Artificial Platelets

When a cut or injury draws blood, specialized cells called platelets form clots to stem the flow. Materials scientists have now developed a synthetic platelet that helps speed up clotting in rats and could one day be useful at accident scenes or on battlefields (Sci. Transl. Med. 2009, 1, 11ra22). Instead of trying to mimic platelets outright, a team led by Erin B. Lavik of Case Western Reserve University developed a nanoparticle that bolsters the action of a person’s own platelets. Starting with a core made of a lactic acid-glycolic acid copolymer, the team appended polyethylene glycol (PEG) arms capped off by a tripeptide composed of arginine, glycine, and aspartate. This peptide sequence binds to endogenous platelets that have been activated to begin clotting. When injected, the nanoparticles attach to platelets accumulating at a cut and help bulk up the growing clot. The fact that these nanoparticles bind only to activated platelets means they won’t spontaneously cause clotting in other parts of the body. When the research team tried out the artificial platelets by injecting them into rats, bleeding time was cut in half.