Strategy for effective brain drug delivery

Brain-targeted drug delivery - nanovesicles directed to specific brain cells by brain-targeting ligands

Neurodegenerative diseases are characterized by extensive loss of function or death of brain cells, hampering the life quality of patients. Brain-targeted drug delivery is challenging, with a low success rate this far. Therefore, the application of targeting ligands in drug vehicles, such as lipid-based and polymeric nanoparticles, holds the promise to overcome the blood-brain barrier (BBB) and direct therapies to the brain, in addition to protect their cargo from degradation and metabolization. In this review, we discuss the barriers to brain delivery and the different types of brain-targeting ligands currently in use in brain-targeted nanoparticles, such as peptides, proteins, aptamers, small molecules, and antibodies. Moreover, we present a detailed review of the different targeting ligands used to direct nanoparticles to specific brain cells, like neurons (C4-3 aptamer, neurotensin, Tet-1, RVG, and IKRG peptides), astrocytes (Aquaporin-4, D4, and Bradykinin B2 antibodies), oligodendrocytes (NG-2 antibody and the biotinylated DNA aptamer conjugated to a streptavidin core Myaptavin-3064), microglia (CD11b antibody), neural stem cells (QTRFLLH, VPTQSSG, and NFL-TBS.40-63 peptides), and to endothelial cells of the BBB (transferrin and insulin proteins, and choline). Reports demonstrated enhanced brain-targeted delivery with improved transport to the specific cell type targeted with the conjugation of these ligands to nanoparticles. Hence, this strategy allows the implementation of high-precision medicine, with reduced side effects or unwanted therapy clearance from the body. Nevertheless, the accumulation of some of these nanoparticles in peripheral organs has been reported indicating that there are still factors to be improved to achieve higher levels of brain targeting. This review is a collection of studies exploring targeting ligands for the delivery of nanoparticles to the brain and we highlight the advantages and limitations of this type of approach in precision therapies.

Synergizing drug repurposing and target identification for neurodegenerative diseases

Despite dedicated research efforts, the absence of disease-curing remedies for neurodegenerative diseases (NDDs) continues to jeopardize human society and stands as a challenge. Drug repurposing is an attempt to find new functionality of existing drugs and take it as an opportunity to discourse the clinically unmet need to treat neurodegeneration. However, despite applying this approach to rediscover a drug, it can also be used to identify the target on which a drug could work. The primary objective of target identification is to unravel all the possibilities of detecting a new drug or repurposing an existing drug. Lately, scientists and researchers have been focusing on specific genes, a particular site in DNA, a protein, or a molecule that might be involved in the pathogenesis of the disease. However, the new era discusses directing the signaling mechanism involved in the disease progression, where receptors, ion channels, enzymes, and other carrier molecules play a huge role. This review aims to highlight how target identification can expedite the whole process of drug repurposing. Here, we first spot various target-identification methods and drug-repositioning studies, including drug-target and structure-based identification studies. Moreover, we emphasize various drug repurposing approaches in NDDs, namely, experimental-based, mechanism-based, and in silico approaches. Later, we draw attention to validation techniques and stress on drugs that are currently undergoing clinical trials in NDDs. Lastly, we underscore the future perspective of synergizing drug repurposing and target identification in NDDs and present an unresolved question to address the issue.

The SH-SY5Y cell line: a valuable tool for Parkinson's disease drug discovery

INTRODUCTION

Owing to limited efficient treatment strategies for highly prevalent and distressing Parkinson's disease (PD), an impending need emerged for deciphering new modes and mechanisms for effective management. SH-SY5Y-based in vitro neuronal models have emerged as a new possibility for the elucidation of cellular and molecular processes in the pathogenesis of PD. SH-SY5Y cells are of human origin, adhered to catecholaminergic neuronal attributes, which consequences in imparting wide acceptance and significance to this model over conventional in vitro PD models for high-throughput screening of therapeutics.

AREAS COVERED

Herein, the authors review the SH-SY5Y cell line and its value to PD research. The authors also provide the reader with their expert perspectives on how these developments can lead to the development of new impactful therapeutics.

EXPERT OPINION

Encouraged by recent research on SH-SY5Y cell lines, it was envisaged that this in vitro model can serve as a primary model for assessing efficacy and toxicity of new therapeutics as well as for nanocarriers' capacity in delivering therapeutic agents across BBB. Considering the proximity with human neuronal environment as in pathogenic PD conditions, SH-SY5Y cell lines vindicated consistency and reproducibility in experimental results. Accordingly, exploitation of this standardized SH-SY5Y cell line can fast-track the drug discovery and development path for novel therapeutics.

Pharmacokinetics, biodistribution, and in vivo toxicity of 7-nitroindazole loaded in pegylated and non-pegylated nanoemulsions in rats

Sepsis is a life-threatening condition caused by a dysregulated host response to infection. The development of sepsis is associated with excessive nitric oxide (NO) production, which plays an important role in controlling vascular homeostasis. 7-nitroindazole (7-NI) is a selective inhibitor of neuronal nitric oxide synthase (NOS-1) with potential application for treating NO imbalance conditions. However, 7-NI exhibits a low aqueous solubility and a short plasma half-life. To circumvent these biopharmaceutical limitations, pegylated (NEPEG7NI) and non-pegylated nanoemulsions (NENPEG7NI) containing 7-NI were developed. This study evaluates the pharmacokinetic profiles and toxicological properties of 7-NI loaded into the nanoemulsions. After a single intravenous administration of the free drug and the nanoemulsions at a dose of 10 mg.kg-1 in Wistar rats, 7-NI was widely distributed in the organs. The pharmacokinetic parameters of Cmax, t1/2, and AUC0-t were significantly increased after administration of the NEPEG7NI, compared to both free 7-NI and NENPEG7NI (p < 0.05). No observable adverse effects were observed after administering the free 7-NI, NEPEG7NI, or NENPEG7NI in the animals after a single dose of up to 3.0 mg.kg-1. The results indicated that 7-NI-loaded nanoemulsions are safe, constituting a promising approach to treating sepsis.

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.

Nanotechnological advances in the treatment of epilepsy: a comprehensive review

Epilepsy is one of the most prevalent chronic neurological disorders characterized by frequent unprovoked epileptic seizures. Epileptic seizures can develop from a broad range of underlying abnormalities such as tumours, strokes, infections, traumatic brain injury, developmental abnormalities, autoimmune diseases, and genetic predispositions. Sometimes epilepsy is not easily diagnosed and treated due to the large diversity of symptoms. Undiagnosed and untreated seizures deteriorate over time, impair cognition, lead to injuries, and can sometimes result in death. This review gives details about epilepsy, its classification on the basis of International League Against Epilepsy, current therapeutics which are presently offered for the treatment of epilepsy. Despite of the fact that more than 30 different anti-epileptic medication and antiseizure drugs are available, large number of epileptic patients fail to attain prolonged seizure independence. Poor onsite bioavailability of drugs due to blood brain barrier poses a major challenge in drug delivery to brain. The present review covers the limitations with the state-of-the-art strategies for managing seizures and emphasizes the role of nanotechnology in overcoming these issues. Various nano-carriers like polymeric nanoparticles, dendrimers, lipidic nanoparticles such as solid lipid nanoparticles, nano-lipid carriers, have been explored for the delivery of anti-epileptic drugs to brain using oral and intranasal routes. Nano-carries protect the encapsulated drugs from degradation and provide a platform to deliver controlled release over prolonged periods, improved permeability and bioavailability at the site of action. The review also emphasises in details about the role of neuropeptides for the treatment of epilepsy.

Digital automation of transdermal drug delivery with high spatiotemporal resolution

Transdermal drug delivery is of vital importance for medical treatments. However, user adherence to long-term repetitive drug delivery poses a grand challenge. Furthermore, the dynamic and unpredictable disease progression demands a pharmaceutical treatment that can be actively controlled in real-time to ensure medical precision and personalization. Here, we report a spatiotemporal on-demand patch (SOP) that integrates drug-loaded microneedles with biocompatible metallic membranes to enable electrically triggered active control of drug release. Precise control of drug release to targeted locations (<1 mm2), rapid drug release response to electrical triggers (<30 s), and multi-modal operation involving both drug release and electrical stimulation highlight the novelty. Solution-based fabrication ensures high customizability and scalability to tailor the SOP for various pharmaceutical needs. The wireless-powered and digital-controlled SOP demonstrates great promise in achieving full automation of drug delivery, improving user adherence while ensuring medical precision. Based on these characteristics, we utilized SOPs in sleep studies. We revealed that programmed release of exogenous melatonin from SOPs improve sleep of mice, indicating potential values for basic research and clinical treatments.

In silico exploration of venlafaxine, a potential non-tricyclic antidepressant in a liposomal formulation for nose-to-brain drug delivery

OBJECTIVE

Non-tricyclic antidepressants (non-TCAs) work by preventing the intake of norepinephrine and serotonin. Therefore, the aim of this study was to identify a potent non-TCAs and to develop liposomal formulation, characterize and to determine the drug release study across model of dialysis membrane via in vitro and in silico techniques.

METHODS

The in silico docking analysis identified venlafaxine (VLF) as the best non-TCAs with the depressant targets (PDB ID: 3PBL and 4BVN). VLF-loaded liposomal formulation was prepared by the thin-film hydration technique and characterized by physicochemical properties, including entrapment efficacy, in vitro drug release, particle size analysis, and FTIR. Moreover, this article also compares VLF and VLF-loaded with liposome carriers (LPs) based on nose-to-brain drug delivery approaches to treating depression.

RESULTS

Drug release profiles of the optimal liposomal formulation of VLF-LPs were examined in the high entrapment efficiency 94.13 ± 1.20% was attained at 224 nm, composed of spherical particles having a mean particle size of 191 ± 2.0 nm, a polydispersity index of 0.281 ± 0.06 and zeta potential of -20.3 mV. The best formulation of VLF-LPs was more effective than oral VLF treatment, as shown by the in vitro drug release data.

CONCLUSION

The results show that the VLF-LPs formulation is a promising potential platform for application in nose-to-brain drug delivery. Thus, highlighting the robustness of the intranasal drug delivery system with enhanced pharmaceutical properties, efficacy, and bioavailability for the anti-depression effect.

An overview: Radiotracers and nano-radiopharmaceuticals for diagnosis of Parkinson's disease

Parkinson's disease (PD) is a widespread progressive neurodegenerative disease. Clinical diagnosis approaches are insufficient to provide an early and accurate diagnosis before a substantial of loss of dopaminergic neurons. PET and SPECT can be used for accurate and early diagnosis of PD by using target-specific radiotracers. Additionally, the importance of BBB penetrating targeted nanosystems has increased in recent years. This article reviews targeted radiopharmaceuticals used in clinics and novel nanocarriers for research purposes of PD imaging.

Niosomes: A Smart Drug Delivery System for Brain Targeting

Niosomes are lipid-based nanovesicles that have the potential to act as drug-delivery vehicles for a variety of agents. They are effective drug delivery systems for both ASOs and AAV vectors, with advantages such as improved stability, bioavailability, and targeted administration. In the context of brain-targeted drug delivery, niosomes have been investigated as a drug delivery system for brain targeting, but more research is needed to optimize their formulation to improve their stability and release profile and address the challenges of scale-up and commercialization. Despite these challenges, several applications of niosomes have demonstrated the potential of novel nanocarriers for targeted drug delivery to the brain. This review briefly overviews the current use of niosomes in treating brain disorders and diseases.

Nose-to-Brain (N2B) Delivery: An Alternative Route for the Delivery of Biologics in the Management and Treatment of Central Nervous System Disorders

In recent years, there have been a growing number of small and large molecules that could be used to treat diseases of the central nervous system (CNS). Nose-to-brain delivery can be a potential option for the direct transport of molecules from the nasal cavity to different brain areas. This review aims to provide a compilation of current approaches regarding drug delivery to the CNS via the nose, with a focus on biologics. The review also includes a discussion on the key benefits of nasal delivery as a promising alternative route for drug administration and the involved pathways or mechanisms. This article reviews how the application of various auxiliary agents, such as permeation enhancers, mucolytics, in situ gelling/mucoadhesive agents, enzyme inhibitors, and polymeric and lipid-based systems, can promote the delivery of large molecules in the CNS. The article also includes a discussion on the current state of intranasal formulation development and summarizes the biologics currently in clinical trials. It was noted that significant progress has been made in this field, and these are currently being applied to successfully transport large molecules to the CNS via the nose. However, a deep mechanistic understanding of this route, along with the intimate knowledge of various excipients and their interactions with the drug and nasal physiology, is still necessary to bring us one step closer to developing effective formulations for nasal-brain drug delivery.

Novel drug delivery strategies for antidepressant active ingredients from natural medicinal plants: the state of the art

Depression is a severe mental disorder among public health issues. Researchers in the field of mental health and clinical psychiatrists have long been faced with difficulties in slow treatment cycles, high recurrence rates, and lagging efficacy. These obstacles have forced us to seek more advanced and effective treatments. Research has shown that novel drug delivery strategies for natural medicinal plants can effectively improve the utilization efficiency of the active molecules in these plants and therefore improve their efficacy. Currently, with the development of treatment technologies and the constant updating of novel drug delivery strategies, the addition of natural medicinal antidepressant therapy has given new significance to the study of depression treatment against the background of novel drug delivery systems. Based on this, this review comprehensively evaluates and analyses the research progress in novel drug delivery systems, including nanodrug delivery technology, in intervention research strategies for neurological diseases from the perspective of natural medicines for depression treatment. This provided a new theoretical foundation for the development and application of novel drug delivery strategies and drug delivery technologies in basic and clinical drug research fields.

Alomrani A. Optimization of Bromocriptine-Mesylate-Loaded Polycaprolactone Nanoparticles Coated with Chitosan for Nose-to-Brain Delivery: In Vitro and In Vivo Studies

Bromocriptine mesylate (BM), primarily ergocryptine, is a dopamine agonist derived from ergot alkaloids. This study aimed to formulate chitosan (CS)-coated poly ε-caprolactone nanoparticles (PCL NPs) loaded with BM for direct targeting to the brain via the nasal route. PCL NPs were optimized using response surface methodology and a Box-Behnken factorial design. Independent formulation parameters for nanoparticle attributes, including PCL payload (A), D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) concentration (B), and sonication time (C), were investigated. The dependent variables were nanoparticle size (Y1), zeta potential (Y2), entrapment efficiency (EE; Y3), and drug release rate (Y4). The optimal formulation for BM-PCL NPs was determined to be 50 mg PCL load, 0.0865% TPGS concentration, and 8 min sonication time, resulting in nanoparticles with a size of 296 ± 2.9 nm having a zeta potential of -16.2 ± 3.8 mV, an EE of 90.7 ± 1.9%, and a zero-order release rate of 2.6 ± 1.3%/min. The optimized BM-PCL NPs were then coated with CS at varying concentrations (0.25, 0.5, and 1%) to enhance their effect. The CS-PCL NPs exhibited different particle sizes and zeta potentials depending on the CS concentration used. The highest EE (88%) and drug load (DL; 5.5%) were observed for the optimized BM-CS-PCL NPs coated with 0.25% CS. The BM-CS-PCL NPs displayed a biphasic release pattern, with an initial rapid drug release lasting for 2 h, followed by a sustained release for up to 48 h. The 0.25% CS-coated BM-CS-PCL NPs showed a high level of permeation across the goat nasal mucosa, with reasonable mucoadhesive strength. These findings suggested that the optimized 0.25% CS-coated BM-CS-PCL NPs hold promise for successful nasal delivery, thereby improving the therapeutic efficacy of BM.

Rabies virus glycoprotein 29 (RVG29) promotes CAR-T immunotherapy for glioma

Chimeric antigen receptor T cell (CAR-T) therapy has limited efficacy for treating glioma because of the infiltrative nature of the blood-brain barrier (BBB) and T cell exhaustion. Conjugation with rabies virus glycoprotein (RVG) 29 enhances the brain-related efficacy of various agents. Here we assess whether RVG enhances the ability of CAR-T cells to cross the BBB and improves their immunotherapy. We generated 70R CAR-T cells (anti-CD70 CAR-T modified with RVG29) and validated their tumor-killing efficacy in vitro and in vivo. We validated their effects on tumor regression in a human glioma mouse orthotopic xenograft model as well as in patient-derived orthotopic xenograft (PDOX) models. The signaling pathways activated in 70R CAR-T cells were revealed by RNA sequencing. The 70R CAR-T cells we generated showed effective antitumor function against CD70+ glioma cells both in vitro and in vivo. 70R CAR-T cells were better able to cross the BBB into the brain than CD70 CAR-T cells under the same treatment conditions. Moreover, 70R CAR-T cells significantly promote the regression of glioma xenografts and improve the physical characteristics of mice without causing overt adverse effects. RVG modification enables CAR-T cells to cross the BBB, and stimulation with glioma cells induces 70R CAR-T cells to expand in a resting state. The modification of RVG29 has a positive impact on CAR-T therapy for brain tumors and may have potential in CAR-T therapy for glioma.

Nanogels as novel drug nanocarriers for CNS drug delivery

Nanogels are highly recognized as adaptable drug delivery systems that significantly contribute to improving various therapies and diagnostic examinations for different human diseases. These three-dimensional, hydrophilic cross-linked polymers have the ability to absorb large amounts of water or biological fluids. Due to the growing demand for enhancing current therapies, nanogels have emerged as the next-generation drug delivery system. They effectively address the limitations of conventional drug therapy, such as poor stability, large particle size, and low drug loading efficiency. Nanogels find extensive use in the controlled delivery of therapeutic agents, reducing adverse drug effects and enabling lower therapeutic doses while maintaining enhanced efficacy and patient compliance. They are considered an innovative drug delivery system that highlights the shortcomings of traditional methods. This article covers several topics, including the involvement of nanogels in the nanomedicine sector, their advantages and limitations, ideal properties like biocompatibility, biodegradability, drug loading capacity, particle size, permeability, non-immunological response, and colloidal stability. Additionally, it provides information on nanogel classification, synthesis, drug release mechanisms, and various biological applications. The article also discusses barriers associated with brain targeting and the progress of nanogels as nanocarriers for delivering therapeutic agents to the central nervous system.

Therapeutic potential of targeting kynurenine pathway in neurodegenerative diseases

Kynurenine pathway (KP), the primary pathway of L-tryptophan (Trp) metabolism in mammals, contains several neuroactive metabolites such as kynurenic acid (KA) and quinolinic acid (QA). Its imbalance involved in aging and neurodegenerative diseases (NDs) has attracted much interest in therapeutically targeting KP enzymes and KP metabolite-associated receptors, especially kynurenine monooxygenase (KMO). Currently, many agents have been discovered with significant improvement in animal models but only one aryl hydrocarbon receptor (AHR) agonist 30 (laquinimod) has entered clinical trials for treating Huntington's disease (HD). In this review, we describe neuroactive KP metabolites, discuss the dysregulation of KP in aging and NDs and summarize the development of KP regulators in preclinical and clinical studies, offering an outlook of targeting KP for NDs treatment in future.

Solid-Phase Synthesis of the Bicyclic Peptide OL-CTOP Containing Two Disulfide Bridges, and an Assessment of Its In Vivo μ-Opioid Receptor Antagonism after Nasal Administration

New strategies facilitate the design of cyclic peptides which can penetrate the brain. We have designed a bicyclic peptide, OL-CTOP, composed of the sequences of a selective μ-opioid receptor antagonist, CTOP (f-cyclo(CYwOTX)T) (X = penicillamine, Pen; O = ornithine) and odorranalectin, OL (YASPK-cyclo(CFRYPNGVLAC)T), optimized its solid-phase synthesis and demonstrated its ability for nose-to-brain delivery and in vivo activity. The differences in reactivity of Cys and Pen thiol groups protected with trityl and/or acetamidomethyl protecting groups toward I2 in different solvents were exploited for selective disulfide bond formation on the solid phase. Both the single step and the sequential strategy applied to macrocyclization reactions generated the desired OL-CTOP, with the sequential strategy yielding a large quantity and better purity of crude OL-CTOP. Importantly, intranasally (i.n.s.) administered OL-CTOP dose-dependently antagonized the analgesic effect of morphine administered to mice through the intracerebroventricular route and prevented morphine-induced respiratory depression. In summary, the results demonstrate the feasibility of our solid-phase synthetic strategy for the preparation of the OL-CTOP bicyclic peptide containing two disulfide bonds and reveal the potential of odorranalectin for further modifications and the targeted delivery to the brain.

Nose-to-brain delivery of galantamine loaded nanospray dried polyacrylic acid/taurodeoxycholate mixed matrix as a protective therapy in lipopolysaccharide-induced Alzheimer's in mice model

One of the promising drug delivery approaches is performed by nanosizing the administered drug product using the nanospray drying technique. In this study, a combination of several formulation factors was integrated and exploited to augment the bioavailability of galantamine hydrobromide (GAL) via the intranasal route. Nanosized polymeric particles were fabricated using the mucoadhesive polymer, polyacrylic acid (PAA), and the permeability booster, sodium taurodeoxycholate (TDC). First, a preliminary study was conducted to adjust the nanospray drying conditions. Then, formulations were prepared on the basis of a mixed factorial experimental design and further analyzed using Design Expert® software. Different responses were investigated: particle size, polydispersity index, spray rate, drying efficiency, and percent yield. The optimized formulation was further assessed for physical morphology using the scanning electron microscope, flowability, in vitro drug release, and in vivo brain cell uptake using confocal laser scanning microscopy. The promising formulation (F6), composed of equal ratio of PAA and TDC and 20 mg GAL, exhibited a particle size of 185.55 ± 4.3 nm, polydispersity index of 0.413 ± 0.02, and yield-value of 69.58 ± 5.82 %. It also displayed good flowability, complete drug release within 2 h, and enhanced in vivo fluorescent dye uptake and penetration in brain cells. The efficacy of the optimized formulation was examined using lipopolysaccharide-induced Alzheimer's in mice. Results revealed the advantageous influence of the optimized formulation (F6) through downregulation of NF-κβ, IL-1β and GFAP as well as upregulating TGF-1β in adult mice.

Drug delivery to the brain – lipid nanoparticles-based approach

The complex structure of the human brain defines it as one of the most inaccessible organs in terms of drug delivery. The blood-brain barrier (BBB) represents a microvascular network involved in transporting substances between the blood and the central nervous system (CNS) – enabling the entry of nutrients and simultaneously restricting the influx of pathogens and toxins. However, its role as a protective shield for CNS also restricts drug access to the brain. Since many drugs cannot cross the BBB due to unsuitable physicochemical characteristics (i.e., high molecular weight, aqueous solubility, etc.), different technological strategies have been developed to ensure sufficient drug bioavailability. Among these, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) are promising approaches thanks to their lipid nature, facilitating their brain uptake, small sizes, and the possibilities for subsequent functionalization to achieve targeted delivery. The review focuses on applying SLNs and NLCs as nanocarriers for brain delivery, outlining the physiological factors of BBB and the physicochemical characteristics of nanocarriers influencing this process. Recent advances in this area have also been summarized.

CNS Delivery of Nucleic Acid Therapeutics: Beyond the Blood-Brain Barrier and Towards Specific Cellular Targeting

Nucleic acid-based therapeutic molecules including small interfering RNA (siRNA), microRNA(miRNA), antisense oligonucleotides (ASOs), messenger RNA (mRNA), and DNA-based gene therapy have tremendous potential for treating diseases in the central nervous system (CNS). However, achieving clinically meaningful delivery to the brain and particularly to target cells and sub-cellular compartments is typically very challenging. Mediating cell-specific delivery in the CNS would be a crucial advance that mitigates off-target effects and toxicities. In this review, we describe these challenges and provide contemporary evidence of advances in cellular and sub-cellular delivery using a variety of delivery mechanisms and alternative routes of administration, including the nose-to-brain approach. Strategies to achieve subcellular localization, endosomal escape, cytosolic bioavailability, and nuclear transfer are also discussed. Ultimately, there are still many challenges to translating these experimental strategies into effective and clinically viable approaches for treating patients.

Nanoparticles in Drug Delivery: From History to Therapeutic Applications

Current research into the role of engineered nanoparticles in drug delivery systems (DDSs) for medical purposes has developed numerous fascinating nanocarriers. This paper reviews the various conventionally used and current used carriage system to deliver drugs. Due to numerous drawbacks of conventional DDSs, nanocarriers have gained immense interest. Nanocarriers like polymeric nanoparticles, mesoporous nanoparticles, nanomaterials, carbon nanotubes, dendrimers, liposomes, metallic nanoparticles, nanomedicine, and engineered nanomaterials are used as carriage systems for targeted delivery at specific sites of affected areas in the body. Nanomedicine has rapidly grown to treat certain diseases like brain cancer, lung cancer, breast cancer, cardiovascular diseases, and many others. These nanomedicines can improve drug bioavailability and drug absorption time, reduce release time, eliminate drug aggregation, and enhance drug solubility in the blood. Nanomedicine has introduced a new era for drug carriage by refining the therapeutic directories of the energetic pharmaceutical elements engineered within nanoparticles. In this context, the vital information on engineered nanoparticles was reviewed and conferred towards the role in drug carriage systems to treat many ailments. All these nanocarriers were tested in vitro and in vivo. In the coming years, nanomedicines can improve human health more effectively by adding more advanced techniques into the drug delivery system.

Nucleic acid therapies for CNS diseases: Pathophysiology, targets, barriers, and delivery strategies

Nucleic acid therapeutics have emerged as one of the very advanced and efficacious treatment approaches for debilitating health conditions, including those diseases affecting the central nervous system (CNS). Precise targeting with an optimal control over gene regulation confers long-lasting benefits through the administration of nucleic acid payloads via viral, non-viral, and engineered vectors. The current review majorly focuses on the development and clinical translational potential of non-viral vectors for treating CNS diseases with a focus on their specific design and targeting approaches. These carriers must be able to surmount the various intracellular and extracellular barriers, to ensure successful neuronal transfection and ultimately attain higher therapeutic efficacies. Additionally, the specific challenges associated with CNS administration also include the presence of blood-brain barrier (BBB), the complex pathophysiological and biochemical changes associated with different disease conditions and the existence of non-dividing cells. The advantages offered by lipid-based or polymeric systems, engineered proteins, particle-based systems coupled with various approaches of neuronal targeting have been discussed in the context of a variety of CNS diseases. The possibilities of rapid yet highly efficient gene modifications rendered by the breakthrough methodologies for gene editing and gene manipulation have also opened vast avenues of research in neuroscience and CNS disease therapy. The current review also underscores the extensive scientific efforts to optimize specialized, efficacious yet non-invasive and safer administration approaches to overcome the therapeutic delivery challenges specifically posed by the CNS transport barriers and the overall obstacles to clinical translation.

Drug Delivery Systems as a Strategy to Improve the Efficacy of FDA-Approved Alzheimer's Drugs

Alzheimer's disease (AD) is the most common form of dementia, with a high impact worldwide, accounting for more than 46 million cases. The continuous increase of AD demands the fast development of preventive and curative therapeutic strategies that are truly effective. The drugs approved for AD treatment are classified into acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists. The therapeutic effectiveness of those drugs is hindered by their restricted access to the brain due to the blood-brain barrier, low bioavailability, and poor pharmacokinetic properties. In addition, the drugs are reported to have undesirable side effects. Several drug delivery systems (DDSs) have been widely exploited to address these issues. DDSs serve as drug carriers, combining the ability to deliver drugs locally and in a targeted manner with the ability to release them in a controlled and sustained manner. As a result, the pharmacological therapeutic effectiveness is raised, while the unwanted side effects induced by the unspecific distribution decrease. This article reviews the recently developed DDSs to increase the efficacy of Food and Drug Administration-approved AD drugs.

Therapeutic drug repositioning with special emphasis on neurodegenerative diseases: Threats and issues

Drug repositioning or repurposing is the process of discovering leading-edge indications for authorized or declined/abandoned molecules for use in different diseases. This approach revitalizes the traditional drug discovery method by revealing new therapeutic applications for existing drugs. There are numerous studies available that highlight the triumph of several drugs as repurposed therapeutics. For example, sildenafil to aspirin, thalidomide to adalimumab, and so on. Millions of people worldwide are affected by neurodegenerative diseases. According to a 2021 report, the Alzheimer's disease Association estimates that 6.2 million Americans are detected with Alzheimer's disease. By 2030, approximately 1.2 million people in the United States possibly acquire Parkinson's disease. Drugs that act on a single molecular target benefit people suffering from neurodegenerative diseases. Current pharmacological approaches, on the other hand, are constrained in their capacity to unquestionably alter the course of the disease and provide patients with inadequate and momentary benefits. Drug repositioning-based approaches appear to be very pertinent, expense- and time-reducing strategies for the enhancement of medicinal opportunities for such diseases in the current era. Kinase inhibitors, for example, which were developed for various oncology indications, demonstrated significant neuroprotective effects in neurodegenerative diseases. This review expounds on the classical and recent examples of drug repositioning at various stages of drug development, with a special focus on neurodegenerative disorders and the aspects of threats and issues viz. the regulatory, scientific, and economic aspects.

Involvement of trigeminal axons in nose-to-brain delivery of glucagon-like peptide-2 derivative

In our previous study, we created a glucagon-like peptide-2 (GLP-2) derivative with the functional sequence PAS-CPP to achieve efficient uptake by the respiratory epithelium and trigeminal nerve. By using octaarginine for cell penetrating peptides (CPP) and FFLIPKG, a reverse sequence of a part of the cathepsin D sequence for the penetration accelerating sequence (PAS), we found that the derivative was taken up by the cells through macropinocytosis and efficiently escaped from the endosomes and exited the cells. Moreover, it showed drug effects by intranasal (in.) administration at the same dose as intracerebroventricular (icv.) administration, which is direct drug administration into the brain. The purpose of this study was to elucidate the cause of the drug effect of in. administered PAS-CPP-GLP-2 at the same dose as that by icv. Administration. The present results suggested that although icv. Administered PAS-CPP-GLP-2 entered the cerebrospinal fluid, it barely penetrated the perivascular space of the brain, and therefore, only a small amount of the administered dose may have reached the site of action in the brain. In contrast, it was qualitatively suggested that in. administered PAS-CPP-GLP-2 migrates from the trigeminal nerve to the central nervous system via the principal sensory trigeminal nucleus and then through the trigeminal lemniscus. The present results show that nose-to-brain delivery by trigeminal axons, which is assumed to be a transcellular pathway, may be possible. As the drug can be delivered into the nerve, it is expected to be applied not only as a central delivery route but also for the treatment of neurological diseases.

Oxime Therapy for Brain AChE Reactivation and Neuroprotection after Organophosphate Poisoning

One of the main problems in the treatment of poisoning with organophosphorus (OPs) inhibitors of acetylcholinesterase (AChE) is low ability of existing reactivators of AChE that are used as antidotes to cross the blood-brain barrier (BBB). In this work, modified cationic liposomes were developed that can penetrate through the BBB and deliver the reactivator of AChE pralidoxime chloride (2-PAM) into the brain. Liposomes were obtained on the basis of phosphatidylcholine and imidazolium surfactants. To obtain the composition optimized in terms of charge, stability, and toxicity, the molar ratio of surfactant/lipid was varied. For the systems, physicochemical parameters, release profiles of the substrates (rhodamine B, 2-PAM), hemolytic activity and ability to cause hemagglutination were evaluated. Screening of liposome penetration through the BBB, analysis of 2-PAM pharmacokinetics, and in vivo AChE reactivation showed that modified liposomes readily pass into the brain and reactivate brain AChE in rats poisoned with paraoxon (POX) by 25%. For the first time, an assessment was made of the ability of imidazolium liposomes loaded with 2-PAM to reduce the death of neurons in the brains of mice. It was shown that intravenous administration of liposomal 2-PAM can significantly reduce POX-induced neuronal death in the hippocampus.

Exploring the role of nanomedicines for the therapeutic approach of central nervous system dysfunction: At a glance

In recent decades, research scientists, molecular biologists, and pharmacologists have placed a strong emphasis on cutting-edge nanostructured materials technologies to increase medicine delivery to the central nervous system (CNS). The application of nanoscience for the treatment of neurodegenerative diseases (NDs) such as Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), Huntington’s disease (HD), brain cancer, and hemorrhage has the potential to transform care. Multiple studies have indicated that nanomaterials can be used to successfully treat CNS disorders in the case of neurodegeneration. Nanomedicine development for the cure of degenerative and inflammatory diseases of the nervous system is critical. Nanoparticles may act as a drug transporter that can precisely target sick brain sub-regions, boosting therapy success. It is important to develop strategies that can penetrate the blood–brain barrier (BBB) and improve the effectiveness of medications. One of the probable tactics is the use of different nanoscale materials. These nano-based pharmaceuticals offer low toxicity, tailored delivery, high stability, and drug loading capacity. They may also increase therapeutic effectiveness. A few examples of the many different kinds and forms of nanomaterials that have been widely employed to treat neurological diseases include quantum dots, dendrimers, metallic nanoparticles, polymeric nanoparticles, carbon nanotubes, liposomes, and micelles. These unique qualities, including sensitivity, selectivity, and ability to traverse the BBB when employed in nano-sized particles, make these nanoparticles useful for imaging studies and treatment of NDs. Multifunctional nanoparticles carrying pharmacological medications serve two purposes: they improve medication distribution while also enabling cell dynamics imaging and pharmacokinetic study. However, because of the potential for wide-ranging clinical implications, safety concerns persist, limiting any potential for translation. The evidence for using nanotechnology to create drug delivery systems that could pass across the BBB and deliver therapeutic chemicals to CNS was examined in this study.

Convection-Enhanced Delivery of Antiangiogenic Drugs and Liposomal Cytotoxic Drugs to Heterogeneous Brain Tumor for Combination Therapy

Simple Summary

Although developed anticancer drugs have shown desirable effects in preclinical trials, the clinical efficacy of chemotherapy against brain cancer remains disappointing. One of the important obstacles is the highly heterogeneous environment in tumors. This study aims to evaluate the performance of an emerging treatment using antiangiogenic and cytotoxic drugs. Our mathematical modelling confirms the advantage of this combination therapy in homogenizing the intratumoral environment for better drug delivery outcomes. In addition, the effects of local microvasculature and cell density on this therapy are also discussed. The results would contribute to the development of more effective treatments for brain cancer.

Abstract

Although convection-enhanced delivery can successfully bypass the blood-brain barrier, its clinical performance remains disappointing. This is primarily attributed to the heterogeneous intratumoral environment, particularly the tumor microvasculature. This study investigates the combined convection-enhanced delivery of antiangiogenic drugs and liposomal cytotoxic drugs in a heterogeneous brain tumor environment using a transport-based mathematical model. The patient-specific 3D brain tumor geometry and the tumor’s heterogeneous tissue properties, including microvascular density, porosity and cell density, are extracted from dynamic contrast-enhanced magnetic resonance imaging data. Results show that antiangiogenic drugs can effectively reduce the tumor microvascular density. This change in tissue structure would inhibit the fluid loss from the blood to prevent drug concentration from dilution, and also reduce the drug loss by blood drainage. The comparisons between different dosing regimens demonstrate that the co-infusion of liposomal cytotoxic drugs and antiangiogenic drugs has the advantages of homogenizing drug distribution, increasing drug accumulation, and enlarging the volume where tumor cells can be effectively killed. The delivery outcomes are susceptible to the location of the infusion site. This combination treatment can be improved by infusing drugs at higher microvascular density sites. In contrast, infusion at a site with high cell density would lower the treatment effectiveness of the whole brain tumor. Results obtained from this study can deepen the understanding of this combination therapy and provide a reference for treatment design and optimization that can further improve survival and patient quality of life.

IntraBrain Injector (IBI): A Stereotactic-Guided Device for Repeated Delivery of Therapeutic Agents Into the Brain Parenchyma

BACKGROUND

To deliver therapeutics into the brain, it is imperative to overcome the issue of the blood-brain-barrier (BBB). One of the ways to circumvent the BBB is to administer therapeutics directly into the brain parenchyma. To enhance the treatment efficacy for chronic neurodegenerative disorders, repeated administration to the target location is required. However, this increases the number of operations that must be performed. In this study, we developed the IntraBrain Injector (IBI), a new implantable device to repeatedly deliver therapeutics into the brain parenchyma.

METHODS

We designed and fabricated IBI with medical grade materials, and evaluated the efficacy and safety of IBI in 9 beagles. The trajectory of IBI to the hippocampus was simulated prior to surgery and the device was implanted using 3D-printed adaptor and surgical guides. Ferumoxytol-labeled mesenchymal stem cells (MSCs) were injected into the hippocampus via IBI, and magnetic resonance images were taken before and after the administration to analyze the accuracy of repeated injection.

RESULTS

We compared the planned vs. insertion trajectory of IBI to the hippocampus. With a similarity of 0.990 ± 0.001 (mean ± standard deviation), precise targeting of IBI was confirmed by comparing planned vs. insertion trajectories of IBI. Multiple administrations of ferumoxytol-labeled MSCs into the hippocampus using IBI were both feasible and successful (success rate of 76.7%). Safety of initial IBI implantation, repeated administration of therapeutics, and long-term implantation have all been evaluated in this study.

CONCLUSION

Precise and repeated delivery of therapeutics into the brain parenchyma can be done without performing additional surgeries via IBI implantation.

Intranasal Delivery of Granisetron to the Brain via Nanostructured Cubosomes-Based In Situ Gel for Improved Management of Chemotherapy-Induced Emesis

This research aimed to boost granisetron (GS) delivery to the brain via the intranasal route to better manage chemotherapy-induced emesis. Glycerol monooleate (GMO), Poloxamer 407 (P 407) and Tween 80 (T 80) were used to formulate GS-loaded cubosomes (GS-CBS) utilizing a melt dispersion-emulsification technique. GS-CBS were characterized by testing particle diameter, surface charge and entrapment efficiency. The formulations were optimized using a Box–Behnken statistical design, and the optimum formula (including GMO with a concentration of 4.9%, P 407 with a concentration of 10%, and T 80 with a concentration of 1%) was investigated for morphology, release behavior, ex vivo permeation through the nasal mucosa, and physical stability. Moreover, the optimal formula was incorporated into a thermosensitive gel and subjected to histopathological and in vivo biodistribution experiments. It demonstrated sustained release characteristics, increased ex vivo permeability and improved physical stability. Moreover, the cubosomal in situ gel was safe and biocompatible when applied to the nasal mucosa. Furthermore, compared to a drug solution, the nose-to-brain pathway enhanced bioavailability and brain distribution. Finally, the cubosomal in situ gel may be a potential nanocarrier for GS delivery to the brain through nose-to-brain pathway.

Liposomes: An emerging carrier for targeting Alzheimer's and Parkinson's diseases

The function of the brain can be affected by various factors that include infection, tumor, and stroke. The major disorders reported with altered brain function are Alzheimer's disease (AD), Parkinson's disease (PD), dementia, brain cancer, seizures, mental disorders, and other movement disorders. The major barrier in treating CNS disease is the blood-brain barrier (BBB), which protects the brain from toxic molecules, and the cerebrospinal fluid (CSF) barrier, which separates blood from CSF. Brain endothelial cells and perivascular elements provide an integrated cellular barrier, the BBB, which hamper the invasion of molecules from the blood to the brain. Even though many drugs are available to treat neurological disorders, it fails to reach the desired site with the required concentration. In this purview, liposomes can carry required concentrations of molecules intracellular by diverse routes such as carrier-mediated transport and receptor-mediated transcytosis. Surface modification of liposomes enables them to deliver drugs to various brain cells, including neurons, astrocytes, oligodendrocytes, and microglia. The research studies supported the role of liposomes in delivering drugs across BBB and in reducing the pathogenesis of AD and PD. The liposomes were surface-functionalized with various molecules to reach the cells intricated with the AD or PD pathogenesis. The targeted and sustained delivery of drugs by liposomes is disturbed due to the antibody formation, renal clearance, accelerated blood clearance, and complement activation-related pseudoallergy (CARPA). Hence, this review will focus on the characteristics, surface functionalization, drug loading, and biodistribution of liposomes respective to AD and PD. In addition, the alternative strategies to overcome immunogenicity are discussed briefly.

Role of Tissue Hydraulic Permeability in Convection-Enhanced Delivery of Nanoparticle-Encapsulated Chemotherapy Drugs to Brain Tumour

PURPOSE

Tissue hydraulic permeability of brain tumours can vary considerably depending on the tissue microstructure, compositions in interstitium and tumour cells. Its effects on drug transport and accumulation remain poorly understood.

METHODS

Mathematical modelling is applied to predict the drug delivery outcomes in tumours with different tissue permeability upon convection-enhanced delivery. The modelling is based on a 3-D realistic tumour model that is extracted from patient magnetic resonance images.

RESULTS

Modelling results show that infusing drugs into a permeable tumour can facilitate a more favourable hydraulic environment for drug transport. The infused drugs will exhibit a relatively uniform distribution and cover a larger tumour volume for effective cell killing. Cross-comparisons show the delivery outcomes are more sensitive to the changes in tissue hydraulic permeability and blood pressure than the fluid flow from the brain ventricle. Quantitative analyses demonstrate that increasing the fluid gain from both the blood and brain ventricle can further improve the interstitial fluid flow, and thereby enhance the delivery outcomes. Furthermore, similar responses to the changes in tissue hydraulic permeability can be found for different types of drugs.

CONCLUSIONS

Tissue hydraulic permeability as an intrinsic property can influence drug accumulation and distribution. Results from this study can deepen the understanding of the interplays between drug and tissues that are involved in the drug delivery processes in chemotherapy.

Intranasal Administration of a TRAIL Neutralizing Monoclonal Antibody Adsorbed in PLGA Nanoparticles and NLC Nanosystems: An In Vivo Study on a Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder that progressively compromises cognitive functions. Tumor necrosis factor (TNF)-Related Apoptosis Inducing Ligand (TRAIL), a proinflammatory cytokine belonging to the TNF superfamily, appears to be a key player in the inflammatory/immune orchestra of the AD brain. Despite the ability of an anti-TRAIL monoclonal antibody to reach the brain producing beneficial effects in AD mice, we attempted to develop such a TRAIL-neutralizing monoclonal antibody adsorbed on lipid and polymeric nanocarriers, for intranasal administration, in a valid approach to overcome issues related to both high dose and drug transport across the blood–brain barrier. The two types of nanomedicines produced showed physico-chemical characteristics appropriate for intranasal administration. As confirmed by enzyme-linked immunosorbent assay (ELISA), both nanomedicines were able to form a complex with the antibody with an encapsulation efficiency of ≈99%. After testing in vitro the immunoneutralizing properties of the nanomedicines, the latter were intranasally administered in AD mice. The antibody–nanocarrier complexes were detectable in the brain in substantial amounts at concentrations significantly higher compared to the free form of the anti-TRAIL antibody. These data support the use of nanomedicine as an optimal method for the delivery of the TRAIL neutralizing antibody to the brain through the nose-to-brain route, aiming to improve the biological attributes of anti-TRAIL-based therapy for AD treatment.

Lipid-Based Nanocarriers for Neurological Disorders: A Review of the State-of-the-Art and Therapeutic Success to Date

Neurodegenerative disorders including Alzheimer's, Parkinson's, and dementia are chronic and advanced diseases that are associated with loss of neurons and other related pathologies. Furthermore, these disorders involve structural and functional defections of the blood-brain barrier (BBB). Consequently, advances in medicines and therapeutics have led to a better appreciation of various pathways associated with the development of neurodegenerative disorders, thus focusing on drug discovery and research for targeted drug therapy to the central nervous system (CNS). Although the BBB functions as a shield to prevent toxins in the blood from reaching the brain, drug delivery to the CNS is hindered by its presence. Owing to this, various formulation approaches, including the use of lipid-based nanocarriers, have been proposed to address shortcomings related to BBB permeation in CNS-targeted therapy, thus showing the potential of these carriers for translation into clinical use. Nevertheless, to date, none of these nanocarriers has been granted market authorization following the successful completion of all stages of clinical trials. While the aforementioned benefits of using lipid-based carriers underscores the need to fast-track their translational development into clinical practice, technological advances need to be initiated to achieve appropriate capacity for scale-up and the production of affordable dosage forms.

Role of miRNAs in Neurodegeneration: From Disease Cause to Tools of Biomarker Discovery and Therapeutics

Neurodegenerative diseases originate from neuronal loss in the central nervous system (CNS). These debilitating diseases progress with age and have become common due to an increase in longevity. The National Institute of Environmental Health Science’s 2021 annual report suggests around 6.2 million Americans are living with Alzheimer’s disease, and there is a possibility that there will be 1.2 million Parkinson’s disease patients in the USA by 2030. There is no clear-cut universal mechanism for identifying neurodegenerative diseases, and therefore, they pose a challenge for neurobiology scientists. Genetic and environmental factors modulate these diseases leading to familial or sporadic forms. Prior studies have shown that miRNA levels are altered during the course of the disease, thereby suggesting that these noncoding RNAs may be the contributing factor in neurodegeneration. In this review, we highlight the role of miRNAs in the pathogenesis of neurodegenerative diseases. Through this review, we aim to achieve four main objectives: First, we highlight how dysregulation of miRNA biogenesis led to these diseases. Second, we highlight the computational or bioinformatics tools required to identify the putative molecular targets of miRNAs, leading to biological molecular pathways or mechanisms involved in these diseases. Third, we focus on the dysregulation of miRNAs and their target genes leading to several neurodegenerative diseases. In the final section, we highlight the use of miRNAs as potential diagnostic biomarkers in the early asymptomatic preclinical diagnosis of these age-dependent debilitating diseases. Additionally, we discuss the challenges and advances in the development of miRNA therapeutics for brain targeting. We list some of the innovative strategies employed to deliver miRNA into target cells and the relevance of these viral and non-viral carrier systems in RNA therapy for neurodegenerative diseases. In summary, this review highlights the relevance of studying brain-enriched miRNAs, the mechanisms underlying their regulation of target gene expression, their dysregulation leading to progressive neurodegeneration, and their potential for biomarker marker and therapeutic intervention. This review thereby highlights ways for the effective diagnosis and prevention of these neurodegenerative disorders in the near future.

Controlled supramolecular interaction to enhance the bioavailability of hesperetin to targeted cancer cells through graphyne: a comprehensive in silico study

In the current study, the drug carrier efficiency of graphyne (GRP) for the transfer of the hesperetin (HPT) drug is evaluated for the first time. The GRP efficacy as a carrier is investigated using the density functional theory (DFT) technique to calculate various physiochemical characteristics such as dipole moment, bandgap, and chemical reactivity-descriptors for HPT, GRP and HPT@GRP complex. The non-covalent-interaction (NCI) plot indicated that GRP and HPT have weak interaction force, which is fundamental for the drug's noticeable offloading from the GRP carrier at its target location. According to frontier molecular orbital analysis, the highest occupied molecular orbital (HOMO) of HPT distributes the charge to the GRP, the lowest unoccupied molecular orbital (LUMO) during excitation. Charge transfer is further supported by charge-decomposition-analysis, which interprets the extensive overlap between HPT and GRP orbitals. In the case of the gas phase, the λ_max of the HPT@GRP-complex is redshifted by 9 nm from GRP. In the solvent phase, the λ_max value is also redshifted. These theoretically calculated spectra also match experimentally observed spectra rather well. The PET (photoinduced electron-transfer) method and electron–hole theory were used for the graphical explication of distinct excited states. The photoinduced electron transfer (PET) mechanism interprets fluorescence dimming because of interaction. Furthermore, GRP with cationic (+1) and anionic (−1) charge states (GRP^+1/−1) showed minor structural disfigurement and formed stable HPT complexes. In the current study, HRP is loading and unloading on GRP very effectively, that can potentially be used in the oncology field. Due to this theoretical study, researchers will be interested in looking at other 2D nanomaterials for drug delivery applications.

In the current study, the drug carrier efficiency of graphyne (GRP) for the transfer of the hesperetin (HPT) drug is evaluated for the first time.

Industrial applications of immobilized nano-biocatalysts

Immobilized enzyme-based catalytic constructs could greatly improve various industrial processes due to their extraordinary catalytic activity and reaction specificity. In recent decades, nano-enzymes, defined as enzyme immobilized on nanomaterials, gained popularity for the enzymes' improved stability, reusability, and ease of separation from the biocatalytic process. Thus, enzymes can be strategically incorporated into nanostructured materials to engineer nano-enzymes, such as nanoporous particles, nanofibers, nanoflowers, nanogels, nanomembranes, metal-organic frameworks, multi-walled or single-walled carbon nanotubes, and nanoparticles with tuned shape and size. Surface-area-to-volume ratio, pore-volume, chemical compositions, electrical charge or conductivity of nanomaterials, protein charge, hydrophobicity, and amino acid composition on protein surface play fundamental roles in the nano-enzyme preparation and catalytic properties. With proper understanding, the optimization of the above-mentioned factors will lead to favorable micro-environments for biocatalysts of industrial relevance. Thus, the application of nano-enzymes promise to further strengthen the advances in catalysis, biotransformation, biosensing, and biomarker discovery. Herein, this review article spotlights recent progress in nano-enzyme development and their possible implementation in different areas, including biomedicine, biosensors, bioremediation of industrial pollutants, biofuel production, textile, leather, detergent, food industries and antifouling.

MicroRNA-21 Is a Versatile Regulator and Potential Treatment Target in Central Nervous System Disorders

MicroRNAs (miRNAs) are a class of endogenous, non-coding, single-stranded RNAs with a length of approximately 22 nucleotides that are found in eukaryotes. miRNAs are involved in the regulation of cell differentiation, proliferation, invasion, apoptosis, and metabolism by regulating the expression of their target genes. Emerging studies have suggested that various miRNAs play key roles in the pathogenesis of central nervous system (CNS) disorders and may be viable therapeutic targets. In particular, miR-21 has prominently emerged as a focus of increasing research on the mechanisms of its involvement in CNS disorders. Herein, we reviewed recent studies on the critical roles of miR-21, including its dysregulated expression and target genes, in the regulation of pathophysiological processes of CNS disorders, with a special focus on apoptosis and inflammation. Collectively, miR-21 is a versatile regulator in the progression of CNS disorders and could be a promising biomarker and therapeutic target for these diseases. An in-depth understanding of the mechanisms by which miR-21 affects the pathogenesis of CNS disorders could pave the way for miR-21 to serve as a therapeutic target for these conditions.

Increased phosphorylation of HexM improves lysosomal uptake and potential for managing GM2 gangliosidoses

Tay-Sachs and Sandhoff diseases are genetic disorders resulting from mutations in HEXA or HEXB, which code for the α- and β-subunits of the heterodimer β-hexosaminidase A (HexA), respectively. Loss of HexA activity results in the accumulation of GM2 ganglioside (GM2) in neuronal lysosomes, culminating in neurodegeneration and death, often by age 4. Previously, we combined critical features of the α- and β-subunits of HexA into a single subunit to create a homodimeric enzyme known as HexM. HexM is twice as active as HexA and degrades GM2 in vivo, making it a candidate for enzyme replacement therapy (ERT). Here we show HexM production is scalable to meet ERT requirements and we describe an approach that enhances its cellular uptake via co-expression with an engineered GlcNAc-1-phosphotransferase that highly phosphorylates lysosomal proteins. Further, we developed a HexA overexpression system and functionally compared the recombinant enzyme to HexM, revealing the kinetic differences between the enzymes. This study further advances HexM as an ERT candidate and provides a convenient system to produce HexA for comparative studies.

Review of Current Strategies for Delivering Alzheimer's Disease Drugs Across the Blood-Brain Barrier

(Appeared originally in the International Journal of Molecular Sciences 2019; 20:381) Reprinted under Creative Commons CC-BY license.

Quercetin-biapigenin nanoparticles are effective to penetrate the blood-brain barrier

Search for efficient therapeutic agents for central nervous system (CNS) disorders has been extensive. Nevertheless, blood-brain barrier (BBB) is an obstacle that prevents the majority of compounds to act in these diseases. It is, thus, of extreme relevance the BBB overcome, in order to deliver a drugs therapeutically active concentration to the action site, with the least losses and interaction with other organs, tissues, or cells. The present study aimed to investigate the potential protective effect of quercetin-biapigenin encapsulated into poly(Ɛ-polycaprolactone) (PCL) nanoparticles against t-BOOH-induced oxidative stress in several brain cell lines, as well as evaluate the permeability of those active molecules through an in vitro BBB model. The three cell lines under study (BV-2, hcmec/D3, and U87) presented different reactions to t-BOOH. In general, quercetin-biapigenin PCL-loaded nanoparticles were able to minimize compound toxicity they convey, regardless the cell line. Quercetin-biapigenin PCL-loaded nanoparticles (Papp of approximately 80 × 10-6 cm/s) revealed to be more permeable than free compounds (Papp of approximately 50 × 10-6 cm/s). As of our knowledge, this is the first report of quercetin-biapigenin PCL-loaded nanoparticle activity in brain cells. It is also the first determining its permeability through BBB, as an effective nanocarrier for brain delivery.

Drug Delivery Systems and Strategies to Overcome the Barriers of Brain

The transport of drugs to the central nervous system is the most challenging task for conventional drug delivery systems. Reduced permeability of drugs through the blood-brain barrier is a major hurdle in delivering drugs to the brain. Hence, various strategies for improving drug delivery through the blood-brain barrier are currently being explored. Novel drug delivery systems (NDDS) offer several advantages, including high chemical and biological stability, suitability for both hydrophobic and hydrophilic drugs, and can be administered through different routes. Furthermore, the conjugation of suitable ligands with these carriers tend to potentiate targeting to the endothelium of the brain and could facilitate the internalization of drugs through endocytosis. Further, the intranasal route has also shown potential, as a promising alternate route, for the delivery of drugs to the brain. This can deliver the drugs directly to the brain through the olfactory pathway. In recent years, several advancements have been made to target and overcome the barriers of the brain. This article deals with a detailed overview of the diverse strategies and delivery systems to overcome the barriers of the brain for effective delivery of drugs.

Multifunctional lipidic nanocarriers for effective therapy of glioblastoma: recent advances in stimuli-responsive, receptor and subcellular targeted approaches

Background

Glioblastoma, or glioblastoma multiforme (GBM), remains a fatal cancer type despite the remarkable progress in understanding the genesis and propagation of the tumor. Current treatment modalities, comprising mainly of surgery followed by adjuvant chemoradiation, are insufficient for improving patients' survival owing to existing hurdles, including the blood–brain barrier (BBB). In contemporary practice, the prospect of long-term survival or cure continues to be a challenge for patients suffering from GBM. This review provides an insight into the drug delivery strategies and the significant efforts made in lipid-based nanoplatform research to circumvent the challenges in optimal drug delivery in GBM.

Area covered

Owing to the unique properties of lipid-based nanoplatforms and advancements in clinical translation, this article describes the application of various stimuli-responsive lipid nanocarriers and tumor subcellular organelle-targeted therapy to give an idea about the strategies that can be applied to enhance site-specific drug delivery for GBM. Furthermore, active targeting of drugs via surface-modified lipid-based nanostructures and recent findings in alternative therapeutic platforms such as gene therapy, immunotherapy, and multimodal therapy have also been overviewed.

Expert opinion

Lipid-based nanoparticles stand out among the other nanocarriers explored for GBM drug delivery, as they support both passive and active drug targeting by crossing/bypassing the BBB at the same time minimizing toxicity and projects better pharmacological parameters. Although these nanocarriers could be a plausible choice for treating GBM, in-depth research is essential to advance neuro-oncology research and enhance outcomes in patients with brain tumors.

Nanoparticle-Guided Brain Drug Delivery: Expanding the Therapeutic Approach to Neurodegenerative Diseases

Neurodegenerative diseases (NDs) represent a heterogeneous group of aging-related disorders featured by progressive impairment of motor and/or cognitive functions, often accompanied by psychiatric disorders. NDs are denoted as 'protein misfolding' diseases or proteinopathies, and are classified according to their known genetic mechanisms and/or the main protein involved in disease onset and progression. Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD) are included under this nosographic umbrella, sharing histopathologically salient features, including deposition of insoluble proteins, activation of glial cells, loss of neuronal cells and synaptic connectivity. To date, there are no effective cures or disease-modifying therapies for these NDs. Several compounds have not shown efficacy in clinical trials, since they generally fail to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells that greatly limits the brain internalization of endogenous substances. By engineering materials of a size usually within 1-100 nm, nanotechnology offers an alternative approach for promising and innovative therapeutic solutions in NDs. Nanoparticles can cross the BBB and release active molecules at target sites in the brain, minimizing side effects. This review focuses on the state-of-the-art of nanoengineered delivery systems for brain targeting in the treatment of AD, PD and HD.

Lamivudine-conjugated and efavirenz-loaded G2 dendrimers: Novel anti-retroviral nano drug delivery systems

Infection with human immunodeficiency virus (HIV)‐1 causes immunological disorders and death worldwide which needs to be further assisted by novel anti‐retroviral drug delivery systems. Consequently, finding newer anti‐retroviral pharmaceuticals by using biocompatible, biodegradable nanomaterials comprising a nanoparticle as core and a therapeutic agent is of high global interest. In this experiment, a second generation of a negatively charged nano‐biopolymer linear globular G2 dendrimer was carefully conjugated and loaded with well‐known anti‐HIV drugs lamivudine and efavirenz, respectively. They were characterised by a variety of analytical methods such as Zetasizer, Fourier‐transform infrared spectroscopy, elemental analysis and liquid chromatography‐mass spectroscopy. Additionally, conjugated lamivudine and loaded efazirenz with globular PEGylated G2 dendrimer were tested on an HEK293 T cell infected by single‐cycle replicable HIV‐1 virion and evaluated using XTT test and HIV‐1 P24 protein load. The results showed that lamivudine‐conjugated G2 significantly decreased retroviral activity without any cell toxicity. This effect was more or less observed by efavirenz‐loaded G2. These nano‐constructs are strongly suggested for further in vivo anti‐HIV assays.

IFNγ-stimulated dendritic cell extracellular vesicles can be nasally administered to the brain and enter oligodendrocytes

Extracellular vesicles secreted from IFNγ-stimulated rat dendritic cells (referred to here as IFNγ-DC-EVs) contain miRNAs which promote myelination (including but not limited to miR-219), and preferentially enter oligodendrocytes in brain slice cultures. IFNγ-DC-EVs also increase myelination when nasally administered to naïve rats. While we can infer that these extracellular vesicles enter the CNS from functional studies, here we demonstrate biodistribution throughout the brain after nasal delivery by way of imaging studies. After nasal administration, Xenolight DiR-labelled IFNγ-DC-EVs were detected 30 minutes later throughout the brain and the cervical spinal cord. We next examined cellular uptake of IFNγ-DC-EVs by transfecting IFNγ-DC-EVs with mCherry mRNA prior to nasal administration. mCherry-positive cells were found along the rostrocaudal axis of the brain to the brainstem. These cells morphologically resembled oligodendrocytes, and indeed cell-specific co-staining for neurons, astrocytes, microglia and oligodendrocytes showed that mcherry positive cells were predominantly oligodendrocytes. This is in keeping with our prior in vitro results showing that IFNγ-DC-EVs are preferentially taken up by oligodendrocytes, and to a lesser extent, microglia. To confirm that IFNγ-DC-EVs delivered cargo to oligodendrocytes, we quantified protein levels of miR-219 mRNA targets expressed in oligodendrocyte lineage cells, and found significantly reduced expression. Finally, we compared intranasal versus intravenous delivery of Xenolight DiR-labelled IFNγ-DC-EVs. Though labelled IFNγ-DC-EVs entered the CNS via both routes, we found that nasal delivery more specifically targeted the CNS with less accumulation in the liver. Taken together, these data show that intranasal administration is an effective route for delivery of IFNγ-DC-EVs to the CNS, and provides additional support for their development as an EV-based neurotherapeutic that, for the first time, targets oligodendrocytes.