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SEAS Researchers Develop New Portable, Injectable Blood Clotting Agent

Harvard researchers developed a promising new blood clotting agent, according to a study released last month.
Harvard researchers developed a promising new blood clotting agent, according to a study released last month. By Karina G. Gonzalez-Espinoza
By Meera S. Nair, Crimson Staff Writer

Researchers at the School of Engineering and Applied Sciences developed a portable, injectable blood clotting agent which has demonstrated high efficacy in preliminary trials with mice models.

The novel hemostat — dubbed HAPPI, or Hemostatic Agents via Polymer Peptide Interfusion — reduced bleeding time by 99 percent and overall blood loss by 97 percent in mice models, according to a paper published in Science Advances last month. It can be stored at room temperature for several months prior to being reconstituted with saline and then intravenously injected in patients.

Bioengineering professor Samir S. Mitragotri, the senior author of the paper, said in an interview that a critical motivation for developing the new hemostat is the gap that occurs between the time of injury and the time of treatment for trauma patients at hospitals.

“Many trauma deaths arising from blood loss occur in the first hour of the trauma — the so-called golden hour,” Mitragotri said. “We sought to develop an easily storable agent that the emergency care providers can carry with them and inject in patients on site to reduce blood loss and save lives.”

SEAS researchers developed HAPPI in collaboration with scientists from Massachusetts General Hospital, Beth Israel Deaconess Medical Center, and Case Western Reserve University. First author of the study and postdoctoral fellow Yongsheng Gao described the hemostat as having the consistency of “cotton candy” when kept freeze-dried for storage.

“Intravenous injectable, easy synthesis and storage, and the availability for first responders are the defining characteristics,” Gao said.

He added that biomimicry was key to the new hemostatic agent’s design.

“Platelets are the key players in the natural hemostasis process,” Gao said. “They are constantly circulating in our blood and once they find a vascular injury, they will activate, attach to the injury site and form a platelet plug to stop the bleeding.

Mitragotri characterized HAPPI as “enhancing the efficacy of the natural process of hemostasis by working with activated platelets.”

“Our hemostatic agent binds to activated platelets as well as the damage sites on the blood vessels,” Mitragotri said. “This leads to the recruitment of platelets to the site of the damage. By recruiting more activated platelets to the site of trauma, the clotting process can be accelerated, thus leading to reduced blood loss.”

HAPPI “showed signs of working almost instantaneously” to stem blood loss upon being injected in mice, according to Mitragotri.

Still, Gao noted that the hemostat has to be tested for both “potential toxicity and therapeutic effect” in larger animal models prior to becoming widely-available for use by first responders.

While researchers have yet to explore translating the hemostat to human patients through commercialization, Mitragotri said he views the latest published findings as “exciting.”

“Stopping internal bleeding is a challenging task,” Mitragotri said. “It needs an agent that is strong enough to induce clots at the bleeding site, but not too strong to induce clots at unwanted sites. So the outcomes of the first studies confirming efficacy in mice was a significant milestone in the project.”

—Staff writer Meera S. Nair can be reached at

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