Improved Localization to Sites of Hemorrhage via Peptide Amphiphile Nanofibers Containing a Factor VII-mimetic Epitope.

Abstract

Hemorrhage is a leading cause of potentially preventable deaths in pre-hospital settings. Hence, there is a great need to develop a therapeutic that can be administered in the field to slow or stop hemorrhage before definitive treatment can be sought. The aim of this work was to develop a nanoscale delivery vehicle that could successfully localize to sites of active hemorrhage in the vasculature. We first synthesized four peptides derived from Factor VII as putative targeting epitopes for tissue factor (TF). The peptide sequence ERTFSERT was chosen after microscale thermophoresis revealed a micromolar dissociation constant for TF. The ERTFSERT peptide was covalently linked to a peptide amphiphile (PA) molecule and co-assembled to form supramolecular nanofibers, which were found to have a parallelepiped shape with a width of ∼12 nm and β-sheet secondary structure. Using a microfluidic channel with cultured human umbilical vein endothelial cells, we found that co-assemblies of the targeted nanofibers preferentially localized to endothelial cells activated with tumor necrosis factor alpha, validating the targeting capability of ERTFSERT in a physiologically relevant in vitro model. When administered intravenously in a rat model of liver hemorrhage, biodistribution assessed using ex vivo imaging revealed an increased concentration of targeted nanofibers near the site of liver injury with no adverse effect on mean arterial pressure or blood loss. Overall, these data suggest that TF-targeted PA nanofiber co-assemblies can be used in future studies to deliver therapeutic agents to the site of injury to treat hemorrhage. STATEMENT OF SIGNIFICANCE: We developed and validated a peptide amphiphile with a targeting moiety derived from Factor VII that can localize to tissue factor at the site of hemorrhage. This can be used in future studies to deliver hemostatic agents to the site of injury to treat hemorrhage or to treat other conditions where tissue factor is upregulated.