Abstract 420: Synthesis and Targeted Spatiotemporal Delivery of Peptide Amphiphile to the Vasculature
Introduction: The aim of this study is to develop and evaluate a novel systemically delivered targeted therapy that will prevent restenosis after all cardiovascular interventions. To accomplish this aim, our goal is to synthesize a self-assembled peptide amphiphile (PA) targeted to a unique collagen-binding sequence, and demonstrate binding to the site of vascular intervention. Our hypothesis is that our collagen binding PA will bind to the site of vascular injury.
Methods: PA was synthesized using solid-phase peptide synthesis and purified by reversed-phase HPLC. The collagen-binding sequence and a fluorescent tag (AlexaFluor546) was incorporated into the PA. Vascular smooth muscle cells (VSMC) and adventitial fibroblasts (AF) were exposed to the PA (0.25-1.0 mM) in culture and metabolic activity was assessed with the MTT assay. Male Sprague Dawley rats underwent the carotid artery injury model followed by intra-arterial injection of the PA (5mg) for 10min. Carotid arteries and arterial cross-sections were imaged for fluorescence using excitation and emission wavelengths of 535 nm and 580 nm, resp.
Results: VSMC and AF exposed to the targeted PA for 24hrs showed similar metabolic activity compared to controls except at the highest concentration (1mM) at which a 50% decrease was detected (P<0.05). Carotid arteries injured and exposed to intra-arterial PA followed by intraluminal flushing with PBS exhibited positive binding of the PA to the site of injury with 5-fold greater fluorescent intensity compared to background levels. Similarly, carotid arteries injured and exposed to PA in a similar manner followed by re-establishment of blood flow for 20min exhibited 3-fold greater fluorescent intensity than background levels. Arterial cross sections demonstrated binding of the PA to the intima. No significant fluorescent signal was detected in the uninjured arteries.
Conclusion: These data demonstrate that our novel targeted PA is biocompatible with vascular cells in vitro. Furthermore, we successfully demonstrated specific binding of our injectable targeted PA to the site of injury. This research serves as the foundation upon which a targeted drug-eluting therapy will be designed and evaluated to prevent restenosis following vascular interventions.
- © 2012 by American Heart Association, Inc.