New gel seals wounds fast

BOSTON — A new gel may provide a cheap means of stanching blood flow on the battlefield or in any other situation where there isn’t time for stitches. Estimates suggest that the gel would cost less than $10 per application, a fraction of the cost of other gels in use today, researchers reported August 23 at the American Chemical Society’s fall meeting.

The new blood-clotting material is a hydrogel, a Jell-O–like mixture of water and a fibrous polymer, in this case acrylamide decorated with positively charged nitrogen-containing groups. Experiments with blood plasma reveal that the gel kicks into gear a blood-clotting protein known as factor VII, a key player in the cascade of events that leads to coagulation, said biomedical engineer Brendan Casey of the University of Maryland in College Park.

“You can just slap it on a wound,” Casey said. In experiments in which Casey and colleagues made incisions in sheep lung and liver tissue, the hydrogel stopped the lung from bleeding in about two minutes, the liver in four to five minutes. The research team suspects that the polymer’s positive charge and stiffness induce the clotting.

Many other hydrogels used in medicine today are based on biological materials such as chitin, a structural component found in the cell walls of certain fungi, the beaks of squid and the shells of lobsters and crabs. While these materials have their plus sides, such as breaking down in a friendly manner inside the human body, they are more easily contaminated by viruses and other microorganisms than synthetic gels are and can trigger an allergic response in some people. And those biobased hydrogels cost $400 to $500 a pop, said Casey.

The team’s approach using a synthetic polymer seems like a promising strategy, said Sasa Andjelic of Ethicon, a Johnson & Johnson company in Somerville, N.J. While the gel isn’t absorbable by the body, he said, it looks like it would work well as a topical treatment.