Niosomes decorated with dual ligands targeting brain endothelial transporters increase cargo penetration across the blood-brain barrier

Advancing Central Nervous System Drug Delivery with Microtubule-Dependent Transcytosis of Novel Aqueous Compounds

The challenge of delivering therapeutics to the central nervous system due to the restrictive nature of the blood-brain barrier (BBB) is a substantial hurdle in neuropharmacology. Our research introduces a breakthrough approach using microtubule-dependent transcytosis facilitated by novel aqueous compounds. We synthesized a series of red-emitting pyran nitrile derivatives. The molecular structure of compounds, photophysical properties, and water solubility were characterized. BBB permeability of BN1 was assessed in an in vitro BBB model. The transmembrane transport mechanism was next analyzed. The derivative was injected in the wild-type mouse for evaluation of brain penetration and biodistribution in the brain. We further investigated the potential of BN1-functionalized BBB-nonpenetrated silica nanoparticles for brain targeting. This compound demonstrated an ability to form endosomes within the phospholipid layer, thus enabling efficient penetration of the BBB via microtubule-mediated transcytosis, as evidenced in vitro model. This was further confirmed by in vivo experiments that BN1 displays the excellent BBB penetration and retained in brain parenchyma. Furthermore, BBB-impermeable mesoporous silica nanoparticle codelivery system markedly enhanced the transport efficiency to the brain in vivo by BN1-functionalized. These findings indicate that our designed aqueous molecules not only are capable of traversing the BBB but also serve as a viable new strategy for central-nervous-system-targeted drug delivery.

Impact of mechanical cues on key cell functions and cell-nanoparticle interactions

In recent years, it has been recognized that mechanical forces play an important regulative role in living organisms and possess a direct impact on crucial cell functions, ranging from cell growth to maintenance of tissue homeostasis. Advancements in mechanobiology have revealed the profound impact of mechanical signals on diverse cellular responses that are cell type specific. Notably, numerous studies have elucidated the pivotal role of different mechanical cues as regulatory factors influencing various cellular processes, including cell spreading, locomotion, differentiation, and proliferation. Given these insights, it is unsurprising that the responses of cells regulated by physical forces are intricately linked to the modulation of nanoparticle uptake kinetics and processing. This complex interplay underscores the significance of understanding the mechanical microenvironment in shaping cellular behaviors and, consequently, influencing how cells interact with and process nanoparticles. Nevertheless, our knowledge on how localized physical forces affect the internalization and processing of nanoparticles by cells remains rather limited. A significant gap exists in the literature concerning a systematic analysis of how mechanical cues might bias the interactions between nanoparticles and cells. Hence, our aim in this review is to provide a comprehensive and critical analysis of the existing knowledge regarding the influence of mechanical cues on the complicated dynamics of cell-nanoparticle interactions. By addressing this gap, we would like to contribute to a detailed understanding of the role that mechanical forces play in shaping the complex interplay between cells and nanoparticles.

An Overview on the Physiopathology of the Blood-Brain Barrier and the Lipid-Based Nanocarriers for Central Nervous System Delivery

The state of well-being and health of our body is regulated by the fine osmotic and biochemical balance established between the cells of the different tissues, organs, and systems. Specific districts of the human body are defined, kept in the correct state of functioning, and, therefore, protected from exogenous or endogenous insults of both mechanical, physical, and biological nature by the presence of different barrier systems. In addition to the placental barrier, which even acts as a linker between two different organisms, the mother and the fetus, all human body barriers, including the blood-brain barrier (BBB), blood-retinal barrier, blood-nerve barrier, blood-lymph barrier, and blood-cerebrospinal fluid barrier, operate to maintain the physiological homeostasis within tissues and organs. From a pharmaceutical point of view, the most challenging is undoubtedly the BBB, since its presence notably complicates the treatment of brain disorders. BBB action can impair the delivery of chemical drugs and biopharmaceuticals into the brain, reducing their therapeutic efficacy and/or increasing their unwanted bioaccumulation in the surrounding healthy tissues. Recent nanotechnological innovation provides advanced biomaterials and ad hoc customized engineering and functionalization methods able to assist in brain-targeted drug delivery. In this context, lipid nanocarriers, including both synthetic (liposomes, solid lipid nanoparticles, nanoemulsions, nanostructured lipid carriers, niosomes, proniosomes, and cubosomes) and cell-derived ones (extracellular vesicles and cell membrane-derived nanocarriers), are considered one of the most successful brain delivery systems due to their reasonable biocompatibility and ability to cross the BBB. This review aims to provide a complete and up-to-date point of view on the efficacy of the most varied lipid carriers, whether FDA-approved, involved in clinical trials, or used in in vitro or in vivo studies, for the treatment of inflammatory, cancerous, or infectious brain diseases.

Composition, preparation methods, and applications of nanoniosomes as codelivery systems: a review of emerging therapies with emphasis on cancer

Nanoniosome-based drug codelivery systems have become popular therapeutic instruments, demonstrating tremendous promise in cancer therapy, infection treatment, and other therapeutic domains. An emerging form of vesicular nanocarriers, niosomes are self-assembling vesicles composed of nonionic surfactants, along with cholesterol or other amphiphilic molecules. This comprehensive review focuses on how nanosystems may aid in making anticancer and antibacterial pharmaceuticals more stable and soluble. As malleable nanodelivery instruments, the composition, types, preparation procedures, and variables affecting the structure and stability of niosomes are extensively investigated. In addition, the advantages of dual niosomes for combination therapy and the administration of multiple medications simultaneously are highlighted. Along with categorizing niosomal drug delivery systems, a comprehensive analysis of various preparation techniques, including thin-layer injection, ether injection, and microfluidization, is provided. Dual niosomes for cancer treatment are discussed in detail regarding the codelivery of two medications and the codelivery of a drug with organic, plant-based bioactive compounds or gene agents. In addition, niogelosomes and metallic niosomal carriers for targeted distribution are discussed. The review also investigates the simultaneous delivery of bioactive substances and gene agents, including siRNA, microRNA, shRNA, lncRNA, and DNA. Additional sections discuss the use of dual niosomes for cutaneous drug delivery and treating leishmanial infections, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. The study concludes by delineating the challenges and potential routes for nanoniosome-based pharmaceutical codelivery systems, which will be useful for nanomedicine practitioners and researchers.

In vitro hepatotoxicity evaluation of methotrexate-loaded niosome formulation: fabrication, characterization and cell culture studies

BACKGROUND

Methotrexate (MTX) is a folic acid antagonist that is widely used to treat osteosarcoma, leukemia, breast cancer, and autoimmune and inflammatory diseases. The most important concerns with MTX are its poor solubility and high toxicity, particularly in liver cells. To enhance its solubility and to minimize its toxicity, we encapsulated MTX in niosomes and investigated its hepatotoxicity mechanisms using genetic biomarkers.

METHODS

Niosomes were successfully prepared using a modified thin film method, and the prepared monodisperse smallsized formulation was subsequently characterized. In vitro cytotoxicity studies were performed both in hepatocarcinoma (HEP3G) and healthy liver (AML12) cell lines. Specifically, immunofluorescence assay and evaluation of the expression levels of apoptotic, antioxidant, heat shock protein, and oxidative stress genes were performed.

RESULTS

The formulation had a particle size of 117.1 ± 33 nm, a surface charge of -38.41 ± 0.7 mV, and an encapsulation efficiency of 59.7% ± 2.3%. The results showed that the niosomal formulation exhibited significantly higher cytotoxic effects in HEP3G than in AML12. The immunofluorescence and genetic analyses showed that the increased cytotoxicity of niosomes resulted mainly from oxidative stress and slight apoptosis.

DISCUSSION

These results demonstrated that niosomal drug delivery systems could be a new potential formulation for minimizing MTX-related hepatotoxicity.

Niosomes in cancer treatment: A focus on curcumin encapsulation

Curcumin is widely used as a therapeutic drug for cancer treatment. However, its limited absorption and rapid excretion are the major therapeutic limitations to its clinical use. Using niosomes as a curcumin delivery system is a cheap, easy, and less toxic strategy for enhancing the absorption of curcumin by cells and delaying its excretion. Thus, there is a vital need to explore curcumin niosomes to configure the curcumin to suitably serve and aid current pharmacokinetics in treatments for cancer. To date, no comprehensive review has focused on the cytotoxic effects of curcumin niosomes on malignant cells. Thus, this review provides a critical analysis of the curcumin niosomes in cancer treatment, formulations of curcumin niosomes, characterizations of curcumin niosomes, and factors influencing their performance. The findings from this review article can strongly accelerate the understanding of curcumin niosomes and pave a brighter direction towards advances in the pharmaceutical, biotechnology, and medical industries.

Receptor-mediated transcytosis of macromolecules across the blood-brain barrier

INTRODUCTION

The blood-brain barrier (BBB) restricts brain access of virtually all macromolecules. Receptor-mediated transcytosis (RMT) is one strategy toward their brain delivery. In this strategy, targeting ligands conjugated to therapeutic payload or decorating particles containing the payload interact with targets on brain capillary endothelial cells (BCEC), triggering internalization, trafficking, and release from BCEC.

AREAS COVERED

RMT at the BBB has leveraged multiple formats of macromolecules and large particles. Interactions between those and BCEC have been studied primarily using antibodies, with findings applicable to the design of larger particles. BBB-penetrant constructs have also been identified in screening campaigns and directed evolution, and subsequently found to interact with RMT targets. In addition, BCEC targeted by constructs incorporating genomic payload can be made to produce therapeutic proteins.

EXPERT OPINION

While targeting may not be strictly necessary to reach a therapeutic effect for all macromolecules, it can improve a molecule's BBB transport, exposing it to the entire brain parenchyma and enhancing its effect. Constructs with better BCEC transcytosis may be designed rationally, leveraging knowledge about BCEC trafficking, and found in screening campaigns, where this knowledge can reduce the search space and improve iterative refinement. Identification of new targets may also help generate BBB-crossing constructs.

Shear stress regulation of nanoparticle uptake in vascular endothelial cells

Nanoparticles (NPs) hold tremendous targeting potential in cardiovascular disease and regenerative medicine, and exciting clinical applications are coming into light. Vascular endothelial cells (ECs) exposure to different magnitudes and patterns of shear stress (SS) generated by blood flow could engulf NPs in the blood. However, an unclear understanding of the role of SS on NP uptake is hindering the progress in improving the targeting of NP therapies. Here, the temporal and spatial distribution of SS in vascular ECs and the effect of different SS on NP uptake in ECs are highlighted. The mechanism of SS affecting NP uptake through regulating the cellular ROS level, endothelial glycocalyx and membrane fluidity is summarized, and the molecules containing clathrin and caveolin in the engulfment process are elucidated. SS targeting NPs are expected to overcome the current bottlenecks and change the field of targeting nanomedicine. This assessment on how SS affects the cell uptake of NPs and the marginalization of NPs in blood vessels could guide future research in cell biology and vascular targeting drugs.

Endocrine Regulation of Microvascular Receptor-Mediated Transcytosis and Its Therapeutic Opportunities: Insights by PCSK9-Mediated Regulation

Currently, many neurological disorders lack effective treatment options due to biological barriers that effectively separate the central nervous system (CNS) from the periphery. CNS homeostasis is maintained by a highly selective exchange of molecules, with tightly controlled ligand-specific transport systems at the blood-brain barrier (BBB) playing a key role. Exploiting or modifying these endogenous transport systems could provide a valuable tool for targeting insufficient drug delivery into the CNS or pathological changes in the microvasculature. However, little is known about how BBB transcytosis is continuously regulated to respond to temporal or chronic changes in the environment. The aim of this mini-review is to draw attention to the sensitivity of the BBB to circulating molecules derived from peripheral tissues, which may indicate a fundamental endocrine-operating regulatory system of receptor-mediated transcytosis at the BBB. We present our thoughts in the context of the recent observation that low-density lipoprotein receptor-related protein 1 (LRP1)-mediated clearance of brain amyloid-β (Aβ) across the BBB is negatively regulated by peripheral proprotein convertase subtilisin/kexin type 9 (PCSK9). We hope that our conclusions will inspire future investigations of the BBB as dynamic communication interface between the CNS and periphery, whose peripheral regulatory mechanisms could be easily exploited for therapeutic purposes.

Interactions of Nanoscale Self-Assembled Peptide-Based Assemblies with Glioblastoma Cell Models and Spheroids

Peptide nanoassemblies have garnered remarkable importance in the development of novel nanoscale biomaterials for drug delivery into tumor cells. Taking advantage of receptor mediated recognition of two known peptides, angiopep-2 (TFFYGGSRGKRNNFKTEEY) and A-COOP-K (ACGLSGLC10 VAK) that bind to the over-expressed receptors low density lipoprotein (LRP-1) and fatty acid binding protein (FABP3) respectively, we have developed new peptide conjugates by combining the anti-inflammatory, antitumor compound azelaic acid with angiopep-2, which efficiently self-assembled into nanofibers. Those nanofibers were then functionalized with the A-COOP-K sequence and formed supramolecular hierarchical structures that were found to entrap the chemotherapeutic drug doxorubicin efficaciously. Furthermore, the nanoassemblies were found to release the drug in a dose-dependent manner and showed a stepwise increase over a period of 2 weeks under acidic conditions. Two cell lines (U-87-MG and U-138-MG) were utilized as models for glioblastoma cells grown in the presence of serum and under serum-free conditions to mimic the growth conditions of natural tumors. The drug entrapped assemblies were found to inhibit the cell proliferation of both U-87 and U-138MG glioblastoma cells. Three dimensional spheroids of different sizes were grown to mimic the tumors and evaluate the efficacy of drug release and internalization. Our results indicated that the nanoassemblies were found to have higher internalization of DOX and were well-spread throughout the spheroids grown, particularly under serum-free conditions. The nanoassemblies also displayed blood-brain barrier penetration when tested with a multicellular in vitro model. Such self-assembled nanostructures with targeting ability may provide a suitable platform for the development of new peptide-based biomaterials that can provide more insights about the mechanistic approach for drug delivery for not only 2D cell cultures but also 3D tumoroids that mimic the tumor microenvironments.

Targeting Human Endothelial Cells with Glutathione and Alanine Increases the Crossing of a Polypeptide Nanocarrier through a Blood-Brain Barrier Model and Entry to Human Brain Organoids

Nanoparticles (NPs) are the focus of research efforts that aim to develop successful drug delivery systems for the brain. Polypeptide nanocarriers are versatile platforms and combine high functionality with good biocompatibility and biodegradability. The key to the efficient brain delivery of NPs is the specific targeting of cerebral endothelial cells that form the blood-brain barrier (BBB). We have previously discovered that the combination of two different ligands of BBB nutrient transporters, alanine and glutathione, increases the permeability of vesicular NPs across the BBB. Our aim here was to investigate whether the combination of these molecules can also promote the efficient transfer of 3-armed poly(l-glutamic acid) NPs across a human endothelial cell and brain pericyte BBB co-culture model. Alanine and glutathione dual-targeted polypeptide NPs showed good cytocompatibility and elevated cellular uptake in a time-dependent and active manner. Targeted NPs had a higher permeability across the BBB model and could subsequently enter midbrain-like organoids derived from healthy and Parkinson's disease patient-specific stem cells. These results indicate that poly(l-glutamic acid) NPs can be used as nanocarriers for nervous system application and that the right combination of molecules that target cerebral endothelial cells, in this case alanine and glutathione, can facilitate drug delivery to the brain.

Surface Modification of Lipid-Based Nanocarriers: A Potential Approach to Enhance Targeted Drug Delivery

Nanocarriers have the utmost significance for advancements in drug delivery and nanomedicine technology. They are classified as polymer-based nanocarriers, lipid-based nanocarriers, viral nanoparticles, or inorganic nanoparticles, depending on their constituent parts. Lipid-based nanocarrier systems have gained tremendous attention over the years because of their noteworthy properties like high drug-loading capacity, lower toxicity, better bioavailability and biocompatibility, stability in the gastrointestinal tract, controlled release, simpler scale-up, and validation process. Nanocarriers still have some disadvantages like poor drug penetration, limited drug encapsulation, and poor targeting. These disadvantages can be overcome by their surface modification. Surface-modified nanocarriers result in controlled release, enhanced penetration efficiency, and targeted medication delivery. In this review, the authors summarize the numerous lipid-based nanocarriers and their functionalization through various surface modifiers such as polymers, ligands, surfactants, and fatty acids. Recent examples of newly developing surface-modified lipid-based nanocarrier systems from the available literature, along with their applications, have been compiled in this work.

In Vitro Models of Biological Barriers for Nanomedical Research

Nanoconstructs developed for biomedical purposes must overcome diverse biological barriers before reaching the target where playing their therapeutic or diagnostic function. In vivo models are very complex and unsuitable to distinguish the roles plaid by the multiple biological barriers on nanoparticle biodistribution and effect; in addition, they are costly, time-consuming and subject to strict ethical regulation. For these reasons, simplified in vitro models are preferred, at least for the earlier phases of the nanoconstruct development. Many in vitro models have therefore been set up. Each model has its own pros and cons: conventional 2D cell cultures are simple and cost-effective, but the information remains limited to single cells; cell monolayers allow the formation of cell–cell junctions and the assessment of nanoparticle translocation across structured barriers but they lack three-dimensionality; 3D cell culture systems are more appropriate to test in vitro nanoparticle biodistribution but they are static; finally, bioreactors and microfluidic devices can mimicking the physiological flow occurring in vivo thus providing in vitro biological barrier models suitable to reliably assess nanoparticles relocation. In this evolving context, the present review provides an overview of the most representative and performing in vitro models of biological barriers set up for nanomedical research.

The role of the cell surface glycocalyx in drug delivery to and through the endothelium

Cell membranes are key interfaces where materials engineering meets biology. Traditionally regarded as just the location of receptors regulating the uptake of molecules, we now know that all mammalian cell membranes are 'sugar coated'. These sugars, or glycans, form a matrix bound at the cell membrane via proteins and lipids, referred to as the glycocalyx, which modulate access to cell membrane receptors crucial for interactions with drug delivery systems (DDS). Focusing on the key blood-tissue barrier faced by most DDS to enable transport from the place of administration to target sites via the circulation, we critically assess the design of carriers for interactions at the endothelial cell surface. We also discuss the current challenges for this area and provide opportunities for future research efforts to more fully engineer DDS for controlled, efficient, and targeted interactions with the endothelium for therapeutic application.

A Triple Combination of Targeting Ligands Increases the Penetration of Nanoparticles across a Blood-Brain Barrier Culture Model

Nanosized drug delivery systems targeting transporters of the blood-brain barrier (BBB) are promising carriers to enhance the penetration of therapeutics into the brain. The expression of solute carriers (SLC) is high and shows a specific pattern at the BBB. Here we show that targeting ligands ascorbic acid, leucine and glutathione on nanoparticles elevated the uptake of albumin cargo in cultured primary rat brain endothelial cells. Moreover, we demonstrated the ability of the triple-targeted nanovesicles to deliver their cargo into midbrain organoids after crossing the BBB model. The cellular uptake was temperature- and energy-dependent based on metabolic inhibition. The process was decreased by filipin and cytochalasin D, indicating that the cellular uptake of nanoparticles was partially mediated by endocytosis. The uptake of the cargo encapsulated in triple-targeted nanoparticles increased after modification of the negative zeta potential of endothelial cells by treatment with a cationic lipid or after cleaving the glycocalyx with an enzyme. We revealed that targeted nanoparticles elevated plasma membrane fluidity, indicating the fusion of nanovesicles with endothelial cell membranes. Our data indicate that labeling nanoparticles with three different ligands of multiple transporters of brain endothelial cells can promote the transfer and delivery of molecules across the BBB.

Chitosan-coated niosome as an efficient curcumin carrier to cross the blood-brain barrier: an animal study

This study aims to improve the curcumin bio-stability and brain permeability by loading in bare niosome (BN) and chitosan-coated niosome (ChN). Span 60, tween 60, and cholesterol were optimized as niosome shell components to attain the highest encapsulation efficiency (EE), besides the lowest particle size, using the mixture design method. The resulting optimized BN had a mean diameter of 80 ± 0.2 nm and surface charge of -31 ± 0.1 mv, which changed to 85 ± 0.15 nm and 35 ± 0.12 mv, respectively, after applying the chitosan layer. The EE% in bare niosome were about 80 ± 0.2, which changed to 82 ± 0.21 in ChN. The optimized formulation displayed sustained release, following the Hixson-Crowell model.Wistar rats were subjected to intraperitoneal injection (i.p.) of BN and ChN to evaluate the blood-brain barrier permeability of the curcumin. In this regard, ChN significantly increased curcumin concentration in different parts of the liver, plasma, and central nervous system (cerebral cortex, cerebellum, and stratum), compared with BN. Altogether, our results showed that ChN could be used as a promising delivery system for the treatment of some neurological diseases such as Alzheimer^'s.

Nanoarchitectonics of Multifunctional Niosomes for Advanced Drug Delivery

Niosomes are a type of vesicular nanocarrier exploited for enhancing the therapeutic efficacy of various drugs in clinical practice. Niosomes comprise a bilayer hydrophobic membrane enclosing a central cavity filled with an aqueous phase, and therefore, they can encapsulate and deliver both hydrophobic and hydrophilic substances. Niosomal nanocarriers are preferred over other bilayer structures such as liposomes due to their chemical stability, biodegradability, biocompatibility, low production cost, low toxicity, and easy storage and handling. In addition, the niosomal membrane can be easy modified by the inclusion of ligands or stimulus-sensitive segments for achieving targeted delivery and triggered release of the encapsulated cargo. This mini-review outlines the current advances in designing functional niosomes and their use as platforms for developing advanced drug and gene delivery systems.

Polymeric Nanoparticles Properties and Brain Delivery

Safe and reliable entry to the brain is essential for successful diagnosis and treatment of diseases, but it still poses major challenges. As a result, many therapeutic approaches to treating disorders associated with the central nervous system (CNS) still only show limited success. Nano-sized systems are being explored as drug carriers and show great improvements in the delivery of many therapeutics. The systemic delivery of nanoparticles (NPs) or nanocarriers (NCs) to the brain involves reaching the neurovascular unit (NVU), being transported across the blood-brain barrier, (BBB) and accumulating in the brain. Each of these steps can benefit from specifically controlled properties of NPs. Here, we discuss how brain delivery by NPs can benefit from careful design of the NP properties. Properties such as size, charge, shape, and ligand functionalization are commonly addressed in the literature; however, properties such as ligand density, linker length, avidity, protein corona, and stiffness are insufficiently discussed. This is unfortunate since they present great value against multiple barriers encountered by the NPs before reaching the brain, particularly the BBB. We further highlight important examples utilizing targeting ligands and how functionalization parameters, e.g., ligand density and ligand properties, can affect the success of the nano-based delivery system.

Functionalized niosomes as a smart delivery device in cancer and fungal infection

Various diseases remain untreated due to lack of suitable therapeutic moiety or a suitable drug delivery device, especially where toxicities and side effects are the primary reason for concern. Cancer and fungal infections are diseases where treatment schedules are not completed due to severe side effects or lengthy treatment protocols. Advanced treatment approaches such as active targeting and inhibition of angiogenesis may be preferred method for the treatment for malignancy over the conventional method. Niosomes may be a better alternative drug delivery carrier for various therapeutic moieties (either hydrophilic or hydrophobic) and also due to ease of surface modification, non-immunogenicity and economical. Active targeting approach may be done by targeting the receptors through coupling of suitable ligand on niosomal surface. Moreover, various receptors (CD44, folate, epidermal growth factor receptor (EGFR) & Vascular growth factor receptor (VGFR)) expressed by malignant cells have also been reviewed. The preparation of suitable niosomal formulation also requires considerable attention, and its formulation depends upon various factors such as selection of non-ionic surfactant, method of fabrication, and fabrication parameters. A combination therapy (dual drug and immunotherapy) has been proposed for the treatment of fungal infection with special consideration for surface modification with suitable ligand on niosomal surface to sensitize the receptors (C-type lectin receptors, Toll-like receptors & Nucleotide-binding oligomerization domain-like receptors) present on immune cells involved in fungal immunity. Certain gene silencing concept has also been discussed as an advanced alternative treatment for cancer by silencing the mRNA at molecular level using short interfering RNA (si-RNA).

Targeted Propolis-Loaded Poly (Butyl) Cyanoacrylate Nanoparticles: An Alternative Drug Delivery Tool for the Treatment of Cryptococcal Meningitis

In this study, we describe a nano-carrier system for propolis that is able to cross an in vitro model of the blood-brain barrier (BBB) and effectively reduce the virulence of Cryptococcus neoformans in animal models. Antimicrobial properties of propolis have been widely studied. However, propolis applications are limited by its low water solubility and poor bioavailability. Therefore, we recently formulated novel poly (n-butyl cyanoacrylate) nanoparticles (PBCA-NP) containing propolis. PBCA-NP are biocompatible, biodegradable and have been shown to effectively cross the BBB using apolipoprotein E (ApoE) as a ligand. Prepared nanoparticles were characterized for particle size, zeta potential, propolis entrapment efficiency and in vitro release. Additionally, the PBCA-NP were functionalized with polysorbate 80, which then specifically adsorbs ApoE. Using an in vitro BBB model of human brain microvascular endothelial cells hCMEC/D3, it was shown that fluorescence labelled ApoE-functionalized PBCA-NP were internalized by the cells and translocated across the cell monolayer. Propolis-loaded PBCA-NP had in vitro, antifungal activity against C. neoformans, which causes meningitis. To utilize the invertebrate model, Galleria mellonella larvae were infected with C. neoformans and treated with propolis-loaded PBCA-NP. The larvae exhibited normal behavior in toxicity testing, and treatment with propolis-loaded PBCA-NP increased survival in the C. neoformans-infected larvae group. In addition, following cryptococcal infection and then 7 days of treatment, the tissue fungal burden of mice treated with propolis-loaded PBCA-NP was significantly lower than control groups. Therefore, our ApoE-functionalized propolis-loaded PBCA-NP can be deemed as a potential targeted nanoparticle in the therapeutic treatment of cerebral cryptococcosis.

Optically Manipulated Microtools to Measure Adhesion of the Nanoparticle-Targeting Ligand Glutathione to Brain Endothelial Cells

Targeting nanoparticles as drug delivery platforms is crucial to facilitate their cellular entry. Docking of nanoparticles by targeting ligands on cell membranes is the first step for the initiation of cellular uptake. As a model system, we studied brain microvascular endothelial cells, which form the anatomical basis of the blood-brain barrier, and the tripeptide glutathione, one of the most effective targeting ligands of nanoparticles to cross the blood-brain barrier. To investigate this initial docking step between glutathione and the membrane of living brain endothelial cells, we applied our recently developed innovative optical method. We present a microtool, with a task-specific geometry used as a probe, actuated by multifocus optical tweezers to characterize the adhesion probability and strength of glutathione-coated surfaces to the cell membrane of endothelial cells. The binding probability of the glutathione-coated surface and the adhesion force between the microtool and cell membrane was measured in a novel arrangement: cells were cultured on a vertical polymer wall and the mechanical forces were generated laterally and at the same time, perpendicularly to the plasma membrane. The adhesion force values were also determined with more conventional atomic force microscopy (AFM) measurements using functionalized colloidal probes. The optical trapping-based method was found to be suitable to measure very low adhesion forces (≤ 20 pN) without a high level of noise, which is characteristic for AFM measurements in this range. The holographic optical tweezers-directed functionalized microtools may help characterize the adhesion step of nanoparticles initiating transcytosis and select ligands to target nanoparticles.

Surface charge, glycocalyx, and blood-brain barrier function

The negative surface charge of brain microvessel endothelial cells is derived from the special composition of their membrane lipids and the thick endothelial surface glycocalyx. They are important elements of the unique defense systems of the blood-brain barrier. The tissue-specific properties, components, function and charge of the brain endothelial glycocalyx have only been studied in detail in the past 15 years. This review highlights the importance of the negative surface charge in the permeability of macromolecules and nanoparticles as well as in drug interactions. We discuss surface charge and glycoxalyx changes in pathologies related to the brain microvasculature and protective measures against glycocalyx shedding and damage. We present biophysical techniques, including a microfluidic chip device, to measure surface charge of living brain endothelial cells and imaging methods for visualization of surface charge and glycocalyx.

ApoE-Targeting Increases the Transfer of Solid Lipid Nanoparticles with Donepezil Cargo across a Culture Model of the Blood-Brain Barrier

Pharmacological treatment of central nervous system (CNS) disorders is difficult, because the blood-brain barrier (BBB) restricts the penetration of many drugs into the brain. To solve this unmet therapeutic need, nanosized drug carriers are the focus of research efforts to develop drug delivery systems for the CNS. For the successful delivery of nanoparticles (NPs) to the brain, targeting ligands on their surface is necessary. Our research aim was to design a nanoscale drug delivery system for a more efficient transfer of donepezil, an anticholinergic drug in the therapy of Alzheimer's disease across the BBB. Rhodamine B-labeled solid lipid nanoparticles with donepezil cargo were prepared and targeted with apolipoprotein E (ApoE), a ligand of BBB receptors. Nanoparticles were characterized by measurement of size, polydispersity index, zeta potential, thermal analysis, Fourier-transform infrared spectroscopy, in vitro release, and stability. Cytotoxicity of nanoparticles were investigated by metabolic assay and impedance-based cell analysis. ApoE-targeting increased the uptake of lipid nanoparticles in cultured brain endothelial cells and neurons. Furthermore, the permeability of ApoE-targeted nanoparticles across a co-culture model of the BBB was also elevated. Our data indicate that ApoE, which binds BBB receptors, can potentially be exploited for successful CNS targeting of solid lipid nanoparticles.

A chip device to determine surface charge properties of confluent cell monolayers by measuring streaming potential

Cell surface charge is an important element of the function of biological barriers, but no chip device has been described to measure cell surface charge properties of confluent barrier cell monolayers. The aim of this study was the design and fabrication of a dynamic lab-on-a-chip (LOC) device which is suitable to monitor transcellular electrical resistance, as well as streaming potential parallel to the surface of cell layers. We successfully measured the streaming potential of a biological barrier culture model with the help of our previously published versatile lab-on-a-chip device equipped with two Ag/AgCl electrodes. The inclusion of these "zeta electrodes", a voltage preamplifier and an oscilloscope in our set-up made it possible to successfully record signals describing the surface charge properties of brain endothelial cell monolayers, used as a barrier model in our experiments. Data obtained on the new chip device were verified by comparing streaming potential results measured in the LOC device and zeta potential results by the commonly used laser-Doppler velocimetry (LDv) method and model simulations. Changes in the negative surface charge of the barrier model by treatments with neuraminidase enzyme modifying the cell membrane glycocalyx or lidocaine altering the lipid membrane charge could be measured by both the upgraded LOC device and LDv. The new chip device can help to gain meaningful new information on how surface charge is linked to barrier function in both physiological and pathological conditions.

Combination of Alanine and Glutathione as Targeting Ligands of Nanoparticles Enhances Cargo Delivery into the Cells of the Neurovascular Unit

Inefficient drug delivery across the blood–brain barrier (BBB) and into target cells in the brain hinders the treatment of neurological diseases. One strategy to increase the brain penetration of drugs is to use vesicular nanoparticles functionalized with multiple ligands of BBB transporters as vehicles. Once within the brain, however, drugs must also be able to reach their therapeutic targets in the different cell types. It is, therefore, favorable if such nanocarriers are designed that can deliver their cargo not only to brain endothelial cells, but to other cell types as well. Here, we show that alanine-glutathione dual-targeting of niosomes enhances the delivery of a large protein cargo into cultured cells of the neurovascular unit, namely brain endothelial cells, pericytes, astrocytes and neurons. Furthermore, using metabolic and endocytic inhibitors, we show that the cellular uptake of niosomes is energy-dependent and is partially mediated by endocytosis. Finally, we demonstate the ability of our targeted nanovesicles to deliver their cargo into astroglial cells after crossing the BBB in vitro. These data indicate that dual-labeling of nanoparticles with alanine and glutathione can potentially be exploited to deliver drugs, even biopharmacons, across the BBB and into multiple cell types in the brain.

Salidroside as a potential neuroprotective agent for ischemic stroke: a review of sources, pharmacokinetics, mechanism and safety

Salidroside (Sal) is a bioactive extract principally from traditional herbal medicine such as Rhodiola rosea L., which has been commonly used for hundreds of years in Asia countries. The excellent neuroprotective capacity of Sal has been illuminated in recent studies. This work focused on the source, pharmacokinetics, safety and anti-ischemic stroke (IS) effect of Sal, especially emphasizing its mechanism of action and BBB permeability. Extensive databases, including Pubmed, Web of science (WOS), Google Scholar and China National Knowledge Infrastructure (CNKI), were applied to obtain relevant online literatures. Sal exerts powerful therapeutic effects on IS in experimental models either in vitro or in vivo due to its neuroprotection, with significantly diminishing infarct size, preventing cerebral edema and improving neurological function. Also, the findings suggest the underlying mechanisms involve anti-oxidation, anti-inflammation and anti-apoptosis by regulating multiple signaling pathways and key molecules, such as NF-κB, TNF-α and PI3K/Akt pathway. In pharmacokinetics, although showing a rapid absorption and elimination, bioavailability of Sal is elevated under some non-physiological conditions. The component and its metabolite (tyrosol) are capable of distributing to brain tissue and the later keeps a higher level of concentration. Moreover, Sal scarcely has obvious toxicity or side effects in a variety of animal experiments and clinical trials, but combination of drugs and perinatal use of medicine should be taken more attentions. Finally, as an active ingredient, not only is Sal isolated from diverse plants with limited yield, but also large batches of the products can be harvested by biological and chemical synthesis. With higher efficacy and better safety profiles, Sal could sever as a promising neuroprotectant for preventing and treating IS. Nevertheless, further investigations are still required to explore the pharmacodynamic and pharmacokinetic properties of Sal in the treatment of IS.

Effect of small molecule signaling in PepFect14 transfection

Cell-penetrating peptides can be used to deliver oligonucleotide-based cargoes into cells. Previous studies have shown that the use of small molecule drugs could be an efficient method to increase the efficacy of delivery of oligonucleotides by cell-penetrating peptides either as targeting agents that can be used in formulation with the cell-penetrating peptide and its cargo or as cell signaling modulators that facilitates the cellular uptake of the treatment. This study presents two aims. The first aim is the identification of small molecule drugs that would induce a synergic effect on the transfection of splice correcting oligonucleotides assisted by PepFect14. The second aim is to identify the mechanisms behind the effect of small molecule drugs modulation of cell-penetrating peptide assisted transfection of oligonucleotides. Through an optimized, high-throughput luciferase assay for short oligonucleotide delivery using cell-penetrating peptides, and the simultaneous addition of a small molecule drug library, we show that three small molecule drugs (MPEP, VU0357121 and Ciproxifan) induced an increase in the transfection efficacy of PepFect14 in complex with a short single-stranded oligonucleotide in HeLa pLuc705 cells. These three drugs are described in the literature to be highly specific for their respective target receptors. However, none of those receptors are expressed in our cell line, indicating a yet non-described pathway of action for these small molecules. We show that the indicated small molecules, without interfering with the particles formed by PepFect14 and the oligonucleotide, interfere via still unidentified interactions in cell signaling, leading to an up-regulation of endocytosis and a higher efficacy in the delivery of short splice correcting oligonucleotides in complex with PepFect14.

Molecular and Cellular Risk Assessment of Healthy Human Cells and Cancer Human Cells Exposed to Nanoparticles

Nanodrugs have in recent years been a subject of great debate. In 2017 alone, almost 50 nanodrugs were approved for clinical use worldwide. Despite the advantages related to nanodrugs/nanomedicine, there is still a lack of information regarding the biological safety, as the real behavior of these nanodrugs in the body. In order to better understand these aspects, in this study, we evaluated the effect of polylactic acid (PLA) nanoparticles (NPs) and magnetic core mesoporous silica nanoparticles (MMSN), of 1000 nm and 50 nm, respectively, on human cells. In this direction we evaluated the cell cycle, cytochemistry, proliferation and tubulogenesis on tumor cells lines: from melanoma (MV3), breast cancer (MCF-7, MDA-MB-213), glioma (U373MG), prostate (PC3), gastric (AGS) and colon adenocarcinoma (HT-29) and non-tumor cell lines: from human melanocyte (NGM), fibroblast (FGH) and endothelial (HUVEC), respectively. The data showed that an acute exposure to both, polymeric nanoparticles or MMSN, did not show any relevant toxic effects on neither tumor cells nor non-tumor cells, suggesting that although nanodrugs may present unrevealed aspects, under acute exposition to human cells they are harmless.

Niosomal Formulation of a Lipoyl-Carnosine Derivative Targeting TRPA1 Channels in Brain

The transient receptor potential akyrin type-1 (TRPA1) is a non-selective cation channel playing a pivotal role in pain sensation and neurogenic inflammation. TRPA1 channels expressed in the central nervous system (CNS) have a critical role in the modulation of cortical spreading depression (CSD), which is a key pathophysiological basis of migraine pain. ADM_09 is a recently developed lipoic acid-based TRPA1 antagonist that is able to revert oxaliplatin-induced neuropathic pain and inflammatory trigeminal allodynia. In this context, aiming at developing drugs that are able to target TRPA1 channels in the CNS and promote an antioxidant effect, permeability across the blood-brain barrier (BBB) represents a central issue. Niosomes are nanovesicles that can be functionalized with specific ligands selectively recognized by transporters expressed on the BBB. In this work, the activity of ADM_09 on neocortex cultures was studied, and an efficient formulation to cross the BBB was developed with the aim of increasing the concentration of ADM_09 into the brain and selectively delivering it to the CNS rapidly after parenteral administration.

The solute carrier transporters and the brain: Physiological and pharmacological implications

Solute carriers (SLCs) are the largest family of transmembrane transporters that determine the exchange of various substances, including nutrients, ions, metabolites, and drugs across biological membranes. To date, the presence of about 287 SLC genes have been identified in the brain, among which mutations or the resultant dysfunctions of 71 SLC genes have been reported to be correlated with human brain disorders. Although increasing interest in SLCs have focused on drug development, SLCs are currently still under-explored as drug targets, especially in the brain. We summarize the main substrates and functions of SLCs that are expressed in the brain, with an emphasis on selected SLCs that are important physiologically, pathologically, and pharmacologically in the blood-brain barrier, astrocytes, and neurons. Evidence suggests that a fraction of SLCs are regulated along with the occurrences of brain disorders, among which epilepsy, neurodegenerative diseases, and autism are representative. Given the review of SLCs involved in the onset and procession of brain disorders, we hope these SLCs will be screened as promising drug targets to improve drug delivery to the brain.

Liposomal delivery of CRISPR/Cas9

Liposomes are one of the most widely investigated carriers for CRISPR/Cas9 delivery. The surface properties of liposomal carriers, including the surface charge, PEGylation, and ligand modification can significantly affect the gene silencing efficiency. Three barriers of systemic CRISPR/Cas9 delivery (long blood circulation, efficient tumor penetration, and efficient cellular uptake/endosomal escape) are analyzed on liposomal carriers with different surface charges, PEGylations, and ligand modifications. Cationic formulations dominate CRISPR/Cas9 delivery and neutral formulations also have good performance while anionic formulations are generally not proper for CRISPR/Cas9 delivery. The PEG dilemma (prolonged blood circulation vs. reduced cellular uptake/endosomal escape) and the side effect of repeated PEGylated formulation (accelerated blood clearance) were discussed. Effects of ligand modification on cationic and neutral formulations were analyzed. Finally, we summarized the achievements in liposomal CRISPR/Cas9 delivery, outlined existing problems, and provided some future perspectives. Liposomes are one of the most widely investigated carriers for CRISPR/Cas9 delivery. The surface properties of liposomal carriers, including the surface charge, PEGylation, and ligand modification can significantly affect the gene silencing efficiency. Three barriers of systemic siRNA delivery (long blood circulation, efficient tumor penetration, and efficient cellular uptake/endosomal escape) are analyzed on liposomal carriers with different surface charges, PEGylations, and ligand modifications. Cationic formulations dominate CRISPR/Cas9 delivery and neutral formulations also have good performance while anionic formulations are generally not proper for CRISPR/Cas9 delivery. The PEG dilemma (prolonged blood circulation vs. reduced cellular uptake/endosomal escape) and the side effect of repeated PEGylated formulation (accelerated blood clearance) were discussed. Effects of ligand modification on cationic and neutral formulations were analyzed. Finally, we summarized the achievements in liposomal CRISPR/Cas9 delivery, outlined existing problems, and provided some future perspectives.

Preparation, physicochemical properties, in vitro evaluation and release behavior of cephalexin-loaded niosomes

In this study, optimized cephalexin-loaded niosomal formulations based on span 60 and tween 60 were prepared as a promising drug carrier system. The niosomal formulations were characterized using a series of techniques such as scanning electron microscopy, Fourier transformed infrared spectroscopy, dynamic light scattering, and zeta potential measurement. The size and drug encapsulation efficiency are determined by the type and composition of surfactant. The developed niosomal formulations showed great storage stability up to 30 days with low change in size and drug entrapment during the storage, making them potential candidates for real applications. Moreover, the prepared niosomes showed negligible cytotoxicity for HepG2 cells, measured by MTT assay. The antibacterial properties of cephalexin-loaded niosome were investigated using S. aureus and E. coli as gram-positive and gram-negative bacteria, respectively. The results showed that the encapsulation of antibiotic drug in niosomal formulation could enhance the antibacterial efficiency of the drug, where the minimum inhibitory concentration was droped from 8 µg/mL (cephalexin) to 4 µg/mL (cephalexin-loaded niosome) and from 4 µg/mL (cephalexin) to 1 µg/mL (cephalexin-loaded niosome) against E. coli and S. aureus, respectively. The findings of our study show that the improvement of cephalexin bioavailability and prolonged drug release profile could be obtained by niosomal formulation as a favorable antibiotic drug delivery system.