Transporting therapeutics across the blood-brain barrier

A review of chitosan polysaccharides: Neuropharmacological implications and tissue regeneration

One of the current challenges in targeting neurological disorders is that many therapeutic molecules cannot cross the blood-brain barrier (BBB), which limits the use of natural molecules in nervous tissue regeneration. Thus, the development of new drugs to effectively treat neurological disorders would be a challenge. Natural resources are well known as a source of several therapeutic agents for the treatment of neurologic disorders. Recently, chitosan (CTS) and its derivatives from arthropod exoskeletons, have attracted much attention as a drug delivery system to transport therapeutic substances across the BBB and thanks to other neuroprotective effects including the participation to the CNS regenerations scaffolds to replicate the extracellular matrix and microenvironment of the body. This review will discuss the place of natural resource therapy in targeting neurological disorders. In particular, it will highlight recent understanding and progress in the applications of CTS as drug delivery systems and their therapeutic effects on these disorders through tissue regeneration, as well as the molecular mechanisms by which they exert these effects.

Local Delivery of Irinotecan to Recurrent GBM Patients at Reoperation Offers a Safe Route of Administration

Glioblastomas are impossible to completely resect and almost always recur at the borders of the resection margin. There is no established chemotherapy regimen available to patients who recur, while systemic treatment is hampered by the blood-brain barrier. Here, we report on the first evaluation in humans of the intraparenchymal injection of irinotecan into the resection cavity after surgical resection of recurrent glioblastoma patients. The cytotoxicity of irinotecan was compared to SN-38 in primary cells from recurrent glioblastoma patients. Irinotecan was injected at multiple (~30) sites of the resection cavity wall at a depth of 3 to 5 mm. SN-38 was more cytotoxic than irinotecan at concentrations below 1 µM due to enzyme kinetics. The intraparenchymal administration of irinotecan was safe, with good wound healing and an absence of swelling, inflammation, or pseudo-abscess formation. The median survival post irinotecan administration was 32.6 weeks. The median overall survival was 30.5 months, with a two-year survival rate of 56%. This study demonstrates that local delivery of irinotecan into the brain parenchyma offers a safe route of administration over systemic delivery in the treatment of recurrent glioblastoma.

Comparative Neuroprotective Potential of Nanoformulated and Free Resveratrol Against Cuprizone-Induced Demyelination in Rats

Demyelination is a frequent yet crippling neurological disease associated with multiple sclerosis (MS). The cuprizone (CZ) model, which causes demyelination through oxidative stress and neuroinflammation, is a popular tool used by researchers to examine this process. The polyphenol resveratrol (RESV) has become a promising neuroprotective agent in seeking for efficient therapies. In a rat model given CZ, we created and examined iron oxide nanoparticles (IONPs) loaded with RESV (IONP-RESV) to see how effective they were as a therapeutic agent against free RESV. According to molecular mechanisms, exposure to CZ resulted in a marked downregulation of myelin proteolipid protein (PLP) expression and an overexpression of the inflammatory markers tumor necrosis factor-α (TNF-α) and S100β, which are indicators of demyelination and neuroinflammation. It is remarkable that these CZ-induced alterations could be reversed by therapy with either RESV or IONP-RESV. Interestingly, IONP-RESV showed even stronger anti-inflammatory activity, as shown by a more noticeable downregulation of TNF-α and S100β expression. These results were confirmed by histopathological examination of the cerebral cortices. Our findings support the better neuroprotective benefits of RESV-loaded IONPs over free RESV in reducing demyelination and neuroinflammation brought on by CZ. Owing to their pro-remyelinating, anti-inflammatory, and antioxidant properties, RESV-loaded IONPs show promise as a neurotherapeutic intervention in the future for neurological diseases such as multiple sclerosis.

A novel histone deacetylase inhibitor W2A-16 improves the barrier integrity in brain vascular endothelial cells

The maturation of brain microvascular endothelial cells leads to the formation of a tightly sealed monolayer, known as the blood-brain barrier (BBB). The BBB damage is associated with the pathogenesis of age-related neurodegenerative diseases including vascular cognitive impairment and Alzheimer's disease. Growing knowledge in the field of epigenetics can enhance the understanding of molecular profile of the BBB and has great potential for the development of novel therapeutic strategies or targets to repair a disrupted BBB. Histone deacetylases (HDACs) inhibitors are epigenetic regulators that can induce acetylation of histones and induce open chromatin conformation, promoting gene expression by enhancing the binding of DNA with transcription factors. We investigated how HDAC inhibition influences the barrier integrity using immortalized human endothelial cells (HCMEC/D3) and the human induced pluripotent stem cell (iPSC)-derived brain vascular endothelial cells. The endothelial cells were treated with or without a novel compound named W2A-16. W2A-16 not only activates Wnt/β-catenin signaling but also functions as a class I HDAC inhibitor. We demonstrated that the administration with W2A-16 sustained barrier properties of the monolayer of endothelial cells, as evidenced by increased trans-endothelial electrical resistance (TEER). The BBB-related genes and protein expression were also increased compared with non-treated controls. Analysis of transcript profiles through RNA-sequencing in hCMEC/D3 cells indicated that W2A-16 potentially enhances BBB integrity by influencing genes associated with the regulation of the extracellular microenvironment. These findings collectively propose that the HDAC inhibition by W2A-16 plays a facilitating role in the formation of the BBB. Pharmacological approaches to inhibit HDAC may be a potential therapeutic strategy to boost and/or restore BBB integrity.

Laser-activated perfluorocarbon nanodroplets for intracerebral delivery and imaging via blood-brain barrier opening and contrast-enhanced imaging

BACKGROUND

Ultrasound and photoacoustic (US/PA) imaging is a promising tool for in vivo visualization and assessment of drug delivery. However, the acoustic properties of the skull limit the practical application of US/PA imaging in the brain. To address the challenges in targeted drug delivery to the brain and transcranial US/PA imaging, we introduce and evaluate an intracerebral delivery and imaging strategy based on the use of laser-activated perfluorocarbon nanodroplets (PFCnDs).

METHODS

Two specialized PFCnDs were developed to facilitate blood‒brain barrier (BBB) opening and contrast-enhanced US/PA imaging. In mice, PFCnDs were delivered to brain tissue via PFCnD-induced BBB opening to the right side of the brain. In vivo, transcranial US/PA imaging was performed to evaluate the utility of PFCnDs for contrast-enhanced imaging through the skull. Ex vivo, volumetric US/PA imaging was used to characterize the spatial distribution of PFCnDs that entered brain tissue. Immunohistochemical analysis was performed to confirm the spatial extent of BBB opening and the accuracy of the imaging results.

RESULTS

In vivo, transcranial US/PA imaging revealed localized photoacoustic (PA) contrast associated with delivered PFCnDs. In addition, contrast-enhanced ultrasound (CEUS) imaging confirmed the presence of nanodroplets within the same area. Ex vivo, volumetric US/PA imaging revealed PA contrast localized to the area of the brain where PFCnD-induced BBB opening had been performed. Immunohistochemical analysis revealed that the spatial distribution of immunoglobulin (IgG) extravasation into the brain closely matched the imaging results.

CONCLUSIONS

Using our intracerebral delivery and imaging strategy, PFCnDs were successfully delivered to a targeted area of the brain, and they enabled contrast-enhanced US/PA imaging through the skull. Ex vivo imaging, and immunohistochemistry confirmed the accuracy and precision of the approach.

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.

Unraveling the Role of the Blood-Brain Barrier in the Pathophysiology of Depression: Recent Advances and Future Perspectives

Depression is a highly prevalent psychological disorder characterized by persistent dysphoria, psychomotor retardation, insomnia, anhedonia, suicidal ideation, and a remarkable decrease in overall well-being. Despite the prevalence of accessible antidepressant therapies, many individuals do not achieve substantial improvement. Understanding the multifactorial pathophysiology and the heterogeneous nature of the disorder could lead the way toward better outcomes. Recent findings have elucidated the substantial impact of compromised blood-brain barrier (BBB) integrity on the manifestation of depression. BBB functions as an indispensable defense mechanism, tightly overseeing the transport of molecules from the periphery to preserve the integrity of the brain parenchyma. The dysfunction of the BBB has been implicated in a multitude of neurological disorders, and its disruption and consequent brain alterations could potentially serve as important factors in the pathogenesis and progression of depression. In this review, we extensively examine the pathophysiological relevance of the BBB and delve into the specific modifications of its components that underlie the complexities of depression. A particular focus has been placed on examining the effects of peripheral inflammation on the BBB in depression and elucidating the intricate interactions between the gut, BBB, and brain. Furthermore, this review encompasses significant updates on the assessment of BBB integrity and permeability, providing a comprehensive overview of the topic. Finally, we outline the therapeutic relevance and strategies based on BBB in depression, including COVID-19-associated BBB disruption and neuropsychiatric implications. Understanding the comprehensive pathogenic cascade of depression is crucial for shaping the trajectory of future research endeavors.

O-Glycome Profiling of Breast Cancer Cell Lines to Understand Breast Cancer Brain Metastasis

Breast cancer is the second leading cause of cancer-related death among women and a major source of brain metastases. Despite the increasing incidence of brain metastasis from breast cancer, the underlying mechanisms remain poorly understood. Altered glycosylation is known to play a role in various diseases including cancer metastasis. However, profiling studies of O-glycans and their isomers in breast cancer brain metastasis (BCBM) are scarce. This study analyzed the expression of O-glycans and their isomers in human breast cancer cell lines (MDA-MB-231, MDA-MB-361, HTB131, and HTB22), a brain cancer cell line (CRL-1620), and a brain metastatic breast cancer cell line (MDA-MB-231BR) using nanoLC-MS/MS, identifying 27 O-glycan compositions. We observed significant upregulation in the expression of HexNAc1Hex1NeuAc2 and HexNAc2Hex3, whereas the expression of HexNAc1Hex1NeuAc1 was downregulated in MDA-MB-231BR compared to other cell lines. In our isomeric analysis, we observed notable alterations in the isomeric forms of the O-glycan structure HexNAc1Hex1NeuAc1 in a comparison of different cell lines. Our analysis of O-glycans and their isomers in cancer cells demonstrated that changes in their distribution can be related to the metastatic process. We believe that our investigation will contribute to an enhanced comprehension of the significance of O-glycans and their isomers in BCBM.

In Vitro Blood-Brain Barrier Models for Neuroinfectious Diseases: A Narrative Review

The blood-brain barrier (BBB) is a complex, dynamic, and adaptable barrier between the peripheral blood system and the central nervous system. While this barrier protects the brain and spinal cord from inflammation and infection, it prevents most drugs from reaching the brain tissue. With the expanding interest in the pathophysiology of BBB, the development of in vitro BBB models has dramatically evolved. However, due to the lack of a standard model, a range of experimental protocols, BBB-phenotype markers, and permeability flux markers was utilized to construct in vitro BBB models. Several neuroinfectious diseases are associated with BBB dysfunction. To conduct neuroinfectious disease research effectively, there stems a need to design representative in vitro human BBB models that mimic the BBB's functional and molecular properties. The highest necessity is for an in vitro standardised BBB model that accurately represents all the complexities of an intact brain barrier. Thus, this in-depth review aims to describe the optimization and validation parameters for building BBB models and to discuss previous research on neuroinfectious diseases that have utilized in vitro BBB models. The findings in this review may serve as a basis for more efficient optimisation, validation, and maintenance of a structurally- and functionally intact BBB model, particularly for future studies on neuroinfectious diseases.

Cerebrospinal fluid solute transport associated with sensorimotor brain activity in rodents

Cerebrospinal fluid (CSF) is crucial for maintaining neuronal homeostasis, providing nutrition, and removing metabolic waste from the brain. However, the relationship between neuronal activity and CSF solute transport remains poorly understood. To investigate the effect of regional neuronal activity on CSF solute transport, Sprague-Dawley rats (all male, n = 30) under anesthesia received an intracisternal injection of a fluorescent tracer (Texas Red ovalbumin) and were subjected to unilateral electrical stimulation of a forelimb. Two groups (n = 10 each) underwent two different types of stimulation protocols for 90 min, one including intermittent 7.5-s resting periods and the other without rest. The control group was not stimulated. Compared to the control, the stimulation without resting periods led to increased transport across most of the cortical areas, including the ventricles. The group that received intermittent stimulation showed an elevated level of solute uptake in limited areas, i.e., near/within the ventricles and on the ventral brain surface. Interhemispheric differences in CSF solute transport were also found in the cortical regions that overlap with the forelimb sensorimotor area. These findings suggest that neuronal activity may trigger local and brain-wide increases in CSF solute transport, contributing to waste clearance.

Cell-Penetrating and Targeted Peptides Delivery Systems as Potential Pharmaceutical Carriers for Enhanced Delivery across the Blood-Brain Barrier (BBB)

Among the challenges to the 21st-century health care industry, one that demands special mention is the transport of drugs/active pharmaceutical agents across the blood-brain barrier (BBB). The epithelial-like tight junctions within the brain capillary endothelium hinder the uptake of most pharmaceutical agents. With an aim to understand more deeply the intricacies of cell-penetrating and targeted peptides as a powerful tool for desirable biological activity, we provide a critical review of both CPP and homing/targeted peptides as intracellular drug delivery agents, especially across the blood-brain barrier (BBB). Two main peptides have been discussed to understand intracellular drug delivery; first is the cell-penetrating peptides (CPPs) for the targeted delivery of compounds of interest (primarily peptides and nucleic acids) and second is the family of homing peptides, which specifically targets cells/tissues based on their overexpression of tumour-specific markers and are thus at the heart of cancer research. These small, amphipathic molecules demonstrate specific physical and chemical modifications aimed at increased ease of cellular internalisation. Because only a limited number of drug molecules can bypass the blood-brain barrier by free diffusion, it is essential to explore all aspects of CPPs that can be exploited for crossing this barrier. Considering siRNAs that can be designed against any target RNA, marking such molecules with high therapeutic potential, we present a synopsis of the studies on synthetic siRNA-based therapeutics using CPPs and homing peptides drugs that can emerge as potential drug-delivery systems as an upcoming requirement in the world of pharma- and nutraceuticals.

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.

Experimental Models to Study the Functions of the Blood-Brain Barrier

The purpose of this paper was to discuss the achievements of in vitro modeling in terms of the blood-brain barrier [BBB] and to create a clear overview of this research area, which is useful in research planning. The text was divided into three main parts. The first part describes the BBB as a functional structure, its constitution, cellular and noncellular components, mechanisms of functioning and importance for the central nervous system, in terms of both protection and nourishment. The second part is an overview of parameters important in terms of establishing and maintaining a barrier phenotype that allows for formulating criteria of evaluation of the BBB in vitro models. The third and last part discusses certain techniques for developing the BBB in vitro models. It describes subsequent research approaches and models, as they underwent change alongside technological advancement. On the one hand, we discuss possibilities and limitations of different research approaches: primary cultures vs. cell lines and monocultures vs. multicultures. On the other hand, we review advantages and disadvantages of specific models, such as models-on-a-chip, 3D models or microfluidic models. We not only attempt to state the usefulness of specific models in different kinds of research on the BBB but also emphasize the significance of this area of research for advancement of neuroscience and the pharmaceutical industry.

Cdh5-mediated Fpn1 deletion exerts neuroprotective effects during the acute phase and inhibitory effects during the recovery phase of ischemic stroke

Ischemic stroke is associated with high mortality and morbidity rates worldwide. However, the molecular mechanisms underlying the neuronal damage incurred by stroke victims remain unclear. It has previously been reported that ischemic stroke can induce an increase in the levels of brain iron, which is an important factor of in the associated brain damage. Ferroportin 1 (FPN1), the only known cellular iron export protein, is found in brain microvascular endothelial cells (BMVECs) at the blood-brain barrier, and is considered the gateway for entry of plasma iron into the central nervous system. Despite the connection of brain iron to neuronal damage, the role of BMVECs FPN1 in ischemic stroke remains unexplored. Herein, we conditionally deleted Fpn1 in mouse endothelial cells (ECs), using VE-cadherin-Cre transgenic mice, and explored the impact on brain iron homeostasis after stroke. Our data demonstrated that Fpn1 knockout in ECs decreased the brain iron levels in mice, attenuated the oxidative stress and inflammatory responses after stroke, and inhibited both ferroptosis and apoptosis, ultimately alleviating neurological impairment and decreasing cerebral infarct volume during the acute phase of ischemic stroke. By contrast, we found that Fpn1 knockout in ECs delayed the recovery of neurological function in mice following ischemic stroke. We also found that ECs Fpn1 knockout decreased the brain iron levels after stroke, exacerbated glial cell proliferation, and inhibited neuronal development, indicating that the diminished brain iron levels hindered the repair of neural injury in mice. In conclusion, our findings reveal a dual consequence of FPN1 deficiency in ECs in the development of ischemic stroke. More specifically, iron deficiency initially exerts a neuroprotective effect during the acute phase of ischemic stroke but inhibits recovery during the later stages. Our findings are important to the development of iron- or FPN1-targeting therapeutics for the treatment of ischemic stroke.

Advances in BBB on Chip and Application for Studying Reversible Opening of Blood-Brain Barrier by Sonoporation

The complex structure of the blood-brain barrier (BBB), which blocks nearly all large biomolecules, hinders drug delivery to the brain and drug assessment, thus decelerating drug development. Conventional in vitro models of BBB cannot mimic some crucial features of BBB in vivo including a shear stress environment and the interaction between different types of cells. There is a great demand for a new in vitro platform of BBB that can be used for drug delivery studies. Compared with in vivo models, an in vitro platform has the merits of low cost, shorter test period, and simplicity of operation. Microfluidic technology and microfabrication are good tools in rebuilding the BBB in vitro. During the past decade, great efforts have been made to improve BBB penetration for drug delivery using biochemical or physical stimuli. In particular, compared with other drug delivery strategies, sonoporation is more attractive due to its minimized systemic exposure, high efficiency, controllability, and reversible manner. BBB on chips (BOC) holds great promise when combined with sonoporation. More details and mechanisms such as trans-endothelial electrical resistance (TEER) measurements and dynamic opening of tight junctions can be figured out when using sonoporation stimulating BOC, which will be of great benefit for drug development. Herein, we discuss the recent advances in BOC and sonoporation for BBB disruption with this in vitro platform.

The Blood-Brain Barrier and Pharmacokinetic/Pharmacodynamic Optimization of Antibiotics for the Treatment of Central Nervous System Infections in Adults

Bacterial central nervous system (CNS) infections are serious and carry significant morbidity and mortality. They encompass many syndromes, the most common being meningitis, which may occur spontaneously or as a consequence of neurosurgical procedures. Many classes of antimicrobials are in clinical use for therapy of CNS infections, some with established roles and indications, others with experimental reporting based on case studies or small series. This review delves into the specifics of the commonly utilized antibacterial agents, updating their therapeutic use in CNS infections from the pharmacokinetic and pharmacodynamic perspectives, with a focus on the optimization of dosing and route of administration that have been described to achieve good clinical outcomes. We also provide a concise synopsis regarding the most focused, clinically relevant information as pertains to each class and subclass of antimicrobial therapeutics. CNS infection morbidity and mortality remain high, and aggressive management is critical in ensuring favorable patient outcomes while averting toxicity and upholding patient safety.

Crotalphine Modulates Microglia M1/M2 Phenotypes and Induces Spinal Analgesia Mediated by Opioid-Cannabinoid Systems

Pain is a worldwide public health problem and its treatment is still a challenge since clinically available drugs do not completely reverse chronic painful states or induce undesirable effects. Crotalphine is a 14 amino acids synthetic peptide that induces a potent and long-lasting analgesic effect on acute and chronic pain models, peripherally mediated by the endogenous release of dynorphin A and the desensitization of the transient receptor potential ankyrin 1 (TRPA1) receptor. However, the effects of crotalphine on the central nervous system (CNS) and the signaling pathway have not been investigated. Thus, the central effect of crotalphine was evaluated on the partial sciatic nerve ligation (PSNL)-induced chronic neuropathic pain model. Crotalphine (100 µg/kg, p.o.)-induced analgesia on the 14th day after surgery lasting up to 24 h after administration. This effect was prevented by intrathecal administration of CB1 (AM251) or CB2 (AM630) cannabinoid receptor antagonists. Besides that, crotalphine-induced analgesia was reversed by CTOP, nor-BNI, and naltrindole, antagonists of mu, kappa, and delta-opioid receptors, respectively, and also by the specific antibodies for β-endorphin, dynorphin-A, and met-enkephalin. Likewise, the analgesic effect of crotalphine was blocked by the intrathecal administration of minocycline, an inhibitor of microglial activation and proliferation. Additionally, crotalphine decreased the PSNL-induced IL-6 release in the spinal cord. Importantly, in vitro, crotalphine inhibited LPS-induced CD86 expression and upregulated CD206 expression in BV-2 cells, demonstrating a polarization of microglial cells towards the M2 phenotype. These results demonstrated that crotalphine, besides activating opioid and cannabinoid analgesic systems, impairs central neuroinflammation, confirming the neuromodulatory mechanism involved in the crotalphine analgesic effect.

Enhancement of cerebrospinal fluid tracer movement by the application of pulsed transcranial focused ultrasound

Efficient transport of solutes in the cerebrospinal fluid (CSF) plays a critical role in their clearance from the brain. Convective bulk flow of solutes in the CSF in the perivascular space (PVS) is considered one of the important mechanisms behind solute movement in the brain, before their ultimate drainage to the systemic lymphatic system. Acoustic pressure waves can impose radiation force on a medium in its path, inducing localized and directional fluidic flow, known as acoustic streaming. We transcranially applied low-intensity focused ultrasound (FUS) to rats that received an intracisternal injection of fluorescent CSF tracers (dextran and ovalbumin, having two different molecular weights-Mw). The sonication pulsing parameter was determined on the set that propelled the aqueous solution of toluidine blue O dye into a porous media (melamine foam) at the highest level of infiltration. Fluorescence imaging of the brain showed that application of FUS increased the uptake of ovalbumin at the sonicated plane, particularly around the ventricles, whereas the uptake of high-Mw dextran was unaffected. Numerical simulation showed that the effects of sonication were non-thermal. Sonication did not alter the animals' behavior or disrupt the blood-brain barrier (BBB) while yielding normal brain histology. The results suggest that FUS may serve as a new non-invasive means to promote interstitial CSF solute transport in a region-specific manner without disrupting the BBB, providing potential for enhanced clearance of waste products from the brain.

Involvement of Resveratrol against Brain Cancer: A Combination Strategy with a Pharmaceutical Approach

A brain tumor (BT) is a condition in which there is growth or uncontrolled development of the brain cells, which usually goes unrecognized or is diagnosed at the later stages. Since the mechanism behind BT is not clear, and the various physiological conditions are difficult to diagnose, the success rate of BT is not very high. This is the central issue faced during drug development and clinical trials with almost all types of neurodegenerative disorders. In the first part of this review, we focus on the concept of brain tumors, their barriers, and the types of delivery possible to target the brain cells. Although various treatment methods are available, they all have side effects or toxic effects. Hence, in the second part, a correlation was made between the use of resveratrol, a potent antioxidant, and its advantages for brain diseases. The relationship between brain disease and the blood-brain barrier, multi-drug resistance, and the use of nanomedicine for treating brain disorders is also mentioned. In short, a hypothetical concept is given with a background investigation into the use of combination therapy with resveratrol as an active ingredient, the possible drug delivery, and its formulation-based approach.

Noninvasive ultrasonic induction of cerebrospinal fluid flow enhances intrathecal drug delivery

Intrathecal drug delivery is routinely used in the treatment and prophylaxis of varied central nervous system conditions, as doing so allows drugs to directly bypass the blood-brain barrier. However, the utility of this route of administration is limited by poor brain and spinal cord parenchymal drug uptake from the cerebrospinal fluid. We demonstrate that a simple noninvasive transcranial ultrasound protocol can significantly increase influx of cerebrospinal fluid into the perivascular spaces of the brain, to enhance the uptake of intrathecally administered drugs. Specifically, we administered small (~1 kDa) and large (~155 kDa) molecule agents into the cisterna magna of rats and then applied low, diagnostic-intensity focused ultrasound in a scanning protocol throughout the brain. Using real-time magnetic resonance imaging and ex vivo histologic analyses, we observed significantly increased uptake of small molecule agents into the brain parenchyma, and of both small and large molecule agents into the perivascular space from the cerebrospinal fluid. Notably, there was no evidence of brain parenchymal damage following this intervention. The low intensity and noninvasive approach of transcranial ultrasound in this protocol underscores the ready path to clinical translation of this technique. In this manner, this protocol can be used to directly bypass the blood-brain barrier for whole-brain delivery of a variety of agents. Additionally, this technique can potentially be used as a means to probe the causal role of the glymphatic system in the variety of disease and physiologic processes to which it has been correlated.

High-Frequency Irreversible Electroporation (H-FIRE) Induced Blood-Brain Barrier Disruption Is Mediated by Cytoskeletal Remodeling and Changes in Tight Junction Protein Regulation

Glioblastoma is the deadliest malignant brain tumor. Its location behind the blood-brain barrier (BBB) presents a therapeutic challenge by preventing effective delivery of most chemotherapeutics. H-FIRE is a novel tumor ablation method that transiently disrupts the BBB through currently unknown mechanisms. We hypothesized that H-FIRE mediated BBB disruption (BBBD) occurs via cytoskeletal remodeling and alterations in tight junction (TJ) protein regulation. Intracranial H-FIRE was delivered to Fischer rats prior to sacrifice at 1-, 24-, 48-, 72-, and 96 h post-treatment. Cytoskeletal proteins and native and ubiquitinated TJ proteins (TJP) were evaluated using immunoprecipitation, Western blotting, and gene-expression arrays on treated and sham control brain lysates. Cytoskeletal and TJ protein expression were further evaluated with immunofluorescent microscopy. A decrease in the F/G-actin ratio, decreased TJP concentrations, and increased ubiquitination of TJP were observed 1-48 h post-H-FIRE compared to sham controls. By 72-96 h, cytoskeletal and TJP expression recovered to pretreatment levels, temporally corresponding with increased claudin-5 and zonula occludens-1 gene expression. Ingenuity pathway analysis revealed significant dysregulation of claudin genes, centered around claudin-6 in H-FIRE treated rats. In conclusion, H-FIRE is capable of permeating the BBB in a spatiotemporal manner via cytoskeletal-mediated TJP modulation. This minimally invasive technology presents with applications for localized and long-lived enhanced intracranial drug delivery.

Basic considerations on magnesium in the management of neurocritical patients

Magnesium is an essential chemical element in human life. In the brain, it is physiologically responsible for a large number of processes involved in intracellular homeostasis, blood-brain barrier integrity, protein synthesis, neuronal proliferation, aging, and apoptosis. Considering that neurocritical care is a relatively new discipline in certain regions of the world and is an independent protective factor of neurological diseases in critical care, it is essential to disseminate basic concepts and utilities of tools that can positively impact the neurological disease burden. Magnesium and its use in neurocritical care are poorly understood. Therefore, this study aimed to review basic concepts regarding the physiology of magnesium in neurological dynamics, its role in the pathophysiology of neurological disorders, and the outcome of its use in the management of neurocritical illnesses.

Successful Application of Alpha Lipoic Acid Niosomal Formulation in Cerebral Ischemic Reperfusion Injury in Rat Model

Purpose: Free radicals such as hydroxyl and peroxide are contributing factors to neuronal destruction in cerebral ischemia. Alpha-lipoic acid (ALA) is one of the potent known antioxidants. Preparation of ALA niosomes allows IV injection and can increase bioavailability and penetration into the central nervous system (CNS).

Methods: Film hydration method was used to prepare different niosomes composed of Span®, Tween®, and cholesterol at different molar ratio. ALA and niosome-forming compounds were dissolved in chloroform, before removing the organic solvent by rotary evaporator. Animals were randomly divided into four groups: Sham, control group, intravenous (IV) injection of empty niosomes plus intraperitoneal (IP) injection of ALA solution, and finally, IV injection of ALA niosomes. Rats were subjected to deep anesthesia before inducing cerebral ischemia, then, their internal common carotid arteries were clamped for 15 min and reperfusion was done for 30 min. Niosomal ALA was injected intravenously just before declamping.

Results: Mean volume diameter of the prepared niosomes was between 4.36 ± 0.82 and 19.95 ± 1.21 μm in different formulations. Encapsulation efficiency percent (EE%) of ALA in the selected formulation, Span60/Tween60/cholesterol (35:35:30 molar ratio), was 94.5 ± 0.2, and 59.27 ± 5.61% of ALA was released after 4h. In the niosomal group, the rate of reduction in complications of cerebral ischemia such as histopathologic changes and acute damage (from score 3 to 1) in CNS was higher than other groups.

Conclusion: The obtained results show that niosomes can be used as effective drug delivery systems for ALA in cerebral ischemia.

Emerging Therapeutic Strategies for Brain Tumors

Nearly thirty thousand incidences of primary and 300 thousand incidences of metastatic brain cancer are diagnosed in the USA each year. It has a high mortality rate and is often unresponsive to the standard of care, which includes surgical resection, radiation, and chemotherapy. These treatment strategies are also hindered by their invasiveness and toxic effects on healthy cells and tissues. Furthermore, the blood-brain/tumor barrier severely limits delivery of anti-cancer therapeutics administered intravenously to brain tumors, resulting in poor tumor response to the treatment. There is a critical need to develop new approaches to brain cancer therapy that can overcome these limitations. Focused ultrasound has emerged as a modality that addresses many of these limitations and has the potential to alter the treatment paradigm for brain cancer. Ultrasound transmitted through the skull can be focused on tumors and used for targeted ablation or opening the vascular barriers for drug delivery. This review provides insight on the current status of these unique ultrasound techniques, different strategies of using this technique for brain cancer, experience in preclinical models, and potential for clinical translation. We also debate the safety perspective of these techniques and discuss potential avenues for future work in noninvasive planning, monitoring, and evaluation of the ultrasonic neurointervention.

Role of microRNAs in glioblastoma

Glioblastoma is the most common and aggressive primary human brain cancer. MicroRNAs (miRNAs) are a set of small endogenous non-coding RNA molecules which play critical roles in different biological processes including cancer. The realization of miRNA regulatory functions in GBM has demonstrated that these molecules play a critical role in its initiation, progression and response to therapy. In this review we discuss the studies related to miRNA discovery and function in glioblastoma. We first summarize the typical miRNAs and their roles in GBM. Then we debate the potential for miRNA-based therapy for glioblastoma, including various delivery strategies. We surmise that future directions identified by these studies will point towards the necessity for therapeutic development and optimization to improve the outcomes for patients with glioblastoma.

Chemical tools for epichaperome-mediated interactome dysfunctions of the central nervous system

Diseases are a manifestation of how thousands of proteins interact. In several diseases, such as cancer and Alzheimer’s disease, proteome-wide disturbances in protein-protein interactions are caused by alterations to chaperome scaffolds termed epichaperomes. Epichaperome-directed chemical probes may be useful for detecting and reversing defective chaperomes. Here we provide structural, biochemical, and functional insights into the discovery of epichaperome probes, with a focus on their use in central nervous system diseases. We demonstrate on-target activity and kinetic selectivity of a radiolabeled epichaperome probe in both cells and mice, together with a proof-of-principle in human patients in an exploratory single group assignment diagnostic study (ClinicalTrials.gov Identifier: NCT03371420). The clinical study is designed to determine the pharmacokinetic parameters and the incidence of adverse events in patients receiving a single microdose of the radiolabeled probe administered by intravenous injection. In sum, we introduce a discovery platform for brain-directed chemical probes that specifically modulate epichaperomes and provide proof-of-principle applications in their use in the detection, quantification, and modulation of the target in complex biological systems.

Here, the authors show structural, biochemical, and functional insights into the discovery of epichaperome‐ directed chemical probes for use in central nervous system diseases. Probes emerging from this work have translated to human clinical studies in Alzheimer’s disease and cancer.

Equivalent time active cavitation imaging

RATIONALE

Despite the development of a large number of neurologically active drugs, brain diseases are difficult to treat due to the inability of many drugs to penetrate the blood-brain barrier. High-intensity focused ultrasound blood-brain barrier opening in a site-specific manner could significantly expand the spectrum of available drug treatments. However, without monitoring, brain damage and off target effects can occur during these treatments. While some methods can monitor inertial cavitation, temperature increase, or passively monitor cavitation events, to the best of our knowledge none of them can actively and spatiotemporally map the high intensity focused ultrasound pressure field during treatment.

METHODS

Here we detail the development of a novel ultrasound imaging modality called Equivalent Time Active Cavitation Imaging capable of characterizing the high-intensity focused ultrasound pressure field through stable cavitation events across the field of view with an ultrafast active imaging setup. This work introduces 1) a novel plane wave sequence whose transmit delays increase linearly with transmit events enabling the sampling of high-frequency cavitation events, and 2) an algorithm allowing the filtration of the microbubble signal for pressure field mapping. The pressure measurements with our modality were first carried out in vitro for hydrophone comparison and then in vivo during blood-brain barrier opening treatment in mice.

RESULTS

This study demonstrates the ability of our modality to spatiotemporally characterize a modulation pressure field with an active imaging setup. The resulting pressure field mapping reveals a good correlation with hydrophone measurements. Further proof is provided experimentally in vivo with promising results.

CONCLUSION

This proof of concept establishes the first steps towards a novel ultrasound modality for monitoring focused ultrasound blood-brain barrier opening, allowing new possibilities for a safe and precise monitoring method.

Photoacoustic Neuroimaging - Perspectives on a Maturing Imaging Technique and its Applications in Neuroscience

A prominent goal of neuroscience is to improve our understanding of how brain structure and activity interact to produce perception, emotion, behavior, and cognition. The brain's network activity is inherently organized in distinct spatiotemporal patterns that span scales from nanometer-sized synapses to meter-long nerve fibers and millisecond intervals between electrical signals to decades of memory storage. There is currently no single imaging method that alone can provide all the relevant information, but intelligent combinations of complementary techniques can be effective. Here, we thus present the latest advances in biomedical and biological engineering on photoacoustic neuroimaging in the context of complementary imaging techniques. A particular focus is placed on recent advances in whole-brain photoacoustic imaging in rodent models and its influential role in bridging the gap between fluorescence microscopy and more non-invasive techniques such as magnetic resonance imaging (MRI). We consider current strategies to address persistent challenges, particularly in developing molecular contrast agents, and conclude with an overview of potential future directions for photoacoustic neuroimaging to provide deeper insights into healthy and pathological brain processes.

Harnessing the immune system for the treatment of Parkinson's disease

Current treatment options for Parkinson's disease (PD) typically aim to replace dopamine, and hence only provide symptomatic relief. However, in the long run, this approach alone loses its efficacy as it is associated with debilitating side effects. Hence there is an unmet clinical need for addressing levodopa resistant symptoms, and an urgency to develop therapies that can halt or prevent the course of PD. The premise that α-syn can transmit from cell-to-cell in a prion like manner has opened up the possibility for the use of immunotherapy in PD. There is evidence for inflammation in PD as is evidenced by microglial activation, as well as the involvement of the peripheral immune system in PD, and peripheral inflammation can exacerbate dopaminergic degeneration as seen in animal models of the disease. However, mechanisms that link the immune system with PD are not clear, and the sequence of immune responses with respect to PD are still unknown. Nevertheless, our present knowledge offers avenues for the development of immune-based therapies for PD. In order to successfully employ such strategies, we must comprehend the state of the peripheral immune system during the course of PD. This review describes the developments in the field of both active and passive immunotherapies in the treatment of PD, and highlights the crucial need for future research for clarifying the role of inflammation and immunity in this debilitating disease.

Emerging applications at the interface of DNA nanotechnology and cellular membranes: Perspectives from biology, engineering, and physics

DNA nanotechnology has proven exceptionally apt at probing and manipulating biological environments as it can create nanostructures of almost arbitrary shape that permit countless types of modifications, all while being inherently biocompatible. Emergent areas of particular interest are applications involving cellular membranes, but to fully explore the range of possibilities requires interdisciplinary knowledge of DNA nanotechnology, cell and membrane biology, and biophysics. In this review, we aim for a concise introduction to the intersection of these three fields. After briefly revisiting DNA nanotechnology, as well as the biological and mechanical properties of lipid bilayers and cellular membranes, we summarize strategies to mediate interactions between membranes and DNA nanostructures, with a focus on programmed delivery onto, into, and through lipid membranes. We also highlight emerging applications, including membrane sculpting, multicell self-assembly, spatial arrangement and organization of ligands and proteins, biomechanical sensing, synthetic DNA nanopores, biological imaging, and biomelecular sensing. Many critical but exciting challenges lie ahead, and we outline what strikes us as promising directions when translating DNA nanostructures for future in vitro and in vivo membrane applications.

The New Frontiers in Neurodegenerative Diseases Treatment: Liposomal-Based Strategies

In the last decade, the onset of neurodegenerative (ND) diseases is strongly widespread due to the age increase of the world population. Despite the intensive investigations boosted by the scientific community, an efficacious therapy has not been outlined yet. The drugs commonly used are only able to relieve symptom severity; following their oral or intravenous administration routes, their effectiveness is strictly limited due to their low ability to reach the Central Nervous System (CNS) overcoming the Blood Brain Barrier (BBB). Starting from these assumptions, the engineered-nanocarriers, such as lipid-nanocarriers, are suitable agents to enhance the delivery of drugs into the CNS due to their high solubility, bioavailability, and stability. Liposomal delivery systems are considered to be the ideal carriers, not only for conventional drugs but also for neuroprotective small molecules and green-extracted compounds. In the current work, the LP-based drug delivery improvements in in vivo applications against ND disorders were carefully assessed.

A local difference in blood-brain barrier permeability in the caudate putamen and thalamus of a rat brain induced by focused ultrasound

A blood–brain barrier (BBB) opening induced by focused ultrasound (FUS) has been widely studied as an effective way of treating brain diseases. We investigate the effect of ultrasound’s incidence angle at caudate putamen (Cp) and thalamus (Th) of the rat brain by inducing the same power of focused ultrasound that corresponds to the acoustic pressure of 0.65 MPa in free field. The BBB permeability (K_trans) was quantitatively evaluated with dynamic contrast-enhanced magnetic resonance imaging. The group averaged (n = 11) maximum K_trans at Cp (0.021 ± 0.012 min⁻¹) was 1.39 times smaller than the K_trans of Th (0.029 ± 0.01 min⁻¹) with p = 0.00343. The group averaged (n = 6) ultrasound’s incidence angles measured using the computed tomography image of rat skulls were compared with the maximum K_trans and showed a negatively linear relation R² = 0.7972). The maximum acoustic pressure computed from the acoustic simulation showed higher average acoustic pressures at Th (0.37 ± 0.02 MPa) compared to pressures at Cp (0.32 ± 0.01 MPa) with p = 0.138 × 10⁻¹¹. More red blood cell were observed at the Th region compared to the Cp region in the tissue staining. These results indicate that localized characteristics of the sonication target within the subject should be considered for safer and more efficient BBB disruption induced by FUS.

Heparan sulfate proteoglycan-mediated dynamin-dependent transport of neural stem cell exosomes in an in vitro blood-brain barrier model

Drug delivery to the brain is greatly hampered by the presence of the blood–brain barrier (BBB) which tightly regulates the passage of molecules from blood to brain and vice versa. Nanocarriers, in which drugs can be encapsulated, can move across the blood–brain barrier (BBB) via the process of transcytosis, thus showing promise to improve drug delivery to the brain. Here, we demonstrate the use of natural nanovesicles, that is, exosomes, derived from C17.2 neural stem cells (NSCs) to efficiently carry a protein cargo across an in vitro BBB model consisting of human brain microvascular endothelial cells. We show that the exosomes are primarily taken up in brain endothelial cells via endocytosis, while heparan sulfate proteoglycans (HSPGs) act as receptors. Taken together, our data support the view that NSC exosomes may act as biological nanocarriers for efficient passage across the BBB. Nanomedicines that target HSPGs may improve their binding to brain endothelial cells and, possibly, show subsequent transcytosis across the BBB.

Therapeutic Potentials of Localized Blood-Brain Barrier Disruption by Noninvasive Transcranial Focused Ultrasound: A Technical Review

The demands for region-specific, noninvasive therapies for neurologic/psychiatric conditions are growing. The rise of transcranial focused ultrasound technology has witnessed temporary and reversible disruptions of the blood-brain barrier in the brain with exceptional control over the spatial precisions and depth, all in a noninvasive manner. Starting with small animal studies about a decade ago, the technique is now being explored in nonhuman primates and humans for the assessment of its efficacy and safety. The ability to transfer exogenous/endogenous therapeutic agents, cells, and biomolecules across the blood-brain barrier opens up new therapeutic avenues for various neurologic conditions, with a possibility to modulate the excitability of regional brain function. This review addresses the technical fundamentals, sonication parameters, experimental protocols, and monitoring techniques to examine the efficacy/safety in focused ultrasound-mediated blood-brain barrier disruption and discuss its potential translations to clinical use.

Mesenchymal stem cell therapy for the treatment of traumatic brain injury: progress and prospects

Traumatic brain injury (TBI) is a major cause of injury-related mortality and morbidity in the USA and around the world. The survivors may suffer from cognitive and memory deficits, vision and hearing loss, movement disorders, and different psychological problems. The primary insult causes neuronal damage and activates astrocytes and microglia which evokes immune responses causing further damage to the brain. Clinical trials of drugs to recover the neuronal loss are not very successful. Regenerative approaches for TBI using mesenchymal stem cells (MSCs) seem promising. Results of preclinical research have shown that transplantation of MSCs reduced secondary neurodegeneration and neuroinflammation, promoted neurogenesis and angiogenesis, and improved functional outcome in the experimental animals. The functional improvement is not necessarily related to cell engraftment; rather, immunomodulation by molecular factors secreted by MSCs is responsible for the beneficial effects of this therapy. However, MSC therapy has a few drawbacks including tumor formation, which can be avoided by the use of MSC-derived exosomes. This review has focused on the research works published in the field of regenerative therapy using MSCs after TBI and its future direction.

Development and in vivo evaluation of Irinotecan-loaded Drug Eluting Seeds (iDES) for the localised treatment of recurrent glioblastoma multiforme

Glioblastoma multiforme (GBM) is impossible to fully remove surgically and almost always recurs at the borders of the resection cavity, while systemic delivery of therapeutic drug levels to the brain tumour is limited by the blood-brain barrier. This research describes the development of a novel formulation of Irinotecan-loaded Drug Eluting Seeds (iDES) for insertion into the margin of the GBM resection cavity to provide a sustained high local dose with reduced systemic toxicities. We used primary GBM cells from both the tumour core and Brain Around the Tumour tissue from recurrent GBM patients to demonstrate that irinotecan is more effective than temozolomide. Irinotecan had a 75% response rate, while only 50% responded to temozolomide. With temozolomide the cell viability was never below 80% whereas irinotecan achieved cell viabilities of less than 44%. The iDES were manufactured using a hot melt extrusion process with accurate irinotecan drug loadings and the same cytotoxicity as unformulated irinotecan. The iDES released irinotecan in a sustained fashion for up to 7 days. However, only the 30, 40 and 50% w/w loaded iDES formulations released the 300 to 1000 μg of irinotecan needed to be effective in vivo. The 30 and 40% w/w iDES formulations containing 10% plasticizer and either 60 or 50% PLGA prolonged survival from 27 to 70 days in a GBM xenograft mouse resection model with no sign of tumour recurrence. The 30% w/w iDES formulations showed equivalent toxicity to a placebo in non-tumour bearing mice. This innovative drug delivery approach could transform the treatment of recurrent GBM patients by improving survival and reducing toxicity.

Glutathione in Brain: Overview of Its Conformations, Functions, Biochemical Characteristics, Quantitation and Potential Therapeutic Role in Brain Disorders

Glutathione (GSH) is an important antioxidant found abundantly and synthesized intracellularly in the cytosol in a tightly regulated fashion. It has diverse physiological functions, including protection against reactive oxygen species and nitrogen species, antioxidant defense as well as maintenance of cellular thiol status. The human brain due to the high oxygen consumption is extremely susceptible to the generation of reactive oxygen species. GSH plays a paramount role in brain antioxidant defense, maintaining redox homeostasis. The depletion of brain GSH has also been observed from both autopsies as well as in vivo MRS studies with aging and varied neurological disorders (Alzheimer's disease, Parkinson's disease, etc.). Therefore, GSH enrichment using supplementation is a promising avenue in the therapeutic development for these neurological disorders. This review will enrich the information on the importance of GSH synthesis, metabolism, functions, compartmentation and inter-organ transport, structural conformations and its quantitation via different techniques. The transportation of GSH in the brain via different interventional routes and its potential role in the development of therapeutic strategies for various brain disorders is also addressed. Very recent study found significant improvement of behavioral deficits including cognitive decline, depressive-like behaviors, in APP (NL-G-F/NL-G-FG-) mice due to oral GSH administration. This animal model study put an emergent need to complete GSH supplementation trial in MCI and AD patients for cognitive improvement as proposed earlier.

Modulation of Th17 Proliferation and IL-17A Gene Expression by Acetylated Form of Apigenin in Patients with Multiple Sclerosis

The presence of Th17 cells in CNS lesion of MS patients due to their inflammatory cytokines secretion is in line with the deterioration of the disease. Currently, the use of natural compounds with anti-inflammatory properties such as flavonoids have been considered to reduce inflammation in these patients, but the remaining issue is how deliver these compounds to the site of inflammation. Acetylation is a way to better uptake compound by cells and cross through cellular layers with tight junctions. This study aimed to investigate the in vitro effects of the Apigenin 3-Acetate on Th17 cells of MS patients and compare its efficacy with Apigenin and Methyl Prednisolone Acetate. IC50 for Apigenin 3-Acetate, and Methyl Prednisolone Acetate were determined using three healthy volunteers. The peripheral blood mononuclear cells (PBMCs) of five MS patients were isolated and co-cultured with a selected dose of Apigenin, Apigenin 3-Acetate, and Methyl Prednisolone Acetate for 48 hr, and then theproliferation of Th17 cells in isolated PBMCs was assessed by flow cytometry. The levels of RAR-related orphan receptor (RORC) and IL-17A expression were also determined by quantitative real-time PCR. The results showed that Apigenin 3-Acetate inhibited Th17 cells proliferation (P value: 0.018) at 80 µM concentration after 48 hr. Additionally, IL-17A gene expression significantly (P value≤ 0.0001) inhibited by Apigenin, Apigenin 3-Acetate and Methyl Prednisolone Acetate in 80 µM, 80 µM and 2.5 µM (selected dose in IC50 determination) respectively These results demonstrate that Acetate increases anti-inflammatory effects of Apigenin on Th17 cells.

Improving In Vivo Brain Delivery of Monoclonal Antibody Using Novel Cyclic Peptides

Many proteins can be used to treat brain diseases; however, the presence of the blood–brain barrier (BBB) creates an obstacle to delivering them into the brain. Previously, various molecules were delivered through the paracellular pathway of the BBB via its modulation, using ADTC5 and HAV6 peptides. This study goal was to design new cyclic peptides with N-to-C terminal cyclization for better plasma stability and modulation of the BBB. Cyclic HAVN1 and HAVN2 peptides were derived from a linear HAV6 peptide. Linear and N-to-C terminal cyclic ADTHAV peptides were designed by combining the sequences of ADTC5 and HAV6. These novel cyclic peptides were used to deliver an IRdye800CW-labeled IgG monoclonal antibody into the brain. Cyclic HAVN1 and HAVN2 peptides deliver IgG into the brain, while the parent linear HAV6 peptide does not. Cyclic and linear ADTHAV and ADTC5 peptides enhanced brain delivery of IgG mAb, in which cyclic ADTHAV peptide was better than linear ADTHAV (p = 0.07). Cyclic ADTHAV and ADTC5 influenced the distribution of IgG mAb in other organs while HAV6, HAVN1 and HAVN2 did not. In summary, the novel cyclic peptides are generally better BBB modulators than their linear counterparts for delivering IgG mAb into the brain.

Localized Blood-Brain Barrier Opening in Ovine Model Using Image-Guided Transcranial Focused Ultrasound

Transcranial application of focused ultrasound (FUS) combined with vascular introduction of microbubble contrast agents (MBs) has emerged as a non-invasive technique that can temporarily create a localized opening in the blood-brain barrier (BBB). Under image-guidance, we administered FUS to sheep brain after intravenous injection of microbubbles. BBB opening was confirmed by performing dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to detect the extravasated gadolinium-based magnetic resonance contrast agents. Through pharmacokinetic analysis as well as independent component analysis of the DCE-MRI data, we observed localized enhancement in BBB permeability at the area that subjected to acoustic pressure of 0.48 MPa (mechanical index = 0.96). On the other hand, application of a higher pressure at 0.58 MPa resulted in localized, minor cerebral hemorrhage. No animals exhibited abnormal behavior during the post-FUS survival periods up to 2 mo. Our data suggest that monitoring for excessive BBB disruption is important for safe translation of the method to humans.

The Discovery of RNA Aptamers that Selectively Bind Glioblastoma Stem Cells

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults. Despite progress in surgical and medical neuro-oncology, prognosis for GBM patients remains dismal, with a median survival of only 14–15 months. The modest benefit of conventional therapies is due to the presence of GBM stem cells (GSCs) that cause tumor relapse and chemoresistance and, therefore, that play a key role in GBM aggressiveness and recurrence. So far, strategies to identify and target GSCs have been unsuccessful. Thus, the development of an approach for GSC detection and targeting would be fundamental for improving the survival of GBM patients. Here, using the cell-systematic evolution of ligand by exponential (SELEX) methodology on human primary GSCs, we generated and characterized RNA aptamers that selectively bind GSCs versus undifferentiated GBM cells. We found that the shortened version of the aptamer 40L, which we have called A40s, costained with CD133-labeled cells in human GBM tissue, suggestive of an ability to specifically recognize GSCs in fixed human tissues. Of note, both 40L and A40s were rapidly internalized by cells, allowing for the delivery of the microRNA miR-34c and the anti-microRNA anti-miR-10b, demonstrating that these aptamers can serve as selective vehicles for therapeutics. In conclusion, the aptamers 40L and A40s can selectively target GSCs. Given the crucial role of GSCs in GBM recurrence and therapy resistance, these aptamers represent innovative drug delivery candidates with a great potential in the treatment of GBM.

Influence of Nanobubble Concentration on Blood-Brain Barrier Opening Using Focused Ultrasound Under Real-Time Acoustic Feedback Control

Real-time acoustic feedback control based on harmonic emissions of stimulated microbubbles may serve as a way to achieve reliable blood-brain barrier (BBB) opening with focused ultrasound in the brain. Previously, we demonstrated BBB opening was possible using sub-micron bubbles (aka nanobubbles) and produced comparable results to commercially available microbubbles (Optison, Definity, etc.). The harmonic emissions and acoustic control were observed to be more consistent using nanobubbles, which warrants further study of BBB opening using these agents. This study examined the stimulated acoustic emissions of nanobubbles at different concentrations both in vitro and in vivo and evaluated BBB opening under real-time acoustic feedback control across concentrations. Original nanobubbles (10¹¹ bubbles/mL) have long in vitro persistence (7.3 ± 3.3 min) and circulation time in rats (approximately 10 min) under exposures in this study, and both degraded with dilutions. With all three tested dilutions (1:1, 1:10 and 1:100), successful BBB opening was reliably achieved under real-time feedback control.

Recent expansions of novel strategies towards the drug targeting into the brain

The treatment of central nervous system (CNS) disorders always remains a challenge for the researchers. The presence of various physiological barriers, primarily the blood-brain barrier (BBB) limits the accessibility of the brain and hinders the efficacy of various drug therapies. Hence, drug targeting to the brain, particularly to the diseased cells by circumventing the physiological barriers is essential to develop a promising therapy for the treatment of brain disorders. Presently, the investigations emphasize the role of different nanocarrier systems or surface modified target specific novel carrier system to improve the efficiency and reduce the side effects of the brain therapeutics. Such approaches supposed to circumvent the BBB or have the ability to cross the barrier function and thus increases the drug concentration in the brain. Although the efficacy of novel carrier system depends upon various physiological factors like active efflux transport, protein corona of the brain, stability, and toxicity of the nanocarrier, physicochemical properties, patient-related factors and many more. Hence, to develop a promising carrier system, it is essential to understand the physiology of the brain and BBB and also the other associated factors. Along with this, some alternative route like direct nose-to-brain drug delivery can also offer a better means to access the brain without exposure of the BBB. In this review, we have discussed the role of various physiological barriers including the BBB and blood-cerebrospinal fluid barrier (BCSFB) on the drug therapy and the mechanism of drug transport across the BBB. Further, we discussed different novel strategies for brain targeting of drug including, polymeric nanoparticles, lipidic nanoparticles, inorganic nanoparticles, liposomes, nanogels, nanoemulsions, dendrimers, quantum dots, etc. along with the intranasal drug delivery to the brain. We have also illustrated various factors affecting the drug targeting efficiency of the developed novel carrier system.

Crossing biological barriers with nanogels to improve drug delivery performance

The current limitations in the use of nanocarriers to treat constantly evolving diseases call for the design of novel and smarter drug delivery systems (DDS). Nanogels (NGs) are three-dimensional crosslinked polymers with dimensions on the nanoscale and with a great potential for use in the biomedical field. Particular interest focuses on their application as DDS to minimize severe toxic effects and increase the therapeutic index of drugs. They have recently gained attention, since they can include responsive modalities within their structure, which enable them to excerpt a therapeutic function on demand. Their bigger sizes and controlled architecture and functionality, when compared to non-crosslinked polymers, make them particularly interesting to explore novel modalities to cross biological barriers. The present review summarizes the most significant developments of NGs as smart carriers, with focus on smart modalities to cross biological barriers such as cellular membrane, tumor stroma, mucose, skin, and blood brain barrier. We discuss the properties of each barrier and highlight the importance that the NG design has on their capability to overcome them and deliver the cargo at the site of action.

Multi-Organs-on-Chips: Towards Long-Term Biomedical Investigations

With advantageous features such as minimizing the cost, time, and sample size requirements, organ-on-a-chip (OOC) systems have garnered enormous interest from researchers for their ability for real-time monitoring of physical parameters by mimicking the in vivo microenvironment and the precise responses of xenobiotics, i.e., drug efficacy and toxicity over conventional two-dimensional (2D) and three-dimensional (3D) cell cultures, as well as animal models. Recent advancements of OOC systems have evidenced the fabrication of 'multi-organ-on-chip' (MOC) models, which connect separated organ chambers together to resemble an ideal pharmacokinetic and pharmacodynamic (PK-PD) model for monitoring the complex interactions between multiple organs and the resultant dynamic responses of multiple organs to pharmaceutical compounds. Numerous varieties of MOC systems have been proposed, mainly focusing on the construction of these multi-organ models, while there are only few studies on how to realize continual, automated, and stable testing, which still remains a significant challenge in the development process of MOCs. Herein, this review emphasizes the recent advancements in realizing long-term testing of MOCs to promote their capability for real-time monitoring of multi-organ interactions and chronic cellular reactions more accurately and steadily over the available chip models. Efforts in this field are still ongoing for better performance in the assessment of preclinical attributes for a new chemical entity. Further, we give a brief overview on the various biomedical applications of long-term testing in MOCs, including several proposed applications and their potential utilization in the future. Finally, we summarize with perspectives.