Nanoparticles could stanch internal bleeding

Trauma is the leading cause of death in the US for people 45 and under, according to the American Association for the Surgery of Trauma, and main reason for that is blood loss. Erin Lavik, a professor of chemical, biomedical, and environmental engineering at the University of Maryland, Baltimore County, is developing a nanoparticle-based treatment to promote blood clotting.

“There’s no good treatment for internal bleeding,” Lavik told a session at ACS Fall 2023 on Tuesday, Aug. 15. She and her students are trying to develop one that uses polyurethane nanoparticles with polyethylene glycol (PEG) side chains attached.

Lavik had spent several years developing so-called hemostatic nanoparticles made of a degradable polyester, polylactic-co-glycolic acid, with PEG, but when tested in pigs these particles often caused an immune response (Nano Lett. 2021, DOI: 10.1021/acs.nanolett.1c02746). Meanwhile, her lab was developing polyurethane nanocapsules to deliver drugs to the eyes of people with age-related macular degeneration, a leading cause of blindness. They noticed that the capsules were sealing damaged blood vessels and decided to adapt them for blood clotting by adding either methoxy-PEG or carboxyl-PEG, or both.

The researchers found that the particles need to be between 250 and 350 nm in diameter—any smaller, and they can decrease coagulation; larger, they start to accumulate in blood vessels. One question that they don’t yet have enough data to answer is whether the particles could cause too much clotting, which can also be deadly. Tests in two pigs showed the nanoparticles were successful at reducing bleeding with no immune reaction. Lavik says she has her fingers crossed that further testing will show positive results, which could then lead to human trials.