BBB-on-a-chip with integrated micro-TEER for permeability evaluation of multi-functionalized gold nanorods against Alzheimer's disease

Challenges and Future Perspectives in Modeling Neurodegenerative Diseases Using Organ-on-a-Chip Technology

Neurodegenerative diseases (NDDs) affect more than 50 million people worldwide, posing a significant global health challenge as well as a high socioeconomic burden. With aging constituting one of the main risk factors for some NDDs such as Alzheimer's disease (AD) and Parkinson's disease (PD), this societal toll is expected to rise considering the predicted increase in the aging population as well as the limited progress in the development of effective therapeutics. To address the high failure rates in clinical trials, legislative changes permitting the use of alternatives to traditional pre-clinical in vivo models are implemented. In this regard, microphysiological systems (MPS) such as organ-on-a-chip (OoC) platforms constitute a promising tool, due to their ability to mimic complex and human-specific tissue niches in vitro. This review summarizes the current progress in modeling NDDs using OoC technology and discusses five critical aspects still insufficiently addressed in OoC models to date. Taking these aspects into consideration in the future MPS will advance the modeling of NDDs in vitro and increase their translational value in the clinical setting.

Modeling of the brain-lung axis using organoids in traumatic brain injury: an updated review

Clinical outcome after traumatic brain injury (TBI) is closely associated conditions of other organs, especially lungs as well as degree of brain injury. Even if there is no direct lung damage, severe brain injury can enhance sympathetic tones on blood vessels and vascular resistance, resulting in neurogenic pulmonary edema. Conversely, lung damage can worsen brain damage by dysregulating immunity. These findings suggest the importance of brain-lung axis interactions in TBI. However, little research has been conducted on the topic. An advanced disease model using stem cell technology may be an alternative for investigating the brain and lungs simultaneously but separately, as they can be potential candidates for improving the clinical outcomes of TBI.In this review, we describe the importance of brain-lung axis interactions in TBI by focusing on the concepts and reproducibility of brain and lung organoids in vitro. We also summarize recent research using pluripotent stem cell-derived brain organoids and their preclinical applications in various brain disease conditions and explore how they mimic the brain-lung axis. Reviewing the current status and discussing the limitations and potential perspectives in organoid research may offer a better understanding of pathophysiological interactions between the brain and lung after TBI.

Revolutionizing renal research: The future of kidney-on-a-chip in biotechnology

In vitro models of kidneys have limited effectiveness owing to the complex structure and functions of the kidney when compared with other organs. Therefore many renal function evaluations are currently being carried out through animal experiments. In contrast, efforts are being made to apply biomimetic systems, such as organ-on-a-chip, which is based on microfluidic device technology, to serve as an in vitro model for the kidney. These systems aimed to recreate a physiological cultivation environment. This review has provided an overview of organ-on-a-chip research focused on glomeruli and tubules as in vitro models for the kidney and discusses future prospects.

Peptide-conjugated Nanoparticle Platforms for Targeted Delivery, Imaging, and Biosensing Applications

Peptides have become an indispensable tool in engineering of multifunctional nanostructure platforms for biomedical applications such as targeted drug and gene delivery, imaging and biosensing. They can be covalently incorporated into a variety of nanoparticles (NPs) including polymers, metallic nanoparticles, and others. Using different bioconjugation techniques, multifunctional peptide-modified NPs can be formulated to produce therapeutical and diagnostic platforms offering high specificity, lower toxicity, biocompatibility, and stimuli responsive behavior. Targeting peptides can direct the nanoparticles into specific tissues for targeted drug and gene delivery and imaging applications due to their specificity towards certain receptors. Furthermore, due to their stimuli-responsive features, they can offer controlled release of therapeutics into desired sites of disease. In addition, peptide-based biosensors and imaging agents can provide non-invasive detection and monitoring of diseases including cancer, infectious diseases, and neurological disorders. In this review, we covered the design and formulation of recent peptide-based NP platforms, as well as their utilization in in vitro and in vivo applications such as targeted drug and gene delivery, targeting, sensing, and imaging applications. In the end, we provided the future outlook to design new peptide conjugated nanomaterials for biomedical applications.

Tau- and α-synuclein-targeted gold nanoparticles: applications, opportunities, and future outlooks in the diagnosis and therapy of neurodegenerative diseases

The use of nanomaterials in medicine offers multiple opportunities to address neurodegenerative disorders such as Alzheimer's and Parkinson's disease. These diseases are a significant burden for society and the health system, affecting millions of people worldwide without sensitive and selective diagnostic methodologies or effective treatments to stop their progression. In this sense, the use of gold nanoparticles is a promising tool due to their unique properties at the nanometric level. They can be functionalized with specific molecules to selectively target pathological proteins such as Tau and α-synuclein for Alzheimer's and Parkinson's disease, respectively. Additionally, these proteins are used as diagnostic biomarkers, wherein gold nanoparticles play a key role in enhancing their signal, even at the low concentrations present in biological samples such as blood or cerebrospinal fluid, thus enabling an early and accurate diagnosis. On the other hand, gold nanoparticles act as drug delivery platforms, bringing therapeutic agents directly into the brain, improving treatment efficiency and precision, and reducing side effects in healthy tissues. However, despite the exciting potential of gold nanoparticles, it is crucial to address the challenges and issues associated with their use in the medical field before they can be widely applied in clinical settings. It is critical to ensure the safety and biocompatibility of these nanomaterials in the context of the central nervous system. Therefore, rigorous preclinical and clinical studies are needed to assess the efficacy and feasibility of these strategies in patients. Since there is scarce and sometimes contradictory literature about their use in this context, the main aim of this review is to discuss and analyze the current state-of-the-art of gold nanoparticles in relation to delivery, diagnosis, and therapy for Alzheimer's and Parkinson's disease, as well as recent research about their use in preclinical, clinical, and emerging research areas.

Hopping the Hurdle: Strategies to Enhance the Molecular Delivery to the Brain through the Blood-Brain Barrier

Modern medicine has allowed for many advances in neurological and neurodegenerative disease (ND). However, the number of patients suffering from brain diseases is ever increasing and the treatment of brain diseases remains an issue, as drug efficacy is dramatically reduced due to the existence of the unique vascular structure, namely the blood-brain barrier (BBB). Several approaches to enhance drug delivery to the brain have been investigated but many have proven to be unsuccessful due to limited transport or damage induced in the BBB. Alternative approaches to enhance molecular delivery to the brain have been revealed in recent studies through the existence of molecular delivery pathways that regulate the passage of peripheral molecules. In this review, we present recent advancements of the basic research for these delivery pathways as well as examples of promising ventures to overcome the molecular hurdles that will enhance therapeutic interventions in the brain and potentially save the lives of millions of patients.

Sensor-integrated brain-on-a-chip platforms: Improving the predictive validity in neurodegenerative research

Affecting millions of individuals worldwide, neurodegenerative diseases (NDDs) pose a significant and growing health concern in people over the age of 60 years. Contributing to this trend are the steady increase in the aging population coupled with a persistent lack of disease-altering treatment strategies targeting NDDs. The absence of efficient therapeutics can be attributed to high failure rates in clinical trials and the ineptness of animal models in preceding preclinical studies. To that end, in recent years, significant research effort has been dedicated to the development of human cell-based preclinical disease models characterized by a higher degree of predictive validity. However, a key requirement of any in vitro model constitutes the precise knowledge and replication of the target tissues' (patho-)physiological microenvironment. Herein, microphysiological systems have demonstrated superiority over conventional static 2D/3D in vitro cell culture systems, as they allow for the emulation and continuous monitoring of the onset, progression, and remission of disease-associated phenotypes. This review provides an overview of recent advances in the field of NDD research using organ-on-a-chip platforms. Specific focus is directed toward non-invasive sensing strategies encompassing electrical, electrochemical, and optical sensors. Additionally, promising on- and integrable off-chip sensing strategies targeting key analytes in NDDs will be presented and discussed in detail.

Advancing Intelligent Organ-on-a-Chip Systems with Comprehensive In Situ Bioanalysis

In vitro models are essential to a broad range of biomedical research, such as pathological studies, drug development, and personalized medicine. As a potentially transformative paradigm for 3D in vitro models, organ-on-a-chip (OOC) technology has been extensively developed to recapitulate sophisticated architectures and dynamic microenvironments of human organs by applying the principles of life sciences and leveraging micro- and nanoscale engineering capabilities. A pivotal function of OOC devices is to support multifaceted and timely characterization of cultured cells and their microenvironments. However, in-depth analysis of OOC models typically requires biomedical assay procedures that are labor-intensive and interruptive. Herein, the latest advances toward intelligent OOC (iOOC) systems, where sensors integrated with OOC devices continuously report cellular and microenvironmental information for comprehensive in situ bioanalysis, are examined. It is proposed that the multimodal data in iOOC systems can support closed-loop control of the in vitro models and offer holistic biomedical insights for diverse applications. Essential techniques for establishing iOOC systems are surveyed, encompassing in situ sensing, data processing, and dynamic modulation. Eventually, the future development of iOOC systems featuring cross-disciplinary strategies is discussed.

Microphysiological Blood-Brain Barrier Systems for Disease Modeling and Drug Development

The blood-brain barrier (BBB) is a highly controlled microenvironment that regulates the interactions between cerebral blood and brain tissue. Due to its selectivity, many therapeutics targeting various neurological disorders are not able to penetrate into brain tissue. Pre-clinical studies using animals and other in vitro platforms have not shown the ability to fully replicate the human BBB leading to the failure of a majority of therapeutics in clinical trials. However, recent innovations in vitro and ex vivo modeling called organs-on-chips have shown the potential to create more accurate disease models for improved drug development. These microfluidic platforms induce physiological stressors on cultured cells and are able to generate more physiologically accurate BBBs compared to previous in vitro models. In this review, different approaches to create BBBs-on-chips are explored alongside their application in modeling various neurological disorders and potential therapeutic efficacy. Additionally, organs-on-chips use in BBB drug delivery studies is discussed, and advances in linking brain organs-on-chips onto multiorgan platforms to mimic organ crosstalk are reviewed.

Patient-Derived Microphysiological Systems for Precision Medicine

Patient-derived microphysiological systems (P-MPS) have emerged as powerful tools in precision medicine that provide valuable insight into individual patient characteristics. This review discusses the development of P-MPS as an integration of patient-derived samples, including patient-derived cells, organoids, and induced pluripotent stem cells, into well-defined MPSs. Emphasizing the necessity of P-MPS development, its significance as a nonclinical assessment approach that bridges the gap between traditional in vitro models and clinical outcomes is highlighted. Additionally, guidance is provided for engineering approaches to develop microfluidic devices and high-content analysis for P-MPSs, enabling high biological relevance and high-throughput experimentation. The practical implications of the P-MPS are further examined by exploring the clinically relevant outcomes obtained from various types of patient-derived samples. The construction and analysis of these diverse samples within the P-MPS have resulted in physiologically relevant data, paving the way for the development of personalized treatment strategies. This study describes the significance of the P-MPS in precision medicine, as well as its unique capacity to offer valuable insights into individual patient characteristics.

Innovative electrode and chip designs for transendothelial electrical resistance measurements in organs-on-chips

Many different epithelial and endothelial barriers in the human body ensure the proper functioning of our organs by controlling which substances can pass from one side to another. In recent years, organs-on-chips (OoC) have become a popular tool to study such barriers in vitro. To assess the proper functioning of these barriers, we can measure the transendothelial electrical resistance (TEER) which indicates how easily ions can cross the cell layer when a current is applied between electrodes on either side. TEER measurements are a convenient method to quantify the barrier properties since it is a non-invasive and label-free technique. Direct integration of electrodes for TEER measurements into OoC allows for continuous monitoring of the barrier, and fixed integration of the electrodes improves the reproducibility of the measurements. In this review, we will give an overview of different electrode and channel designs that have been used to measure the TEER in OoC. After giving some insight into why biological barriers are an important field of study, we will explain the theory and practice behind measuring the TEER in in vitro systems. Next, this review gives an overview of the state of the art in the field of integrated electrodes for TEER measurements in OoC, with a special focus on alternative chip and electrode designs. Finally, we outline some of the remaining challenges and provide some suggestions on how to overcome these challenges.

Lab-on-a-chip models of the blood-brain barrier: evolution, problems, perspectives

A great progress has been made in the development and use of lab-on-a-chip devices to model and study the blood-brain barrier (BBB) in the last decade. We present the main types of BBB-on-chip models and their use for the investigation of BBB physiology, drug and nanoparticle transport, toxicology and pathology. The selection of the appropriate cell types to be integrated into BBB-on-chip devices is discussed, as this greatly impacts the physiological relevance and translatability of findings. We identify knowledge gaps, neglected engineering and cell biological aspects and point out problems and contradictions in the literature of BBB-on-chip models, and suggest areas for further studies to progress this highly interdisciplinary field. BBB-on-chip models have an exceptional potential as predictive tools and alternatives of animal experiments in basic and preclinical research. To exploit the full potential of this technique expertise from materials science, bioengineering as well as stem cell and vascular/BBB biology is necessary. There is a need for better integration of these diverse disciplines that can only be achieved by setting clear parameters for characterizing both the chip and the BBB model parts technically and functionally.

Emergent trends in organ-on-a-chip applications for investigating metastasis within tumor microenvironment: A comprehensive bibliometric analysis

Background

With the burgeoning advancements in disease modeling, drug development, and precision medicine, organ-on-a-chip has risen to the forefront of biomedical research. Specifically in tumor research, this technology has exhibited exceptional potential in elucidating the dynamics of metastasis within the tumor microenvironment. Recognizing the significance of this field, our study aims to provide a comprehensive bibliometric analysis of global scientific contributions related to organ-on-a-chip.

Methods

Publications pertaining to organ-on-a-chip from 2014 to 2023 were retrieved at the Web of Science Core Collection database. Rigorous analyses of 2305 articles were conducted using tools including VOSviewer, CiteSpace, and R-bibliometrix.

Results

Over the 10-year span, global publications exhibited a consistent uptrend, anticipating continued growth. The United States and China were identified as dominant contributors, characterized by strong collaborative networks and substantial research investments. Predominant institutions encompass Harvard University, MIT, and the Chinese Academy of Sciences. Leading figures in the domain, such as Dr. Donald Ingber and Dr. Yu Shrike Zhang, emerge as pivotal collaboration prospects. Lab on a Chip, Micromachines, and Frontiers in Bioengineering and Biotechnology were the principal publishing journals. Pertinent keywords encompassed Microfluidic, Microphysiological System, Tissue Engineering, Organoid, In Vitro, Drug Screening, Hydrogel, Tumor Microenvironment, and Bioprinting. Emerging research avenues were identified as "Tumor Microenvironment and Metastasis," "Application of organ-on-a-chip in drug discovery and testing" and "Advancements in personalized medicine applications".

Conclusion

The organ-on-a-chip domain has demonstrated a transformative impact on understanding disease mechanisms and drug interactions, particularly within the tumor microenvironment. This bibliometric analysis underscores the ever-increasing importance of this field, guiding researchers and clinicians towards potential collaborative avenues and research directions.

Involvement of Astrocytes in the Formation, Maintenance, and Function of the Blood-Brain Barrier

The blood-brain barrier (BBB) is a fundamental structure that protects the composition of the brain by determining which ions, metabolites, and nutrients are allowed to enter the brain from the blood or to leave it towards the circulation. The BBB is structurally composed of a layer of brain capillary endothelial cells (BCECs) bound to each other through tight junctions (TJs). However, its development as well as maintenance and properties are controlled by the other brain cells that contact the BCECs: pericytes, glial cells, and even neurons themselves. Astrocytes seem, in particular, to have a very important role in determining and controlling most properties of the BBB. Here, we will focus on these latter cells, since the comprehension of their roles in brain physiology has been continuously expanding, even including the ability to participate in neurotransmission and in complex functions such as learning and memory. Accordingly, pathological conditions that alter astrocytic functions can alter the BBB's integrity, thus compromising many brain activities. In this review, we will also refer to different kinds of in vitro BBB models used to study the BBB's properties, evidencing its modifications under pathological conditions.

An overview of systematic reviews of acupuncture for neurodegenerative disease

BACKGROUND

Acupuncture has been widely used in the treatment of neurodegenerative diseases and a large number of systematic reviews (SRs) have been published, but the results are controversial. Therefore, it is necessary to comprehensively summarize and objectively evaluate the clinical evidence of acupuncture for neurodegenerative diseases.

OBJECTIVE

To evaluate the SRs that assess the efficacy and safety of acupuncture for neurodegenerative diseases. This overview is intended to provide evidence for clinical decision making by healthcare providers and policymakers and to provide evidence for clinical decision making by healthcare providers and policymakers and to provide recommendations for researchers to conduct high quality SRs and clinical studies.

METHODS

We searched four Chinese databases (SinoMed, CNKI, Wanfang and VIP) and four international databases (Cochrane Library, Embase, PubMed and Web of Science) for SRs of acupuncture for neurodegenerative diseases. The search period ran from the beginning of the database to March 5, 2023. Literature screening and data extraction were performed independently by two individuals. Methodological quality, risk of bias and associated evidence levels were assessed for all SRs using AMSTER 2, ROBIS and GRADE tools. In addition, the RCT overlap between SRs was calculated by corrected coverage area (CCA). We also conducted quantitative synthesis or descriptive analysis of the relevant data.

RESULTS

Finally, we identified 53 SRs (three were qualitative descriptions and fifty were meta-analyses). Under AMSTAR 2, only one SR was rated as moderate quality, six SRs as low quality and 46 SRs as very low quality. According to ROBIS, 33 SRs were rated as a high risk of bias and 20 as a low risk of bias. Cognitive functions in neurodegenerative diseases, activities of daily living and the motor and non-motor outcomes associated with PD were included to summary description. The pooled results show that acupuncture combined with conventional treatment may have an overall advantage over conventional treatment, but the quality of evidence is low. Specific adverse reactions/events were reported in 20 SRs. Common needle-related adverse events included pain, dizziness, bleeding, or subcutaneous hematoma. No severe adverse events were reported in any SRs.

CONCLUSION

Evidence suggests that acupuncture is generally effective and relatively safe for cognitive function and activities of daily living in neurodegenerative diseases. In addition, acupuncture may have some benefits in improving motor and non-motor symptoms in patients with PD. However, high-quality RCTs and SRs are still needed to further clarify the efficacy and safety of acupuncture in treating neurodegenerative diseases.

Projection Micro-Stereolithography to Manufacture a Biocompatible Micro-Optofluidic Device for Cell Concentration Monitoring

In this work, a 3D printed biocompatible micro-optofluidic (MoF) device for two-phase flow monitoring is presented. Both an air-water bi-phase flow and a two-phase mixture composed of micrometric cells suspended on a liquid solution were successfully controlled and monitored through its use. To manufacture the MoF device, a highly innovative microprecision 3D printing technique was used named Projection Microstereolithography (PμSL) in combination with the use of a novel 3D printable photocurable resin suitable for biological and biomedical applications. The concentration monitoring of biological fluids relies on the absorption phenomenon. More precisely, the nature of the transmission of the light strictly depends on the cell concentration: the higher the cell concentration, the lower the optical acquired signal. To achieve this, the microfluidic T-junction device was designed with two micrometric slots for the optical fibers' insertion, needed to acquire the light signal. In fact, both the micro-optical and the microfluidic components were integrated within the developed device. To assess the suitability of the selected biocompatible transparent resin for optical detection relying on the selected working principle (absorption phenomenon), a comparison between a two-phase flow process detected inside a previously fully characterized micro-optofluidic device made of a nonbiocompatible high-performance resin (HTL resin) and the same made of the biocompatible one (BIO resin) was carried out. In this way, it was possible to highlight the main differences between the two different resin grades, which were further justified with proper chemical analysis of the used resins and their hydrophilic/hydrophobic nature via static water contact angle measurements. A wide experimental campaign was performed for the biocompatible device manufactured through the PμSL technique in different operative conditions, i.e., different concentrations of eukaryotic yeast cells of Saccharomyces cerevisiae (with a diameter of 5 μm) suspended on a PBS (phosphate-buffered saline) solution. The performed analyses revealed that the selected photocurable transparent biocompatible resin for the manufactured device can be used for cell concentration monitoring by using ad hoc 3D printed micro-optofluidic devices. In fact, by means of an optical detection system and using the optimized operating conditions, i.e., the optimal values of the flow rate FR=0.1 mL/min and laser input power P∈{1,3} mW, we were able to discriminate between biological fluids with different concentrations of suspended cells with a robust working ability R2=0.9874 and Radj2=0.9811.

Advances in current in vitro models on neurodegenerative diseases

Many neurodegenerative diseases are identified but their causes and cure are far from being well-known. The problem resides in the complexity of the neural tissue and its location which hinders its easy evaluation. Although necessary in the drug discovery process, in vivo animal models need to be reduced and show relevant differences with the human tissues that guide scientists to inquire about other possible options which lead to in vitro models being explored. From organoids to organ-on-a-chips, 3D models are considered the cutting-edge technology in cell culture. Cell choice is a big parameter to take into consideration when planning an in vitro model and cells capable of mimicking both healthy and diseased tissue, such as induced pluripotent stem cells (iPSC), are recognized as good candidates. Hence, we present a critical review of the latest models used to study neurodegenerative disease, how these models have evolved introducing microfluidics platforms, 3D cell cultures, and the use of induced pluripotent cells to better mimic the neural tissue environment in pathological conditions.

Sensorization of microfluidic brain-on-a-chip devices: Towards a new generation of integrated drug screening systems

Brain-on-a-chip (BoC) devices show typical characteristics of brain complexity, including the presence of different cell types, separation in different compartments, tissue-like three-dimensionality, and inclusion of the extracellular matrix components. Moreover, the incorporation of a vascular system mimicking the blood-brain barrier (BBB) makes BoC particularly attractive, since they can be exploited to test the brain delivery of different drugs and nanoformulations. In this review, we introduce the main innovations in BoC and BBB-on-a-chip models, especially focusing sensorization: electrical, electrochemical, and optical biosensors permit the real-time monitoring of different biological phenomena and markers, such as the release of growth factors, the expression of specific receptors/biomarkers, the activation of immune cells, cell viability, cell-cell interactions, and BBB crossing of drugs and nanoparticles. The recent improvements in signal amplification, miniaturization, and multiplication of the sensors are discussed in an effort to highlight their benefits versus limitations and delineate future challenges in this field.

Polyoxometalate-Decorated Gold Nanoparticles Inhibit β-Amyloid Aggregation and Cross the Blood-Brain Barrier in a µphysiological Model

Alzheimer's disease is characterized by a combination of several neuropathological hallmarks, such as extracellular aggregates of beta amyloid (Aβ). Numerous alternatives have been studied for inhibiting Aβ aggregation but, at this time, there are no effective treatments available. Here, we developed the tri-component nanohybrid system AuNPs@POM@PEG based on gold nanoparticles (AuNPs) covered with polyoxometalates (POMs) and polyethylene glycol (PEG). In this work, AuNPs@POM@PEG demonstrated the inhibition of the formation of amyloid fibrils, showing a 75% decrease in Aβ aggregation in vitro. As it is a potential candidate for the treatment of Alzheimer's disease, we evaluated the cytotoxicity of AuNPs@POM@PEG and its ability to cross the blood-brain barrier (BBB). We achieved a stable nanosystem that is non-cytotoxic below 2.5 nM to human neurovascular cells. The brain permeability of AuNPs@POM@PEG was analyzed in an in vitro microphysiological model of the BBB (BBB-on-a-chip), containing 3D human neurovascular cell co-cultures and microfluidics. The results show that AuNPs@POM@PEG was able to cross the brain endothelial barrier in the chip and demonstrated that POM does not affect the barrier integrity, giving the green light to further studies into this system as a nanotherapeutic.

Development of a dual-flow tissue perfusion device for modeling the gastrointestinal tract-brain axis

Despite the large number of microfluidic devices that have been described over the past decade for the study of tissues and organs, few have become widely adopted. There are many reasons for this lack of adoption, primarily that devices are constructed for a single purpose or because they are highly complex and require relatively expensive investment in facilities and training. Here, we describe a microphysiological system (MPS) that is simple to use and provides fluid channels above and below cells, or tissue biopsies, maintained on a disposable, poly(methyl methacrylate), carrier held between polycarbonate outer plates. All other fittings are standard Luer sizes for ease of adoption. The carrier can be coated with cells on both sides to generate membrane barriers, and the devices can be established in series to allow medium to flow from one cell layer to another. Furthermore, the carrier containing cells can be easily removed after treatment on the device and the cells can be visualized or recovered for additional off-chip analysis. A 0.4 μm membrane with cell monolayers proved most effective in maintaining separate fluid flows, allowing apical and basal surfaces to be perfused independently. A panel of different cell lines (Caco-2, HT29-MTX-E12, SH-SY5Y, and HUVEC) were successfully maintained in the MPS for up to 7 days, either alone or on devices connected in series. The presence of tight junctions and mucin was expressed as expected by Caco-2 and HT-29-MTX-E12, with Concanavalin A showing uniform staining. Addition of Annexin V and PI showed viability of these cells to be >80% at 7 days. Bacterial extracellular vesicles (BEVs) produced by Bacteroides thetaiotaomicron and labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbo-cyanine perchlorate (DiD) were used as a model component of the human colonic microbiota and were visualized translocating from an apical surface containing Caco-2 cells to differentiated SH-SY5Y neuronal cells cultured on the basal surface of connected devices. The newly described MPS can be easily adapted, by changing the carrier to maintain spheroids, pieces, or slices of biopsy tissue and joined in series to study a variety of cell and tissue processes. The cell layers can be made more complex through the addition of multiple cell types and/or different patterning of extracellular matrix and the ability to culture cells adjacent to one another to allow study of cell:cell transfer, e.g., passive or active drug transfer, virus or bacterial entry or BEV uptake and transfer.

Blood-Brain Barrier Breakdown in Neuroinflammation: Current In Vitro Models

The blood-brain barrier, which is formed by tightly interconnected microvascular endothelial cells, separates the brain from the peripheral circulation. Together with other central nervous system-resident cell types, including pericytes and astrocytes, the blood-brain barrier forms the neurovascular unit. Upon neuroinflammation, this barrier becomes leaky, allowing molecules and cells to enter the brain and to potentially harm the tissue of the central nervous system. Despite the significance of animal models in research, they may not always adequately reflect human pathophysiology. Therefore, human models are needed. This review will provide an overview of the blood-brain barrier in terms of both health and disease. It will describe all key elements of the in vitro models and will explore how different compositions can be utilized to effectively model a variety of neuroinflammatory conditions. Furthermore, it will explore the existing types of models that are used in basic research to study the respective pathologies thus far.

Targeted Glioblastoma Treatment via Synthesis and Functionalization of Gold Nanoparticles With De Novo-Engineered Transferrin-Like Peptides: Protocol for a Novel Method

BACKGROUND

Glioblastoma multiforme (GBM) is an aggressive brain tumor with limited treatment options due to the blood-brain barrier's (BBB's) impedance and inherent resistance to chemotherapy. Gold nanoparticles (AuNPs) functionalized with transferrin-like peptides show promise in overcoming these challenges, enhancing drug delivery to the brain, and reducing chemotherapy resistance.

OBJECTIVE

The primary goal of this study is to establish a detailed protocol for synthesizing and stabilizing AuNPs, functionalizing them with de novo-engineered transferrin-like peptides, and conjugating them with the chemotherapeutic agent temozolomide. This strategy aims to improve drug delivery across the BBB and circumvent chemotherapy resistance. The secondary objective includes an assessment of the safety and potential for in vivo use of the synthesized nanoparticle complex.

METHODS

The proposal involves multiple steps with rigorous quality control of AuNP synthesis, stabilization with surfactants, and polyethylene glycol coating. The engineered transferrin-like peptides will be synthesized and attached to the AuNPs' surface, followed by the attachment of temozolomide and O6-methylguanine-DNA methyltransferase inhibitors. The resulting complex will undergo in vitro testing to assess BBB penetration, efficacy against GBM cells, and potential toxicity.

RESULTS

Initial preliminary experiments and simulations suggest successful synthesis and stabilization of AuNPs and effective attachment of transferrin-like peptides. We propose peptide attachment verification using Fourier transform infrared spectroscopy and surface plasmon resonance. Additionally, we will conduct pH stability tests to ensure our functionalized AuNPs retain their properties in acidic brain tumor microenvironments.

CONCLUSIONS

The proposed functionalization of AuNPs with de novo-engineered transferrin-like peptides represents a novel approach to GBM treatment. Our strategy opens new avenues for drug delivery across the BBB and chemotherapy resistance reduction. While we primarily focus on in vitro studies and computational modeling at this stage, successful completion will lead to further development, including in vivo studies and nanoparticle design optimization. This proposal anticipates inspiring future research and funding in neuro-oncology, presenting a potentially innovative and effective treatment option for GBM.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/49417.

On-chip real-time impedance monitoring of hiPSC-derived and artificial basement membrane-supported endothelium

Recent advances have shown the high sensibility of electrochemical impedance spectroscopy in real-time monitoring of cell barriers on a chip. Here, we applied this method to the investigation of human induced pluripotent stem cell (hiPSC) derived and artificial basement membrane (ABM) supported endothelial barrier. The ABM was obtained by self-assembling type IV collagen and laminin with a monolayer of crosslinked gelatin nanofibers. The hiPSCs were differentiated into brain microvascular endothelial cells (BMECs) and then plated on the ABM. After incubation for two days, the ABM-BMEC assembly was placed as a tissue insert into a microfluidic device for culture and real-time impedance monitoring over days. We found a significantly enhanced stability of the BMEC barrier in a serum-free and bromodeoxyuridine (BrdU) containing culture medium compared to the conventional culture due to the restricted cell proliferation. We also found that the BMEC barrier was sensitive to stimuli such as thrombin and that the change of the barrier impedance was mainly due to the change of the cell layer resistance. We can thus advocate this method to investigate the integrity of the cell barrier and the barrier-based assays.

Ferulic acid-loaded polymeric nanoparticles prepared from nano-emulsion templates facilitate internalisation across the blood-brain barrier in model membranes

A hydroxycinnamic acid derivative, namely ferulic acid (FA) has been successfully encapsulated in polymeric nanoparticles (NPs) based on poly(lactic-co-glycolic acid) (PLGA). FA-loaded polymeric NPs were prepared from O/W nano-emulsion templates using the phase inversion composition (PIC) low-energy emulsification method. The obtained PLGA NPs exhibited high colloidal stability, good drug-loading capacity, and particle hydrodynamic diameters in the range of 74 to 117 nm, depending on the FA concentration used. In vitro drug release studies confirmed a diffusion-controlled mechanism through which the amount of released FA reached a plateau at 60% after 6 hours-incubation. Five kinetic models were used to fit the FA release data as a function of time. The Weibull distribution and Korsmeyer-Peppas equation models provided the best fit to our experimental data and suggested quasi-Fickian diffusion behaviour. Moderate dose-response antioxidant and radical scavenging activities of FA-loaded PLGA NPs were demonstrated using the DPPH˙ assay achieving inhibition activities close to 60 and 40%, respectively. Cell culture studies confirmed that FA-loaded NPs were not toxic according to the MTT colorimetric assay, were able to internalise efficiently SH-SY5Y neuronal cells and supressed the intracellular ROS-level induced by H₂O₂ leading to 52% and 24.7% of cellular viability at 0.082 and 0.041 mg mL^-1, respectively. The permeability of the NPs through the blood brain barrier was tested with an in vitro organ-on-a-chip model to evaluate the ability of the FA-loaded PLGA and non-loaded PLGA NPs to penetrate to the brain. NPs were able to penetrate the barrier, but permeability decreased when FA was loaded. These results are promising for the use of loaded PLGA NPs for the management of neurological diseases.

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.