A new study shows how a polymer-based systemic clotting agent binds to activated platelets and enhances their accumulation at a wound site.

Developed at Harvard University (Harvard; Cambridge, MA, USA), Case Western Reserve University (CWRU; Cleveland, OH, USA), and other institutions, the injectable hemostatic agent via polymer peptide interfusion (HAPPI) is a hyaluronic acid conjugate with both a collagen-binding peptide and a von Willebrand factor–binding peptide. The polymer-peptide conjugate selectively binds to damaged blood vessels and activated platelets at the bleeding site, promoting their accumulation at the wound site.

In vivo studies in mouse tail vein laceration model demonstrated a reduction of about 99% in bleeding time and about a 97% reduction in blood loss. A 284% improvement in the survival time was observed in a rat inferior vena cava traumatic model, with the injection of HAPPI increasing the median survival rate beyond one hour, a critical goal for trauma care. According to the researchers, lyophilized HAPPI could be stably stored at room temperature for several months and can be reconstituted during therapeutic intervention on demand. The study was published on July 31, 2020, in Science Advances.

“A lot of trauma-related deaths happen within the first hour when blood loss is happening profusely and there is no intervention,” said co-first author Yongsheng Gao, PhD, of the Harvard School of Engineering and Applied Sciences (SEAS). “A key objective for first responders is to keep trauma patients alive during this so-called golden hour, and in that time bring them to a hospital, because once they get to the hospital, it's a different game altogether.”

As most deaths occur during the initial hour after a traumatic injury, hemostatic intervention within the first hour can determine survival in trauma patients. However, current on-site interventions such as tourniquets and topical dressings can only be used to treat externally accessible, compressible wounds. Some advancements have been made in the development of intratissue or intracavitary injectable, self-expandable hemostatic polymer foam technologies such as the RevMedx (Wilsonville, OR, USA) XStat device.

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