The Nose-To-Brain Transport of Polymeric Nanoparticles Is Mediated by Immune Sentinels and Not by Olfactory Sensory Neurons

Using the Intranasal Route to Administer Drugs to Treat Neurological and Psychiatric Illnesses: Rationale, Successes, and Future Needs

While the intranasal administration of drugs to the brain has been gaining both research attention and regulatory success over the past several years, key fundamental and translational challenges remain to fully leveraging the promise of this drug delivery pathway for improving the treatment of various neurological and psychiatric illnesses. In response, this review highlights the current state of understanding of the nose-to-brain drug delivery pathway and how both biological and clinical barriers to drug transport using the pathway can been addressed, as illustrated by demonstrations of how currently approved intranasal sprays leverage these pathways to enable the design of successful therapies. Moving forward, aiming to better exploit the understanding of this fundamental pathway, we also outline the development of nanoparticle systems that show improvement in delivering approved drugs to the brain and how engineered nanoparticle formulations could aid in breakthroughs in terms of delivering emerging drugs and therapeutics while avoiding systemic adverse effects.

Advances in Non-Animal Testing Approaches towards Accelerated Clinical Translation of Novel Nanotheranostic Therapeutics for Central Nervous System Disorders

Nanotheranostics constitute a novel drug delivery system approach to improving systemic, brain-targeted delivery of diagnostic imaging agents and pharmacological moieties in one rational carrier platform. While there have been notable successes in this field, currently, the clinical translation of such delivery systems for the treatment of neurological disorders has been limited by the inadequacy of correlating in vitro and in vivo data on blood-brain barrier (BBB) permeation and biocompatibility of nanomaterials. This review aims to identify the most contemporary non-invasive approaches for BBB crossing using nanotheranostics as a novel drug delivery strategy and current non-animal-based models for assessing the safety and efficiency of such formulations. This review will also address current and future directions of select in vitro models for reducing the cumbersome and laborious mandate for testing exclusively in animals. It is hoped these non-animal-based modelling approaches will facilitate researchers in optimising promising multifunctional nanocarriers with a view to accelerating clinical testing and authorisation applications. By rational design and appropriate selection of characterised and validated models, ranging from monolayer cell cultures to organ-on-chip microfluidics, promising nanotheranostic particles with modular and rational design can be screened in high-throughput models with robust predictive power. Thus, this article serves to highlight abbreviated research and development possibilities with clinical translational relevance for developing novel nanomaterial-based neuropharmaceuticals for therapy in CNS disorders. By generating predictive data for prospective nanomedicines using validated in vitro models for supporting clinical applications in lieu of requiring extensive use of in vivo animal models that have notable limitations, it is hoped that there will be a burgeoning in the nanotherapy of CNS disorders by virtue of accelerated lead identification through screening, optimisation through rational design for brain-targeted delivery across the BBB and clinical testing and approval using fewer animals. Additionally, by using models with tissue of human origin, reproducible therapeutically relevant nanomedicine delivery and individualised therapy can be realised.

A comparison study of lipid and polymeric nanoparticles in the nasal delivery of meloxicam: Formulation, characterization, and in vitro evaluation

With the increasingly widespread of central nervous system (CNS) disorders and the lack of sufficiently effective medication, meloxicam (MEL) has been reported as a possible medication for Alzheimer's disease (AD) management. Unfortunately, following the conventional application routes, the low brain bioavailability of MEL forms a significant limitation. The intranasal (IN) administration route is considered revolutionary for CNS medications delivery. The objective of the present study was to develop two types of nanocarriers, poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) and solid lipid nanoparticles (SLNs), for the IN delivery of MEL adapting the Quality by Design approach (QbD). Turning then to further enhance the optimized nanoformulation behavior by chitosan-coating. SLNs showed higher encapsulation efficacy (EE) and drug loading (DL) than PLGA NPs 87.26% (EE) and 2.67% (DL); 72.23% (EE) and 2.55% (DL), respectively. MEL encapsulated into the nanoformulations improved in vitro release, mucoadhesion, and permeation behavior compared to the native drug with greater superiority of chitosan-coated SLNs (C-SLNs). In vitro-in vivo correlation (IVIVC) results estimated a significant in vivo brain distribution of the nanoformulations compared to native MEL with estimated greater potential in the C-SLNs. Hence, MEL encapsulation into C-SLNs towards IN route can be promising in enhancing its brain bioavailability.

Nose-to-brain co-delivery of drugs for glioblastoma treatment using nanostructured system

Mutations on the epidermal growth factor receptor (EGFR), induction of angiogenesis, and reprogramming cellular energetics are all biological features acquired by tumor cells during tumor development, and also known as the hallmarks of cancer. Targeted therapies that combine drugs that are capable of acting against such concepts are of great interest, since they can potentially improve the therapeutic efficacy of treatments of complex pathologies, such as glioblastoma (GBM). However, the anatomical location and biological behavior of this neoplasm imposes great challenges for targeted therapies. A novel strategy that combines alpha-cyano-4-hydroxycinnamic acid (CHC) with the monoclonal antibody cetuximab (CTX), both carried onto a nanotechnology-based delivery system, is herein proposed for GBM treatment via nose-to-brain delivery. The biological performance of Poly (D,L-lactic-co-glycolic acid)/chitosan nanoparticles (NP), loaded with CHC, and conjugated with CTX by covalent bonds (conjugated NP) were extensively investigated. The NP platforms were able to control CHC release, indicating that drug release was driven by the Weibull model. An ex vivo study with nasal porcine mucosa demonstrated the capability of these systems to promote CHC and CTX permeation. Blot analysis confirmed that CTX, covalently associated to NP, impairs EGRF activation. The chicken chorioallantoic membrane assay demonstrated a trend of tumor reduction when conjugated NP were employed. Finally, images acquired by fluorescence tomography evidenced that the developed nanoplatform was effective in enabling nose-to-brain transport upon nasal administration. In conclusion, the developed delivery system exhibited suitability as an effective novel co-delivery approaches for GBM treatment upon intranasal administration.

Heterocellular spheroids of the neurovascular blood-brain barrier as a platform for personalized nanoneuromedicine

Nanoneuromedicine investigates nanotechnology to target the brain and treat neurological diseases. In this work, we biofabricated heterocellular spheroids comprising human brain microvascular endothelial cells, brain vascular pericytes and astrocytes combined with primary cortical neurons and microglia isolated from neonate rats. The structure and function are characterized by confocal laser scanning and light sheet fluorescence microscopy, electron microscopy, western blotting, and RNA sequencing. The spheroid bulk is formed by neural cells and microglia and the surface by endothelial cells and they upregulate key structural and functional proteins of the blood-brain barrier. These cellular constructs are utilized to preliminary screen the permeability of polymeric, metallic, and ceramic nanoparticles (NPs). Findings reveal that penetration and distribution patterns depend on the NP type and that microglia would play a key role in this pathway, highlighting the promise of this platform to investigate the interaction of different nanomaterials with the central nervous system in nanomedicine, nanosafety and nanotoxicology.

Molecular and cellular cues governing nanomaterial-mucosae interactions: from nanomedicine to nanotoxicology

Mucosal tissues constitute the largest interface between the body and the surrounding environment and they regulate the access of molecules, supramolecular structures, particulate matter, and pathogens into it. All mucosae are characterized by an outer mucus layer that protects the underlying cells from physicochemical, biological and mechanical insults, a mono-layered or stratified epithelium that forms tight junctions and controls the selective transport of solutes across it and associated lymphoid tissues that play a sentinel role. Mucus is a gel-like material comprised mainly of the glycoprotein mucin and water and it displays both hydrophilic and hydrophobic domains, a net negative charge, and high porosity and pore interconnectivity, providing an efficient barrier for the absorption of therapeutic agents. To prolong the residence time, absorption and bioavailability of a broad spectrum of active compounds upon mucosal administration, mucus-penetrating and mucoadhesive particles have been designed by tuning the chemical composition, the size, the density, and the surface properties. The benefits of utilizing nanomaterials that interact intimately with mucosae by different mechanisms in the nanomedicine field have been extensively reported. To ensure the safety of these nanosystems, their compatibility is evaluated in vitro and in vivo in preclinical and clinical trials. Conversely, there is a growing concern about the toxicity of nanomaterials dispersed in air and water effluents that unintentionally come into contact with the airways and the gastrointestinal tract. Thus, deep understanding of the key nanomaterial properties that govern the interplay with mucus and tissues is crucial for the rational design of more efficient drug delivery nanosystems (nanomedicine) and to anticipate the fate and side-effects of nanoparticulate matter upon acute or chronic exposure (nanotoxicology). This review initially overviews the complex structural features of mucosal tissues, including the structure of mucus, the epithelial barrier, the mucosal-associated lymphatic tissues and microbiota. Then, the most relevant investigations attempting to identify and validate the key particle features that govern nanomaterial-mucosa interactions and that are relevant in both nanomedicine and nanotoxicology are discussed in a holistic manner. Finally, the most popular experimental techniques and the incipient use of mathematical and computational models to characterize these interactions are described.

Mixed Amphiphilic Polymeric Nanoparticles of Chitosan, Poly(vinyl alcohol) and Poly(methyl methacrylate) for Intranasal Drug Delivery: A Preliminary In Vivo Study

Intranasal (i.n.) administration became an alternative strategy to bypass the blood-brain barrier and improve drug bioavailability in the brain. The main goal of this work was to preliminarily study the biodistribution of mixed amphiphilic mucoadhesive nanoparticles made of chitosan-g-poly(methyl methacrylate) and poly(vinyl alcohol)-g-poly(methyl methacrylate) and ionotropically crosslinked with sodium tripolyphosphate in the brain after intravenous (i.v.) and i.n. administration to Hsd:ICR mice. After i.v. administration, the highest nanoparticle accumulation was detected in the liver, among other peripheral organs. After i.n. administration of a 10-times smaller nanoparticle dose, the accumulation of the nanoparticles in off-target organs was much lower than after i.v. injection. In particular, the accumulation of the nanoparticles in the liver was 20 times lower than by i.v. When brains were analyzed separately, intravenously administered nanoparticles accumulated mainly in the "top" brain, reaching a maximum after 1 h. Conversely, in i.n. administration, nanoparticles were detected in the "bottom" brain and the head (maximum reached after 2 h) owing to their retention in the nasal mucosa and could serve as a reservoir from which the drug is released and transported to the brain over time. Overall, results indicate that i.n. nanoparticles reach similar brain bioavailability, though with a 10-fold smaller dose, and accumulate in off-target organs to a more limited extent and only after redistribution through the systemic circulation. At the same time, both administration routes seem to lead to differential accumulation in brain regions, and thus, they could be beneficial in the treatment of different medical conditions.