Nrf2 activator-encapsulating polymeric nanoparticles and LDL-like nanoparticles target atherosclerotic plaque

Abstract

Atherosclerotic vascular disease is the leading cause of death world-wide with few novel therapies available in spite of the ongoing health burden. Oxidative stress is a well-established driver of atherosclerotic progression; however the clinical translation of redox-based therapies is lacking. One of the challenges facing redox-based therapies is their targeted delivery to cellular domains of redox dysregulation. In the current study we sought to develop NPs encapsulating redox-based interventions that exploit passive means of targeting to selectively accumulate in atherosclerotic plaque with the aim of enhancing the intra-plaque bioavailability of interventions. Herein we present two types of nanoparticles (NPs): (i) We have employed flash nanoprecipitation to synthesize polymeric NPs encapsulating the hydrophobic Nrf2 activator drug, CDDO-Methyl, (ii) we have generated LDL-like NPs encapsulating the anti-inflammatory compound, oleic acid (OA). Nrf2-activators are a promising class of redox-active drug molecules whereby activation of Nrf2 results in the expression of several antioxidant and cyto-protective enzymes. Moreover, local activation of Nrf2 within the atherosclerotic plaque can be athero-protective. In this study we characterize the physiochemical properties of these NPs as well as confirm in vitro association of NPs with murine macrophages. In vitro drug release of CDDO-Me from polymeric NPs was determined by Nrf2-ARE-driven GFP fluorescence. In vivo localization was assessed through immunofluorescence of histological sections as well as whole-tissue light sheet fluorescence microscopy. We show that CDDO-Me-NPs and LDL-OA-NPs selectively accumulate in atherosclerotic plaque of two widely-used murine models of atherosclerosis: ApoE-/- and LDLr-/- mice. Overall, these studies underline that targeting of atherosclerotic plaque is an effective means to enhance delivery of redox-based interventions. Future work will assess the therapeutic efficacy of intra-plaque Nrf2 activation or anti-inflammatory actions with CDDO-Me-NPs or LDL-OA-NPs, respectively.