Synthetic Platelets Put the Brakes on Blood Loss

ByABC News
December 16, 2009, 4:23 PM

Dec. 17 -- WEDNESDAY, Dec. 16 (HealthDay News) -- Hoping to improve on nature, researchers have built and tested synthetic versions of the blood-clotting cells called platelets, to be used in trauma or other cases where blood just won't stop flowing.

"We start by making a core, with material that is used in degradable stitches, which dissolve in the body," said Erin B. Lavik, a professor of biomedical engineering at Case Western Reserve University, and lead author of a report published Dec. 16 in Science Translational Medicine. "Then we attach a polymer that is soluble in water and is used in the pharmaceutical industry. Then we attach a molecule that interacts with activated platelets and helps them clot more quickly."

The hope is that the artificial platelets can replace or augment the activity of the currently used clotting medication, known as factor VIIa, Lavik explained.

Factor VIIa is a protein that plays a central role in blood clotting. A genetically engineered version of the protein is now available for medical use. It was introduced for use in people with hemophilia, a genetic condition in which normal clotting does not occur, and it is being increasingly used against uncontrollable hemorrhage.

But factor VIIa must be kept in refrigerated form and has a short shelf life, Lavik said. And it cannot be used for head or spinal cord injuries, for fear of complications.

"The reason we developed this synthetic platelet is that it is stable at all temperatures," Lavik said. "It is a fine powder that can be administered intravenously. The faster you can control bleeding, the better the outcome."

In animal tests, injured rats given injections of the artificial platelets stopped bleeding in half the time of those that went untreated. Rats that got injections 20 seconds after an injury stopped bleeding in 23 percent less time than untreated rats.

"We also did head-to-head comparisons with factor VIIa," Lavik said. "When the artificial platelets were introduced, bleeding was reduced even more." The artificial platelets induced clotting 25 percent faster than factor VIIa, the report said.