Cell-encapsulating devices can play an important role in advancing the types of tissue available for transplantation and further improving transplant success rates. To have an effective device, encapsulated cells must remain viable, respond to external stimulus, and be protected from immune responses, and the device itself must elicit a minimal foreign body response. To address these challenges, we developed a micro- and a nanoporous thin-film cell encapsulation device from polycaprolactone (PCL), a material previously used in FDA-approved biomedical devices. The thin-film device construct allows long-term bioluminescent transfer imaging, which can be used for monitoring cell viability and device tracking. The ability to tune the microporous and nanoporous membrane allows selective protection from immune cell invasion and cytokine-mediated cell death in vitro, all while maintaining typical cell function, as demonstrated by encapsulated cells' insulin production in response to glucose stimulation. To demonstrate the ability to track, visualize, and monitor the viability of cells encapsulated in implanted thin-film devices, we encapsulated and implanted luciferase-positive MIN6 cells in allogeneic mouse models for up to 90 days. Lack of foreign body response in combination with rapid neovascularization around the device shows promise in using this technology for cell encapsulation. These devices can help elucidate the metrics required for cell encapsulation success and direct future immune-isolation therapies.

Objective Lipid mediators derived from omega-3 polyunsaturated fatty acids such as Resolvin D1 (RvD1) accelerate the resolution of inflammation, and have potential as vascular therapeutics. The objective of this study was to evaluate local perivascular delivery of RvD1 as a means to attenuate neointimal hyperplasia in a rat model of arterial injury. Methods Smooth muscle cells were harvested from rat aortas to study the effects of RvD1 on rat arterial vascular smooth muscle cell (RASMC) responses in vitro, with focus on inflammation, proliferation, migration, cytoskeletal changes and cytotoxicity. The safety and efficacy of perivascular delivery of RvD1 via thin biodegradable 3-layered PLGA wraps or 25% Pluronic F127 gels were studied in a rat model of carotid angioplasty. A total of 200 ng RvD1 was loaded into each construct for perivascular delivery after injury. Morphometric and histologic analyses were performed 3 and 14 days after injury. Results RvD1 attenuated RASMC inflammatory pathways, proliferation, migration and mitogen-induced cytoskeletal changes in vitro, without evidence of cytotoxicity. RvD1-loaded wraps reduced neointimal formation after carotid angioplasty by 59% versus no-wrap controls (P = .001) and by 45% versus vehicle-wrap controls (P = .002). RvD1-loaded pluronic gels similarly reduced neointimal formation by 49% versus no-gel controls (P = .02) and by 52% versus vehicle-gel controls (P = .02). No group was associated with infection, thrombosis or negative vessel remodeling. Wraps were found to be easier to apply than gel constructs. Ki67 proliferation index was significantly lower in RvD1-loaded wrap treated arteries compared to both no-wrap and vehicle-wrap controls at both 3 and 14 days post-injury (65% versus no-wrap group and 70% versus vehicle-wrap group at day 3, 49% versus both control groups at day 14, P < .05). Similarly, oxidative stress (30% and 29%, P < .05). and NF-kB activation (42% and 45%, p<.05) were significantly lower in the RvD1-loaded wrap group compared to both no-wrap and vehicle-wrap controls at three days post-injury Conclusions Local perivascular delivery of RvD1 attenuates formation of neointimal hyperplasia without associated toxicity in a rat model of carotid angioplasty. This effect is likely due to attenuation of inflammatory pathways as well as decreased arterial smooth muscle cell proliferation and migration.

Objective: Inflammation is a key driver of excessive neointimal hyperplasia within vein grafts. Recent work demonstrates that specialized proresolving lipid mediators biosynthesized from omega-3 polyunsaturated fatty acids, such as resolvin D1 (RvD1), actively orchestrate the process of inflammation resolution. We investigated the effects of local perivascular delivery of RvD1 in a rabbit vein graft model. Methods: Ipsilateral jugular veins were implanted as carotid interposition grafts through an anastomotic cuff technique in New Zealand white rabbits (3–4 kg; N = 80). RvD1 (1 μg) was delivered to the vein bypass grafts in a perivascular fashion, using either 25% Pluronic F127 gel (Sigma-Aldrich, St. Louis, Mo) or a thin bilayered poly(lactic-co-glycolic acid) (PLGA) film. No treatment (bypass only) and vehicle-loaded Pluronic gels or PLGA films served as controls. Delivery of RvD1 to venous tissue was evaluated 3 days later by liquid chromatography-tandem mass spectrometry. Total leukocyte infiltration, macrophage infiltration, and cell proliferation were evaluated by immunohistochemistry. Elastin and trichrome staining was performed on grafts harvested at 28 days after bypass to evaluate neointimal hyperplasia and vein graft remodeling. Results: Perivascular treatments did not influence rates of graft thrombosis (23%), major wound complications (4%), or death (3%). Leukocyte (CD45) and macrophage (RAM11) infiltration was significantly reduced in the RvD1 treatment groups vs controls at 3 days (60%−72% reduction; P < .01). Cellular proliferation (Ki67 index) was also significantly lower in RvD1-treated vs control grafts at 3 days (40%−50% reduction; P < .01). Treatment of vein grafts with RvD1-loaded gels reduced neointimal thickness at 28 days by 61% vs bypass only (P < .001) and by 63% vs vehicle gel (P < .001). RvD1-loaded PLGA films reduced neointimal formation at 28 days by 50% vs bypass only (P < .001). RvD1 treatment was also associated with reduced collagen deposition in vein grafts at 28 days. Conclusions: Local perivascular delivery of RvD1 attenuates vein graft hyperplasia without associated toxicity in a rabbit carotid bypass model. This effect appears to be mediated by both reduced leukocyte recruitment and decreased cell proliferation within the graft. Perivascular PLGA films may also impart protection through biomechanical scaffolding in this venous arterialization model. Our studies provide further support for the potential therapeutic role of specialized proresolving lipid mediators such as D-series resolvins in modulating vascular injury and repair. (J Vasc Surg 2018;■:1–12.) Clinical Relevance: Autologous vein bypass grafts are the most durable means for revascularization in peripheral vascular disease; however, midterm and long-term outcomes are limited by vein graft hyperplasia with associated vein graft failure. Endogenous proresolving lipid mediators such as resolvin D1 have the potential to attenuate vein graft hyperplasia by accelerating repair. This study provides proof of co...

Herein long-term delivery of proteins from biodegradable thin film devices is demonstrated, where a nanostructured polymer membrane controls release. Protein was sealed between two poly(caprolactone) films, which generated the thin film devices. Protein release for 210 days was shown in vitro, and stable activity was established through 70 days with a model protein. These thin film devices present a promising delivery platform for biologic therapeutics, particularly for application in constrained spaces.

This paper describes the spontaneous formation of well-defined pores in planar lipid bilayers from the self-assembly of a small synthetic molecule that contains a benzothiazole aniline (BTA) group attached to a tetra-ethylene glycol (EG4) moiety. Macroscopic and single-channel current recordings suggest that these pores are formed by the assembly of four BTA-EG4 monomers with an open pore diameter that appears similar to the one of gramicidin pores (~0.4 nm). The single-channel conductance of these pores is modulated by the pH of the electrolyte and has a minimum at pH~3. Self-assembled pores from BTA-EG4 are selective for monovalent cations and have long open channel lifetimes on the order of seconds. BTA-EG4 monomers in these pores appear to be arranged symmetrically across both leaflets of the bilayer, and spectroscopy studies suggest that the fluorescent BTA group is localized inside the lipid bilayers. In terms of biological activity, BTA-EG4 molecules inhibited growth of gram-positive Bacillus subtilis bacteria (IC50~50 μM) and human neuroblastoma SH-SY5Y cells (IC50~60 μM), while they were not toxic to gram-negative Escherichia coli bacteria at a concentration up to 500 μM. Based on these properties, this drug-like, synthetic, pore-forming molecule with a molecular weight below 500 g mol(-1) might be appealing as a starting material for development of antibiotics or membrane-permeating moieties for drug delivery. From a biophysical point of view, long-lived, well-defined ion-selective pores from BTA-EG4 molecules offer an example of a self-assembled synthetic supramolecule with biological function.