthened vesicle,” something like a strong, resilient soap bubble, and to fill it with hemoglobin, the compound that carries oxygen to the body’s cells. The trick is to make the membrane strong enough so it won’t break, yet still permeable to oxygen.
The problem is multifaceted. “It involves engineering the inside of the vesicle, engineering the hemoglobin, and engineering the surface of the vesicle so it doesn’t set off the body’s immune system alarm, causing it to be attacked and cleared away,” Palmer says.
In preliminary experiments, the bioengineer has successfully produced a “mechanically stabilized vesicle.” The next step, he says, is to place hemoglobin inside and characterize its ability to bind and release oxygen.
John Monczunski is an associate editor of this magazine.