Blood clotting assisted by synthetic blood platelets.

Erin Lavik, a biomedical engineer at Case Western Reserve University in Cleveland, Ohio and his team have found an innovative way to stop internal bleeding with the help of nanotechnology.They have done this by developing synthetic blood platelets from biodegradable polymers.

Blood clots are formed naturally at the site of wound with the help of platelets and the thrombin system.  When bleeding occurs, chemical reactions change the surface of the platelet to make it “sticky.” Sticky platelets are said to have become “activated.” These activated platelets begin adhering to the wall of the blood vessel at the site of bleeding, and within a few minutes they form what is called a “white clot.” (A clump of platelets appears white to the naked eye.) The thrombin system consists of several blood proteins that, when bleeding occurs, become activated. The activated clotting proteins engage in a cascade of chemical reactions that finally produce a substance called fibrin. Fibrin can be thought of as a long, sticky string. Fibrin strands stick to the exposed vessel wall, clumping together and forming a web-like complex of strands. Red blood cells become caught up in the web, and a “red clot” forms.

A mature blood clot consists of both platelets and fibrin strands. The strands of fibrin bind the platelets together, and “tighten” the clot to make it stable. The synthetic nanoparticles injected into trauma patients bind at the site of injury with natural platelets and speeds up the clotting process. Bleeding time has found to be halved when such nanoparticles were injected into wounded mice.  To prevent the synthetic platelets from clumping into dangerous clots, each one is built with a surrounding “shield” of water. In the test animals, surplus synthetic platelets were flushed out of the body within 24 hours.

 Lavik remarked that the nanoparticles could complement existing therapies that work to stem internal bleeding or cease bleeding from external or compressible injuries.