Energy-dependent endocytosis is responsible for drug transcorneal penetration following the instillation of ophthalmic formulations containing indomethacin nanoparticles

PLL-g-PEG Polymer Inhibits Antibody-Drug Conjugate Uptake into Human Corneal Epithelial Cells In Vitro

Purpose: Antibody-drug conjugates (ADCs) are a relatively recent advance in the delivery of chemotherapeutics that improve targeting of cytotoxic agents. However, despite their antitumor activity, severe ocular adverse effects, including vision loss, have been reported for several ADCs. The nonspecific uptake of ADCs into human corneal epithelial cells (HCECs) and their precursors via macropinocytosis has been proposed to be the primary mechanism of ocular toxicity. In this study, we evaluated the ability of a novel polymer, poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), to decrease the ADC rituximab-mc monomethylauristatin F (MMAF) (RIX) uptake into human corneal epithelial (HCE-T) cells. Methods: HCE-T cells were exposed to increasing concentrations of RIX to determine inhibition of cell proliferation. HCE-T cells were treated with PLL-g-PEG, the macropinocytosis inhibitor 5-(N-ethyl-N-isopropyl) amiloride (EIPA), or vehicle. After 30 min of incubation, RIX was added. ADC was detected by fluorescent anti-human immunoglobulin G and fluorescently conjugated dextran as viewed by microscopy. Results: RIX caused dose-dependent inhibition of HCE-T cell proliferation. EIPA significantly reduced RIX uptake and decreased macropinocytosis as assessed by direct quantification of RIX using a fluorescently conjugated anti-human antibody as well as quantification of macropinocytosis using fluorescently conjugated dextran. PLL-g-PEG resulted in a dose-dependent inhibition of RIX uptake with half-maximal inhibitory concentrations of 0.022%-0.023% PLL-g-PEG. Conclusion: The data show PLL-g-PEG to be a potent inhibitor of RIX uptake by corneal epithelial cells and support its use as a novel therapeutic approach for the prevention of ocular adverse events associated with ADC therapy.

Alginate di-aldehyde-modified metal-organic framework nanocarriers as delivery platform and adjuvant in inactivated pseudorabies vaccination

Pseudorabies virus (PRV) is a highly contagious viral disease, which leads to severe financial losses in the breeding industry worldwide. Presently, PRV is mainly controlled using live attenuated and inactivated vaccines. However, these vaccines have an innate tendency to lose their structural conformation upon exposure to environmental and chemical stressors and cannot provide full protection against the emerging prevalent PRV variants. In this work, first, we synthesized aminated ZIF-7/8 nanoparticles (NPs), and then chemical bond-coated alginate dialdehyde (ADA, a type of dioxide alginate saccharide) on their surface via Schiff base reaction to obtain ZIF-7/8-ADA NPs. The as-fabricated ZIF-7/8-ADA NPs exhibited high stability, monodispersity and a high loading ratio of antigen. Furthermore, the ZIF-7/8-ADA NPs showed good biocompatibility in vitro and in vivo. Using ZIF-7/8-ADA NPs as an adjuvant and inactivated PRV as a model antigen, we constructed a PR vaccine through a simple mixture. The immunity studies indicated that ZIF-7/8-ADA induced an enhancement in the Th1/Th2 immune response, which was superior to that of the commercial ISA201, alum adjuvant and ZIF-7/8. Due to the pH-sensitive release of the antigen in lysosomes, the as-prepared PR vaccine subsequently accelerated the antigen presentation and improved the immune responses in vitro and in vivo. The results of PRV challenge using mice as the model demonstrated that ZIF-7/8-ADA achieved the same preventive effect as the commercial ISA201 and was much better than the alum adjuvant, and thus can serve as a promising delivery system and adjuvant to enhance humoral and cellular responses against PRV infection.

Inflammatory Cytokines and Chemokines Are Synergistically Induced in a ROS-Dependent Manner by a Co-Culture of Corneal Epithelial Cells and Neutrophil-like Cells in the Presence of Particulate Matter

Ocular exposure to particulate matter (PM) causes local inflammation; however, the influence of neutrophils on PM-induced ocular inflammation is still not fully understood. In this study, we constructed a system to investigate the role of PM in ocular inflammation using a co-culture of human corneal epithelial cells (HCE-T) and differentiation-induced neutrophils (dHL-60). To investigate whether HCE-T directly endocytosed PM, we performed a holographic analysis, which showed the endocytosis of PM in HCE-T. The cytokines and chemokines produced by HCE-T were measured using an ELISA. HCE-T treated with PM produced IL-6 and IL-8, which were inhibited by N-Acetyl-L-cysteine (NAC), suggesting the involvement of ROS. Their co-culture with dHL-60 enhanced their production of IL-6, IL-8, and MCP-1. This suggests an inflammatory loop involving intraocular corneal epithelial cells and neutrophils. These cytokines and chemokines are mainly regulated by NF-κB. Therefore, this co-culture system was examined in the presence of an IKK inhibitor known to downregulate NF-κB activity. The IKK inhibitor dramatically suppressed the production of these factors in co-culture supernatants. The results suggest that the inflammatory loop observed in the co-culture is mediated through ROS and the transcription factor NF-κB. Thus, the co-culture system is considered a valuable tool for analyzing complex inflammations.

GLP-1 derivatives with functional sequences transit and migrate through trigeminal neurons

Patients with dementia are increasing with the aging of the population, and dementia has become a disease with high unmet medical needs. Glucagon-like peptide-1 (GLP-1), a neuropeptide, has been reported to improve learning and memory following intracerebroventricular administration. We focused on intranasal administration, which can deliver drugs noninvasively and efficiently to the brain. Although much of the human nasal mucosa is occupied by respiratory epithelium, many capillaries are present in the paracellular route of respiratory epithelium. Therefore, to incorporate GLP-1 into cells, we created a GLP-1 derivative by adding cell-penetrating peptides (CPP) and penetration accelerating sequences (PAS) to GLP-1. We investigated in vitro and in vivo function of PAS-CPP-GLP-1 to enable the translocation of GLP-1 directly from nose to brain. PAS-CPP-GLP-1 enhanced cellular uptake by macropinocytosis with CPP, efficiently escaped from the endosomes due to PAS, and exited the cells. PAS-CPP-GLP-1 also transited trigeminal nerve cells through axon transport and migrated to the adjacent trigeminal nerve cell. Moreover, PAS-CPP-GLP-1 showed significant improvement in learning memory in mice within 20 min of intranasal administration. These results suggested CPP and PAS may be important for the efficient transfer of GLP-1 to the site of action in the brain following intranasal administration.

Enhancing Ocular Drug Delivery: The Effect of Physicochemical Properties of Nanoparticles on the Mechanism of Their Uptake by Human Cornea Epithelial Cells

This study investigates the effect of nanoparticle size and surface chemistry on interactions of the nanoparticles with human cornea epithelial cells (HCECs). Poly(lactic-co-glycolic) acid (PLGA) nanoparticles were synthesized using the emulsion-solvent evaporation method and surface modified with mucoadhesive (alginate [ALG] and chitosan [CHS]) and mucopenetrative (polyethylene glycol [PEG]) polymers. Particles were found to be monodisperse (polydispersity index (PDI) below 0.2), spherical, and with size and zeta potential ranging from 100 to 250 nm and from -25 to +15 mV, respectively. Evaluation of cytotoxicity with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay indicated that incubating cells with nanoparticles for 24 h at concentrations up to 100 μg/mL caused only mild toxicity (70-100% cell viability). Cellular uptake studies were conducted using an in vitro model developed with a monolayer of HCECs integrated with simulated mucosal solution. Evaluation of nanoparticle uptake revealed that energy-dependent endocytosis is the primary uptake mechanism. Among the different nanoparticles studied, 100 nm PLGA NPs and PEG-PLGA-150 NPs showed the highest levels of uptake by HCECs. Additionally, uptake studies in the presence of various inhibitors suggested that macropinocytosis and caveolae-mediated endocytosis are the dominant pathways. While clathrin-mediated endocytosis was found to also be partially responsible for nanoparticle uptake, phagocytosis did not play a role within the studied ranges of size and surface chemistries. These important findings could lead to improved nanoparticle-based formulations that could improve therapies for ocular diseases.

Enhancing Corneal Drug Penetration Using Penetratin for Ophthalmic Suspensions

Eye drops, including solutions and suspensions, are essential dosage forms to treat ophthalmic diseases, with poorly water-soluble drugs typically formulated as ophthalmic suspensions. In addition to low bioavailability, suspensions exhibit limited efficacy, safety, and usability due to the presence of drug particles. Improving bioavailability can reduce the drug concentrations and the risk of problems associated with suspended drug particles. However, practical penetration enhancers capable of improving bioavailability remain elusive. Herein, we focused on penetratin (PNT), a cell-penetrating peptide (CPP) that promotes active cellular transport related to macromolecule uptake, such as micropinocytosis. According to the in vitro corneal uptake study using a reconstructed human corneal epithelial tissue model, LabCyte CORNEA-MODEL24, PNT enhanced the uptake of Fluoresbrite® YG carboxylate polystyrene microspheres without covalent binding. In an ex vivo porcine eye model, the addition of 10 µM PNT to rebamipide ophthalmic suspension markedly improved the corneal uptake of rebamipide; however, the addition of 100 µM PNT was ineffective due to potentially increased particle size by aggregation. This article provides basic information on the application of PNT as a penetration enhancer in ophthalmic suspensions, including the in vitro and ex vivo studies mentioned above, as well as the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay and storage stability at different pH values.

[Development of Transdermal Formulation Based on Nanotechnology and Elucidation of Its Drug Delivery Pathways]

Transdermal drug delivery is a formulation in which the drug is absorbed through the skin for systemic action. Its advantages include avoidance of first-pass effects, sustained drug supply, and ease of administration and discontinuation. Drugs administered transdermally transfer into the blood circulation through the stratum corneum, epidermis, and dermis. The stratum corneum on the skin surface plays a barrier function in skin absorption. Therefore, developing of transdermal drug delivery systems requires innovations that overcome the barrier function of the stratum corneum and improve skin permeation. This review examines the usefulness of transdermal formulations based on solid nanoparticles using raloxifene. Milled raloxifene was gelled with (mRal-NPs) or without menthol (Ral-NPs) using Carbopol. The drug release and transdermal penetration were measured using a Franz diffusion cell, and the therapeutic evaluation of osteoporosis was determined in an ovariectomized rat model. Although the raloxifene released from Ral-NPs remained in the nanoparticle state, the skin penetration of raloxifene nanoparticles was prevented by the stratum corneum in rat. The inclusion of menthol in the formulation attenuated the barrier function of the stratum corneum and permitted raloxifene nanoparticles to penetrate through the skin. Moreover, macropinocytosis relates to the formulation's skin penetration, including menthol (mRal-NPs). Applying mRal-NPs attenuated the decreases in calcium level and stiffness of bones of ovariectomized rats. This information can support future studies aimed at designing novel transdermal formulations.

Nanomedicines to treat rare neurological disorders: The case of Krabbe disease

The brain remains one of the most challenging therapeutic targets due to the low and selective permeability of the blood-brain barrier and complex architecture of the brain tissue. Nanomedicines, despite their relatively large size compared to small molecules and nucleic acids, are being heavily investigated as vehicles to delivery therapeutics into the brain. Here we elaborate on how nanomedicines may be used to treat rare neurodevelopmental disorders, using Krabbe disease (globoid cell leukodystrophy) to frame the discussion. As a monogenetic disorder and lysosomal storage disease affecting the nervous system, the lessons learned from examining nanoparticle delivery to the brain in the context of Krabbe disease can have a broader impact on the treatment of various other neurodevelopmental and neurodegenerative disorders. In this review, we introduce the epidemiology and genetic basis of Krabbe disease, discuss current in vitro and in vivo models of the disease, as well as current therapeutic approaches either approved or at different stage of clinical developments. We then elaborate on challenges in particle delivery to the brain, with a specific emphasis on methods to transport nanomedicines across the blood-brain barrier. We highlight nanoparticles for delivering therapeutics for the treatment of lysosomal storage diseases, classified by the therapeutic payload, including gene therapy, enzyme replacement therapy, and small molecule delivery. Finally, we provide some useful hints on the design of nanomedicines for the treatment of rare neurological disorders.

Nasal Absorption Enhancement of Mometasone Furoate Nanocrystal Dispersions

Purpose

We designed a 0.05% mometasone furoate (MF) nanocrystal dispersion and investigated whether the application of MF nanocrystals in nasal formulations enhanced local absorption compared to traditional nasal MF formulations (CA-MF).

Methods

MF nanocrystal dispersions (MF-NPs) were prepared by bead milling MF microcrystal dispersions (MF-MPs) consisting of MF, 2-hydroxypropyl-β-cyclodextrin, methylcellulose, and purified water. Pluronic F-127 combined with methylcellulose, Pluronic F-68, or carbopol was used as a base for in situ gelation (thickener). MF concentrations were measured using high-performance liquid chromatography, and nasal absorption of MF was evaluated in 6 week-old male Institute of Cancer Research (ICR) mice.

Results

The particle size range of MF prepared with the bead mill treatment was 80-200 nm, and the nanoparticles increased the local absorption of MF, which was higher than that of CA-MF and MF-MPs. In addition, unlike the results obtained in the small intestine and corneal tissue, the high absorption of nanocrystalline MF in the nasal mucosa was related to a pathway that was not derived from energy-dependent endocytosis. Moreover, the application of the in situ gelling system attenuated the local absorption of MF-NPs, owing to a decrease in drug diffusion in the dispersions.

Conclusion

We found that nanoparticulation of MF enhances local intranasal absorption, and nasal bioavailability is higher than that of CA-MF. In addition, we demonstrate that viscosity regulation is an important factor in the design of nasal formulations based on MF nanocrystals. These findings provide insights for the design of novel nanomedicines with enhanced nasal bioavailability.

Biological interactions of polystyrene nanoplastics: Their cytotoxic and immunotoxic effects on the hepatic and enteric systems

As emerging pollutants in the environment, nanoplastics (NPs) can cross biological barriers and be enriched in organisms, posing a greatest threat to the health of livestock and humans. However, the size-dependent toxic effects of NPs in higher mammals remain largely unknown. To determine the size-dependent potential toxicities of NPs, we exposed mouse (AML-12) and human (L02) liver cell lines in vitro, and 6-week-old C57BL/6 mice (well-known preclinical model) in vivo to five different sizes of polystyrene NPs (PS-NPs) (20, 50, 100, 200 and 500 nm). We found that ultra-small NPs (20 nm) induced the highest cytotoxicity in mouse and human liver cell lines, causing oxidative stress and mitochondrial membrane potential loss on AML-12 cells. Unexpectedly in vivo, after long-term oral exposure to PS-NPs (75 mg/kg), medium NPs (200 nm) and large NPs (500 nm) induced significant hepatotoxicity, evidenced by increased oxidative stress, liver dysfunction, and lipid metabolism disorders. Most importantly, medium or large NPs generated local immunotoxic effects via recruiting and activating more numbers of neutrophils and monocytes in the liver or intestine, which potentially resulted in increased proinflammatory cytokine secretion and the tissue damage. The discrepancy in in vitro-in vivo toxic results might be attributed to the different properties of biodistribution and tissue accumulation of different sized NPs in vivo. Our study provides new insights regarding the hepatotoxicity and immunotoxicity of NPs on human and livestock health, warranting us to take immense measures to prevent these NPs-associated health damage.

In Vitro and Ex Vivo Models for Assessing Drug Permeation across the Cornea

Drug permeation across the cornea remains a major challenge due to its unique and complex anatomy and physiology. Static barriers such as the different layers of the cornea, as well as dynamic aspects such as the constant renewal of the tear film and the presence of the mucin layer together with efflux pumps, all present unique challenges for effective ophthalmic drug delivery. To overcome some of the current ophthalmic drug limitations, the identification and testing of novel drug formulations such as liposomes, nanoemulsions, and nanoparticles began to be considered and widely explored. In the early stages of corneal drug development reliable in vitro and ex vivo alternatives, are required, to be in line with the principles of the 3Rs (Replacement, Reduction, and Refinement), with such methods being in addition faster and more ethical alternatives to in vivo studies. The ocular field remains limited to a handful of predictive models for ophthalmic drug permeation. In vitro cell culture models are increasingly used when it comes to transcorneal permeation studies. Ex vivo models using excised animal tissue such as porcine eyes are the model of choice to study corneal permeation and promising advancements have been reported over the years. Interspecies characteristics must be considered in detail when using such models. This review updates the current knowledge about in vitro and ex vivo corneal permeability models and evaluates their advantages and limitations.

Lipid-based nanoparticles: Enhanced cellular uptake via surface thiolation

The aim of this study was to evaluate the uptake mechanism of thiolated nanostructured lipid carriers (NLCs). NLCs were decorated with a short-chain polyoxyethylene(10)stearyl ether with a terminal thiol group (NLCs-PEG₁₀-SH) or without (NLCs-PEG₁₀-OH) as well as with a long-chain polyoxyethylene(100)stearyl ether with thiolation (NLCs-PEG₁₀₀-SH) or without (NLCs-PEG₁₀₀-OH). NLCs were evaluated for size, polydispersity index (PDI), surface morphology, zeta potential and storage stability over six months. Cytotoxicity, adhesion to the cell surface and internalization of these NLCs in increasing concentrations were evaluated on Caco-2 cells. The influence of NLCs on the paracellular permeability of lucifer yellow was determined. Furthermore, cellular uptake was examined with and without various endocytosis inhibitors as well as reducing and oxidizing agents. NLCs were obtained in a size ranging from 164 to 190 nm, a PDI of 0.2, a negative zeta potential < -33 mV and stability over six months. Cytotoxicity was shown to be concentration dependent and to be lower for NLCs with shorter PEG chains. Permeation of lucifer yellow was 2-fold increased by NLCs-PEG₁₀-SH. All NLCs displayed concentration dependent adhesion to the cell surface and internalization, which was in particular 9.5-fold higher for NLCs-PEG₁₀-SH compared to NLCs-PEG₁₀-OH. Short PEG chain NLCs and especially thiolated short PEG chain NLCs showed higher cellular uptake than NLCs with longer PEG chain. Cellular uptake of all NLCs was mainly clathrin-mediated endocytosis. Thiolated NLCs showed also caveolae-dependent and clathrin- and caveolae-independent uptake. Macropinocytosis was involved in NLCs with long PEG chains. NLCs-PEG₁₀-SH indicated thiol-dependent uptake, which was influenced by reducing and oxidizing agents. Due to thiol groups on the surface of NLCs their cellular uptake and paracellular permeation enhancing properties can be substantially improved.

Recent Progress of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as Ocular Drug Delivery Platforms

Sufficient ocular bioavailability is often considered a challenge by the researchers, due to the complex structure of the eye and its protective physiological mechanisms. In addition, the low viscosity of the eye drops and the resulting short ocular residence time further contribute to the observed low drug concentration at the target site. Therefore, various drug delivery platforms are being developed to enhance ocular bioavailability, provide controlled and sustained drug release, reduce the number of applications, and maximize therapy outcomes. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) exhibit all these benefits, in addition to being biocompatible, biodegradable, and susceptible to sterilization and scale-up. Furthermore, their successive surface modification contributes to prolonged ocular residence time (by adding cationic compounds), enhanced penetration, and improved performance. The review highlights the salient characteristics of SLNs and NLCs concerning ocular drug delivery, and updates the research progress in this area.

Orally disintegrating tablets containing famotidine nanoparticles provide high intestinal absorbability via the energy-dependent endocytosis pathway

The permeability of the Biopharmaceutics Classification System (BCS) class III drugs are low, and their oral bioavailability needs to be improved. In this study, we attempted to design oral formulations containing famotidine (FAM) nanoparticles to overcome the limitations of BCS class III drugs. Dispersions containing FAM nanoparticles with a particle size of approximately 50–220 nm were produced by the bead-milling treatment. Moreover, we succeeded in preparing an orally disintegrating tablet containing FAM nanoparticles using the dispersions described above, additives (D-mannitol, polyvinylpyrrolidone, and gum arabic), and freeze-dry treatment (FAM-NP tablet). The FAM-NP tablet was disaggregated 3.5 s after addition to purified water, and the FAM particles in the redispersion of the FAM-NP tablet stored for 3 months were nano-sized (141 ± 6.6 nm). The ex-vivo intestinal penetration and in vivo absorption of FAM in rats applied with the FAM-NP tablet were significantly higher than those in rats applied with the FAM tablet containing microparticles. In addition, enhanced intestinal penetration of the FAM-NP tablet was attenuated by an inhibitor of clathrin-mediated endocytosis. In conclusion, the orally disintegrating tablet containing FAM nanoparticles improved low mucosal permeability and low oral bioavailability and overcame these issues of BCS class III drugs as oral formulations.

Macrophage membrane-biomimetic adhesive polycaprolactone nanocamptothecin for improving cancer-targeting efficiency and impairing metastasis

The recent remarkable success and safety of mRNA lipid nanoparticle technology for producing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has stimulated intensive efforts to expand nanoparticle strategies to treat various diseases. Numerous synthetic nanoparticles have been developed for pharmaceutical delivery and cancer treatment. However, only a limited number of nanotherapies have enter clinical trials or are clinically approved. Systemically administered nanotherapies are likely to be sequestered by host mononuclear phagocyte system (MPS), resulting in suboptimal pharmacokinetics and insufficient drug concentrations in tumors. Bioinspired drug-delivery formulations have emerged as an alternative approach to evade the MPS and show potential to improve drug therapeutic efficacy. Here we developed a biodegradable polymer-conjugated camptothecin prodrug encapsulated in the plasma membrane of lipopolysaccharide-stimulated macrophages. Polymer conjugation revived the parent camptothecin agent (e.g., 7-ethyl-10-hydroxy-camptothecin), enabling lipid nanoparticle encapsulation. Furthermore, macrophage membrane cloaking transformed the nonadhesive lipid nanoparticles into bioadhesive nanocamptothecin, increasing the cellular uptake and tumor-tropic effects of this biomimetic therapy. When tested in a preclinical murine model of breast cancer, macrophage-camouflaged nanocamptothecin exhibited a higher level of tumor accumulation than uncoated nanoparticles. Furthermore, intravenous administration of the therapy effectively suppressed tumor growth and the metastatic burden without causing systematic toxicity. Our study describes a combinatorial strategy that uses polymeric prodrug design and cell membrane cloaking to achieve therapeutics with high efficacy and low toxicity. This approach might also be generally applicable to formulate other therapeutic candidates that are not compatible or miscible with biomimetic delivery carriers.

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Macrophage membrane-biomimetic platform was exploited for nanodelivery of polycaprolactone nanocamptothecin.

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Macrophage-camouflaged nanocamptothecin exhibited tumor-tropic effects and increased tumor cell adhesion.

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The nanotherapy effectively suppressed primary tumor growth and the metastatic burden in vivo.

Nanoparticle entry into cells; the cell biology weak link

Nanoparticles (NP) are attractive options for the therapeutic delivery of active pharmaceutical drugs, proteins and nucleic acids into cells, tissues and organs. Research into the development and application of NP most often starts with a diverse group of scientists, including chemists, bioengineers and material and pharmaceutical scientists, who design, fabricate and characterize NP in vitro (Stage 1). The next step (Stage 2) generally investigates cell toxicity as well as the processes by which NP bind, are internalized and deliver their cargo to appropriate model tissue culture cells. Subsequently, in Stage 3, selected NP are tested in animal systems, mostly mouse. Whereas the chemistry-based development and analysis in Stage 1 is increasingly sophisticated, the investigations in Stage 2 are not what could be regarded as 'state-of-the-art' for the cell biology field and the quality of research into NP interactions with cells is often sub-standard. In this review we describe our current understanding of the mechanisms by which particles gain entry into mammalian cells via endocytosis. We summarize the most important areas for concern, highlight some of the most common mis-conceptions, and identify areas where NP scientists could engage with trained cell biologists. Our survey of the different mechanisms of uptake into cells makes us suspect that claims for roles for caveolae, as well as macropinocytosis, in NP uptake into cells have been exaggerated, whereas phagocytosis has been under-appreciated.

Native PLGA nanoparticles regulate APP metabolism and protect neurons against β-amyloid toxicity: Potential significance in Alzheimer's disease pathology

Biodegradable poly(lactic-co-glycolic acid)(PLGA) nanoparticles have been used extensively in delivering drugs to target tissues due to their excellent biocompatibility. Evidence suggests that PLGA-conjugated drugs/agents can attenuate pathology in cellular/animal models of Alzheimer's disease (AD), which is initiated by increased level/aggregation of amyloid β (Aβ) peptide generated from amyloid precursor protein (APP). The beneficial effects were attributed to conjugated-drugs rather than to PLGA nanoparticles. Interestingly, we recently reported that PLGA without any drug/agent (native PLGA) can suppress Aβ aggregation/toxicity. However, very little is known about the internalization, subcellular localization or effects of PLGA in neurons. In this study, using primary mouse cortical neurons, we first showed that native PLGA is internalized by an energy-mediated clathrin-dependent/-independent pathway and is localized in endosomal-lysosomal-autophagic vesicles. By attenuating internalization, PLGA can protect neurons against Aβ-mediated toxicity. Additionally, PLGA treatment altered expression profiles of certain AD-associated genes and decreased the levels of APP, its cleaved products α-/β-CTFs and Aβ peptides in mouse as well as iPSC-derived neurons from control and AD patients. Collectively, these results suggest that native PLGA not only protects neurons against Aβ-induced toxicity but also influences the expression of AD-related genes/proteins - highlighting PLGA's implication in normal and AD-related pathology.

Biological and Intracellular Fates of Drug Nanocrystals through Different Delivery Routes: Recent Development Enabled by Bioimaging and PK Modeling

Nanocrystals have contributed to exciting improvements in the delivery of poorly water-soluble drugs. The biological and intracellular fates of nanocrystals are currently under debate. Due to the remarkable commercial success in enhancing oral bioavailability, nanocrystals have originally been regarded as a simple formulation approach to enhance dissolution. However, the latest findings from novel bioimaging tools lead to an expanded view. Intact nanocrystals may offer long-term durability in the body and offer drug delivery capabilities like those of other nano-carriers. This review renews the understanding of the biological fates of nanocrystals administered via oral, intravenous, and parenteral (e.g., dermal, ocular, and pulmonary) routes. The intracellular pathways and dissolution kinetics of nanocrystals are explored. Additionally, the future trends for in vitro and in vivo quantification of nanocrystals, as well as factors impacting the biological and intracellular fates of nanocrystals are discussed. In conclusion, nanocrystals present a promising and underexplored therapeutic opportunity with immense potential.

α-Synuclein fibrils explore actin mediated macropinocytosis for cellular entry into model neuroblastoma neurons

Alpha-Synuclein (α-Syn), an intrinsically disordered protein (IDP), is associated with neurodegenerative disorders, including Parkinson's disease (PD) or other α-synucleinopathies. Recent investigations propose the transmission of α-Syn protein fibrils, in a prion-like manner, by entering proximal cells to seed further fibrillization in PD. Despite the recent advances, the mechanisms by which extracellular protein aggregates internalize into the cells remain poorly understood. Using a simple cell-based model of human neuroblastoma-derived differentiated neurons, we present the cellular internalization of α-Syn PFF to check cellular uptake and recycling kinetics along with the standard endocytic markers Transferrin (Tf) marking clathrin-mediated endocytosis (CME) and Galectin3 (Gal3) marking clathrin-independent endocytosis (CIE). Specific inhibition of endocytic pathways using chemical inhibitors reveals no significant involvement of CME, CIE, and caveolae-mediated endocytosis (CvME). A substantial reduction in cellular uptake was observed after perturbation of actin polymerization and treatment with macropinosomes inhibitor. Our results show that α-Syn PFF mainly internalizes into the SH-SY5Y cells and differentiated neurons via the macropinocytosis pathway. The elucidation of the molecular and cellular mechanism involved in the α-Syn PFF internalization will help improve the understanding of α-synucleinopathies including PD, and further design specific inhibitors for the same.

Brain Endothelial Cells Utilize Glycolysis for the Maintenance of the Transcellular Permeability

Among the components of the blood-brain barrier (BBB), endothelial cells (ECs) play an important role in supplying limited materials, especially glucose, to the brain. However, the mechanism by which glucose is metabolized in brain ECs is still elusive. To address this topic, we assessed the metabolic signature of glucose utilization using live-cell metabolic assays and liquid chromatography-tandem mass spectrometry metabolomic analysis. We found that brain ECs are highly dependent on aerobic glycolysis, generating lactate as its final product with minimal consumption of glucose. Glucose treatment decreased the oxygen consumption rate in a dose-dependent manner, indicating the Crabtree effect. Moreover, when glycolysis was inhibited, brain ECs showed impaired permeability to molecules utilizing transcellular pathway. In addition, we found that the blockade of glycolysis in mouse brain with 2-deoxyglucose administration resulted in decreased transcellular permeability of the BBB. In conclusion, utilizing glycolysis in brain ECs has critical roles in the maintenance and permeability of the BBB. Overall, we could conclude that brain ECs are highly glycolytic, and their energy can be used to maintain the transcellular permeability of the BBB.

Sterolight as imaging tool to study sterol uptake, trafficking and efflux in living cells

Information about cholesterol subcellular localization and transport pathways inside cells is essential for understanding and treatment of cholesterol-related diseases. However, there is a lack of reliable tools to monitor it. This work follows the fate of Sterolight, a BODIPY-labelled sterol, within the cell and demonstrates it as a suitable probe for visualization of sterol/lipid trafficking. Sterolight enters cells through an energy-independent process and knockdown experiments suggest caveolin-1 as its potential cellular carrier. Intracellular transport of Sterolight is a rapid process, and transfer from ER and mitochondria to lysosomes and later to lipid droplets requires the participation of active microtubules, as it can be inhibited by the microtubule disruptor nocodazole. Excess of the probe is actively exported from cells, in addition to being stored in lipid droplets, to re-establish the sterol balance. Efflux occurs through a mechanism requiring energy and may be selectively poisoned with verapamil or blocked in cells with mutated cholesterol transporter NPC1. Sterolight is efficiently transferred within and between different cell populations, making it suitable for monitoring numerous aspects of sterol biology, including the live tracking and visualization of intracellular and intercellular transport.

Instillation of Ophthalmic Formulation Containing Nilvadipine Nanocrystals Attenuates Lens Opacification in Shumiya Cataract Rats

We developed ophthalmic formulations based on nilvadipine (NIL) nanocrystals (NIL-NP dispersions; mean particle size: 98 nm) by using bead mill treatment and investigated whether the instillation of NIL-NP dispersions delivers NIL to the lens and prevents lens opacification in hereditary cataractous Shumiya cataract rats (SCRs). Serious corneal stimulation was not detected in either human corneal epithelial cells or rats treated with NIL-NP dispersions. The NIL was directly delivered to the lens by the instillation of NIL-NP dispersions, and NIL content in the lenses of rats instilled with NIL-NP dispersions was significantly higher than that in the ophthalmic formulations based on NIL microcrystals (NIL-MP dispersions; mean particle size: 21 µm). Moreover, the supply of NIL prevented increases in Ca²⁺ content and calpain activity in the lenses of SCRs and delayed the onset of cataracts. In addition, the anti-cataract effect in the lens of rats instilled with NIL-NP dispersions was also significantly higher than that in NIL-MP dispersions. NIL-NPs could be used to prevent lens opacification.

Preparation and in vitro and in vivo Evaluation Of Panax Notoginseng Saponins-loaded Nanoparticles Coated with Trimethyl Chitosan Derivatives

In this study, novel Panax notoginseng saponins (PNS)-loaded nanoparticles coated with the Trimethyl chitosan (TMC) derivatives TMC-VB₁₂ and TMC-Cys (PPTT-NPs) were developed to improve the oral absorption of the constituents. PPTT-NPs were prepared by the double emulsion method and showed different encapsulation effects on the major components, including Rg1, Rb1, and R1, in PNS. In vivo, the absorption rate constant and apparent absorption coefficient of PPTT-NPs were higher than PNS solution. These findings preliminarily proved that PPTT-NPs can promote intestinal absorption to a certain extent. The pharmacokinetic results indicated that the blood concentration and the area under the curve of Rg1 and Rb1 in the PPTT-NPs were higher than Xueshuantong capsules. The cell viability of PPTT-NPs was above 90% within 25-150 μg/mL. PPTT-NPs promoted the cellular uptake of PNS by receptor-mediated endocytosis. In summary, NPs coated with TMC-VB₁₂ and TMC-Cys can be used as promising drug delivery systems.

Endocytosis of abiotic nanomaterials and nanobiovectors: Inhibition of membrane trafficking

Humans are exposed to nanoscopical nanobiovectors (e.g. coronavirus SARS-CoV-2) as well as abiotic metal/carbon-based nanomaterials that enter cells serendipitously or intentionally. Understanding the interactions of cell membranes with these abiotic and biotic nanostructures will facilitate scientists to design better functional nanomaterials for biomedical applications. Such knowledge will also provide important clues for the control of viral infections and the treatment of virus-induced infectious diseases. In the present review, the mechanisms of endocytosis are reviewed in the context of how nanomaterials are uptaken into cells. This is followed by a detailed discussion of the attributes of man-made nanomaterials (e.g. size, shape, surface functional groups and elasticity) that affect endocytosis, as well as the different human cell types that participate in the endocytosis of nanomaterials. Readers are then introduced to the concept of viruses as nature-derived nanoparticles. The mechanisms in which different classes of viruses interact with various cell types to gain entry into the human body are reviewed with examples published over the last five years. These basic tenets will enable the avid reader to design advanced drug delivery and gene transfer nanoplatforms that harness the knowledge acquired from endocytosis to improve their biomedical efficacy. The review winds up with a discussion on the hurdles to be addressed in mimicking the natural mechanisms of endocytosis in nanomaterials design.

mRNA-Based Nanomedicinal Products to Address Corneal Inflammation by Interleukin-10 Supplementation

The anti-inflammatory cytokine Interleukin-10 (IL-10) is considered an efficient treatment for corneal inflammation, in spite of its short half-life and poor eye bioavailability. In the present work, mRNA-based nanomedicinal products based on solid lipid nanoparticles (SLNs) were developed in order to produce IL-10 to treat corneal inflammation. mRNA encoding green fluorescent protein (GFP) or human IL-10 was complexed with different SLNs and ligands. After, physicochemical characterization, transfection efficacy, intracellular disposition, cellular uptake and IL-10 expression of the nanosystems were evaluated in vitro in human corneal epithelial (HCE-2) cells. Energy-dependent mechanisms favoured HCE-2 transfection, whereas protein production was influenced by energy-independent uptake mechanisms. Nanovectors with a mean particle size between 94 and 348 nm and a positive superficial charge were formulated as eye drops containing 1% (w/v) of polyvinyl alcohol (PVA) with 7.1-7.5 pH. After three days of topical administration to mice, all formulations produced GFP in the corneal epithelium of mice. SLNs allowed the obtaining of a higher transfection efficiency than naked mRNA. All formulations produce IL-10, and the interleukin was even observed in the deeper layers of the epithelium of mice depending on the formulation. This work shows the potential application of mRNA-SLN-based nanosystems to address corneal inflammation by gene augmentation therapy.

The Metabolic Response of Various Cell Lines to Microtubule-Driven Uptake of Lipid- and Polymer-Coated Layer-by-Layer Microcarriers

Lipid structures, such as liposomes or micelles, are of high interest as an approach to support the transport and delivery of active agents as a drug delivery system. However, there are many open questions regarding their uptake and impact on cellular metabolism. In this study, lipid structures were assembled as a supported lipid bilayer on top of biopolymer-coated microcarriers based on the Layer-by-Layer assembly strategy. The functionalized microcarriers were then applied to various human and animal cell lines in addition to primary human macrophages (MΦ). Here, their influence on cellular metabolism and their intracellular localization were detected by extracellular flux analysis and immunofluorescence analysis, respectively. The impact of microcarriers on metabolic parameters was in most cell types rather low. However, lipid bilayer-supported microcarriers induced a decrease in oxygen consumption rate (OCR, indicative for mitochondrial respiration) and extracellular acidification rate (ECAR, indicative for glycolysis) in Vero cells. Additionally, in Vero cells lipid bilayer microcarriers showed a more pronounced association with microtubule filaments than polymer-coated microcarrier. Furthermore, they localized to a perinuclear region and induced nuclei with some deformations at a higher rate than unfunctionalized carriers. This association was reduced through the application of the microtubule polymerization inhibitor nocodazole. Thus, the effect of respective lipid structures as a drug delivery system on cells has to be considered in the context of the respective target cell, but in general can be regarded as rather low.

Balance of Drug Residence and Diffusion in Lacrimal Fluid Determine Ocular Bioavailability in In Situ Gels Incorporating Tranilast Nanoparticles

We previously designed ophthalmic formulations (nTRA) containing tranilast nanoparticles (Tra-NPs) with high uptake into ocular tissues. In this study, we used in situ gel (ISG) bases comprising combinations of pluronic F127 (F127) and methylcellulose (MC/F127), pluronic F68 (F68/F127), and Carbopol (Car/F127), and we developed in situ gels incorporating Tra-NPs (Tra-NP-incorporated ISNGs) such as nTRA-F127, nTRA-MC/F127, nTRA-F68/F127, and nTRA-Car/F127. Moreover, we demonstrated the therapeutic effect on conjunctival inflammation using lipopolysaccharide-induced rats. Each Tra-NP-incorporated ISNG was prepared by the bead mill method, the particle size was 40–190 nm, and the tranilast release and diffusion from formulation were nTRA > nTRA-F127 > nTRA-F68/F127 > nTRA-Car/F127 > nTRA-MC/F127. In the Tra-NP-incorporated ISNGs, the tranilast residence time in the lacrimal fluid, cornea, and conjunctiva was prolonged, although the C_max was attenuated in comparison with nTRA. On the other hand, no significant difference in conjunctival inflammation between non- and nTRA-F127-instilled rats was found; however, the nTRA-F68/F127, nTRA-Car/F127, and nTRA-MC/F127 (combination-ISG) attenuated the vessel leakage, nitric oxide, and tumor necrosis factor-α expression. In particular, nTRA-F68/F127 was significant in preventing the conjunctival inflammation. In conclusion, we found that the combination-ISG base prolonged the residence time of Tra-NPs; however, Tra-NP release from the formulation was attenuated, and the T_max was delayed longer than that in nTRA. The balance of drug residence and diffusion in lacrimal fluid may be important in providing high ocular bioavailability in formulations containing solid nanoparticles.

Nanocrystalline Suspensions of Irbesartan Enhance Oral Bioavailability by Improving Drug Solubility and Leading Endocytosis Uptake into the Intestine

We attempted to design irbesartan nanocrystalline (IRB-NC) suspensions by the bead mill method, and we evaluated the bioavailability (BA) in the oral administration of the nanocrystalline drug. The mean particle size of the IRB-NC suspensions was approximately 140 nm, and the crystalline structure of irbesartan in these suspensions was different using the bead mill method. The aggregation and degradation of irbesartan were not observed for one month, and the solubility increased. Moreover, the inclusion complex formation of IRB-NC suspensions with 2-hydroxypropyl-β-cyclodextrin was higher than that in traditional IRB powder (IRB-P). In addition, the intestinal absorption of IRB-NC suspensions was higher than that of IRB-P suspensions, and the reducing effect on blood pressure in spontaneously hypertensive SHR-SP rats orally administered IRB-NC suspensions was significantly higher than in those administered IRB-P suspensions. On the other hand, the intestinal penetration of IRB-NC suspensions was attenuated by the inhibitors of clathrin-dependent endocytosis (CME). In conclusion, we improved the low oral BA of irbesartan by preparing IRB-NC suspensions and showed that both the solubility and CME are related to the enhanced intestinal absorption of IRB-NC suspensions, resulting in an increase in their antihypertensive effect. These findings provide significant information for the development of oral nanomedicines.

Fixed-Combination Eye Drops Based on Fluorometholone Nanoparticles and Bromfenac/Levofloxacin Solution Improve Drug Corneal Penetration

Purpose

The multi-instillation of three commercially available (CA) eye drops [fluorometholone (FL)-, bromfenac (BF)- and levofloxacin (LV)-eye drops] has been used to manage pain and inflammation post-intraocular surgery. However, the multi-instillation of these three eye drops causes corneal damage, and the FL drops have the disadvantage of low ocular bioavailability. To overcome these problems, we prepared fixed-combination eye drops based on FL nanoparticles (FL-NPs) and BF/LV solution (nFBL-FC), and evaluated the corneal toxicity and transcorneal penetration of the nFBL-FC eye drops.

Methods

FL powder was mixed in 2-hydroxypropyl-β-cyclodextrin solution containing benzalkonium chloride, mannitol and methylcellulose, and milled with a Bead Smash 12 (5500 rpm for 30 s×30 times). The BF/LV solution was then added to the milled-dispersions to be used as nFBL-FC. The FL, BF and LV concentrations were measured by HPLC methods, and transcorneal penetration was evaluated in rabbits.

Results

The FL particle size in nFBL-FC was 40–150 nm, with only 0.0018% in liquid form. No aggregation of FL particles in the nFBL-FC was observed for 1 month. The viability of human corneal epithelial cells treated with nFBL-FC was remarkably higher than that of cells subjected to the multi-instillation of the corresponding three CA-eye drops. In addition, the corneal penetrations (AUC) of the FL, BF and LV in nFBL-FC were 4.9-, 1.8-, and 7.1-fold those of the corresponding CA-eye drops, respectively. Moreover, the caveolae-dependent endocytosis (CavME) inhibitor (nystatin) significantly prevented the transcorneal penetration of these drugs.

Conclusion

We prepared fixed-combination eye drops based on FL-NPs and BF/LV solution (nFBL-FC), and show that high levels of FL-NPs and dissolved BF/LV (liquid drugs) can be delivered into the aqueous humor by the instillation of nFBL-FC. Further, we show that CavME is mainly related to the enhancement of transcorneal penetration of both the solid (NPs) and liquid drugs.

Cellular Uptake Pathways of Nanoparticles: Process of Endocytosis and Factors Affecting Their Fate

BACKGROUND

Efficient and controlled internalization of NPs into the cells depends on their physicochemical properties and dynamics of the plasma membrane. NPs-cell interaction is a complex process that decides the fate of NPs internalization through different endocytosis pathways.

OBJECTIVE

The aim of this review is to highlight the physicochemical properties of synthesized nanoparticles (NPs) and their interaction with the cellular-dynamics and pathways like phagocytosis, pinocytosis, macropinocytosis, clathrin, and caveolae-mediated endocytosis and the involvement of effector proteins domain such as clathrin, AP2, caveolin, Arf6, Cdc42, dynamin and cell surface receptors during the endocytosis process of NPs.

METHOD

An electronic search was performed to explore the focused reviews and research articles on types of endocytosis and physicochemical properties of nanoparticles and their impact on cellular internalizations. The search was limited to peer-reviewed journals in the PubMed database.

RESULTS

This article discusses in detail how different types of NPs and their physicochemical properties such as size, shape, aspect ratio, surface charge, hydrophobicity, elasticity, stiffness, corona formation, surface functionalization changes the pattern of endocytosis in the presence of different pharmacological blockers. Some external forces like a magnetic field, electric field, and ultrasound exploit the cell membrane dynamics to permeabilize them for efficient internalization with respect to fundamental principles of membrane bending and pore formation.

CONCLUSION

This review will be useful to attract and guide the audience to understand the endocytosis mechanism and their pattern with respect to physicochemical properties of NPs to improve their efficacy and targeting to achieve the impactful outcome in drug-delivery and theranostics applications.

Usefulness of cell-penetrating peptides and penetration accelerating sequence for nose-to-brain delivery of glucagon-like peptide-2

Neuropeptides are expected as therapeutic drug candidates for central nervous system (CNS) disorders. Intracerebroventricular (i.c.v.) administration of glucagon-like peptide-2 (GLP-2) has an antidepressant-like effect not only in depression model mice but also in treatment-resistant depression model mice. However, because i.c.v. administration is very invasive, research is progressing on brain delivery using intranasal administration as a non-invasive method. After intranasal administration of the drug, there are two routes to the brain. That of direct delivery from the paracellular route of olfactory epithelium to the brain via the olfactory bulb has been studied, and that of systemic absorption via the paracellular route of respiratory epithelium has been put to practical use. The high degree of vascularization and permeability of the nasal mucosa enables drug delivery via the paracellular route that leads to systemic delivery. Therefore, suppressing systemic absorption may increase drug delivery to brain, so we focused on the transcellular route. We created a GLP-2 derivative by adding cell-penetrating peptides (CPP) and penetration accelerating sequences (PAS), which are reported to provide efficient intracellular uptake, to GLP-2. However, to deliver GLP-2 by the transcellular route, GLP-2 must not only be taken up into cells but also move out of the cells. We investigated in vitro and in vivo function of PAS-CPP-GLP-2 to enable the translocation of GLP-2 directly from the nose to the brain. Derivatization of PAS-CPP-GLP-2 prevented its degradation. In the evaluation of intracellular dynamics, PAS-CPP-GLP-2 enhanced cellular uptake by macropinocytosis with CPP and promoted escape from endosomal vesicles by PAS. This study also showed that PAS-CPP-GLP-2 can move out of cells. Furthermore, only this PAS-CPP-GLP-2 showed an antidepression-like effect within 20 min of intranasal administration. Intranasal administered PAS-CPP-GLP-2 surprisingly showed the effect at the same dose with i.c.v. administration, but intravenous administered PAS-CPP-GLP-2 did not show the effect. These results suggested that PAS-CPP-GLP-2 can be efficiently delivered from the nose to the CNS and show a pharmacological effect, demonstrating the usefulness of PAS and CPP for nose-to-brain delivery of GLP-2.

Energy-Dependent Endocytosis Is Responsible for Skin Penetration of Formulations Based on a Combination of Indomethacin Nanoparticles and l-Menthol in Rat and Göttingen Minipig

We previously designed a Carbopol gel formulation (N-IND/MEN) based on a combination of indomethacin solid nanoparticles (IND-NPs) and l-menthol, and we reported that the N-IND/MEN showed high transdermal penetration. However, the detailed mechanism for transdermal penetration of IND-NPs was not clearly defined. In this study, we investigated whether endocytosis in the skin tissue of rat and Göttingen minipig is related to the transdermal penetration of IND-NPs using pharmacological inhibitors of endocytosis. The pharmacological inhibitors used in this study are as follows: 54 µM nystatin, a caveolae-mediated endocytosis (CavME) inhibitor; 40 µM dynasore, a clathrin-mediated endocytosis (CME) inhibitor; and 2 µM rottlerin, a micropinocytosis (MP) inhibitor. The N-IND/MEN was prepared by a bead mill method, and the particle size of solid indomethacin was 79–216 nm. In both rat and Göttingen minipig skin, skin penetration of approximately 80% IND-NPs was limited by the stratum corneum (SC), although the penetration of SC was improved by the combination of l-menthol. On the other hand, the treatment of nystatin and dynasore decreased the transdermal penetration of indomethacin in rats and Göttingen minipigs treated with N-IND/MEN. Moreover, in addition to nystatin and dynasore, rottlerin attenuated the transdermal penetration of IND-NPs in the Göttingen minipigs’ skin. In conclusion, we found that l-menthol enhanced the SC penetration of IND-NPs. In addition, this study suggests that the SC-passed IND-NPs are absorbed into the skin tissue by energy-dependent endocytosis (CavME, CME, and/or MP pathways) on the epidermis under the SC, resulting in an enhancement in transdermal penetration of IND-NPs. These findings provide significant information for the design of nanomedicines in transdermal formulations.

Prevention of Postprandial Hyperglycemia by Ophthalmic Nanoparticles Based on Protamine Zinc Insulin in the Rabbit

Postprandial hyperglycemia, a so-called blood glucose spike, is associated with enhanced risks of diabetes mellitus (DM) and its complications. In this study, we attempted to design nanoparticles (NPs) of protamine zinc insulin (PZI) by the bead mill method, and prepare ophthalmic formulations based on the PZI-NPs with (nPZI/P) or without polyacrylic acid (nPZI). In addition, we investigated whether the instillation of the newly developed nPZI and nPZI/P can prevent postprandial hyperglycemia in a rabbit model involving the oral glucose tolerance test (OGTT). The particle size of PZI was decreased by the bead mill to a range for both nPZI and nPZI/P of 80-550 nm with no observable aggregation for 6 d. Neither nPZI nor nPZI/P caused any noticeable corneal toxicity. The plasma INS levels in rabbits instilled with nPZI were significantly higher than in rabbits instilled with INS suspensions (commercially available formulations, CA-INS), and the plasma INS levels were further enhanced with the amount of polyacrylic acid in the nPZI/P. In addition, the rapid rise in plasma glucose levels in OGTT-treated rabbits was prevented by a single instillation of nPZI/P, which was significantly more effective at attenuating postprandial hyperglycemia (blood glucose spike) in comparison with nPZI. In conclusion, we designed nPZI/P, and show that a single instillation before OGTT attenuates the rapid enhancement of plasma glucose levels. These findings suggest a better management strategy for the postprandial blood glucose spike, which is an important target of DM therapy.

Incorporation of indomethacin into a mesoporous silica nanoparticle enhances the anti-inflammatory effect Indomethacin into a mesoporous silica

PURPOSE

We evaluated the analgesic, anti-inflammatory and toxicological effects of indomethacin incorporated into mesoporous silica nanoparticles (IND+NP).

METHODS

Nociception was evaluated by the formalin assay. The anti-inflammatory potential was assessed by cell migration and paw edema assays, modulation of nitric oxide and cytokines (IL-6, IL-10 and TNF-α) by macrophages production. Toxicity was evaluated in peritoneal macrophages and by the locomotion assay and assessment of gastric injuries, presence of occult blood and hepatic and renal markers.

RESULTS

IND+NP reduced nociception during phases 1 by 53% and 2 by 79% of the formalin assay and the influx of peritoneal cells by 94%, indicating an analgesic and anti-inflammatory effect more efficiently than indomethacin alone. Indomethacin, but not IND+NP, caused macroscopic gastric injuries, the presence of fecal occult blood, and an increase of ALT levels. In the paw edema assay, IND+NP reduced edema by 21%. IND+NP has no effect on the LPS-induced production of nitric oxide, IL-6, IL-10 and TNF-α on no cytotoxic concentrations.

CONCLUSIONS

The incorporation of indomethacin into mesoporous silica nanoparticles effectively increased the activity of the drug observed in the formalin and cell migration assays and prevented the gastric and hepatic damage associated with its use.

MPC Polymer Promotes Recovery from Dry Eye via Stabilization of the Ocular Surface

The polymer that includes 2-methacryloyloxy ethyl phosphorylcholine (MPC) is well-known as an effectively hydrating multifunction agent. In this study, we prepared an MPC polymer (MPCP) using radical polymerization with co-monomers-MPC/Stearyl Methacrylate/N,N-dimethylacrylamide-and evaluated the MPCP's usefulness for dry eye treatment using a rabbit model treated with N-acetylcysteine. The MPCP particle size was 50-250 nm, and the form was similar to that of micelles. The MPCP viscosity (approximately 0.95 mPa·s) was 1.17-fold that of purified water, and a decrease in the transepithelial electrical resistance value (corneal damage) was not observed in the immortalized human corneal epithelial cell line HCE-T cell (HCE-T cell layer). The MPCP enhanced the water maintenance on the cornea, and the instillation of MPCP increased the lacrimal fluid volume and prolonged the tear film breakup time without an increase in total mucin contents in the lacrimal fluid of the normal rabbits. The therapeutic potential of the MPCP for dry eye was evaluated using an N-acetylcysteine-treated rabbit model, and, in our investigation, we found that MPCP enhanced the volume of lacrimal fluid and promoted an improvement in the tear film breakup levels. These findings regarding the creation and characteristics of a novel MPCP will provide relevant information for designing further studies to develop a treatment for dry eyes.

[Ocular Drug Delivery System-based on Solid Nanoparticles]

The use of eye drops is a well-established practice in the treatment of ophthalmic diseases, although the bioavailability of traditional eye drops, which are either solutions or suspensions, is insufficient, as the corneal barrier and dilution by lacrimation prevent the transcorneal penetration of drugs. Additionally, frequent instillation may cause undesirable systemic side effects and local corneal toxicity. To overcome these problems, micro- and nanoparticles, hydrogels, and viscous solutions have been tested, and solid nanoparticles are also expected to be applied. This review examines the usefulness of ophthalmic formulations based on solid nanoparticles, by using the specific example of indomethacin (IMC). Ophthalmic formulations based on solid IMC nanoparticles (IMC-NP dispersions) have been prepared using various additives (benzalkonium chloride, mannitol, methylcellulose, and cyclodextrin) and a rotation/revolution pulverizer (NP-100), to produce particles of 50-220 nm in size. The solubility of IMC in IMC-NP dispersions was 4.18-fold higher than that in the suspensions containing IMC microparticles (IMC-MP suspensions), and IMC-NP dispersions were better tolerated than commercially available NSAIDs eye drops, such as IMC, pranoprofen, diclofenac, bromfenac, and nepafenac eyedrops, in human corneal epithelial cells. Moreover, the corneal penetration in IMC-NP dispersions was higher than that in commercially available IMC and IMC-MP suspensions, and three energy-dependent endocytosis pathways (clathrin-dependent endocytosis, caveolae-dependent endocytosis, and macropinocytosis) were related to the high ophthalmic bioavailability of IMC-NP dispersions. This information can be used to support future studies aimed at designing novel ophthalmic formulations.

Preparation and Biological Property Evaluation of Novel Cationic Lipid-Based Liposomes for Efficient Gene Delivery

Novel cationic lipid-based liposomes prepared using an amphiphilic cationic lipid material, N,N-dimethyl-(N',N'-di-stearoyl-1-ethyl)1,3-diaminopropane (DMSP), have been proposed to enhance the transfection of nucleic acids. Herein, we designed and investigated liposomes prepared using DMSP, soybean phosphatidylcholine, and cholesterol. This novel gene vector has high gene loading capabilities and excellent protection against nuclease degradation. An in vitro study showed that the liposomes had lower toxicity and superior cellular uptake and transfection efficiency compared with Lipofectamine 2000. An endosomal escape study revealed that the liposomes demonstrated high endosomal escape and released their genetic payload in the cytoplasm efficiently. Mechanistic studies indicated that the liposome/nucleic acid complexes entered cells through energy-dependent endocytosis that was mediated by fossa proteins. These results suggest that such cationic lipid-based liposome vectors have potential for clinical gene delivery.

Non-pigmented ciliary epithelium derived extracellular vesicles uptake mechanism by the trabecular meshwork

Consistent with increasing findings, extracellular vesicles (EVs), consider as a major constituents of the aqueous humor, have a role as signaling mediators in glaucoma. Following secretion, EVs hold immense promise for utilization as bio-therapeutics and drug delivery vehicles due to their nature as biological nanoparticles that facilitate intercellular molecular transport. Yet, the specific pathway utilizing for transferring signals by EVs in the ocular drainage system is not fully understood. Hence, the objective of this study was to examine internalization mechanisms by which Non-Pigmented Ciliary Epithelium (NPCE)-derived EVs deliver their signals to the Trabecular Meshwork (TM) cells. EVs were isolated and size and concentration were determined. Internalization study of treated EVs with Proteinase-K to achieve removal of surface membrane proteins on EVs was conducted. Energy dependent uptake mechanism was examined under various temperatures. Using uptake inhibitors endocytosis, phagocytosis, and Wnt-TGFβ2 signaling were investigated. TM cells exposed to NPCE EVs demonstrate a significant decrease in the levels of two proteins in two Wnt-TGFb2 signaling proteins levels: p-GSK3β and β-catenin. A significant decrease in the uptake by TM cells of Proteinase-K-treated EVs was found, followed by attenuation of the Wnt-TGFβ2 proteins expression. Energy dependent uptake revealed a significant decrease in EVs internalization. The exposure of TM cells to endocytosis uptake inhibitors abolished the decrease of the Wnt-TGFβ2 proteins levels. Exposure to phagocytosis uptake inhibitor resulted in a partial inhibition of NPCE EVs effect in TM cells. The attenuation of proteins expression levels following uptake inhibitors treatment or EVs membrane proteins removal indicates that Wnt-TGFβ2 signaling in TM cells is mediated through NPCE EVs surface proteins in an active manner that involves endocytosis-dependent routes.

In Situ Gelling Systems Using Pluronic F127 Enhance Corneal Permeability of Indomethacin Nanocrystals

We previously designed an ophthalmic dispersion containing indomethacin nanocrystals (IMC-NCs), showing that multiple energy-dependent endocytoses led to the enhanced absorption of drugs from ocular dosage forms. In this study, we attempted to prepare Pluronic F-127 (PLF-127)-based in situ gel (ISG) incorporating IMC-NCs, and we investigated whether the instillation of the newly developed ISG incorporating IMC-NCs prolonged the precorneal resident time of the drug and improved ocular bioavailability. The IMC-NC-incorporating ISG was prepared using the bead-mill method and PLF-127, which yielded a mean particle size of 50–150 nm. The viscosity of the IMC-NC-incorporating ISG was higher at 37 °C than at 10 °C, and the diffusion and release of IMC-NCs in the IMC-NC-incorporating ISG were decreased by PLF-127 at 37 °C. In experiments using rabbits, the retention time of IMC levels in the lacrimal fluid was enhanced with PLF-127 in the IMC-NC-incorporating ISG, whereby the IMC-NC-incorporating ISG with 5% and 10% PLF-127 increased the transcorneal penetration of the IMCs. In contrast to the results with optimal PLF-127 (5% and 10%), excessive PLF-127 (15%) decreased the uptake of IMC-NCs after instillation. In conclusion, we found that IMC-NC-incorporating ISG with an optimal amount of PLF-127 (5–10%) resulted in higher IMC corneal permeation after instillation than that with excessive PLF-127, probably because of the balance between higher residence time and faster diffusion of IMC-NCs on the ocular surface. These findings provide significant information for developing ophthalmic nanomedicines.

Cutting-edge advances in therapy for the posterior segment of the eye: Solid lipid nanoparticles and nanostructured lipid carriers

Posterior segment eye diseases affect more than 300 million patients worldwide resulting in severe visual impairment. The treatments available are invasive, costly, present irregular effectiveness, and cause serious adverse effects. These drawbacks significantly reduce patient compliance. In the last decade, solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) have shown potential as innovative carriers for lipophilic drug substances to overcome hurdles in treating the eye posterior segment. This review shows the advantages of these formulations, focusing on their compatibility with ocular tissues, which increases the internalization of the drug substances. Additionally, SLN and NLC can reduce the clearance by the eye's protective mechanisms due to adhesive properties related to nanometric size. Therefore, these preparations may allow the treating of several ophthalmic diseases by topical administration, increasing the interval between doses. This feature can decrease adverse effects and enhance efficacy, ultimately improving patient compliance. Thus, this critical review presents the performance of the in vitro, ex vivo, and in vivo assays that support the potential of SLN and NLC to treat diseases of the posterior segment of the eye. These nanoparticles have shown to be promising alternative towards a major shift in developing ophthalmic products.

Potential Therapeutic Usage of Nanomedicine for Glaucoma Treatment

Glaucoma is a group of diseases characterized by progressive degeneration of retinal ganglion cells, leading to irreversible blindness. Currently, intraocular pressure reduction is the only established treatment available for glaucoma. With this treatment, the progression of the disease can only be delayed and there is no recovery. In addition, the commercially available eye drops have the disadvantage of low compliance and short therapeutic time, while glaucoma surgery always has the risk of failure due to wound fibrosis. Nanotechnology can overcome the limitations of the current treatment through the encapsulation and conjugation of drugs used for lowering intraocular pressure and antifibrotic agents using biodegradable or biocompatible nanoparticles for the sustained release of the drugs to protect the damaged ocular cells. Furthermore, using nanotechnology, treatment can be administered in various forms, including eye drops, contact lens, and ocular inserts, according to the convenience of the patients. Despite the promising results of delaying the progression of glaucoma, the regeneration of damaged ocular cells, including trabecular meshwork and retinal ganglion cells, is another critical hurdle to overcome. Bone marrow-derived mesenchymal stem cells and Müller glia cells can secrete neurogenic factors that trigger the regeneration of associated cells, including trabecular meshwork and retinal ganglion cells. In conclusion, this review highlights the potential therapeutic applications of nanotechnology- and stem cell-based methods that can be employed for the protection and regeneration of ocular cells.

Corneal Epithelial Findings in Patients with Multiple Myeloma Treated with Antibody-Drug Conjugate Belantamab Mafodotin in the Pivotal, Randomized, DREAMM-2 Study

INTRODUCTION

Patients with relapsed or refractory multiple myeloma (RRMM) represent an unmet clinical need. Belantamab mafodotin (belamaf; GSK2857916) is a first-in-class antibody-drug conjugate (ADC; or immunoconjugate) that delivers a cytotoxic payload, monomethyl auristatin F (MMAF), to myeloma cells. In the phase II DREAMM-2 study (NCT03525678), single-agent belamaf (2.5 mg/kg) demonstrated clinically meaningful anti-myeloma activity (overall response rate 32%) in patients with heavily pretreated disease. Microcyst-like epithelial changes (MECs) were common, consistent with reports from other MMAF-containing ADCs.

METHODS

Corneal examination findings from patients in DREAMM-2 were reviewed, and the clinical descriptions and accompanying images (slit lamp microscopy and in vivo confocal microscopy [IVCM]) of representative events were selected. A literature review on corneal events reported with other ADCs was performed.

RESULTS

In most patients receiving single-agent belamaf (72%; 68/95), MECs were observed by slit lamp microscopy early in treatment (69% had their first event by dose 4). However, IVCM revealed hyperreflective material. Blurred vision (25%) and dry eye (15%) were commonly reported symptoms. Management of MECs included dose delays (47%)/reductions (25%), with few patients discontinuing due to MECs (1%). The first event resolved in most patients (grade ≥2 MECs and visual acuity [each 77%], blurred vision [67%], and dry eye [86%]), with no reports of permanent vision loss to date. A literature review confirmed that similar MECs were reported with other ADCs; however, event management strategies varied. The pathophysiology of MECs is unclear, though the ADC cytotoxic payload may contribute to on- or off-target effects on corneal epithelial cells.

CONCLUSION

Single-agent belamaf represents a new treatment option for patients with RRMM. As with other ADCs, MECs were observed and additional research is warranted to determine their pathophysiology. A multidisciplinary approach, involving close collaboration between eye care professionals and hematologist/oncologists, is needed to determine appropriate diagnosis and management of these patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier, NCT03525678.

Lentinan-functionalized Selenium Nanoparticles target Tumor Cell Mitochondria via TLR4/TRAF3/MFN1 pathway

Rationale: Malignant ascites caused by cancer cells results in poor prognosis and short average survival time. No effective treatment is currently available for malignant ascites. In this study, the effects of lentinan (LNT)-functionalized selenium nanoparticles (Selene) on malignant ascites were evaluated. Furthermore, the mechanism of Selene targeting mitochondria of tumor cells were also investigated.

Methods: Selene were synthesized and characterized by TEM, AFM and particle size analysis. The OVCAR-3 and EAC cells induced ascites models were used to evaluate the effects of Selene on malignant ascites. Proteomic analysis, immunofluorescence, TEM and ICP-MS were used to determine the location of Selene in tumor cells. Mitochondrial membrane potential, ROS, ATP content, and caspase-1/3 activity were detected to evaluate the effect of Selene on mitochondrial function and cell apoptosis. Immunofluorescence, Co-IP, pull-down, duolink, Western blot, and FPLC were used to investigate the pathway of Selene targeting mitochondria.

Results: Selene could effectively inhibit ascites induced by OVCAR-3 and EAC cells. Selene was mainly located in the mitochondria of tumor cells and induced apoptosis of tumor cells. The LNT in Selene was involved in caveolae-mediated endocytosis through the interaction between toll-like receptor-4 (TLR4) and caveolin 1 (CAV1). Furthermore, the Selene in the endocytic vesicles could enter the mitochondria via the mitochondrial membrane fusion pathway, which was mediated by TLR4/TNF receptor associated factor 3 (TRAF3)/mitofusin-1 (MFN1) protein complex.

Conclusion: Selene is a candidate anticancer drug for the treatment of malignant ascites. And TLR4/TRAF3/MFN1 may be a specific nano-drug delivery pathway that could target the mitochondria.

An in situ Gelling System Based on Methylcellulose and Tranilast Solid Nanoparticles Enhances Ocular Residence Time and Drug Absorption Into the Cornea and Conjunctiva

We previously developed ophthalmic formulations containing tranilast nanopartaicles (ophthalmic TL-NPs formulations), and found them to show high uptake into ocular tissues. In this study, we aimed to design an in situ gel incorporating TL-NPs with 0.5–3% methylcellulose (MC, type SM-4) to ensure long residence time of the drug at the ocular surface. The ophthalmic TL-NPs formulations were prepared by the bead mill method, which yielded a mean particle size of ~93 nm with or without MC (0.5–3%). Although the dispersibility of TL particles in ophthalmic formulations increased with the MC content, the diffusion behavior of TL particles in the dispersion medium decreased with MC content. In an in vivo study using rats, the TL content in the lacrimal fluid was enhanced with MC content in the ophthalmic TL-NPs formulations, and the optimum amount of MC (0.5–1.5%) enhanced the TL content in the cornea and conjunctiva, and an anti-inflammatory effect of TL in rats instilled with ophthalmic TL-NPs formulations was observed. On the other hand, excessive MC (3%) prevented the corneal uptake of TL-NPs after instillation, and the anti-inflammation effect of TL was lower than that of ophthalmic TL-NPs formulations with optimum MC (0.5–1.5%). In conclusion, we found that gel formulations of TL-NPs with 0.5 and 1.5% MC provided a prolonged pre-corneal and pre-conjunctival contact time of TL, and resulted in higher TL contents in the cornea and conjunctiva following instillation in comparison with TL-NPs with or without 3% MC. This is probably due to the balance between the higher residence time and faster diffusion of TL-NPs on the ocular surface. These findings provide significant information that can be used to design further studies aimed at developing ophthalmic nanomedicines.

Ophthalmic In Situ Gelling System Containing Lanosterol Nanoparticles Delays Collapse of Lens Structure in Shumiya Cataract Rats

We attempted to prepare ophthalmic in situ gel formulations containing lanosterol (Lan) nanoparticles (LA-NPs/ISG) and investigated the characteristics, delivery pathway into the lens, and anti-cataract effects of LA-NPs/ISG using SCR-N (rats with slight lens structure collapse) and SCR-C (rats with a combination of remarkable lens structure collapse and opacification). LA-NPs/ISG was prepared by bead milling of the dispersions containing 0.5% Lan powder, 5% 2-hydroxypropyl-β-cyclodextrin, 0.5% methylcellulose, 0.005% benzalkonium chloride, and 0.5% mannitol. The particle size distribution of Lan was 60–250 nm. The LA-NPs/ISG was gelled at 37 °C, and the LA-NPs/ISG was taken into the cornea by energy-dependent endocytosis and then released to the intraocular side. In addition, the Lan contents in the lenses of both SCR-N and SCR-C were increased by the repetitive instillation of LA-NPs/ISG (twice per day). The space and structure collapse in the lens of SCR-N with aging was attenuated by the instillation of LA-NPs/ISG. Moreover, the repetitive instillation of LA-NPs/ISG attenuated the changes in cataract-related factors (the enhancement of nitric oxide levels, calpain activity, lipid peroxidation levels, Ca²⁺ contents, and the decrease of Ca²⁺-ATPase activity) in the lenses of SCR-C, and the repetitive instillation of LA-NPs/ISG delayed the onset of opacification in the SCR-C. It is possible that the LA-NPs/ISG is useful in maintaining lens homeostasis.

Development of Sustained-Release Ophthalmic Formulation Based on Tranilast Solid Nanoparticles

Eye drops containing Tranilast (TL), N-(3,4-dimethoxycinnamoyl) anthramilic acid, are used as an anti-allergic conjunctivitis drug in the ophthalmic field. Traditional eye drops are very patient compliant, although the bioavailability (BA) of most eye drops is low since eye drops cannot be instilled beyond the capacity of the conjunctival sac due to its limited volume. Thus, traditional eye drops have low BA and a short duration of the drug on the ocular surface, so solutions to these problems are highly anticipated. In this study, we designed a sustained-release drug-delivery system (DDS) for TL nanoparticles. TL nanoparticles were prepared by bead mill treatment, and the gel formulations containing TL nanoparticles (TL-NPs-Gel, particle size 50 nm–100 nm) were provided by carboxypolymethylene. The crystal structure of TL with and without bead mill treatment is the same, but the TL solubility in formulations containing nanoparticles was 5.3-fold higher compared with gel formulations containing TL microparticles (TL-MPs-Gel). The photo and thermal stabilities of TL-NPs-Gel are also higher than those of dissolved TL. Moreover, when TL-NPs-Gel is applied to the upper eyelid skin (outside), the TL is released as nanoparticles, and delivered to the lacrimal fluid through the meibomian glands. In addition, the TL release profile for TL-NPs-Gel was sustained over 180 min after the treatment. These findings can be used to develop a sustained-release DDS in the ophthalmic field.

Oral Administration System Based on Meloxicam Nanocrystals: Decreased Dose Due to High Bioavailability Attenuates Risk of Gastrointestinal Side Effects

Meloxicam (MLX) is widely applied as a therapy for rheumatoid arthritis (RA); however, it takes far too long to reach its peak plasma concentration for a quick onset effect, and gastrointestinal toxicity has been observed in RA patients taking it. To solve these problems, we designed MLX solid nanoparticles (MLX-NPs) by the bead mill method and used them to prepare new oral formulations. The particle size of the MLX-NPs was approximately 20-180 nm, and they remained in the nano-size range for 1 month. The tmax of MLX-NPs was shorter than that of traditional MLX dispersions (MLX-TDs), and the intestinal penetration of MLX-NPs was significantly higher in comparison with MLX-TDs (P < 0.05). Caveolae-dependent endocytosis (CavME), clathrin-dependent endocytosis (CME), and micropinocytosis (MP) were found to be related to the high intestinal penetration of MLX-NPs. The area under the plasma MLX concentration-time curve (AUC) for MLX-NPs was 5-fold higher than that for MLX-TDs (P < 0.05), and the AUC in rats administered 0.05 mg/kg MLX-NPs were similar to rats administered the therapeutic dose of 0.2 mg/kg MLX-TDs. In addition, the anti-inflammatory effect of the MLX-NPs was also significantly higher than that of MLX-TDs at the corresponding dose (P < 0.05), and the therapeutic effect of 0.2 mg/kg MLX-TDs and 0.05 mg/kg MLX-NPs in adjuvant-induced arthritis (AA) rats showed no difference. Furthermore, the gastrointestinal lesions in AA rats treated repetitively with 0.05 mg/kg MLX-NPs were fewer than in rats receiving 0.2 mg/kg MLX-TDs (P < 0.05). In conclusion, we demonstrate that MLX solid nanoparticles allow a quick onset of therapeutic effect and that three endocytosis pathways, CavME, CME, and MP, are related to the high absorption of solid nanoparticles. In addition, we found that MLX solid nanoparticles make it possible to reduce the amount of orally administered drugs, and treatment with low doses of MLX-NPs allows RA therapy without intestinal ulcerogenic responses to MLX. These findings are useful for designing therapies for RA patients.