Effect of Cholesterol on Biomimetic Membrane Curvature and Coronavirus Fusion Peptide Encapsulation.

Biomimetic cubic phases can be used for protein encapsulation in a variety of applications such as biosensors and drug delivery. Cubic phases with a high concentration of cholesterol and phospholipids were obtained herein. It is shown that the cubic phase structure can be maintained with a higher concentration of biomimetic membrane additives than has been reported previously. Opposing effects on the curvature of the membrane were observed upon the addition of phospholipids and cholesterol. Furthermore, the coronavirus fusion peptide significantly increased the negative curvature of the biomimetic membrane with cholesterol. We show that the viral fusion peptide can undergo structural changes leading to the formation of hydrophobic α-helices that insert into the lipid bilayer. This is of high importance, as a fusion peptide that induces increased negative curvature as shown by the formation of inverse hexagonal phases allows for greater contact area between two membranes, which is required for viral fusion to occur. The cytotoxicity assay showed that the toxicity toward HeLa cells was dramatically decreased when the cholesterol or peptide level in the nanoparticles increased. This suggests that the addition of cholesterol can improve the biocompatibility of the cubic phase nanoparticles, making them safer for use in biomedical applications. As the results, this work improves the potential for the biomedical end-use applications of the nonlamellar lipid nanoparticles and shows the need of systematic formulation studies due to the complex interplay of all components.

Design, Development, In Vitro and Preliminary In Vivo Evaluation of a Novel Photo-Angioplasty Device: Lumi-Solve.

PURPOSE: Paclitaxel (PTX)-coated drug eluting balloon catheters (DEBc) used in the management of neointimal hyperplasia (NIH) have been associated with safety concerns. Alternative coating agents and targeted delivery systems may improve safety and DEBc efficacy. Utilizing a multi-platform approach we designed, developed and evaluated Lumi-Solve, a novel DEBc, coated with ultraviolet (UV) 365 nm-activated caged metacept-3 (c-MCT-3), an epigenetic agent from the histone deacetylase inhibitor (HDACi) class. METHODS: In vitro catheter and contrast media transmission of UV365nm was evaluated spectroscopically. UV365nm conversion of c-MCT-3 to MCT-3 was evaluated chromatographically. Cellular toxicity and HDACi activity of c-MCT-3 ∓UV365nm was evaluated in vitro. In vivo UV365nm conversion of c-MCT-3 to MCT-3 was evaluated in an ovine carotid artery model. RESULTS: Catheter material and dilute contrast media did not attenuate UV365nm transmission or c-MCT-3 activation. c-MCT-3 demonstrated less cellular toxicity than MCT-3 and PTX. UV365nm-activated c-MCT-3 demonstrated HDACi activity. In vivo activation of c-MCT-3 produced MCT-3. CONCLUSIONS: Lumi-Solve, a novel DEBc device developed utilizing a combination of chemical, fibre-optic and catheter based technology platforms, demonstrated potential for targeted delivery of bioactive HDACi to the blood vessel wall supporting direct application to the management of NIH and warranting additional in vivo studies.

Synthesis and biological evaluation of a novel photo-activated histone deacetylase inhibitor.

Hydroxamic acid-based histone deacetylase inhibitors (HDACi) are a class of epigenetic agents with potentially broad therapeutic application to several disease states including post angioplasty mediated neointimal hyperplasia (NIH). Precise spatiotemporal control over the release of HDACi at the target blood vessel site is required for the safe and successful therapeutic use of HDACi in the setting of drug eluting balloon catheter (DEBc) angioplasty treatment of NIH. We aimed to develop and characterise a novel photoactive HDACi, as a potential coating agent for DEBc. Metacept-3 1 was caged with a photo-labile protecting group (PPG) to synthesise a novel UV365nm active HDACi, caged metacept-3 15. Conversion of caged metacept-3 15 to active/native metacept-3 1 by UV365nm was achievable in significant quantities and at UV365nm power levels in the milliwatt (mW) range. In vitro evaluation of the biological activity of pre and post UV365nm activation of caged metacept-3 15 identified significant HDACi activity in samples exposed to short duration, mW range UV365nm. Toxicity studies performed in human umbilical vein endothelial cells (HUVEC's) identified significantly reduced toxicity of caged metacept-3 15 pre UV365nm exposure compared with native metacept-3 1 and paclitaxel (PTX). Taken together these findings identify a novel photo-activated HDACi, caged metacept-3 15, with pharmacokinetic activation characteristics and biological properties which may make it suitable for evaluation as a novel coating for targeted DEBc angioplasty interventions.

A Novel Epigenetic Drug-Eluting Balloon Angioplasty Device: Evaluation in a Large Animal Model of Neointimal Hyperplasia.

PURPOSE: Drug-eluting balloon catheters (DEBc) coated with paclitaxel (PTX) have been associated with potential safety concerns. An efficacious but less toxic balloon coating may reduce these outcomes. We evaluated a novel DEBc, Epi-Solve, coated with metacept-3 (MCT-3), a member of the histone deacetylase inhibitor (HDACi) class of epigenetic agents, in a large animal model of neointimal hyperplasia (NIH). METHODS: Plain balloon angioplasty (PABA) catheters were ultrasonically coated with MCT-3 to generate Epi-Solve DEBc. An ovine model of NIH formation was established utilising partial left common carotid artery (LCA) ligation. Twenty-eight days post neointima (NI) induction, PABA, Epi-Solve or PTX-coated DEBc were deployed at the site of induced NI formation. Twenty-eight days post-intervention, ligated vessels were evaluated for attenuation of NI formation, gene expression profiles and immunohistochemical analysis. RESULTS: Epi-Solve DEBc demonstrated attenuation of NIH over no intervention and a trend to inhibition of NIH over PABA. Gene expression analysis and immunohistochemical studies identified significant anti-proliferative and anti-inflammatory signatures and reduced vascular endothelial cell activation compared to PABA. CONCLUSIONS: Epi-Solve is a novel HDACi-coated DEBc which demonstrates significant anti-proliferative and anti-inflammatory signatures and reduced vascular endothelial cell activation compared to PABA in an ovine model and may afford endothelial protection.