12 March 2015

PolySTAT will stop bleeding quickly and without harm

Soldiers wounded on the battlefield and people injured in accidents often die on the way to the clinic due to bleeding that cannot be stopped with a hemostatic tourniquet. This problem can be solved with the help of PolySTAT polymer developed by researchers at the University of Washington, which strengthens blood clots. After a single intravenous injection, the polymer quickly finds any hidden or internal bleeding and immediately begins to act.

Three-dimensional model of an emerging blood clot,
in which PolySTAT (blue) binds fibrin fibers together.

The prototype of PolySTAT was blood clotting factor XIII, a protein contained in the blood that helps strengthen blood clots.

Usually, immediately after damage to a blood vessel, platelets circulating in the bloodstream concentrate in the area of damage and form a primary barrier. After that, the fibrin protein fibers are woven into the forming thrombus, strengthening it. If this structure does not withstand the pressure of the blood flow, the thrombus ruptures and the bleeding continues.

Blood clotting factor XIII binds fibrin fibers together due to additional cross-linking. The same function is performed by the polymer PolySTAT developed by the authors. However, it has a pronounced advantage in providing more effective protection against blood clot-dissolving enzymes. These enzymes contribute to the healing process, but at a critical stage of bleeding, they can do the patient a disservice.

In the initial testing on rats, the introduction of PolySTAT significantly reduced the volume of blood loss after a fatal femoral artery injury under normal conditions and ensured the survival of 100% of animals. At the same time, with the introduction of blood clotting factor XIII, the survival rate of rats was only 20%.

PolySTAT ensured the survival of 100% of rats after potentially fatal femoral artery injury.
In the control groups, 40% of animals survived from 0 to (with the introduction of saline, volume control).

According to the developers, the synthetic polymer PolySTAT has other advantages compared to traditional methods of hemostatic therapy. It is cheaper than blood products, does not need special storage conditions, is not at risk of bacterial infection and is not a potential source of infectious diseases. Moreover, the introduction of hundreds of proteins into the patient's body, which are part of blood preparations, can cause various unintended reactions, which does not occur with the introduction of PolySTAT.

With traumatic injuries, the reserves of the precursor protein necessary for the formation of fibrin are rapidly depleted. When a critical level of this protein is reached, traditional methods of stopping bleeding cease to work and the patient, as a rule, dies.

According to the data obtained by the authors, PolySTAT effectively strengthens blood clots even at very low levels of fibrin precursor protein.

The researchers also demonstrated that PolySTAT interacts exclusively with fibrin in the injury area and does not bind to its precursor or fibrin circulating in the bloodstream. This means there is no risk of blood clots forming, which can cause strokes and blockage of blood vessels.

The PolySTAT-treated thrombus (second from right) shows a denser network
fibrin fibers, ensuring its stability.

Despite the promising results of the initial safety testing of PolySTAT, the developers note the need for experiments on large animals and additional screening for the possibility of unintentional interaction of the polymer with any compounds. They also plan to explore the possibility of using PolySTAT for the treatment of hemophilia and its use as a filler for dressing material.

Article by Leslie W. Chan et al. A synthetic fibrin cross-linking polymer for modulating clot properties and inducing hemostasis is published in the journal Science Translational Medicine.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Washington:
An injectable UW polymer could keep soldiers, trauma patients from bleeding to death.


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