A 3-D rendering of fibrin forming a blood clot, with PolySTAT (in blue) binding strands together - (Photo by William Walker/University of Washington)
Researchers at the University of Washington are testing a new injectable polymer which can dramatically strengthen blood clots, possibly saving the lives of trauma casualties who may currently be untreatable in the field with conventional first aid protocols.
The average adult human has between 1.2 and 1.5 gallons of blood circulating through their body at any given time. Lose a third of that and you are in serious trouble; lose half to two-thirds and you will probably die. At the rate the heart pumps blood, if a major artery is severed, this could happen in as little as a few minutes.
Consequently, controlling bleeding has an appropriately high priority in most trauma and first aid protocols, and thanks to widespread education on the subject, many people are aware that applying direct pressure or even more dramatic techniques (such as using pressure points or tourniquets) to control bleeding can be a critical, life-saving step for trauma victims. Unfortunately, there are places where bleeding can occur where these techniques may not be effective; a chest wound, for example, cannot be tourniqueted off.
Health-care professionals have even more options for controlling bleeding, but even those techniques may take longer than the patient has. And in many cases, simply getting the patient in front of a doctor or paramedic may take too much time.
But the new polymer, called PolySTAT, can be injected immediately and with very little training, opening the possibility for stopping potentially deadly bleeding long before victims can reach professional medical care.
PolySTAT works by seeking out and strengthening blood clots forming in wounds with a special agent which helps natural clotting functions form a sort of net within the clot to keep it from breaking apart and helping to resist the pressure of the blood.
Blood clots treated with PolySTAT (second from right) had denser fibrin networks, which helps reinforce and strengthen the clots - (Photo courtesy University of Washington)
The polymer can work even on wounds which are not immediately visible — internal bleeding can be controlled as easily as bleeding from external wounds.
The body attempts similar damage control techniques by itself, which are part of what inspired the team to develop PolySTAT in the first place. A natural protein called factor XIII automatically strengthens clots, reinforcing fibers called fibrin which weave through clots in a lattice to hold them against the pressure of blood trying to escape.
But the body’s natural responses can also fight one another, since clots forming in places other than injury sites can be equally life-threatening. So other enzymes in the blood work against factor XIII by trying to dissolve the fibrin at the same time.
PolySTAT avoids the efforts of those enzymes by making use of synthetic bonding agents which the enzymes do not recognize and will not attack. At the same time, PolySTAT is designed to only promote clotting at wound sites, and not elsewhere in the blood stream, to avoid creating clots which could cut off blood flow to healthy regions.
Other injectable coagulant treatments have been available for some time, but they have tended to be expensive to manufacture and store, and their administration is usually complex enough to require medical professionals to balance and inject them in the correct quantity and order. Some of them are
blood-type specific, requiring testing on the patient before they could even be delivered.
According to
a press release, initial testing in rats has been very successful, and clinical trials in humans could begin within five years.
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