Brigham Young University researchers have developed a way to thin blood during surgeries that doesn't involve drugs. But there's a lot more testing and proving to do before it will be ready for use in the operating room, they predict.

Their research is published today in two articles in the journal of the American Society for Artificial Internal Organs.

When blood comes in contact with medical devices, such as the heart-lung bypass machine used in open-heart surgery, it coagulates. So a blood thinner called heparin is typically used to keep it fluid and flowing. For most people, that works well, said lead researcher Kenneth A. Solen, professor of chemical engineering at BYU. But a small subset of those patients — still numbering hundreds of thousands —have a negative reaction to heparin.

While some researchers have focused on alternatives to heparin, the BYU researchers have been trying to figure out if they can take something out of the blood, in this case proteins called clotting factors. They studied the feasibility in the lab, then moved to benchtop studies where then-doctoral candidate Jared T. Parker was able to extract the clotting-factor proteins.

Most recently, they teamed with other researchers to test their drug-free blood-thinning technique on animals in mock surgery. Instead of opening the animal, as would be done in an open-heart surgery, they did external blood bypass using a catheter in an artery and found the animals weathered it well, without obvious adverse physiological effects, Solen said. They successfully removed the clotting factors, inhibiting coagulation for the duration of the "surgery," then quickly and easily restored it.

Their process hinged on creating a gel that would attract the clotting-factor proteins. They employed an existing gel that already has many uses but added a biological compound with a charge opposite that of the clotting proteins' strong electrical charge, so they would attract. The gel stays immobilized in the bypass process, like a magnet on a fridge, and the clotting proteins stay with it, while the rest of the blood and its important contents flow on.

The first of the published studies outlines the benchtop research, where they explored parameters such as how much gel to use, based on blood volume. The second outlined the animal studies.

The process needs more study to see if there are long-term effects. Human studies are likely years in the future, he said.

Parker, now an engineer at W.L. Gore, had a graduate fellowship from the National Science Foundation that helped fund the studies. Other funding came from an NIH small-business innovation grant to other members of the team at the company Thrombodyne, based in Salt Lake City. Other researchers included David Beutler, then a BYU undergrad, and colleagues at the Utah Artificial Heart Institute, where the animal studies were conducted.

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