title: Platelet-like nanoparticles: mimicking shape, flexibility, and surface biology of platelets to target vascular injuries.
abstract: Targeted delivery of therapeutic and imaging agents in the vascular compartment represents a significant hurdle in using nanomedicine for treating hemorrhage, thrombosis, and atherosclerosis. While several types of nanoparticles have been developed to meet this goal, their utility is limited by poor circulation, limited margination, and minimal targeting. Platelets have an innate ability to marginate to the vascular wall and specifically interact with vascular injury sites. These platelet functions are mediated by their shape, flexibility, and complex surface interactions. Inspired by this, we report the design and evaluation of nanoparticles that exhibit platelet-like functions including vascular injury site-directed margination, site-specific adhesion, and amplification of injury site-specific aggregation. Our nanoparticles mimic four key attributes of platelets, (i) discoidal morphology, (ii) mechanical flexibility, (iii) biophysically and biochemically mediated aggregation, and (iv) heteromultivalent presentation of ligands that mediate adhesion to both von Willebrand Factor and collagen, as well as specific clustering to activated platelets. Platelet-like nanoparticles (PLNs) exhibit enhanced surface-binding compared to spherical and rigid discoidal counterparts and site-selective adhesive and platelet-aggregatory properties under physiological flow conditions in vitro. In vivo studies in a mouse model demonstrated that PLNs accumulate at the wound site and induce ∼65% reduction in bleeding time, effectively mimicking and improving the hemostatic functions of natural platelets. We show that both the biochemical and biophysical design parameters of PLNs are essential in mimicking platelets and their hemostatic functions. PLNs offer a nanoscale technology that integrates platelet-mimetic biophysical and biochemical properties for potential applications in injectable synthetic hemostats and vascularly targeted payload delivery.
authors.affiliation: Department of Chemical Engineering, Center for Bioengineering University of California , Santa Barbara, California 93106, United States.
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Anselmo
authors.forename: Christa Lynn
authors.initials: CL
authors.lastname: Modery-Pawlowski
authors.forename: Stefano
authors.initials: S
authors.lastname: Menegatti
authors.forename: Sunny
authors.initials: S
authors.lastname: Kumar
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Vogus
authors.forename: Lewis L
authors.initials: LL
authors.lastname: Tian
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Todd M
authors.initials: TM
authors.lastname: Squires
authors.forename: Anirban
authors.initials: A
authors.lastname: Sen Gupta
authors.forename: Samir
authors.initials: S
authors.lastname: Mitragotri
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000473:pathology*; D002448:Cell Adhesion; D048430:Cell Shape; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles; D010974:Platelet Aggregation; D017550:Spectroscopy, Fourier Transform Infrared; D057772:Vascular System Injuries / Q000473:pathology*
keywords: hemostat; layer-by-layer; nanotechnology; platelets; synthetic cells; vascular targeting