Self-assembling gel stops bleeding in seconds

• 13:15 10 October 2006
• NewScientist.com news service
• Robert Adler

Swab a clear liquid onto a gaping wound and watch the bleeding stop in seconds. An international team of researchers has accomplished just that in animals, using a solution of protein molecules that self-organise on the nanoscale into a biodegradable gel that stops bleeding.

If the material works as well in humans, it could save thousands of lives and make surgery far easier in many cases, surgeons say.

Molecular biologist Shuguang Zhang, at the Massachusetts Institute of Technology in the US, began experimenting with peptides in 1991. Zhang and colleagues at MIT and the University of Hong Kong in China went on to design several materials that self-assemble into novel nano-structures, including a molecular scaffold that helps the regrowth of severed nerve cells in hamsters (see Nano-scaffolds could help rebuild sight).

Their work exploits the way certain peptide sequences can be made to self-assemble into mesh-like sheets of "nanofibres" when immersed in salt solutions.

In the course of that research they discovered one material's dramatic ability to stop bleeding in the brain and began testing it on a variety of other organs and tissues. When applied to a wound, the peptides form a gel that seals over the wound, without causing harm to any nearby cells.

Vessels and arteries

"In rodents it works in all the blood vessels and arteries, including the femoral artery, the portal vein, and in the liver," says MIT neuroscientist Rutledge Ellis-Behnke.

The peptides assemble into a gel that looks "like a hairy ribbon, but at the nanoscale" says Ellis-Behnke, although precisely how it stops bleeding is not yet clear. "It's critically important to understand the mechanism so we can rationally design new self-assembling materials," Zhang says.

Some surgeons are already excited about the material. "I see great potential in the eye field, the gastro-intestinal field, and in neurosurgery," says Dimitri Azar, head of ophthalmology at the University of Illinois at Chicago, US.

Paradigm shift

"In the eye, even a drop of blood will blur your vision for a long time," Azar adds. "A material that would stop the bleeding could lead to a paradigm shift in how we practice surgery in the eye."

Ed Buchel, who teaches general and plastic surgery at the University of Manitoba, in Winnipeg, Canada, sees equal potential for treating trauma and burns. "If this works as well on humans as it does on rats, it's phenomenal," he says.

Still, they caution that extensive clinical trials are needed to make sure the materials work properly and are safe. The MIT researchers hope to see those crucial human trials within three to five years.

Their research will appear in the 10 October 2006 edition of online journal Nanomedicine.