Search Results (166)

The increasing global health crisis of neurodegenerative diseases such as Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis, and Huntington’s disease is worsening because of a rapidly increasing aging population. Disease-modifying therapies continue to face development challenges due to the blood–brain barrier (BBB), which prevents more than 98% of small molecules and all biologics from entering the central nervous system. The therapeutic landscape for neurodegenerative diseases has recently undergone transformation through advances in targeted drug delivery that include ligand-decorated nanoparticles, bispecific antibody shuttles, focused ultrasound-mediated BBB modulation, intranasal exosomes, and mRNA lipid nanoparticles. This review provides an analysis of the molecular pathways that cause major neurodegenerative diseases, discusses the physiological and physicochemical barriers to drug delivery to the brain, and reviews the most recent drug targeting strategies including receptor-mediated transcytosis, cell-based “Trojan horse” approaches, gene-editing vectors, and spatiotemporally controlled physical methods. The review also critically evaluates the limitations such as immunogenicity, scalability, and clinical translation challenges, proposing potential solutions to enhance therapeutic efficacy. The recent clinical trials are assessed in detail, and current and future trends are discussed, including artificial intelligence (AI)-based carrier engineering, combination therapy, and precision neuro-nanomedicine. The successful translation of these innovations into effective treatments for patients with neurodegenerative diseases will require essential interdisciplinary collaboration between neuroscientists, pharmaceutics experts, clinicians, and regulators. Full article

Tertiary amine oxide (TAO)-containing zwitterionic polymers are a class of zwitterionic materials formed by the oxidation of tertiary amine groups. In recent years, polymers such as poly(2-(N-oxide-N,N-diethylamino)ethyl methacrylate) (OPDEA) have gained significant attention due to their unique antifouling properties, dynamic cell membrane affinity, and responsiveness to microenvironments. These characteristics have made them promising candidates in drug delivery, antibiofouling, and precision therapy. Compared to traditional polyethylene glycol (PEG), these polymers not only exhibit long-circulation properties but can also overcome biological barriers through active transport mechanisms, making them a research hotspot in the field of next-generation biomaterials. This review comprehensively summarizes the recent advancements in this field, covering aspects such as the synthesis, properties, applications, and mechanisms of TAO-containing zwitterionic polymers. Full article

The blood–brain barrier (BBB) is a highly selective and natural protective membrane that restricts the entry of therapeutic agents into the central nervous system (CNS). This restrictive nature poses a major challenge for pharmacological treatment of a wide range of CNS disorders, including neurodegenerative disorders, brain tumors, and psychiatric conditions. Many chemical drugs and biopharmaceuticals are unable to cross the BBB, and conventional drug delivery methods often fail to achieve sufficient brain concentrations, leading to reduced therapeutic efficacy and increased risk of systemic toxicity. In recent years, targeted drug delivery strategies have emerged as promising approaches to overcome the BBB and enhance the delivery of therapeutic agents to the brain. Among these, receptor-mediated transcytosis (RMT) and transporter-mediated transcytosis (TMT) are two of the most extensively studied mechanisms for transporting drugs across brain endothelial cells into the brain parenchyma. Advances in materials science and nanotechnology have facilitated the development of multifunctional carriers with optimized properties, improving drug targeting, stability, and release profiles within the brain. This review summarizes the physiological structure of the BBB and highlights recent innovations in RMT- and TMT-mediated brain drug delivery systems, emphasizing their potential not only to overcome current challenges in CNS drug development, but also to pave the way for next-generation therapies that enable more precise, effective, and personalized treatment of brain-related diseases. Full article

Hydrocephalus is a chronic neurological condition caused by abnormal cerebrospinal fluid (CSF) accumulation, significantly impacting patients’ quality of life. Its causes remain poorly understood, making neurosurgery the primary treatment. Research suggests that hydrocephalus may result from impaired macromolecular clearance, leading to increased osmotic load in the ventricles. Macromolecules are cleared via processes such as transcytosis, involving caveolae- and clathrin-dependent pathways, soluble N-ethylmaleimide-sensitive factor activating protein receptor (SNARE) proteins, and vesicular trafficking. Abnormalities in transcytosis components, such as mutations in alpha-SNAP (α-soluble NSF attachment protein) and SNARE complexes, disrupt membrane organization and vesicle fusion, potentially contributing to hydrocephalus. Other factors, including alpha-synuclein and Rab proteins, may also play roles in vesicle dynamics. Insights from animal models, such as hyh (hydrocephalus with hop gait) mice, highlight the pathological consequences of these disruptions. Understanding transcytosis abnormalities in hydrocephalus could lead to novel therapeutic strategies aimed at enhancing macromolecular clearance, reducing ventricular fluid buildup, and improving patient outcomes. Full article

Background: Interleukin-15 (IL-15) stimulates the proliferation of natural killer cells or T cells, which, in combination with photodynamic therapy (PDT), has emerged as an effective strategy for cancer photoimmunotherapy. Instead of direct cytokine receptor activation, IL-15 necessitates first binding to the IL-15 receptor α chain subunit (IL-15Rα), followed by trans-presentation to the IL-15 receptor β/γ chain subunit on the effector cells for pharmacologic activation. Therefore, the delivery of IL-15 remains a major challenge owing to its short half-life, its lack of targeting activity, and the limited availability of IL-15Rα. Methods: A co-hitchhiking delivery approach using recombinant IL-15 (rIL-15) and a photosensitizer, pheophorbide A (PhA), is developed for enhanced combinatorial cancer immunotherapy with PDT. A recombinant IL-15Rα-sushi-Fc fusion protein (rILR-Fc) is designed to load rIL-15 through the IL-15Rα sushi domain, which mimics its trans-presentation. Moreover, the Fc moiety of rILR-Fc can load PhA based on its high binding affinity. Results: Through self-assembly, rILR-Fc/PhA/rIL-15 nanoparticles (NPs) are formulated to co-hitchhike PhA and rIL-15, which improves the tumor accumulation of PhA and rIL-15 through receptor-mediated transcytosis. Moreover, the nanoparticles prolong the blood half-life of rIL-15 but do not alter the elimination rate of PhA from the blood. The rILR-Fc/PhA/rIL-15 NPs effectively elicit potent systemic antitumor immunity and long-lasting immune memory against tumor rechallenge in model mice bearing orthotopic colon tumors. Conclusions: The enhanced antitumor therapeutic effect demonstrates that the co-hitchhiking delivery strategy, optimizing the pharmacokinetics of both the photosensitizer and IL-15, provides a promising strategy for combinatorial photodynamic and IL-15 immunotherapy. Full article

Low-density lipoprotein (LDL) chemically modified by reactive oxygen species (ROS), for example, leaking from red blood cells in the vascular compartment, more readily crosses the vascular endothelium than does nonoxidatively modified LDL to enter tissue fluid. Oxidatively modified LDL (oxLDL) may also be created in the tissue fluid by ROS leaking from cells by design, for example, by inflammatory white cells, or simply leaking from other cells as a consequence of oxygen metabolism. As well as oxLDL, glycatively modified LDL (glycLDL) is formed in the circulation. High-density lipoprotein (HDL) appears capable of decreasing the burden of lipid peroxides formed on LDL exposed to ROS or to glucose and its metabolites. The mechanism for this that has received the most attention is the antioxidant activity of HDL, which is due in large part to the presence of paraoxonase 1 (PON1). PON1 is intimately associated with its apolipoprotein A1 component and with HDL’s lipid domains into which lipid peroxides from LDL or cell membranes can be transferred. It is frequently overlooked that for PON1 to hydrolyze lipid substrates, it is essential that it remain by virtue of its hydrophobic amino acid sequences within a lipid micellar environment, for example, during its isolation from serum or genetically modified cells in tissue culture. Otherwise, it may retain its capacity to hydrolyze water-soluble substrates, such as phenyl acetate, whilst failing to hydrolyze more lipid-soluble molecules. OxLDL and probably glycLDL, once they have crossed the arterial endothelium by receptor-mediated transcytosis, are rapidly taken up by monocytes in a process that also involves scavenger receptors, leading to subendothelial foam cell formation. These are the precursors of atheroma, inducing more monocytes to cross the endothelium into the lesion and the proliferation and migration of myocytes present in the arterial wall into the developing lesion, where they transform into foam cells and fibroblasts. The atheroma progresses to have a central extracellular lake of cholesteryl ester following necrosis and apoptosis of foam cells with an overlying fibrous cap whilst continuing to grow concentrically around the arterial wall by a process involving oxLDL and glycLDL. Within the arterial wall, additional oxLDL is generated by ROS secreted by inflammatory cells and leakage from cells generally when couplet oxygen is reduced. PON1 is important for the mechanism by which HDL opposes atherogenesis, which may provide a better avenue of inquiry in the identification of vulnerable individuals and the provision of new therapies than have emerged from the emphasis placed on its role in RCT. Full article

The blood–brain barrier (BBB) controls the flow of substances to maintain a homeostatic environment in the brain, which is highly regulated and crucial for the normal function of the central nervous system (CNS). Brain endothelial cells (bECs), which are directly exposed to blood, play the most important role in maintaining the integrity of the BBB. Unlike endothelial cells in other tissues, bECs have two unique features: specialized endothelial tight junctions and actively suppressed transcellular vesicle trafficking (transcytosis). These features help to maintain the relatively low permeability of the CNS barrier. In addition to the predominant role of tight junctions in the BBB, caveolae-mediated adsorptive transcytosis has attracted much interest in recent years. The active suppression of transcytosis is dynamically regulated during development and in response to diseases. Altered caveolae-mediated transcytosis of bECs has been reported in several neurological diseases, but the understanding of this process in bECs is limited. Here, we review the process of caveolae-mediated transcytosis based on previous studies and discuss its function in the breakdown of the BBB in neurological disorders. Full article

The clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system is a promising biotechnology tool for genome editing. However, in living organisms, several pharmacokinetic challenges arise, including off-target side effects due to incorrect distribution, low bioavailability caused by membrane impermeability, and instability resulting from enzymatic degradation. Therefore, innovative delivery strategies must be developed to address these issues. Modified nanoparticles offer a potential solution for the non-invasive delivery of CRISPR/Cas9 ribonucleoproteins (Cas9 RNPs). Cas9 RNPs encapsulated in nanoparticles are protected from enzymatic degradation, similar to how microRNAs are shielded within exosomes. It is well-established that certain materials, including proteins, are expressed selectively in specific cell types. For example, the α-7 nicotinic receptor is expressed in endothelial and neuronal cells, while the αvβ3 integrin is expressed in cancer cells. These endogenous materials can facilitate receptor-mediated endocytosis or transcytosis. Nanoparticles encapsulating Cas9 RNPs and coated with ligands targeting such receptors may be internalized through receptor-mediated mechanisms. Once internalized, Cas9 RNPs could perform the desired gene editing in the nucleus after escaping the endosome through mechanisms such as the proton sponge effect or membrane fusion. In this review, I discuss the potential and advantages of delivering Cas9 RNP-encapsulated nanoparticles coated with ligands through receptor-mediated endocytosis or transcytosis. Full article

Interactions between bacteriophages with mammalian immune cells are of great interest and most phages possess at least one molecular pattern (nucleic acid, sugar residue, or protein structure) that is recognizable to the immune system through pathogen associated molecular pattern (PAMP) receptors (i.e., TLRs). Given that phages reside in the same body niches as bacteria, they share the propensity to stimulate or quench immune responses depending on the nature of their interactions with host immune cells. While most in vitro research focuses on the outcomes of direct application of phages to immune cells of interest, the potential impact of their transcytosis through the intestinal barrier has yet to be considered. As transcytosis through intestinal cells is a necessary step in healthy systems for access by phage to the underlying immune cell populations, it is imperative to understand how this step may play a role in immune activation. We compared the activation of macrophages (as measured by TNFα secretion) following direct phage application to those stimulated by incubation with phage transcytosed through a polarized Caco2 epithelial barrier model. Our results demonstrate that phages capable of activating TNFα secretion upon direct contact maintain the stimulatory capability following transcytosis. Furthermore, activation of macrophages by a transcytosed phage is enhanced as compared to that occurring with an equivalent multiplicity of directly applied phage. Full article

Brain diseases pose significant treatment challenges due to the restrictive nature of the blood–brain barrier (BBB). Recent advances in targeting macromolecules offer promising avenues for overcoming these obstacles through receptor-mediated transcytosis (RMT). We summarize the current progress in targeting brain drug delivery with macromolecules for brain diseases. This exploration details the transport mechanisms across the BBB, focusing on RMT and its use of natural ligands for drug delivery. Furthermore, the review examines macromolecular ligands such as antibodies, peptides, and aptamers that leverage RMT for effective BBB traversal. Advancements in macromolecules-based delivery systems for brain diseases are summarized, emphasizing their therapeutic potential and limitations. Finally, emerging RMT strategies, including viral vectors, exosomes, and boron neutron capture therapy, are discussed for their precision in brain-targeted treatments. This comprehensive overview underscores the potential of RMT-based approaches to revolutionize brain disease therapy. Full article

The tympanic membrane forms an impenetrable barrier between the ear canal and the air-filled middle ear, protecting it from fluid, pathogens, and foreign material entry. We previously screened a phage display library and discovered peptides that mediate transport across the intact membrane. The route by which transport occurs is not certain, but possibilities include paracellular transport through loosened intercellular junctions and transcellular transport through the cells that comprise the various tympanic membrane layers. We used confocal imaging to resolve the phage’s path through the membrane. Phages were observed in puncta within the cytoplasm of tympanic membrane cells, with no evidence of phages within junctions between epithelial cells. This result indicates that transport across the membrane is transcellular and within vesicles, consistent with the transcytosis process. The trans-tympanic peptide phages display a wide range of transport efficiencies for unknown reasons. This could include variation in tympanic membrane binding, entry into the membrane, crossing the membrane, or exiting into the middle ear. To address this, we titered phages recovered from within the membrane for phages with differing transport rates. We found that differences in the transport rate were inversely related to their presence within the tympanic membrane. This suggests that differences in the transport rate primarily reflect the efficiency of an exocytotic exit from the mucosal epithelium rather than entry into, or passage across, the membrane. Full article

Background: The blood–brain barrier (BBB) strictly regulates the penetration of substances into the brain, which, although important for maintaining brain homeostasis, may delay drug development because of the difficulties in predicting pharmacokinetics/pharmacodynamics (PKPD), toxicokinetics/toxicodynamics (TKTD), toxicity, safety, and efficacy in the central nervous system (CNS). Moreover, BBB functional proteins show species differences; therefore, humanized in vitro BBB models are urgently needed to improve the predictability of preclinical studies. Recently, international trends in the 3Rs in animal experiments and the approval of the FDA Modernization Act 2.0 have accelerated the application of microphysiological systems (MPSs) in preclinical studies, and in vitro BBB models have become synonymous with BBB–MPSs. Recently, we developed an industrialized humanized BBB–MPS, BBB–NET. In our previous report, we reproduced transferrin receptor (TfR)–mediated transcytosis with high efficiency and robustness, using hydrogels including fibrin and collagen I microfibers (CMFs). Methods: We investigated how adding CMFs to the fibrin gel benefits BBB-NETs. Results: We showed that CMFs accelerate capillary network formation and maturation by promoting astrocyte (AC) survival, and clarified that integrin β1 is involved in the mechanism of CMFs. Conclusions: Our data suggest that the quality control (QC) of CMFs is important for ensuring the stable production of BBB–NETs. Full article

Background/Objectives: Peptide-based treatments represent an expanding area and require innovative approaches to enhance bioavailability. Combination with cell-penetrating peptides (CPPs) is an attractive strategy to improve non-invasive delivery across nasal epithelial barriers for systemic and direct nose-to-brain transport. We previously developed a modified CPP system termed Glycosaminoglycan-binding Enhanced Transduction (GET) that improves insulin delivery across gastrointestinal epithelium. It contains a membrane docking sequence to promote cellular interactions (P21), a cationic polyarginine domain to stimulate uptake (8R) and an endosomal escaping sequence to maximize availability for onward distribution (LK15). It is synthesized as a single 44-residue peptide (P21-LK15-8R; PLR). Methods: The current research used in vitro assays for a novel exploration of PLR’s ability to improve the transport of two contrasting peptides, insulin (51 residues, net negative charge) and oxytocin (9 residues, weak positive charge) across an RPMI 2650 human nasal epithelial cell barrier cultured at the air–liquid interface. Results: PLR enhanced insulin transcytosis over a 6 h period by 7.8-fold when used at a 2:1 molar ratio of insulin/PLR (p < 0.0001 versus insulin alone). Enhanced oxytocin transcytosis (5-fold) occurred with a 1:10 ratio of oytocin/PLR (p < 0.01). Importantly, these were independent of any impact on transepithelial electrical resistance (TEER) or cell viability (p > 0.05). Conclusions: We advocate the continued evaluation of insulin–PLR and oxytocin–PLR formulations, including longer-term assessments of ciliotoxicity and cytotoxicity in vitro followed by in vivo assessments of systemic and nose-to-brain delivery. Full article

Although decades of intensive drug discovery efforts to treat neurodegenerative disorders (NDs) have failed, around half a million patients in more than 2000 studies continue being tested, costing over USD 100 billion, despite the conclusion that even those drugs which have been approved have no better effect than a placebo. The US Food and Drug Administration (FDA) has established multiple programs to innovate the treatment of rare diseases, particularly NDs, providing millions of USD in funding primarily by encouraging novel clinical trials to account for issues related to study sizes and adopting multi-arm studies to account for patient dropouts. Instead, the FDA should focus on the primary reason for failure: the poor bioavailability of drugs reaching the brain (generally 0.1% at most) due to the blood–brain barrier (BBB). There are several solutions to enhance entry into the brain, and the FDA must require proof of significant entry into the brain as the prerequisite to approving Investigational New Drug (IND) applications. The FDA should also rely on factors other than biomarkers to confirm efficacy, as these are rarely relevant to clinical use. This study summarizes how the drugs used to treat NDs can be made effective and how the FDA should change its guidelines for IND approval of these drugs. Full article

Intestinal digestion and absorption are complex processes; thus, it is a challenge to imitate them realistically. There are numerous approaches available, with different disadvantages and advantages. The simplest methods to mimic absorption are the non-cell-based transport models but these lack important characteristics of enterocytes of the intestine. Therefore, the most often used method is to measure absorption through viable mammalian cells (most commonly Caco-2 cells, cultured on membrane insert plates), which not only assures the incorporation of brush border enzymes (responsible for the final digestion of peptides and disaccharides), it also simulates the absorption process. This means that influx/efflux transporter-facilitated transport, carrier-mediated transport, endocytosis, and transcytosis is also imitated besides passive diffusion. Still, these also lack the complexity of intestinal epithelium. Organoids or ex vivo models are a better approach if we want to attain precision but the highest accuracy can be achieved with microfluidic systems (gut-on-a-chip models). We propose that more research is necessary, and food absorption should also be studied on gut-on-a-chips, especially with fragmented organoids. Our review supports the choices of a proper intestinal epithelium model, which may have a key role in functional food development, nutrition studies, and toxicity assessment. Full article