Image copyright Andrew Shoffstall Image caption The particles are 200 times thinner than human hair

Scientists have developed miniature super-clotting balls which could help stop catastrophic bleeding after injury.

In research published in the journal PNAS, the extremely small particles were injected into mice.

The "super-clotters" clumped cells together quickly, plugging up blood vessels and improving chances of survival after severe trauma.

Further research will determine whether they could one day help treat humans.

Uncontrolled bleeding after explosions is a leading cause of death on the battlefield.

And major haemorrhage after road traffic accidents and other serious injuries contribute to more than two million deaths worldwide each year.

But few options exist to stop internal bleeding quickly in the field.

'Thinner than human hair'

The human body has natural clotting cells such as platelets which clog together to form plugs in injured vessels, stemming blood flow.

This system works well for cuts and scrapes but can be overwhelmed during massive trauma.

Researchers at Case Western Reserve University, Wayne State University and Virginia Tech in the US have synthesised the super-clotting balls - known as haemostatic nanoparticles.

Image copyright Erin Lavik Image caption The extremely small particles have several protein arms which form bonds with blood cells

The tiny spherical particles - some 200 times thinner than a human hair - have tentacle-like arms made of protein chains. These arms form links with natural clotting cells present in blood, clumping them together.

The body then continues with a cascade of processes, leading to a web-like mesh which stops blood flow.

In research published in the Proceedings of the National Academy of Sciences, the scientists found injecting these particles into the bloodstream of injured mice helped improve survival rates from 60% to 90%.

'Just add water'

Prof Erin Lavik of Case Western Reserve University and senior author of the study, told the BBC: "In the blast trauma model there is bleeding from many different organs so being able to administer something simply that can stop bleeding at many sites and improve survival is very exciting."

The super-clotting balls can last up to two weeks as a dry powder and can be made into a solution rapidly by just adding a salt or sugar water mixture.

Currently most blood products used to treat major bleeding need to be refrigerated and have a shelf-life of a few days.

Mark Morrison of the Institute of Nanotechnology, who was not involved in the research, says: "The materials used to synthesise these particles are well-known and have been used for sometime so this should help avoid interactions with the human immune system.

"However, there needs to be further work on how the particles affect the natural clotting cascade and other body processes. We need to know how long they last in the body too."

The researchers plan to do further studies in larger animal models before considering human trials.