A biodegradable protein solution stanches bleeding in mere seconds when applied to open wounds in rodents, according to a new study. How the material works in detail is unclear, but it appears nontoxic and long lasting in animals, suggesting that it may either have advantages over existing bleeding stoppers or be able to complement them, researchers report.

A number of different products are in use or are being developed to control bleeding on the battlefield and in routine surgery. All of them have drawbacks, including the potential for excessive heat, blood clots and allergic reactions. The new liquid does not seem to carry these risks, says neuroscientist Rutledge Ellis-Behnke of the Massachusetts Institute of Technology, who developed the material with his colleagues.

Ellis-Behnke and his colleagues had sought out short proteins, or peptides, suitable for patching severed nerves or wounds in the brain. In March they reported that a liquid made from one such peptide could repair severed optic nerves in hamsters by forming a gel in which stem cells could accumulate and grow. In subsequent research they were startled to discover that dabbing a mix of this and other peptides onto a bleeding mouse brain rapidly controlled the oozing, Ellis-Behnke says. "We put this material in and we saw that all the bleeding stopped," he recounts, apparently because the liquid formed a fibrous network over the wound. In a study published online October 10 in Nanomedicine the researchers report that the liquid controlled bleeding in rodents within 15 seconds in seven other wound types, including cuts to the spinal cord, liver [view video here] and femoral artery as well as skin punctures.

The liquid does not seem to form a conventional blood clot, the group notes. Electron microscopy turned up no sign of the platelets that would normally gather in a clot. The proteins might instead form tangles that act like hair blocking a drain, Ellis-Behnke suggests.

"It certainly has some features that make it intriguing," including its rapid action and the low concentration of protein required, says chemist and biomaterials specialist Galen Stucky of the University of California, Santa Barbara. It still has to be compared head-to-head with other blood stanchers and tested against a really gushing wound, which could conceivably overwhelm the gel if it doesn't trip the clotting process, he notes.