Contribution of Carrier-Mediated Transport Systems to the Blood–Brain Barrier as a Supporting and Protecting Interface for the Brain; Importance for CNS Drug Discovery and Development

Improving glioma drug delivery: A multifaceted approach for glioma drug development

Glioma is one of the most common central nervous system (CNS) cancers that can be found within the brain and the spinal cord. One of the pressing issues plaguing the development of therapeutics for glioma originates from the selective and semipermeable CNS membranes: the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB). It is difficult to bypass these membranes and target the desired cancerous tissue because the purpose of the BBB and BSCB is to filter toxins and foreign material from invading CNS spaces. There are currently four varieties of Food and Drug Administration (FDA)-approved drug treatment for glioma; yet these therapies have limitations including, but not limited to, relatively low transmission through the BBB/BSCB, despite pharmacokinetic characteristics that allow them to cross the barriers. Steps must be taken to improve the development of novel and repurposed glioma treatments through the consideration of pharmacological profiles and innovative drug delivery techniques. This review addresses current FDA-approved glioma treatments' gaps, shortcomings, and challenges. We then outline how incorporating computational BBB/BSCB models and innovative drug delivery mechanisms will help motivate clinical advancements in glioma drug delivery. Ultimately, considering these attributes will improve the process of novel and repurposed drug development in glioma and the efficacy of glioma treatment.

The role of oxidative stress in blood-brain barrier disruption during ischemic stroke: Antioxidants in clinical trials

Ischemic stroke is one of the leading causes of death and disability. Occlusion and reperfusion of cerebral blood vessels (i.e., ischemia/reperfusion (I/R) injury) generates reactive oxygen species (ROS) that contribute to brain cell death and dysfunction of the blood-brain barrier (BBB) via oxidative stress. BBB disruption influences the pathogenesis of ischemic stroke by contributing to cerebral edema, hemorrhagic transformation, and extravasation of circulating neurotoxic proteins. An improved understanding of mechanisms for ROS-associated alterations in BBB function during ischemia/reperfusion (I/R) injury can lead to improved treatment paradigms for ischemic stroke. Unfortunately, progress in developing ROS targeted therapeutics that are effective for stroke treatment has been slow. Here, we review how ROS are produced in response to I/R injury, their effects on BBB integrity (i.e., tight junction protein complexes, transporters), and the utilization of antioxidant treatments in ischemic stroke clinical trials. Overall, knowledge in this area provides a strong translational framework for discovery of novel drugs for stroke and/or improved strategies to mitigate I/R injury in stroke patients.

In Vivo Evaluation of Nose-to-Brain Delivery of Liposomal Donepezil, Memantine, and BACE-1 siRNA for Alzheimer's Disease Therapy

Our study took an innovative approach by evaluating, in vivo, the efficacy of intranasal (IN) administration of liposomal formulations of donepezil, memantine, and beta-site amyloid precursor protein-cleaving enzyme (BACE-1) siRNA, and their combination as a "triple-drug therapy" in treating Alzheimer's disease (AD). Female APP/PS1 homozygous, transgenic mice were used as an AD model. The spatial short-term memory of the APP/PS1 mice was evaluated by a Y-maze behavioral test. IN-administered formulations demonstrated better short-term memory recovery than oral administration. Triple-drug therapy induced short-term memory recovery and lowered beta-amyloid (Aβ) 40 and 42 peptide levels and BACE-1 mRNA expression. Additionally, inflammatory cytokine mRNA expression was downregulated. This innovative approach opens new possibilities for Alzheimer's disease treatment and nose-to-brain delivery.

Liposomal Formulations of Anti-Alzheimer Drugs and siRNA for Nose-to-Brain Delivery: Design, Safety and Efficacy In Vitro

β-site amyloid precursor protein cleaving enzyme (BACE1) represents a key target for Alzheimer's disease (AD) therapy because it is essential for producing the toxic amyloid β (Aβ) peptide that plays a crucial role in the disease's development. BACE1 inhibitors are a promising approach to reducing Aβ levels in the brain and preventing AD progression. However, systemic delivery of such inhibitors to the brain demonstrates limited efficacy because of the presence of the blood-brain barrier (BBB). Nose-to-brain (NtB) delivery has the potential to overcome this obstacle. Liposomal drug delivery systems offer several advantages over traditional methods for delivering drugs and nucleic acids from the nose to the brain. The current study aims to prepare, characterize, and evaluate in vitro liposomal forms of donepezil, memantine, BACE-1 siRNA, and their combination for possible treatment of AD via NtB delivery. All the liposomal formulations were prepared using the rotary evaporation method. Their cellular internalization, cytotoxicity, and the suppression of beta-amyloid plaque and other pro-inflammatory cytokine expressions were studied. The Calu-3 Transwell model was used as an in vitro system for mimicking the anatomical and physiological conditions of the nasal epithelium and studying the suitability of the proposed formulations for possible NtB delivery. The investigation results show that liposomes provided the effective intracellular delivery of therapeutics, the potential to overcome tight junctions in BBB, reduced beta-amyloid plaque accumulation and pro-inflammatory cytokine expression, supporting the therapeutic potential of our approach.

Impact of Peptide Transport and Memory Function in the Brain

Recent studies have reported the benefits of food-derived peptides for memory dysfunction. Beyond the physiological effects of peptides, their bioavailability to the brain still remains unclear since the blood-brain barrier (BBB) strictly controls the transportation of compounds to the brain. Here, updated transportation studies on BBB transportable peptides are introduced and evaluated using in vitro BBB models, in situ perfusion, and in vivo mouse experiments. Additionally, the mechanisms of action of brain health peptides in relation to the pathogenesis of neurodegenerative diseases, particularly Alzheimer's disease, are discussed. This discussion follows a summary of bioactive peptides with neuroprotective effects that can improve cognitive decline through various mechanisms, including anti-inflammatory, antioxidative, anti-amyloid β aggregation, and neurotransmitter regulation.

Minimal Involvement of P-gp and BCRP in Oral Absorption of Ensitrelvir, An Oral SARS-CoV-2 3C-like Protease Inhibitor, in a Non-Clinical Investigation

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are important transporters causing drug-drug interaction (DDI). Here, we investigated the involvement of P-gp and BCRP in the oral absorption of ensitrelvir in non-clinical studies and estimated the DDI risk mediated by P-gp and BCRP inhibition in humans. Although ensitrelvir is an in vitro P-gp and BCRP substrate, it demonstrated high bioavailability in rats and monkeys after oral administration. Plasma exposures of ensitrelvir following oral administration were comparable in wild type (WT) and Bcrp (-/-) mice. On the other hand, the area under the plasma concentration-time curve (AUC) ratio of ensitrelvir in the Mdr1a/1b (-/-) mice to the WT mice was 1.92, indicating that P-gp, but not BCRP, was involved in the oral absorption of ensitrelvir. Based on our previous retrospective analyses, such a low AUC ratio (<3) in the Mdr1a/1b (-/-) mice indicates a minimal impact of P-gp on the oral absorption in humans. In conclusion, our studies demonstrate that the involvement of both P-gp and BCRP in the oral absorption of ensitrelvir is minimal, and suggest that ensitrelvir has a low risk for DDIs mediated by P-gp and BCRP inhibition in humans.

Advanced Noninvasive Strategies for the Brain Delivery of Therapeutic Proteins and Peptides

Recent years have witnessed rapid progress in the discovery of therapeutic proteins and peptides for the treatment of central nervous system (CNS) diseases. However, their clinical applications have been considerably hindered by challenges such as low biomembrane permeability, poor stability, short circulation time, and the formidable blood-brain barrier (BBB). Recently, substantial improvements have been made in understanding the dynamics of the BBB and developing efficient approaches for delivering proteins and peptides to the CNS, especially by using various nanoparticles. Herein, we present an overview of the up-to-date understanding of the BBB under physiological and pathological conditions, emphasizing their effects on brain drug delivery. We summarize advanced strategies and elucidate the underlying mechanisms for delivering proteins and peptides to the brain. We highlight the developments and applications of nanocarriers in treating CNS diseases via BBB crossing. We also provide critical opinions on the limitations and obstacles of the current strategies and put forward prospects for future research.

Advances in Intrathecal Nanoparticle Delivery: Targeting the Blood-Cerebrospinal Fluid Barrier for Enhanced CNS Drug Delivery

The blood-cerebrospinal fluid barrier (BCSFB) tightly regulates molecular exchanges between the bloodstream and cerebrospinal fluid (CSF), creating challenges for effective central nervous system (CNS) drug delivery. This review assesses intrathecal (IT) nanoparticle (NP) delivery systems that aim to enhance drug delivery by circumventing the BCSFB, complementing approaches that target the blood-brain barrier (BBB). Active pharmaceutical ingredients (APIs) face hurdles like restricted CNS distribution and rapid clearance, which diminish the efficacy of IT therapies. NPs can be engineered to extend drug circulation times, improve CNS penetration, and facilitate sustained release. This review discusses key pharmacokinetic (PK) parameters essential for the effectiveness of these systems. NPs can quickly traverse the subarachnoid space and remain within the leptomeninges for extended periods, often exceeding three weeks. Some designs enable deeper brain parenchyma penetration. Approximately 80% of NPs in the CSF are cleared through the perivascular glymphatic pathway, with microglia-mediated transport significantly contributing to their paravascular clearance. This review synthesizes recent progress in IT-NP delivery across the BCSFB, highlighting critical findings, ongoing challenges, and the therapeutic potential of surface modifications and targeted delivery strategies.

Blood-brain barrier alterations and their impact on Parkinson's disease pathogenesis and therapy

There is increasing evidence for blood-brain barrier (BBB) alterations in Parkinson's disease (PD), the second most common neurodegenerative disorder with rapidly rising prevalence. Altered tight junction and transporter protein levels, accumulation of α-synuclein and increase in inflammatory processes lead to extravasation of blood molecules and vessel degeneration. This could result in a self-perpetuating pathophysiology of inflammation and BBB alteration, which contribute to neurodegeneration. Toxin exposure or α-synuclein over-expression in animal models has been shown to initiate similar pathologies, providing a platform to study underlying mechanisms and therapeutic interventions. Here we provide a comprehensive review of the current knowledge on BBB alterations in PD patients and how rodent models that replicate some of these changes can be used to study disease mechanisms. Specific challenges in assessing the BBB in patients and in healthy controls are discussed. Finally, a potential role of BBB alterations in disease pathogenesis and possible implications for therapy are explored. The interference of BBB alterations with current and novel therapeutic strategies requires more attention. Brain region-specific BBB alterations could also open up novel opportunities to target specifically vulnerable neuronal subpopulations.

Development of nanomedicines for the treatment of Alzheimer's disease: Raison d'être, strategies, challenges and regulatory aspects

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of memory. Presently, AD is challenging to treat with current drug therapy as their delivery to the brain is restricted by the presence of the blood-brain barrier. Nanomedicines, due to their size, high surface volume ratio, and ease of tailoring drug release characteristics, showed their potential to treat AD. The nanotechnology-based formulations for brain targeting are expected to enter the market in the near future. So, regulatory frameworks are required to ensure the quality, safety, and effectiveness of the nanomedicines to treat AD. In this review, we discuss different strategies, in-vitro blood-brain permeation models, in-vivo permeation assessment, and regulatory aspects for the development of nanomedicine to treat AD.

Host-defence caerin 1.1 and 1.9 peptides suppress glioblastoma U87 and U118 cell proliferation through the modulation of mitochondrial respiration and induce the downregulation of CHI3L1

Glioblastoma, the most aggressive form of brain cancer, poses a significant global health challenge with a considerable mortality rate. With the predicted increase in glioblastoma incidence, there is an urgent need for more effective treatment strategies. In this study, we explore the potential of caerin 1.1 and 1.9, host defence peptides derived from an Australian tree frog, in inhibiting glioblastoma U87 and U118 cell growth. Our findings demonstrate the inhibitory impact of caerin 1.1 and 1.9 on cell growth through CCK8 assays. Additionally, these peptides effectively curtail the migration of glioblastoma cells in a cell scratch assay, exhibiting varying inhibitory effects among different cell lines. Notably, the peptides hinder the G0/S phase replication in both U87 and U118 cells, pointing to their impact on the cell cycle. Furthermore, caerin 1.1 and 1.9 show the ability to enter the cytoplasm of glioblastoma cells, influencing the morphology of mitochondria. Proteomics experiments reveal intriguing insights, with a decrease in CHI3L1 expression and an increase in PZP and JUNB expression after peptide treatment. These proteins play roles in cell energy metabolism and inflammatory response, suggesting a multifaceted impact on glioblastoma cells. In conclusion, our study underscores the substantial anticancer potential of caerin 1.1 and 1.9 against glioblastoma cells. These findings propose the peptides as promising candidates for further exploration in the realm of glioblastoma management, offering new avenues for developing effective treatment strategies.

Treating Alzheimer's disease using nanoparticle-mediated drug delivery strategies/systems

The administration of promising medications for the treatment of neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) is significantly hampered by the blood-brain barrier (BBB). Nanotechnology has recently come to light as a viable strategy for overcoming this obstacle and improving drug delivery to the brain. With a focus on current developments and prospects, this review article examines the use of nanoparticles to overcome the BBB constraints to improve drug therapy for AD The potential for several nanoparticle-based approaches, such as those utilizing lipid-based, polymeric, and inorganic nanoparticles, to enhance drug transport across the BBB are highlighted. To shed insight on their involvement in aiding effective drug transport to the brain, methods of nanoparticle-mediated drug delivery, such as surface modifications, functionalization, and particular targeting ligands, are also investigated. The article also discusses the most recent findings on innovative medication formulations encapsulated within nanoparticles and the therapeutic effects they have shown in both preclinical and clinical testing. This sector has difficulties and restrictions, such as the need for increased safety, scalability, and translation to clinical applications. However, the major emphasis of this review aims to provide insight and contribute to the knowledge of how nanotechnology can potentially revolutionize the worldwide treatment of NDDs, particularly AD, to enhance clinical outcomes.

Insulin receptor at the blood-brain barrier: Transport and signaling

The blood-brain barrier (BBB) is a unique system of the brain microvasculature that limits the exchange between the blood and the brain. Brain microvascular endothelial cells form the BBB as part of the neurovascular unit and express insulin receptors. The insulin receptor at the BBB has been studied in two different functional aspects. These functions include (1) the supplying of blood insulin to the brain and (2) the modulation of BBB function via insulin signaling. The first function involves drug delivery to the brain, while the second function is related to the association between central nervous system diseases and type 2 diabetes through insulin resistance. This chapter summarizes recent progress in research on the function of insulin receptors at the BBB.

The time interval between injection of nicotine and tremor initiation: a new index for evaluating nicotine efficacy in rodents

Tremor is one of the effects of nicotine as a toxic substance, especially in animal models. The intensity and duration of tremors were used to evaluate the effect of nicotine on locomotor activity in laboratory animals. In our observations, the time interval between nicotine injection and the onset of tremor changed depending on the dose. Therefore, by increasing the dose of nicotine in rats, the time interval of tremor onset was also shortened. These results suggest that the time interval between nicotine injection and the onset of tremors can be used as a complementary index for better evaluation of nicotine-derived motor disturbances.

[Blood-brain barrier breakdown and autoimmune cerebellar ataxia]

Autoimmune cerebellar ataxia is a disease entity that affects the cerebellum and is induced by autoimmune mechanisms. The disease is classified into several etiologies, including gluten ataxia, anti-glutamate decarboxylase (GAD) ataxia, paraneoplastic cerebellar degeneration, primary autoimmune cerebellar ataxia and postinfectious cerebellar ataxia. The autoimmune response in the periphery cross-reacts with similar antigens in the cerebellum due to molecular mimicry. Breakdown of the blood‒brain barrier (BBB) could potentially explain the vulnerability of the cerebellum during the development of autoimmune cerebellar ataxia, as it gives rise to the entry of pathogenic autoantibodies or lymphocytes into the cerebellum. In this review, the maintenance of the BBB under normal conditions and the molecular basis of BBB disruption under pathological conditions are highlighted. Next, the pathomechanism of BBB breakdown in each subtype of autoimmune cerebellar ataxia is discussed. We recently identified glucose-regulated protein (GRP) 78 antibodies in paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome, and GRP78 antibodies induced by cross-reactivity with tumors can disrupt the BBB and penetrate anti-P/Q type voltage-gated calcium channel (VGCC) antibodies into the cerebellum, thus leading to cerebellar ataxia in this disease.

Blood-brain barrier disruption in dementia: Nano-solutions as new treatment options

Candidate drugs targeting the central nervous system (CNS) demonstrate extremely low clinical success rates, with more than 98% of potential treatments being discontinued due to poor blood-brain barrier (BBB) permeability. Neurological conditions were shown to be the second leading cause of death globally in 2016, with the number of people currently affected by neurological disorders increasing rapidly. This increasing trend, along with an inability to develop BBB permeating drugs, is presenting a major hurdle in the treatment of CNS-related disorders, like dementia. To overcome this, it is necessary to understand the structure and function of the BBB, including the transport of molecules across its interface in both healthy and pathological conditions. The use of CNS drug carriers is rapidly gaining popularity in CNS research due to their ability to target BBB transport systems. Further research and development of drug delivery vehicles could provide essential information that can be used to develop novel treatments for neurological conditions. This review discusses the BBB and its transport systems and evaluates the potential of using nanoparticle-based delivery systems as drug carriers for CNS disease with a focus on dementia.

Modular tissue-in-a-CUBE platform to model blood-brain barrier (BBB) and brain interaction

With the advent of increasingly sophisticated organoids, there is growing demand for technology to replicate the interactions between multiple tissues or organs. This is challenging to achieve, however, due to the varying culture conditions of the different cell types that make up each tissue. Current methods often require complicated microfluidic setups, but fragile tissue samples tend not to fare well with rough handling. Furthermore, the more complicated the human system to be replicated, the more difficult the model becomes to operate. Here, we present the development of a multi-tissue chip platform that takes advantage of the modularity and convenient handling ability of a CUBE device. We first developed a blood-brain barrier-in-a-CUBE by layering astrocytes, pericytes, and brain microvascular endothelial cells in the CUBE, and confirmed the expression and function of important tight junction and transporter proteins in the blood-brain barrier model. Then, we demonstrated the application of integrating Tissue-in-a-CUBE with a chip in simulating the in vitro testing of the permeability of a drug through the blood-brain barrier to the brain and its effect on treating the glioblastoma brain cancer model. We anticipate that this platform can be adapted for use with organoids to build complex human systems in vitro by the combination of multiple simple CUBE units.

Mannose-Integrated Nanoparticle Hitchhike Glucose Transporter 1 Recycling to Overcome Various Barriers of Oral Delivery for Alzheimer's Disease Therapy

A brain-targeting nanodelivery system has been a hot topic and has undergone rapid progression. However, due to various obstacles such as the intestinal epithelial barrier (IEB) and the blood-brain barrier (BBB), few nanocarriers can achieve brain-targeting through oral administration. Herein, an intelligent oral brain-targeting nanoparticle (FTY@Man NP) constructed from a PLGA-PEG skeleton loaded with fingolimod (FTY) and externally modified with mannose was designed in combination with a glucose control strategy for the multitarget treatment of Alzheimer's disease (AD). The hydrophilic and electronegative properties of the nanoparticle facilitated its facile penetration through the mucus barrier, while the mannose ligand conferred IEB targeting abilities to the nanoparticle. Subsequently, glycemic control allowed the mannose-integrated nanoparticle to hitchhike the glucose transporter 1 (GLUT1) circulation across the BBB. Finally, the released FTY modulated the polarity of microglia from pro-inflammatory M1 to anti-inflammatory M2 and normalized the activated astrocyte, enhancing the clearance of toxic protein Amyloid-β (Aβ) while alleviating oxidative stress and neuroinflammation. Notably, both in vitro and in vivo results have consistently demonstrated that the oral administration of FTY@Man NP could effectively traverse the multiple barriers, thereby exerting significant therapeutic effects. This breakthrough holds the promise of realizing a highly effective orally administered treatment for AD.

How Much is Enough? Impact of Efflux Transporters on Drug delivery Leading to Efficacy in the Treatment of Brain Tumors

The lack of effective chemotherapeutic agents for the treatment of brain tumors is a serious unmet medical need. This can be attributed, in part, to inadequate delivery through the blood-brain barrier (BBB) and the tumor-cell barrier, both of which have active efflux transporters that can restrict the transport of many potentially effective agents for both primary and metastatic brain tumors. This review briefly summarizes the components and function of the normal BBB with respect to drug penetration into the brain and the alterations in the BBB due to brain tumor that could influence drug delivery. Depending on what is rate-limiting a compound's distribution, the limited permeability across the BBB and the subsequent delivery into the tumor cell can be greatly influenced by efflux transporters and these are discussed in some detail. Given these complexities, it is necessary to quantify the extent of brain distribution of the active (unbound) drug to compare across compounds and to inform potential for use against brain tumors. In this regard, the metric, Kp,uu, a brain-to-plasma unbound partition coefficient, is examined and its current use is discussed. However, the extent of active drug delivery is not the only determinant of effective therapy. In addition to Kp,uu, drug potency is an important parameter that should be considered alongside drug delivery in drug discovery and development processes. In other words, to answer the question - How much is enough? - one must consider how much can be delivered with how much needs to be delivered.

Molecular Trojan Horses for treating lysosomal storage diseases

Lysosomal storage diseases (LSDs) are caused by monogenic mutations in genes encoding for proteins related to the lysosomal function. Lysosome plays critical roles in molecule degradation and cell signaling through interplay with many other cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes. Even though several strategies (i.e., protein replacement and gene therapy) have been attempted for LSDs with promising results, there are still some challenges when hard-to-treat tissues such as bone (i.e., cartilages, ligaments, meniscus, etc.), the central nervous system (mostly neurons), and the eye (i.e., cornea, retina) are affected. Consistently, searching for novel strategies to reach those tissues remains a priority. Molecular Trojan Horses have been well-recognized as a potential alternative in several pathological scenarios for drug delivery, including LSDs. Even though molecular Trojan Horses refer to genetically engineered proteins to overcome the blood-brain barrier, such strategy can be extended to strategies able to transport and deliver drugs to specific tissues or cells using cell-penetrating peptides, monoclonal antibodies, vesicles, extracellular vesicles, and patient-derived cells. Only some of those platforms have been attempted in LSDs. In this paper, we review the most recent efforts to develop molecular Trojan Horses and discuss how this strategy could be implemented to enhance the current efficacy of strategies such as protein replacement and gene therapy in the context of LSDs.

Blood-brain barrier dysfunction in intensive care unit

The central nervous system is characterized by a peculiar vascularization termed blood-brain barrier (BBB), which regulates the exchange of cells and molecules between the cerebral tissue and the whole body. BBB dysfunction is a life-threatening condition since its presence corresponds to a marker of severity in most diseases encountered in the intensive care unit (ICU). During critical illness, inflammatory response, cytokine release, and other phenomena activating the brain endothelium contribute to alterations in the BBB and increase its permeability to solutes, cells, nutrients, and xenobiotics. Moreover, patients in the ICU are often old, with underlying acute or chronic diseases, and overly medicated due to their critical condition; these factors could also contribute to the development of BBB dysfunction. An accurate diagnostic approach is critical for the identification of the mechanisms underlying BBB alterations, which should be rapidly managed by intensivists. Several methods were developed to investigate the BBB and assess its permeability. Nevertheless, in humans, exploration of the BBB requires the use of indirect methods. Imaging and biochemical methods can be used to study the abnormal passage of molecules through the BBB. In this review, we describe the structural and functional characteristics of the BBB, present tools and methods for probing this interface, and provide examples of the main diseases managed in the ICU that are related to BBB dysfunction.

Intranasal administration of molecular-gated mesoporous nanoparticles to increase ponatinib delivery to the brain

Background: Glioblastoma is the most common and lethal brain cancer. New treatments are needed. However, the presence of the blood-brain barrier is limiting the development of new treatments directed toward the brain, as it restricts the access and distribution of drugs to the CNS. Materials & methods: In this work, two different nanoparticles (i.e., mesoporous silica nanoparticles and magnetic mesoporous silica nanoparticles) loaded with ponatinib were prepared. Results & conclusion: Both particles were characterized and tested in vitro and in vivo, proving that they are not toxic for blood-brain barrier cells and they increase the amount of drug reaching the brain when administered intranasally in comparison with the results obtained for the free drug.

Gold and silver nanoparticles in Alzheimer's and Parkinson's diagnostics and treatments

Neurodegenerative diseases (NDs) impose substantial medical and public health burdens on people worldwide and represent one of the major threats to human health. The prevalence of these age-dependent disorders is dramatically increasing over time, a process intrinsically related to a constantly rising percentage of the elderly population in recent years. Among all the NDs, Alzheimer's and Parkinson's are considered the most debilitating as they cause memory and cognitive loss, as well as severely affecting basic physiological conditions such as the ability to move, speak, and breathe. There is an extreme need for new and more effective therapies to counteract these devastating diseases, as the available treatments are only able to slow down the pathogenic process without really stopping or resolving it. This review aims to elucidate the current nanotechnology-based tools representing a future hope for NDs treatment. Noble metal nano-systems, that is, gold and silver nanoparticles (NPs), have indeed unique physicochemical characteristics enabling them to deliver any pharmacological treatment in a more effective way within the central nervous system. This can potentially make NPs a new hope for reversing the actual therapeutic strategy based on slowing down an irreversible process into a more effective and permanent treatment.

Liposomes for the Treatment of Brain Cancer-A Review

Due to their biocompatibility, non-toxicity, and surface-conjugation capabilities, liposomes are effective nanocarriers that can encapsulate chemotherapeutic drugs and facilitate targeted delivery across the blood-brain barrier (BBB). Additionally, strategies have been explored to synthesize liposomes that respond to internal and/or external stimuli to release their payload controllably. Although research into liposomes for brain cancer treatment is still in its infancy, these systems have great potential to fundamentally change the drug delivery landscape. This review paper attempts to consolidate relevant literature regarding the delivery to the brain using nanocarriers, particularly liposomes. The paper first briefly explains conventional treatment modalities for cancer, followed by describing the blood-brain barrier and ways, challenges, and techniques involved in transporting drugs across the BBB. Various nanocarrier systems are introduced, with attention to liposomes, due to their ability to circumvent the challenges imposed by the BBB. Relevant studies involving liposomal systems researched to treat brain tumors are reviewed in vitro, in vivo, and clinical studies. Finally, the challenges associated with the use of liposomes to treat brain tumors and how they can be addressed are presented.

Pathophysiology and probable etiology of cerebral small vessel disease in vascular dementia and Alzheimer's disease

Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.

Drug Delivery of Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs) to Target Brain Tumors

Brain, predisposed to local and metastasized tumors, has always been the focus of oncological studies. Glioblastoma multiforme (GBM), the most common invasive primary tumor of the brain, is responsible for 4% of all cancer-related deaths worldwide. Despite novel technologies, the average survival rate is 2 years. Physiological barriers such as blood-brain barrier (BBB) prevent drug molecules penetration into brain. Most of the pharmaceuticals present in the market cannot infiltrate BBB to have their maximum efficacy and this in turn imposes a major challenge. This mini review discusses GBM and physiological and biological barriers for anticancer drug delivery, challenges for drug delivery across BBB, drug delivery strategies focusing on SLNs and NLCs and their medical applications in on-going clinical trials. Numerous nanomedicines with various characteristics have been introduced in the last decades to overcome the delivery challenge. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were introduced as oral drug delivery nanomedicines which can be encapsulated by both hydrophilic and lipophilic pharmaceutical compounds. Their biocompatibility, biodegradability, lower toxicity and side effects, enhanced bioavailability, solubility and permeability, prolonged half-life and stability and finally tissue-targeted drug delivery makes them unique among all.

Development of a method for isolating brain capillaries from a single neonatal mouse brain and comparison of proteomic profiles between neonatal and adult brain capillaries

BACKGROUND

The functions and protein expressions of the blood-brain barrier are changed throughout brain development following birth. This study aimed to develop a method to isolate brain capillaries from a single frozen neonatal mouse brain and elucidate the enrichment of brain capillaries by quantitative proteomic analysis. We further compared the expression profile of proteins between neonatal and adult brain capillary fractions.

METHODS

The brain capillary fraction was prepared by the optimized method from a single frozen mouse neonatal brain on postnatal day 7. The brain capillary fractions and brain lysates were digested by trypsin and analyzed by liquid chromatography-mass spectrometry for quantitative proteomics.

RESULTS

By optimizing the isolation method, we observed brain capillaries in the fraction prepared from a single neonatal mouse brain (nBC fraction). A protein amount of 31.5 μg, which is enough for proteomic analysis, was recovered from the nBC fraction. By proteomics analysis, the brain capillary selective proteins, including Abcb1a/Mdr1, Slc2a1/Glut1, Claudin-5, and Pecam-1, were found to be concentrated > 13.4-fold more in nBC fractions than in whole brain lysates. The marker proteins for neurons and astrocytes were not concentrated in nBC fractions, while those of pericytes and microglia were concentrated. Compared to adult mouse brain capillary fractions (aBC fractions), the expressions of Abcb1a/Mdr1a, Abcc4/Mrp4, and Slc2a1/Glut1 were significantly lower in nBC fractions than in aBC fractions, whereas those of Slc1a4/Asct1, Slc1a5/Asct2, Slc7a1/Cat1, and Slc16a1/Mct1 were significantly higher. Amino acid transporters, Slc38a5/Snat5, showed the greatest nBC-to-aBC ratio among transporters (9.83-fold). Network analysis of proteins expressed differentially between nBC and aBC fractions revealed that the proteins with terms related to the extracellular matrix were enriched.

CONCLUSIONS

We succeeded in isolating brain capillaries from a single frozen brain of a neonatal mouse at postnatal day 7. Proteomic analysis revealed the differential expression in brain capillaries between neonatal and adult mice. Specifically, amino acid transporters, including Slc1a5/Asct2 and Slc38a5/Snat5, were found to be induced in neonatal brain capillaries. The present isolation method will promote the study of the function and expression of the neonatal blood-brain barrier.

Gut Dysbiosis and Blood-Brain Barrier Alteration in Hepatic Encephalopathy: From Gut to Brain

A common neuropsychiatric complication of advanced liver disease, hepatic encephalopathy (HE), impacts the quality of life and length of hospital stays. There is new evidence that gut microbiota plays a significant role in brain development and cerebral homeostasis. Microbiota metabolites are providing a new avenue of therapeutic options for several neurological-related disorders. For instance, the gut microbiota composition and blood-brain barrier (BBB) integrity are altered in HE in a variety of clinical and experimental studies. Furthermore, probiotics, prebiotics, antibiotics, and fecal microbiota transplantation have been shown to positively affect BBB integrity in disease models that are potentially extendable to HE by targeting gut microbiota. However, the mechanisms that underlie microbiota dysbiosis and its effects on the BBB are still unclear in HE. To this end, the aim of this review was to summarize the clinical and experimental evidence of gut dysbiosis and BBB disruption in HE and a possible mechanism.

Synthesis and analysis of novel catecholic ligands as inhibitors of catechol-O-methyltransferase

L-DOPA, a dopamine precursor, is commonly used as a treatment for patients with conditions such as Parkinson's disease. This therapeutic L-DOPA, as well as the dopamine derived from L-DOPA, can be deactivated via metabolism by catechol-O-methyltransferase (COMT). Targeted inhibition of COMT prolongs the effectiveness of L-DOPA and dopamine, resulting in a net increase in pharmacological efficiency of the treatment strategy. Following the completion of a previous ab initio computational analysis of 6-substituted dopamine derivatives, several novel catecholic ligands with a previously unexplored neutral tail functionality were synthesized in good yields and their structures were confirmed. The ability of the catecholic nitriles and 6-substituted dopamine analogues to inhibit COMT was tested. The nitrile derivatives inhibited COMT most effectively, in agreement with our previous computational work. pKa values were used to further examine the factors involved with the inhibition and molecular docking studies were performed to support the ab initio and experimental work. The nitrile derivatives with a nitro substituent show the most promise as inhibitors, confirming that both the neutral tail and the electron withdrawing group are essential on this class of inhibitors.

One messenger shared by two systems: How cytokines directly modulate neurons

Cytokines are small, secreted proteins that are known for their roles in the immune system. An accumulating body of evidence indicates that cytokines also work as neuromodulators in the central nervous system (CNS). Cytokines can access the CNS through multiple routes to directly impact neurons. The neuromodulatory effects of cytokines maintain the overall homeostasis of neural networks. In addition, cytokines regulate a diverse repertoire of behaviors both at a steady state and in inflammatory conditions by acting on discrete brain regions and neural networks. In this review, we discuss recent findings that provide insight into how combinatorial codes of cytokines might mediate neuro-immune communications to orchestrate functional responses of the brain to changes in immunological milieus.

Near-infrared fluorescence lifetime imaging of amyloid-β aggregates and tau fibrils through the intact skull of mice

Non-invasive methods for the in vivo detection of hallmarks of Alzheimer's disease can facilitate the study of the progression of the disease in mouse models and may enable its earlier diagnosis in humans. Here we show that the zwitterionic heptamethine fluorophore ZW800-1C, which has peak excitation and emission wavelengths in the near-infrared optical window, binds in vivo and at high contrast to amyloid-β deposits and to neurofibrillary tangles, and allows for the microscopic imaging of amyloid-β and tau aggregates through the intact skull of mice. In transgenic mouse models of Alzheimer's disease, we compare the performance of ZW800-1C with that of the two spectrally similar heptamethine fluorophores ZW800-1A and indocyanine green, and show that ZW800-1C undergoes a longer fluorescence-lifetime shift when bound to amyloid-β and tau aggregates than when circulating in blood vessels. ZW800-1C may prove advantageous for tracking the proteinic aggregates in rodent models of amyloid-β and tau pathologies.

Access to the CNS: Strategies to overcome the BBB

The blood-brain barrier (BBB) limits the access of substances to the central nervous system (CNS) which hinders the treatment of pathologies affecting the brain and the spinal cord. Nowadays, research is focus on new strategies to overcome the BBB and can treat the pathologies affecting the CNS are needed. In this review, the different strategies that allow and increase the access of substances to the CNS are analysed and extended commented, not only invasive strategies but also non-invasive ones. The invasive techniques include the direct injection into the brain parenchyma or the CSF and the therapeutic opening of the BBB, while the non-invasive techniques include the use of alternative routes of administration (nose-to-brain route), the inhibition of efflux transporters (as it is important to prevent the drug efflux from the brain and enhance the therapeutic efficiency), the chemical modification of the molecules (prodrugs and chemical drug delivery systems (CDDS)) and the use of nanocarriers. In the future, knowledge about nanocarriers to treat CNS diseases will continue to increase, but the use of other strategies such as drug repurposing or drug reprofiling, which are cheaper and less time consuming, may limit its transfer to society. The main conclusion is that the combination of different strategies may be the most interesting approach to increase the access of substances to the CNS.

Comparative Efficacy of ALK Inhibitors for Treatment-Naïve ALK-Positive Advanced Non-Small Cell Lung Cancer with Central Nervous System Metastasis: A Network Meta-Analysis

Central nervous system (CNS) metastases and acquired resistance complicate the treatment of anaplastic lymphoma kinase (ALK) rearrangement-positive (ALK-p) advanced non-small cell lung cancer (NSCLC). Thus, this review aimed to provide a comprehensive overview of brain metastasis, acquired resistance, and prospects for overcoming these challenges. A network meta-analysis of relevant phase III randomized controlled trials was performed to compare the efficacies of multiple ALK inhibitors by drug and generation in overall patients with ALK-p untreated advanced NSCLC and a subgroup of patients with CNS metastases. The primary endpoint was progression-free survival (PFS). Generation-specific comparison results showed that third-generation ALK inhibitors were significantly more effective than second-generation ALK inhibitors in prolonging the PFS of the subgroup of patients with CNS metastases. Drug-specific comparison results demonstrated that lorlatinib was the most effective in prolonging PFS, followed by brigatinib, alectinib, ensartinib, ceritinib, crizotinib, and chemotherapy. While lorlatinib was superior to brigatinib for PFS in the overall patient population, no significant difference between the two was found in the subgroup of patients with CNS metastases. These results can serve as a foundation for basic, clinical, and translational research and guide clinical oncologists in developing individualized treatment strategies for patients with ALK-p, ALK inhibitor-naive advanced NSCLC.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Current Update on Transcellular Brain Drug Delivery

It is well known that the presence of a blood-brain barrier (BBB) makes drug delivery to the brain more challenging. There are various mechanistic routes through which therapeutic molecules travel and deliver the drug across the BBB. Among all the routes, the transcellular route is widely explored to deliver therapeutics. Advances in nanotechnology have encouraged scientists to develop novel formulations for brain drug delivery. In this article, we have broadly discussed the BBB as a limitation for brain drug delivery and ways to solve it using novel techniques such as nanomedicine, nose-to-brain drug delivery, and peptide as a drug delivery carrier. In addition, the article will help to understand the different factors governing the permeability of the BBB, as well as various formulation-related factors and the body clearance of the drug delivered into the brain.

Enhanced drug delivery by a prodrug approach effectively relieves neuroinflammation in mice

AIMS

Neuroinflammation is a prominent hallmark in several neurodegenerative diseases (NDs). Halting neuroinflammation can slow down the progression of NDs. Improving the efficacy of clinically available non-steroidal anti-inflammatory drugs (NSAIDs) is a promising approach that may lead to fast-track and effective disease-modifying therapies for NDs. Here, we aimed to utilize the L-type amino acid transporter 1 (LAT1) to improve the efficacy of salicylic acid as an example of an NSAID prodrug, for which brain uptake and intracellular localization have been reported earlier.

MAIN METHODS

Firstly, we confirmed the improved LAT1 utilization of the salicylic acid prodrug (SA-AA) in freshly isolated primary mouse microglial cells. Secondly, we performed behavioural rotarod, open field, and four-limb hanging tests in mice, and a whole-brain proteome analysis.

KEY FINDINGS

The SA-AA prodrug alleviated the lipopolysaccharide (LPS)-induced inflammation in the rotarod and hanging tests. The proteome analysis indicated decreased neuroinflammation at the molecular level. We identified 399 proteins linked to neuroinflammation out of 7416 proteins detected in the mouse brain. Among them, Gps2, Vamp8, Slc6a3, Slc18a2, Slc5a7, Rgs9, Lrrc1, Ppp1r1b, Gnal, and Adcy5/6 were associated with the drug's effects. The SA-AA prodrug attenuated the LPS-induced neuroinflammation through the regulation of critical pathways of neuroinflammation such as the cellular response to stress and transmission across chemical synapses.

SIGNIFICANCE

The efficacy of NSAIDs can be improved via the utilization of LAT1 and repurposed for the treatment of neuroinflammation. This improved brain delivery and microglia localisation can be applied to other inflammatory modulators to achieve effective and targeted CNS therapies.

New insight into neurological degeneration: Inflammatory cytokines and blood–brain barrier

Neurological degeneration after neuroinflammation, such as that resulting from Alzheimer’s disease (AD), stroke, multiple sclerosis (MS), and post-traumatic brain injury (TBI), is typically associated with high mortality and morbidity and with permanent cognitive dysfunction, which places a heavy economic burden on families and society. Diagnosing and curing these diseases in their early stages remains a challenge for clinical investigation and treatment. Recent insight into the onset and progression of these diseases highlights the permeability of the blood–brain barrier (BBB). The primary factor that influences BBB structure and function is inflammation, especially the main cytokines including IL-1β, TNFα, and IL-6, the mechanism on the disruption of which are critical component of the aforementioned diseases. Surprisingly, the main cytokines from systematic inflammation can also induce as much worse as from neurological diseases or injuries do. In this review, we will therefore discuss the physiological structure of BBB, the main cytokines including IL-1β, TNFα, IL-6, and their mechanism on the disruption of BBB and recent research about the main cytokines from systematic inflammation inducing the disruption of BBB and cognitive impairment, and we will eventually discuss the need to prevent the disruption of BBB.

Blood-Brain Barrier Solute Carrier Transporters and Motor Neuron Disease

Defective solute carrier (SLC) transporters are responsible for neurotransmitter dysregulation, resulting in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). We provided the role and kinetic parameters of transporters such as ASCTs, Taut, LAT1, CAT1, MCTs, OCTNs, CHT, and CTL1, which are mainly responsible for the transport of essential nutrients, acidic, and basic drugs in blood-brain barrier (BBB) and motor neuron disease. The affinity for LAT1 was higher in the BBB than in the ALS model cell line, whereas the capacity was higher in the NSC-34 cell lines than in the BBB. Affinity for MCTs was lower in the BBB than in the NSC-34 cell lines. CHT in BBB showed two affinity sites, whereas no expression was observed in ALS cell lines. CTL1 was the main transporter for choline in ALS cell lines. The half maximal inhibitory concentration (IC50) analysis of [3H]choline uptake indicated that choline is sensitive in TR-BBB cells, whereas amiloride is most sensitive in ALS cell lines. Knowledge of the transport systems in the BBB and motor neurons will help to deliver drugs to the brain and develop the therapeutic strategy for treating CNS and neurological diseases.

Naltrexone Transport by a Proton-Coupled Organic Cation Antiporter in hCMEC/D3 Cells, an in Vitro Human Blood-Brain Barrier Model

Naltrexone is a mu-opioid receptor antagonist used in the treatment of opioid and alcohol dependence. The blood-brain barrier (BBB) transport characteristics of naltrexone was investigated by means of hCMEC/D3 cells, a human immortalized brain capillary endothelial cell line. In hCMEC/D3 cells, naltrexone is taken up in a concentration-dependent manner. Furthermore, naltrexone uptake significantly decreased in the presence of H⁺/organic cation (OC) antiporter substrates, during the little alteration exhibited by substrates of well-identified OC transporters classified into SLC22A family. Although naltrexone uptake by hCMEC/D3 cells was partially affected by changes of ionic conditions, it was markedly decreased in the presence of the metabolic inhibitor sodium azide. Furthermore, when treated by ammonium chloride, naltrexone uptake by hCMEC/D3 cells was altered by intracellular acidification and alkalization, suggesting the involvement of oppositely directed proton gradient in naltrexone transport across the BBB. The results obtained in the present in vitro study suggest the active transport of naltrexone from blood to the brain across the BBB by the H⁺/OC antiporter.

Engineering antibody and protein therapeutics to cross the blood-brain barrier

Diseases in the central nervous system (CNS) are often difficult to treat. Antibody- and protein-based therapeutics hold huge promises in CNS disease treatment. However, proteins are restricted from entering the CNS by the blood-brain barrier (BBB). To achieve enhanced BBB crossing, antibody-based carriers have been developed by utilizing the endogenous macromolecule transportation pathway, known as receptor-mediated transcytosis. In this report, we first provided an overall review on key CNS diseases and the most promising antibody- or protein-based therapeutics approved or in clinical trials. We then reviewed the platforms that are being explored to increase the macromolecule brain entry to combat CNS diseases. Finally, we have analyzed the lessons learned from past experiences and have provided a perspective on the future engineering of novel delivery vehicles for antibody- and protein-based therapies for CNS diseases.

Overcoming the blood-brain barrier for the therapy of malignant brain tumor: current status and prospects of drug delivery approaches

Besides the broad development of nanotechnological approaches for cancer diagnosis and therapy, currently, there is no significant progress in the treatment of different types of brain tumors. Therapeutic molecules crossing the blood-brain barrier (BBB) and reaching an appropriate targeting ability remain the key challenges. Many invasive and non-invasive methods, and various types of nanocarriers and their hybrids have been widely explored for brain tumor treatment. However, unfortunately, no crucial clinical translations were observed to date. In particular, chemotherapy and surgery remain the main methods for the therapy of brain tumors. Exploring the mechanisms of the BBB penetration in detail and investigating advanced drug delivery platforms are the key factors that could bring us closer to understanding the development of effective therapy against brain tumors. In this review, we discuss the most relevant aspects of the BBB penetration mechanisms, observing both invasive and non-invasive methods of drug delivery. We also review the recent progress in the development of functional drug delivery platforms, from viruses to cell-based vehicles, for brain tumor therapy. The destructive potential of chemotherapeutic drugs delivered to the brain tumor is also considered. This review then summarizes the existing challenges and future prospects in the use of drug delivery platforms for the treatment of brain tumors.

CPEB2 m6A methylation regulates blood-tumor barrier permeability by regulating splicing factor SRSF5 stability

The blood–tumor barrier (BTB) contributes to poor therapeutic efficacy by limiting drug uptake; therefore, elevating BTB permeability is essential for glioma treatment. Here, we prepared astrocyte microvascular endothelial cells (ECs) and glioma microvascular ECs (GECs) as in vitro blood–brain barrier (BBB) and BTB models. Upregulation of METTL3 and IGF2BP3 in GECs increased the stability of CPEB2 mRNA through its m6A methylation. CPEB2 bound to and increased SRSF5 mRNA stability, which promoted the ETS1 exon inclusion. P51-ETS1 promoted the expression of ZO-1, occludin, and claudin-5 transcriptionally, thus regulating BTB permeability. Subsequent in vivo knockdown of these molecules in glioblastoma xenograft mice elevated BTB permeability, promoted doxorubicin penetration, and improved glioma-specific chemotherapeutic effects. These results provide a theoretical and experimental basis for epigenetic regulation of the BTB, as well as insight into comprehensive glioma treatment.

The methyl transferase METTL3 is up-regulated in brain tumors leading to the methylation of CPEB2 mRNA, which in turn stabilizes the splicing factor SRSF5 mRNA, leading to the incorporation of exon 7 in ETS-1 in models of the Blood–Tumor Barrier.

Lymphatic cells do not functionally integrate into 3D organotypic brain slice cultures, but aggregate around penetrating blood vessels

Brain slice culture (BSC) is a well-known three-dimensional model of the brain. In this study, we use organotypic slices for studying neuro-lymphatic physiology, to directly test the longstanding assumption that the brain is not a hospitable milieu for typical lymphatic vessels. An additional objective is to model fluid egress through brain perivascular space systems and to visualize potential cellular interactions among cells in the leptomeninges including alterations of cellular geometry and number of processes. Immortalized lymphatic rat cell lines were used to seed organotypic brain slices. The brain slice model was characterized by monitoring morphologies, growth rates, degree of apoptosis, and transport properties of brain slices with or without a lymphatic component. The model was then challenged with fibroblast co-cultures, as a control cell that is not normally found in the brain. Immortalized lymphatic cells penetrated the brain slices within 2-4 days. Typical cell morphology is spindly with bipolar and tripolar forms well represented. Significantly more indigo carmine marker passed through lymphatic seeded BSCs compared to arachnoid BSCs. Significantly more indigo carmine passed through brain slices co-cultured with fibroblast compared to lymphatic and arachnoid BSCs alone. We have developed an organotypic model in which lymphatic cells are able to interact with parenchymal cells in the cerebrum. Their presence appears to alter the small molecule transport ability of whole-brain slices. Lymphatic cells decreased dye transport in BSCs, possibly by altering the perivascular space. Given their direct contact with the CSF, they may affect convectional and diffusional processes. Our model shows that a decrease in lymphatic cell growth may reduce the brain slice's transport capabilities.

Nanomedicine for Glioblastoma: Progress and Future Prospects

Glioblastoma is the most aggressive form of brain tumor, accounting for the highest mortality and morbidity rates. Current treatment for patients with glioblastoma includes maximal safe tumor resection followed by radiation therapy with concomitant temozolomide (TMZ) chemotherapy. The addition of TMZ to the conformal radiation therapy has improved the median survival time only from 12 months to 16 months in patients with glioblastoma. Despite these aggressive treatment strategies, patients' prognosis remains poor. This therapeutic failure is primarily attributed to the blood-brain barrier (BBB) that restricts the transport of TMZ from reaching the tumor site. In recent years, nanomedicine has gained considerable attention among researchers and shown promising developments in clinical applications, including the diagnosis, prognosis, and treatment of glioblastoma tumors. This review sheds light on the morphological and physiological complexity of the BBB. It also explains the development of nanomedicine strategies to enhance the permeability of drug molecules across the BBB.

Gut Microbes Regulate Innate Immunity and Epilepsy

Epilepsy is a common chronic brain disease. There are many clinical methods to control epileptic seizures, such as anti-seizure medications (ASMs) or surgical removal of epileptogenic lesions. However, the pathophysiology of epilepsy is still unknown, making it difficult to control or prevent it. The host’s immune system monitors gut microbes, interacts with microbes through pattern recognition receptors such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs) expressed by innate immune cells, and activates immune responses in the body to kill pathogens and balance the relationship between microbes and host. In addition, inflammatory responses induced by the innate immune system are seen in animal models of epilepsy and temporal lobe epilepsy brain tissue to combat pathogens or injuries. This review summarizes the potential relationship between gut microbes, innate immunity, and epilepsy based on recent research to provide more hints for researchers to explore this field further.

Blood-brain barrier: emerging trends on transport models and new-age strategies for therapeutics intervention against neurological disorders

The integrity of the blood–brain barrier (BBB) is essential for normal central nervous system (CNS) functioning. Considering the significance of BBB in maintaining homeostasis and the neural environment, we aim to provide an overview of significant aspects of BBB. Worldwide, the treatment of neurological diseases caused by BBB disruption has been a major challenge. BBB also restricts entry of neuro-therapeutic drugs and hinders treatment modalities. Hence, currently nanotechnology-based approaches are being explored on large scale as alternatives to conventional methodologies. It is necessary to investigate the in-depth characteristic features of BBB to facilitate the discovery of novel drugs that can successfully cross the barrier and target the disease effectively. It is imperative to discover novel strategies to treat life-threatening CNS diseases in humans. Therefore, insights regarding building blocks of BBB, activation of immune response on breach of this barrier, and various autoimmune neurological disorders caused due to BBB dysfunction are discussed. Further, special emphasis is given on delineating BBB disruption leading to CNS disorders. Moreover, various mechanisms of transport pathways across BBB, several novel strategies, and alternative routes by which drugs can be properly delivered into CNS are also discussed.

Breaking through the barrier: Modelling and exploiting the physical microenvironment to enhance drug transport and efficacy

Pharmaceutical compounds are the main pillar in the treatment of various illnesses. To administer these drugs in the therapeutic setting, multiple routes of administration have been defined, including ingestion, inhalation, and injection. After administration, drugs need to find their way to the intended target for high effectiveness, and this penetration is greatly dependent on obstacles the drugs encounter along their path. Key hurdles include the physical barriers that are present within the body and knowledge of those is indispensable for progress in the development of drugs with increased therapeutic efficacy. In this review, we examine several important physical barriers, such as the blood-brain barrier, the gut-mucosal barrier, and the extracellular matrix barrier, and evaluate their influence on drug transport and efficacy. We explore various in vitro model systems that aid in understanding how parameters within the barrier model affect drug transfer and therapeutic effect. We conclude that physical barriers in the body restrict the quantity of drugs that can pass through, mainly as a consequence of the barrier architecture. In addition, the specific physical properties of the tissue can trigger intracellular changes, altering cell behavior in response to drugs. Though the barriers negatively influence drug distribution, physical stimulation of the surrounding environment may also be exploited as a mechanism to control drug release. This drug delivery approach is explored in this review as a potential alternative to the conventional ways of delivering therapeutics.

Construction and Functional Evaluation of a Three-Dimensional Blood–Brain Barrier Model Equipped With Human Induced Pluripotent Stem Cell-Derived Brain Microvascular Endothelial Cells

Purpose

The purpose of this study was to construct and validate an in vivo three-dimensional blood–brain barrier (3D-BBB) model system equipped with brain microvascular endothelial cells derived from human induced pluripotent stem cells (hiPS-BMECs).

Methods

The 3D-BBB system was constructed by seeding hiPS-BMECs onto the capillary lane of a MIMETAS OrganoPlate® 3-lane coated with fibronectin/collagen IV. hiPS-BMECs were incubated under continuous switchback flow with an OrganoFlow® for 2 days. The 3D capillary structure and expression of tight-junction proteins and transporters were confirmed by immunocytochemistry. The mRNA expression of transporters in the 3D environment was determined using qRT-PCR, and the permeability of endogenous substances and drugs was evaluated under various conditions.

Results and Discussion

The expression of tight-junction proteins, including claudin-5 and ZO-1, was confirmed by immunohistochemistry. The permeability rate constant of lucifer yellow through hiPS-BMECs was undetectably low, indicating that paracellular transport is highly restricted by tight junctions in the 3D-BBB system. The mRNA expression levels of transporters and receptors in the 3D-BBB system differed from those in the 2D-culture system by 0.2- to 5.8-fold. The 3D-cultured hiPS-BMECs showed asymmetric transport of substrates of BCRP, CAT1 and LAT1 between the luminal (blood) and abluminal (brain) sides. Proton-coupled symport function of MCT1 was also confirmed.

Conclusion

The 3D-BBB system constructed in this study mimics several important characteristics of the human BBB, and is expected to be a useful high-throughput evaluation tool in the development of CNS drugs.