A polymer‐based systemic hemostat for managing uncontrolled bleeding

Introduction: Uncontrolled bleeding is a life-threatening emergency that requires immediate intervention. Currently, available on-site bleeding interventions largely rely on the use of tourniquets, pressure dressing, and other topical hemostatic agents, which can only treat bleeding injuries that are known, accessible, and potentially compressible. Synthetic hemostats that are stable at room temperature, easy to carry, field-usable, and able to stop internal bleeding at multiple or unknown sources, are still lacking. We recently developed a hemostatic agent via polymer peptide interfusion (HAPPI), which can selectively bind to activated platelets and injury sites after intravascular administration. Here we report that HAPPI is highly effective in treating multiple lethal traumatic bleeding conditions in normal as well as hemophilia models via either systemic administration. In a rat liver traumatic model, intravenous injection of HAPPI resulted in a significant decrease in blood loss and a four-fold reduction in mortality rate within 2 h after injury. HAPPI also exhibited hemostatic efficacy in hemophilia A mice by reducing blood loss. These results demonstrate that HAPPI is a promising field-usable hemostatic agent for a broad range of different hemorrhagic conditions.

Materials and

Methods: HAPPI was synthesized by conjugating HA with CBP ([GPO]7H) and VBP (TRYLRIHPQSQVHQI) using the EDC/NHS reaction. The conjugate products were purified by dialysis and characterized by NMR and FTIR. All animal experiments were performed as per protocols approved by the Institutional Animal Care and Use Committee of Harvard University. Rat liver laceration model: Sixteen SD rats were randomized into two groups: saline and HAPPI. After anesthesia, rats were cannulated at the left femoral vein. Subsequently, the abdomen was entered via a midline incision. The liver was exposed, and the left and right lateral lobes were resected at around 2.5 cm from the edge. Immediately following the resection, saline (1 mL/kg) or HAPPI (1 mL/kg) was infused through the femoral vein catheter. This was the time zero, and the rat was monitored for another 2 h or until death, whichever came first. Tail-vein bleeding model in hemophilia mice: mutant mice with severe factor VIII deficiency were used (B6;129S-F8tm1Kaz/J, Female, 8–10 weeks, Jackson Laboratory, stock #004424). The tail-vein bleeding model in these mice was established based on a previously reported procedure (2) with sight modification.

Results, Conclusions, and Discussions: Our results demonstrate that HAPPI is highly effective in treating lethal traumatic and hemophilic bleeding via either systemic administration or topical application. In a rat liver laceration model, intravenous injection of HAPPI results in a significant decrease in blood loss from 19.0 g/kg (in the saline group) to 14.9 g/kg (p = 0.0070) with a mortality rate decrease from 50% to 12.5% within the 2-h monitoring period after injury. In case of bleeding episodes from hemophilia A mice, compared to the saline group, HAPPI-treated mice showed much slower bleeding and three-fold less blood loss with the 20-min monitoring period, presumably due to the enhanced primary hemostasis step. HAPPI represents a promising hemostatic agent for a broad range of different hemorrhagic conditions.

Acknowledgements (Optional): Reference
1. Gao Y, Ikeda-Imafuku M, Zhao Z, Joshi M, Mitragotri S. A polymer-based systemic hemostat for managing uncontrolled bleeding. Bioeng Transl Med. 2023 Apr 13;8(3):e10516. doi: 10.1002/btm2.10516. PMID: 37206230; PMCID: PMC10189483.
2. Gao Y, Sarode A, Kokoroskos N, Ukidve A, Zhao Z, Guo S, Flaumenhaft R, Gupta AS, Saillant N, Mitragotri S. A polymer-based systemic hemostatic agent. Sci Adv. 2020 Jul 31;6(31):eaba0588. doi: 10.1126/sciadv.aba0588. PMID: 32775633; PMCID: PMC7394519.