An Injectable Hydrogel Platform for Sustained Delivery of Anti-inflammatory Nanocarriers and Induction of Regulatory T Cells in Atherosclerosis

Advances in engineered nanosystems: immunomodulatory interactions for therapeutic applications

Advances in nanotechnology have led to significant progress in the design and fabrication of nanoparticles (NPs) with improved therapeutic properties. NPs have been explored for modulating the immune system, serving as carriers for drug delivery or vaccine adjuvants, or acting as therapeutics themselves against a wide range of deadly diseases. The combination of NPs with immune system-targeting moieties has facilitated the development of improved targeted immune therapies. Targeted delivery of therapeutic agents using NPs specifically to the disease-affected cells, distinguishing them from other host cells, offers the major advantage of concentrating the therapeutic effect and reducing systemic side effects. Furthermore, the properties of NPs, including size, shape, surface charge, and surface modifications, influence their interactions with the targeted biological components. This review aims to provide insights into these diverse emerging and innovative approaches that are being developed and utilized for modulating the immune system using NPs. We reviewed various types of NPs composed of different materials and their specific application for modulating the immune system. Furthermore, we focused on the mechanistic effects of these therapeutic NPs on primary immune components, including T cells, B cells, macrophages, dendritic cells, and complement systems. Additionally, a recent overview of clinically approved immunomodulatory nanomedicines and potential future perspectives, offering new paradigms of this field, is also highlighted.

Precise modulation and use of reactive oxygen species for immunotherapy

Reactive oxygen species (ROS) play an important role in regulating the immune system by affecting pathogens, cancer cells, and immune cells. Recent advances in biomaterials have leveraged this mechanism to precisely modulate ROS levels in target tissues for improving the effectiveness of immunotherapies in infectious diseases, cancer, and autoimmune diseases. Moreover, ROS-responsive biomaterials can trigger the release of immunotherapeutics and provide tunable release kinetics, which can further boost their efficacy. This review will discuss the latest biomaterial-based approaches for both precise modulation of ROS levels and using ROS as a stimulus to control the release kinetics of immunotherapeutics. Finally, we will discuss the existing challenges and potential solutions for clinical translation of ROS-modulating and ROS-responsive approaches for immunotherapy, and provide an outlook for future research.

Control of the post-infarct immune microenvironment through biotherapeutic and biomaterial-based approaches

Ischemic heart failure (IHF) is a leading cause of morbidity and mortality worldwide, for which heart transplantation remains the only definitive treatment. IHF manifests from myocardial infarction (MI) that initiates tissue remodeling processes, mediated by mechanical changes in the tissue (loss of contractility, softening of the myocardium) that are interdependent with cellular mechanisms (cardiomyocyte death, inflammatory response). The early remodeling phase is characterized by robust inflammation that is necessary for tissue debridement and the initiation of repair processes. While later transition toward an immunoregenerative function is desirable, functional reorientation from an inflammatory to reparatory environment is often lacking, trapping the heart in a chronically inflamed state that perpetuates cardiomyocyte death, ventricular dilatation, excess fibrosis, and progressive IHF. Therapies can redirect the immune microenvironment, including biotherapeutic and biomaterial-based approaches. In this review, we outline these existing approaches, with a particular focus on the immunomodulatory effects of therapeutics (small molecule drugs, biomolecules, and cell or cell-derived products). Cardioprotective strategies, often focusing on immunosuppression, have shown promise in pre-clinical and clinical trials. However, immunoregenerative therapies are emerging that often benefit from exacerbating early inflammation. Biomaterials can be used to enhance these therapies as a result of their intrinsic immunomodulatory properties, parallel mechanisms of action (e.g., mechanical restraint), or by enabling cell or tissue-targeted delivery. We further discuss translatability and the continued progress of technologies and procedures that contribute to the bench-to-bedside development of these critically needed treatments.

Atherosclerosis treatment with nanoagent: potential targets, stimulus signals and drug delivery mechanisms

Cardiovascular disease (CVDs) is the first killer of human health, and it caused up at least 31% of global deaths. Atherosclerosis is one of the main reasons caused CVDs. Oral drug therapy with statins and other lipid-regulating drugs is the conventional treatment strategies for atherosclerosis. However, conventional therapeutic strategies are constrained by low drug utilization and non-target organ injury problems. Micro-nano materials, including particles, liposomes, micelles and bubbles, have been developed as the revolutionized tools for CVDs detection and drug delivery, specifically atherosclerotic targeting treatment. Furthermore, the micro-nano materials also could be designed to intelligently and responsive targeting drug delivering, and then become a promising tool to achieve atherosclerosis precision treatment. This work reviewed the advances in atherosclerosis nanotherapy, including the materials carriers, target sites, responsive model and treatment results. These nanoagents precisely delivery the therapeutic agents to the target atherosclerosis sites, and intelligent and precise release of drugs, which could minimize the potential adverse effects and be more effective in atherosclerosis lesion.

ROS-Responsive Glycopolymeric Nanoparticles for Enhanced Drug Delivery to Macrophages

Macrophages play a diverse, key role in many pathologies, including inflammatory diseases, cardiovascular diseases, and cancer. However, many therapeutic strategies targeting macrophages suffer from systemic off-target toxicity resulting in notoriously narrow therapeutic windows. To address this shortcoming, the development of poly(propylene sulfide)-b-poly(methacrylamidoglucopyranose) [PPS-b-PMAG] diblock copolymer-based nanoparticles (PMAG NPs) capable of targeting macrophages and releasing drug in the presence of reactive oxygen species (ROS) is reported. PMAG NPs have desirable physicochemical properties for systemic drug delivery, including slightly negative surface charge, ≈100 nm diameter, and hemo-compatibility. Additionally, due to the presence of PPS in the NP core, PMAG NPs release drug cargo preferentially in the presence of ROS. Importantly, PMAG NPs display high cytocompatibility and are taken up by macrophages in cell culture at a rate ≈18-fold higher than PEGMA NPs-NPs composed of PPS-b-poly(oligoethylene glycol methacrylate). Computational studies indicate that PMAG NPs likely bind with glucose transporters such as GLUT 1/3 on the macrophage cell surface to facilitate high levels of internalization. Collectively, this study introduces glycopolymeric NPs that are uniquely capable of both receptor-ligand targeting to macrophages and ROS-dependent drug release and that can be useful in many immunotherapeutic settings.

Immunomodulating Hydrogels as Stealth Platform for Drug Delivery Applications

Non-targeted persistent immune activation or suppression by different drug delivery platforms can cause adverse and chronic physiological effects including cancer and arthritis. Therefore, non-toxic materials that do not trigger an immunogenic response during delivery are crucial for safe and effective in vivo treatment. Hydrogels are excellent candidates that can be engineered to control immune responses by modulating biomolecule release/adsorption, improving regeneration of lymphoid tissues, and enhancing function during antigen presentation. This review discusses the aspects of hydrogel-based systems used as drug delivery platforms for various diseases. A detailed investigation on different immunomodulation strategies for various delivery options and deliberate upon the outlook of such drug delivery platforms are conducted.

Nanotechnology for Targeted Therapy of Atherosclerosis

Atherosclerosis is the major cause of heart attack and stroke that are the leading causes of death in the world. Nanomedicine is a powerful tool that can be engineered to target atherosclerotic plaques for therapeutic and diagnosis purposes. In this review, advances in designing nanoparticles with therapeutic effects on atherosclerotic plaques known as atheroprotective nanomedicine have been summarized to stimulate further development and future translation.

Innovations in Disease State Responsive Soft Materials for Targeting Extracellular Stimuli Associated with Cancer, Cardiovascular Disease, Diabetes, and Beyond

Recent advances in polymer chemistry, materials sciences, and biotechnology have allowed the preclinical development of sophisticated programmable nanomedicines and materials that are able to precisely respond to specific disease-associated triggers and microenvironments. These stimuli, endogenous to the targeted diseases, include pH, redox-state, small molecules, and protein upregulation. Herein, recent advances and innovative approaches in programmable soft materials capable of sensing the aforementioned disease-associated stimuli and responding via a range of dynamic processes including morphological and size transitions, changes in mobility and retention, as well as disassembly are described. In this field generally, the majority of ongoing and past research effort has focused on oncology. Given this interest, examples of the latest innovative approaches to chemo- and immunotherapy treatment strategies for cancer are presented. Moreover, as the field broadens its attention, applications of programmable materials in other diseases are highlighted, with a special focus on cardiovascular disease and diabetes mellitus, where limited attention is paid by the field, but where many promising avenues exist with high potential impact.

Pi-stacking Enhances Stability, Scalability of Formation, Control over Flexibility and Circulation Time of Polymeric Filaments

Self-assembling filomicelles (FM) are of great interest to nanomedicine due to their structural flexibility, extensive systemic circulation time, and amenability to unique "cylinder-to-sphere" morphological transitions. However, current fabrication techniques for FM self-assembly are highly variable and difficult to scale. Here, we demonstrate that tetrablock copolymers composed of poly(ethylene glycol)-b-poly(propylene sulfide) (PEG-b-PPS) diblocks linked by a pi-stacking perylene bisimide (PBI) moiety permit rapid, scalable, and facile assembly of FM via the flash nanoprecipitation (FNP) method. Co-assembling the tetrablocks and PEG-b-PPS diblocks at different molar ratios resulted in mixed PBI-containing FM (mPBI-FM) with tunable length and flexibility. The flexibility of mPBI-FM can be optimized to decrease uptake by macrophages in vivo, leading to increased circulation time versus (-)PBI-FM without PBI tetrablocks after intravenous administration in mice. While PEG-b-PPS diblocks form FM within a narrow range of hydrophilic weight fractions, incorporation of pi-stacking PBI groups expanded this range to increase favorability of FM assembly. Furthermore, the aggregation-dependent fluorescence of PBI shifted during oxidation-induced "cylinder-to-sphere" transitions of mPBI-FM into micelles, resulting in a distinct emission wavelength for filamentous versus spherical nanostructures. Thus, incorporation of pi-stacking allows for rapid, scalable assembly of FM with tunable flexibility and stability for theranostic and nanomedicine applications.

The role of anti-inflammatory drugs and nanoparticle-based drug delivery models in the management of ischemia-induced heart failure

Ongoing advancements in the treatment of acute myocardial infarction (MI) have significantly decreased MI related mortality. Consequently, the number of patients experiencing post-MI heart failure (HF) has continued to rise. Infarction size and the extent of left ventricular (LV) remodeling are largely determined by the extent of ischemia at the time of myocardial injury. In the setting of MI or acute phase of post-MI LV remodeling, anti-inflammatory drugs including intravenous immunoglobulin (IVIG) and Pentoxifylline have shown potential efficacy in preventing post-MI remodeling in-vitro and in some clinical trials. However, systemic administration of anti-inflammatory drugs are not without their off-target side effects. Herein, we explore the clinical feasibility of targeted myocardial delivery of anti-inflammatory drugs via biodegradable polymers, liposomes, hydrogels, and nano-particle based drug delivery models (NDDM) based on existing pre-clinical and clinical models. We summarize the barriers to clinical application of targeted anti-inflammatory delivery post-MI, including challenges in achieving sufficient retention and distribution, as well as the potential need for multiple dosing. Collectively, we suggest that localized delivery of anti-inflammatory agents to the myocardium using NDDM is a promising approach for successful treatment of ischemic HF. Future studies will be instrumental in determining the most effective target and delivery modalities for orchestrating NDDM-mediated treatment of HF.

The Combination of Morphology and Surface Chemistry Defines the Immunological Identity of Nanocarriers in Human Blood

Upon exposure to blood, a corona of proteins adsorbs to nanocarrier surfaces to confer a biological identity that interfaces with the immune system. While the nanocarrier surface chemistry has long been the focus of protein corona formation, the influence of nanostructure has remained unclear despite established influences on biodistribution, clearance, and inflammation. Here, combinations of nanocarrier morphology and surface chemistry are engineered to i) achieve compositionally distinct protein coatings in human blood and ii) control protein-mediated interactions with the immune system. A library of nine PEGylated nanocarriers differing in their combination of morphology (spheres, vesicles, and cylinders) and surface chemistry (methoxy, hydroxyl, and phosphate) are synthesized to represent properties of therapeutic and biomimetic delivery vehicles. Analysis by quantitative label-free proteomic techniques reveal that specific surface chemistry and morphology combinations adsorb unique protein signatures from human blood, resulting in differential complement activation and elicitation of distinct proinflammatory cytokine responses. Furthermore, nanocarrier morphology is shown to primarily influence uptake and clearance by human monocytes, macrophages, and dendritic cells. This comprehensive analysis provides mechanistic insights into rational design choices that impact the immunological identity of nanocarriers in human blood, which can be leveraged to engineer drug delivery vehicles for precision medicine and immunotherapy.

Just add water: hydratable, morphologically diverse nanocarrier powders for targeted delivery

Two major obstacles that limit the widespread usage of polymeric nanocarriers include the complexity of formulation methods and their stability during storage. To address both of these issues, here we present morphologically complex nanocarriers in a hydratable powder form, which bypasses the need for expensive, harsh, and/or time-consuming nanocarrier fabrication techniques. The powders are composed of carbohydrates and self-assembling polymer amphiphiles having a low glass transition temperature. Hydration requires less than one minute and only involves the addition of aqueous media (water or saline) to rapidly obtain self-assembled micelles, worm-like micelles (i.e. filomicelles), or polymersomes from poly(ethylene glycol)-b-poly(propylene sulfide) (PEG-b-PPS) polymers. The formulated powders are highly stable, achieving hydration into monodisperse nanocarriers following >6 months of storage. Diverse drug cargoes were efficiently encapsulated during hydration, including hydrophobic small molecules for micellar morphologies, as well as individual and concurrent loading of both hydrophobic and hydrophilic molecules for vesicular morphologies. Hydrated polymersomes are shown to load hydrophilic biological macromolecules, and encapsulated enzymes retain bioactivity. Furthermore, we demonstrate that inclusion of lipid-anchored ligands in powder form permits the surface-display of targeting ligands and enhances target cell uptake, thereby extending this technology to targeted drug delivery applications. Our powder-based formulation strategy was extendable to commercially available polymer amphiphiles, including PEG-b-polystyrene and PEG-b-polycaprolactone. The formulated nanotechnologies described herein are highly modular, require minimal preparation, and remain stable in ambient long-term storage (bypassing cold chain requirements), which will enable their use in medicine (human and veterinary), research, and commercial applications from cosmetics to agriculture.

Nanocarrier-enhanced intracellular delivery of benznidazole for treatment of Trypanosoma cruzi infection

Chagas disease is caused by infection with the protozoan parasite Trypanosoma cruzi (T. cruzi), an intracellular pathogen that causes significant morbidity and death among millions in the Americas from Canada to Argentina. Current therapy involves oral administration of the nitroimidazole benznidazole (BNZ), which has serious side effects that often necessitate cessation of treatment. To both avoid off-target side effects and reduce the necessary dosage of BNZ, we packaged the drug within poly(ethylene glycol)-block-poly(propylene sulfide) polymersomes (BNZ-PSs). We show that these vesicular nanocarriers enhanced intracellular delivery to phagocytic cells and tested this formulation in a mouse model of T. cruzi infection. BNZ-PS is not only nontoxic but also significantly more potent than free BNZ, effectively reducing parasitemia, intracellular infection, and tissue parasitosis at a 466-fold lower dose of BNZ. We conclude that BNZ-PS was superior to BNZ for treatment of T. cruzi infection in mice and that further modifications of this nanocarrier formulation could lead to a wide range of custom controlled delivery applications for improved treatment of Chagas disease in humans.

Inflammation-responsive delivery systems for the treatment of chronic inflammatory diseases

Inflammation is the biological response of immune system to protect living organisms from injurious factors. However, excessive and uncontrolled inflammation is implicated in a variety of devastating chronic diseases including atherosclerosis, inflammatory bowel disease (IBD), and rheumatoid arthritis (RA). Improved understanding of inflammatory response has unveiled a rich assortment of anti-inflammatory therapeutics for the treatment and management of relevant chronic diseases. Notwithstanding these successes, clinical outcomes are variable among patients and serious adverse effects are often observed. Moreover, there exist some limitations for clinical anti-inflammatory therapeutics such as aqueous insolubility, low bioavailability, off-target effects, and poor accessibility to subcellular compartments. To address these challenges, the rational design of inflammation-specific drug delivery systems (DDSs) holds significant promise. Moreover, as compared to normal tissues, inflamed tissue-associated pathological milieu (e.g., oxidative stress, acidic pH, and overexpressed enzymes) provides vital biochemical stimuli for triggered delivery of anti-inflammatory agents in a spatiotemporally controlled manner. In this review, we summarize recent advances in the development of anti-inflammatory DDSs with built-in pathological inflammation-specific responsiveness for the treatment of chronic inflammatory diseases.

Recent advances in nanomaterials for therapy and diagnosis for atherosclerosis

Atherosclerosis is a chronic inflammatory disease driven by lipid accumulation in arteries, leading to narrowing and thrombosis. It affects the heart, brain, and peripheral vessels and is the leading cause of mortality in the United States. Researchers have strived to design nanomaterials of various functions, ranging from non-invasive imaging contrast agents, targeted therapeutic delivery systems to multifunctional nanoagents able to target, diagnose, and treat atherosclerosis. Therefore, this review aims to summarize recent progress (2017-now) in the development of nanomaterials and their applications to improve atherosclerosis diagnosis and therapy during the preclinical and clinical stages of the disease.

Targeted Delivery of Cell Softening Micelles to Schlemm's Canal Endothelial Cells for Treatment of Glaucoma

Increased stiffness of the Schlemm's canal (SC) endothelium in the aqueous humor outflow pathways has been associated with elevated intraocular pressure (IOP) in glaucoma. Novel treatments that relax this endothelium, such as actin depolymerizers and rho kinase inhibitors, are in development. Unfortunately, these treatments have undesirable off-target effects and a lower than desired potency. To address these issues, a targeted PEG-b-PPS micelle loaded with actin depolymerizer latrunculin A (tLatA-MC) is developed. Targeting of SC cells is achieved by modifying the micelle surface with a high affinity peptide that binds the VEGFR3/FLT4 receptor, a lymphatic lineage marker found to be highly expressed by SC cells relative to other ocular cells. During in vitro optimization, increasing the peptide surface density increased micellar uptake in SC cells while unexpectedly decreasing uptake by human umbilical vein endothelial cells (HUVEC). The functional efficacy of tLatA-MC, as measured by decreased SC cell stiffness compared to non-targeted micelles (ntLatA-MC) or targeted blank micelles (tBL-MC), is verified using atomic force microscopy. tLatA-MC reduced IOP in an in vivo mouse model by 30-50%. The results validate the use of a cell-softening nanotherapy to selectively modulate stiffness of SC cells for therapeutic reduction of IOP and treatment of glaucoma.