Emerging trends in organ-on-a-chip systems for drug screening

Microfluidic organoid-slice-on-a-chip system for studying anti-cholangiocarcinoma drug efficacy and hepatorenal toxicity

Organ-chip technology, in contrast to cell culture and animal models, offers a promising platform for accelerating drug development. However, current chip designs simulate human organ functions and there is a lack of multi-organ chip designs that can simultaneously study drug efficacy and hepatorenal toxicity. Here, we developed a novel microfluidic multi-organ chip that integrated cholangiocarcinoma organoids (CCOs) with recellularized liver slices (RLS) and recellularized kidney slices (RKS), to simultaneously assess anti-cholangiocarcinoma drug efficacy and hepatorenal toxicity. Co-culture of patient-derived CCOs with RLS and RKS was successfully achieved for 7 days under flow conditions with enhanced liver and renal cell functions. Furthermore, an in vitro biomimetic model showed IC50 values of trastuzumab emtansine (T-DM1) of around 6.42 ± 7.34 μg mL-1 in four clinical cases, with one outlier of 77.77 μg mL-1 due to patient variability. Post-treatment, RLS and RKS cell viability remained high at 75.67% and 81.03%, respectively, suggesting low hepatorenal toxicity of T-DM1 for treating cholangiocarcinoma. Our study demonstrates the use of an organoid-slice-on-a-chip (OSOC) platform for personalized drug efficacy and toxicity assessment, particularly aiming at leveraging anticancer drugs for off-label use to save patient lives.

Advanced Animal Replacement Testing Strategies Using Stem Cell and Organoids

The increasing ethical concerns and regulatory restrictions surrounding animal testing have accelerated the development of advanced in vitro models that more accurately replicate human physiology. Among these, stem cell-based systems and organoids have emerged as revolutionary tools, providing ethical, scalable, and physiologically relevant alternatives. This review explores the key trends and driving factors behind the adoption of these models, such as technological advancements, the principles of the 3Rs (Replacement, Reduction, and Refinement), and growing regulatory support from agencies like the OECD and FDA. It also delves into the development and application of various model systems, including 3D reconstructed tissues, induced pluripotent stem cell-derived cells, and microphysiological systems, highlighting their potential to replace animal models in toxicity evaluation, disease modeling, and drug development. A critical aspect of implementing these models is ensuring robust quality control protocols to enhance reproducibility and standardization, which is necessary for gaining regulatory acceptance. Additionally, we discuss advanced strategies for assessing toxicity and efficacy, focusing on organ-specific evaluation methods and applications in diverse fields such as pharmaceuticals, cosmetics, and food safety. Despite existing challenges related to scalability, standardization, and regulatory alignment, these innovative models represent a transformative step towards reducing animal use and improving the relevance and reliability of preclinical testing outcomes.

Receptor-mediated transcytosis of nanobodies targeting the heparin-binding EGF-like growth factor in human blood-brain barrier models

Transport of molecules into the brain is regulated by the blood-brain barrier (BBB). Receptor-mediated transcytosis (RMT) is a targeted vesicular transport mechanism of brain endothelial cells that can be employed to specifically transport large therapeutic molecules into the brain. ProHB-EGF is the transmembrane precursor of the heparin-binding EGF-like growth factor (HB-EGF) present on the intraluminal side of the brain endothelial cells. This molecule is characterized as an internalizing transport receptor with so far no discovery of endogenous ligands. In this study, we describe the selection and characterization of two nanobodies (named F12 and H7) with high binding affinity for proHB-EGF and their BBB transcytosis potential were tested in vitro. For the human BBB model, we found that a polarized co-culture environment was crucial for the expression and cell surface display of proHB-EGF. The ability of F12 and H7 to pass the BBB via RMT was demonstrated in both a primary human brain microvascular endothelial cell-based BBB model and a human induced pluripotent stem cell (hiPSC)-derived iBBB model. Our studies demonstrate that the proHB-EGF targeting Nbs are promising BBB shuttle molecules for delivery of therapeutic molecules into the brain.

Cancer-on-a-chip for precision cancer medicine

Many cancer therapies fail in clinical trials despite showing potent efficacy in preclinical studies. One of the key reasons is the adopted preclinical models cannot recapitulate the complex tumor microenvironment (TME) and reflect the heterogeneity and patient specificity in human cancer. Cancer-on-a-chip (CoC) microphysiological systems can closely mimic the complex anatomical features and microenvironment interactions in an actual tumor, enabling more accurate disease modeling and therapy testing. This review article concisely summarizes and highlights the state-of-the-art progresses in CoC development for modeling critical TME compartments including the tumor vasculature, stromal and immune niche, as well as its applications in therapying screening. Current dilemma in cancer therapy development demonstrates that future preclinical models should reflect patient specific pathophysiology and heterogeneity with high accuracy and enable high-throughput screening for anticancer drug discovery and development. Therefore, CoC should be evolved as well. We explore future directions and discuss the pathway to develop the next generation of CoC models for precision cancer medicine, such as patient-derived chip, organoids-on-a-chip, and multi-organs-on-a-chip with high fidelity. We also discuss how the integration of sensors and microenvironmental control modules can provide a more comprehensive investigation of disease mechanisms and therapies. Next, we outline the roadmap of future standardization and translation of CoC technology toward real-world applications in pharmaceutical development and clinical settings for precision cancer medicine and the practical challenges and ethical concerns. Finally, we overview how applying advanced artificial intelligence tools and computational models could exploit CoC-derived data and augment the analytical ability of CoC.

Patient-derived organoid co-culture systems as next-generation models for bladder cancer stem cell research

Three-dimensional patient-derived organoids (PDOs) have emerged as a powerful model for investigating the molecular and cellular mechanisms underlying bladder cancer, particularly in the context of cancer stem cells (CSCs) and drug screening. However, a significant limitation of conventional PDOs is the absence of tumor microenvironment (TME), which includes critical stromal, immune and microbial components that influence tumor behavior and treatment response. In this review, we provide a comprehensive overview of the recent advancements in PDO co-culture systems designed to integrate TME elements. Additionally, we emphasize the role of biomedical engineering technologies, such as 3D bioprinting and organoids-on-a-chip, in enhancing the physiological relevance of these models. Furthermore, we explore how bladder PDO co-culture systems are applied in research on bladder CSC characterization, evolution and treatment responses. Finally, we discuss future directions for improving PDO systems to achieve more accurate preclinical modeling and drug discovery.

Advancing drug delivery research: sustainable strategies for innovation and translation

Sustainable systems are designed to promote lasting viability and resilience while reducing negative effects on the environment, society, and economy. Like many others, the drug delivery field is facing the challenges of the global environmental crisis. Despite its rapid growth and significant funding, there has been a noticeable slowdown in the rate of advancement, impacting the economy, society, and environment. This paper delves into sustainable strategies for drug delivery research, including reducing pill burden through controlled release systems, use of bio-degradable/absorbable polymers, reduction in excipient requirements and use of functional excipients, clinically viable drug delivery system designs, non-invasive/self-administration technologies, and use of relevant in vitro and in vivo tools and computational approaches. When adopted, these strategies can help researchers create widely available, reasonably priced, and ecologically friendly drug delivery systems, thereby advancing sustainable healthcare for all. The manuscript also advocates for funding policies that support sustainable drug delivery research. It underscores the need to integrate sustainability principles into drug delivery research to achieve the broader agenda of global sustainability and well-being, such as SDG 3 (Good Health and Well-being), SDG 7 (Affordable and Clean Energy), SDG 9 (Industry, Innovation, and Infrastructure), and SDG 12 (Responsible Consumption and Production).

Organoids and organs-on-chips: Recent advances, applications in drug development, and regulatory challenges

Organoids and organs-on-chips (OoCs) are rapidly evolving technologies for creating miniature human tissue models. They can mimic complex physiological functions and pathological conditions, offering more realistic platforms for disease modeling, drug screening, precision medicine, and regenerative therapies. The passing of the FDA Modernization Act 2.0 has reduced animal testing requirements for drug trials, marking a significant milestone in using advanced in vitro models such as organoids and OoCs for therapeutic discovery. Apart from technical and ethical challenges, regulatory issues persist in ensuring the reliability, scientificity, and applicability of these models in drug development. This perspective explores the concept, advancements, pros and cons, and applications of organoids and OoCs, particularly in drug research and development. It also examines global regulatory agencies' policies and actions on using these models in drug evaluation, aiming to guide industry standard setting and advance regulatory science.

Cardiac-Focused Multi-Organ Chips: Advanced Disease Modeling, Drug Testing, and Inter-Organ Communication

Heart disease remains a leading cause of mortality worldwide, posing a significant challenge to global healthcare systems. Traditional animal models and cell culture techniques are instrumental in advancing the understanding of cardiac pathophysiology. However, these methods are limited in their ability to fully replicate the heart's intricate functions. This underscores the need for a deeper investigation into the fundamental mechanisms of heart disease. Notably, cardiac pathology is often influenced by systemic factors, with conditions in other organs contributing to disease onset and progression. Cardiac-focused multi-organ chip technology has emerged to better elucidate these complex inter-organ communications and address the limitations of current in vitro models. This technology offers a novel approach by recreating the cardiac microenvironment and integrating it with other organ systems, thereby enabling more precise disease modeling and drug toxicity assessment. This review provides a comprehensive overview of the heart's structure and function, explores the advancements in cardiac organ chip development, and highlights the applications of cardiac-focused multi-organ chips in medical research. Finally, the future potential of this technology in enhancing disease modeling and therapeutic evaluation is discussed.

Advancements of paper-based microfluidics and organ-on-a-chip models in cosmetics hazards

Cosmetics have been used in society for centuries for beautification and personal hygiene maintenance. Modern cosmetics include various makeup, hair, and skincare products that range from moisturizers and shampoos to lipsticks and foundations and have become a quintessential part of our daily grooming activities. However, dangerous adulterants are added during the production of these cosmetics, which range from heavy metals to microbial contaminants. These adulterants not only reduce the quality and efficacy of cosmetic products but also pose a significant risk to human health. Detecting the presence of adulterants in cosmetics is crucial for regulating substandard cosmetic products in the industry. The conventional methods to detect such adulterants and quality testing are expensive and take a lot of effort, particularly when involving advanced analytical detection and clinical trials. Recently, efficient methods such as microfluidic methods have emerged to detect adulterants rapidly. In this review, we mainly focus on various adulterants present in cosmetics and their detection using paper-based microfluidic devices. In addition, this review also sheds light on the organ-on-a-chip model with the goal of developing a human tissue model for cosmetic testing. Combined, these approaches provide an efficient, inexpensive, and sustainable approach for quality testing in the cosmetics industry.

Biomimetic Approaches in the Development of Optimised 3D Culture Environments for Drug Discovery in Cardiac Disease

Cardiovascular disease remains the leading cause of death worldwide, yet despite massive investment in drug discovery, the progress of cardiovascular drugs from lab to clinic remains slow. It is a complex, costly pathway from drug discovery to the clinic and failure becomes more expensive as a drug progresses along this pathway. The focus has begun to shift to optimisation of in vitro culture methodologies, not only because these must be undertaken are earlier on in the drug discovery pathway, but also because the principles of the 3Rs have become embedded in national and international legislation and regulation. Numerous studies have shown myocyte cell behaviour to be much more physiologically relevant in 3D culture compared to 2D culture, highlighting the advantages of using 3D-based models, whether microfluidic or otherwise, for preclinical drug screening. This review aims to provide an overview of the challenges in cardiovascular drug discovery, the limitations of traditional routes, and the successes in the field of preclinical models for cardiovascular drug discovery. It focuses on the particular role biomimicry can play, but also the challenges around implementation within commercial drug discovery.

Bone-on-a-Chip Systems for Hematological Cancers

Hematological malignancies originating from blood, bone marrow, and lymph nodes include leukemia, lymphoma, and myeloma, which necessitate the use of a distinct chemotherapeutic approach. Drug resistance frequently complicates their treatment, highlighting the need for predictive tools to guide therapeutic decisions. Conventional 2D/3D cell cultures do not fully encompass in vivo criteria, and translating disease models from mice to humans proves challenging. Organ-on-a-chip technology presents an avenue to surmount genetic disparities between species, offering precise design, concurrent manipulation of various cell types, and extrapolation of data to human physiology. The development of bone-on-a-chip (BoC) systems is crucial for accurately representing the in vivo bone microenvironment, predicting drug responses for hematological cancers, mitigating drug resistance, and facilitating personalized therapeutic interventions. BoC systems for modeling hematological cancers and drug research can encompass intricate designs and integrated platforms for analyzing drug response data to simulate disease scenarios. This review provides a comprehensive examination of BoC systems applicable to modeling hematological cancers and visualizing drug responses within the intricate context of bone. It thoroughly discusses the materials pertinent to BoC systems, suitable in vitro techniques, the predictive capabilities of BoC systems in clinical settings, and their potential for commercialization.

Exploring oncology treatment strategies with tyrosine kinase inhibitors through advanced 3D models (Review)

The limitations of two-dimensional (2D) models in cancer research have hindered progress in fully understanding the complexities of drug resistance and therapeutic failures. However, three-dimensional (3D) models provide a more accurate representation of in vivo environments, capturing critical cellular interactions and dynamics that are essential in evaluating the efficacy and toxicity of tyrosine kinase inhibitors (TKIs). These advanced models enable researchers to explore drug resistance mechanisms with greater precision, optimizing treatment strategies and improving the predictive accuracy of clinical outcomes. By leveraging 3D models, it will be possible to deepen the current understanding of TKIs and drive forward innovations in cancer treatment. The present review discusses the limitations of 2D models and the transformative impact of 3D models on oncology research, highlighting their roles in addressing the challenges of 2D systems and advancing TKI studies.

Organoid, organ-on-a-chip and traditional Chinese medicine

In the past few years, the emergence of organoids and organ-on-a-chip (OOAC) technologies, which are complementary to animal models and two-dimensional cell culture methods and can better simulate the internal environment of the human body, provides a new platform for traditional Chinese medicine (TCM) studies. Organoids and OOAC techniques have been increasingly applied in the fields of drug screening, drug assessment and development, personalized therapies, and developmental biology, and there have been some application cases in the TCM studies. In this review, we summarized the current status of using organoid and OOAC technologies in TCM research and provide key insights for future study. It is believed that organoid and OOAC technologies will play more and more important roles in research and make greater contributions to the innovative development of TCM.

Bridging silicon and carbon worlds with digital twins and on-chip systems in drug discovery

This perspective discusses the convergence of digital twin (DT) technology and on-the-chip systems as pivotal innovations in precision medicine, substantially advancing drug discovery. DT leverages extensive health data to create dynamic virtual patient models, enabling predictive insights and optimized treatment strategies. Concurrently, on-the-chip systems from the Carbon world replicate human biological processes on microfluidic platforms, providing detailed insights into disease mechanisms and pharmacological interactions. The convergence of these technologies promises to revolutionize drug development by enhancing therapeutic precision, accelerating discovery timelines, and reducing costs. Specifically, it assesses their role in drug development, from refining therapeutic precision to expediting discovery timelines and reducing the final price. Nevertheless, integrating these technologies faces challenges, including data collection and privacy concerns, technical intricacies, and clinical adoption barriers. This manuscript argues for interdisciplinary cooperation to navigate these challenges, positing DTs and on-the-chip technologies as foundational elements in personalized healthcare and drug discovery.

Novel bioassays based on 3D-printed device for sensing of hypoxia and p53 pathway in 3D cell models

Cell-based assays are widely exploited for drug screening and biosensing, providing useful information about bioactivity of target analytes and complex biological samples. It is well recognized that 3D cell models are required to achieve highly valuable information, also from the perspective of replacing animal models. However, bioassays relying on 3D cell models are generally highly demanding in terms of facilities, equipment, and skilled personnel requirements. To reduce cost, increase sustainability, and provide a flexible 3D cell-based platform for bioassays, we here report a novel approach based on a 3D-printed microtissue device. To assess the suitability of this strategy for reporter gene technology, we selected to monitor two molecular pathways which were of interest in several applications, hypoxia signaling and the p53 pathway. The investigation of such pathways is highly relevant in fields spanning from drug screening to bioactivity monitoring for industrial by-product valorization. Microtissues of human hepatocarcinoma (HepG2) and human embryonic kidney (Hek293T) cell lines were obtained with a low-cost and sustainable chip platform and bioassays were developed to monitor the hypoxia-inducible factors (HIFs) and the p53 tumor suppressor pathway. HepG2 and Hek293T 3D cell models were genetically engineered to express the Luc2P from Photinus pyralis firefly either under the regulation of p53 or HIF response elements. The bioassays allowed quantitative assessment of hypoxia and tumoral activity with 1,10-phenanthroline for HIF and with doxorubicin for p53 pathway activation, respectively, showing good potential for applications of this sustainable and low-cost 3D-printed microfluidic platform for bioactivity analyses, drug screening, and precision medicine.

Patient-derived organoids in precision cancer medicine

Organoids are three-dimensional (3D) cultures, normally derived from stem cells, that replicate the complex structure and function of human tissues. They offer a physiologically relevant model to address important questions in cancer research. The generation of patient-derived organoids (PDOs) from various human cancers allows for deeper insights into tumor heterogeneity and spatial organization. Additionally, interrogating non-tumor stromal cells increases the relevance in studying the tumor microenvironment, thereby enhancing the relevance of PDOs in personalized medicine. PDOs mark a significant advancement in cancer research and patient care, signifying a shift toward more innovative and patient-centric approaches. This review covers aspects of PDO cultures to address the modeling of the tumor microenvironment, including extracellular matrices, air-liquid interface and microfluidic cultures, and organ-on-chip. Specifically, the role of PDOs as preclinical models in gene editing, molecular profiling, drug testing, and biomarker discovery and their potential for guiding personalized treatment in clinical practice are discussed.

Thyroid cancer risk associated with perfluoroalkyl carboxylate exposure: Assessment using a human dermal fibroblast-derived extracellular matrix-based thyroid cancer organoid

The burgeoning incidence of thyroid cancer globally necessitates a deeper understanding of its etiological factors. Emerging research suggests a link to environmental contaminants, notably perfluoroalkyl carboxylates (PFACs). This study introduces a novel biomaterial-based approach for modeling thyroid cancer and assesses PFAC exposure-related health risks. This biomaterial-centric methodology enabled a realistic simulation of long-term, low-dose PFAC exposure, yielding critical insights into their carcinogenic potential. Initially, the no observed adverse effect level concentration of 10 μM for four different PFACs, determined using cytotoxicity tests in 2D cell cultures, was employed with thyroid cancer organoids. Specifically, these organoids were exposed to 10 μM of PFACs, refreshed every 3 days over a period of 21 days. The impact of these PFACs on the organoids was assessed using western blotting and immunofluorescence, complemented by high-content screening imaging. This evaluation focused on thyroid-specific biomarkers, epithelial-mesenchymal transition markers, and the proliferation marker Ki-67. Findings indicated significant alterations in these markers, particularly with long-chain PFACs, suggesting an increased risk of thyroid cancer progression and metastasis upon prolonged exposure. This research advances our understanding of thyroid cancer pathology within the context of environmental health risks by investigating the effects of low-dose, long-term exposure to PFACs on human thyroid cancer organoids. The findings reveal the potential carcinogenic risk associated with these substances, emphasizing the urgent need for stricter regulatory controls.

Leveraging Xenobiotic-Responsive Cancer Stemness in Cell Line-Based Tumoroids for Evaluating Chemoresistance: A Proof-of-Concept Study on Environmental Susceptibility

Emerging evidence suggests that cancer stemness plays a crucial role in tumor progression, metastasis, and chemoresistance. Upon exposure to internal or external stress, ribosomes stand sentinel and facilitate diverse biological processes, including oncological responses. In the present study, ribosome-inactivating stress (RIS) was evaluated for its modulation of cancer cell stemness as a pivotal factor of tumor cell reprogramming. Based on the concept of stress-responsive cancer cell stemness, we addressed human intestinal cancer cell line-based off-the-shelf spheroid cultures. Intestinal cancer cell line-based spheroids exhibited heightened levels of CD44+CD133+ cancer stemness, which was improved by chemical-induced RIS. Further evaluations revealed the potential of these stress-imprinted spheroids as a platform for chemoresistance screening. Compared to adherent cells, stemness-improved spheroid cultures displayed reduced apoptosis in response to 5-fluorouracil (5-FU), a frontline chemotherapeutic agent against colorectal cancer. Moreover, serial subcultures with repeated RIS exposure maintained and even enhanced cancer stemness and chemoresistance patterns. In particular, isolated CD44+CD133+ cancer stem cells exhibited higher chemoresistance compared to unsorted cells. To elucidate the mechanisms underlying RIS-induced stemness, RNA-seq analysis identified Wnt signaling pathways and stemness-associated signals as notable features in spheroids exposed to RIS. Loss-of-function studies targeting connective tissue growth factor (CTGF), a negative regulator of Wnt signaling, revealed that CTGF-deficient spheroids exhibited improved cancer stemness and resistance to 5-FU, with RIS further enhancing these effects. In conclusion, this proof-of-concept study demonstrates the feasibility of leveraging stress-responsive cancer stemness for the development of spheroid-based platforms for chemoresistance evaluation and elucidation of pathophysiological processes of colorectal tumorigenesis under environmental stress.

Tumor-microenvironment-on-a-chip: the construction and application

Currently, despite the vast amounts of time and money invested in cancer treatment, cancer remains one of the primary threats to human life. The primary factor contributing to the low treatment efficacy is cancer heterogeneity. The unclear molecular mechanisms underlying tumorigenesis, coupled with the complexity of human physiology, and the inability of animal models to accurately replicate the human tumor microenvironment, pose significant hurdles in the development of novel cancer therapies. Tumor-microenvironment-on-chip (TMOC) represents a research platform that integrates three-dimensional cell culture with microfluidic systems, simulating the essential components and physiological traits of the in vivo tumor microenvironment. It offers a dynamic setting within the chip system to study tumor progression, potentially heralding a breakthrough in cancer research. In this review, we will summarize the current advancements in this platform, encompassing various types of TMOCs and their applications in different types of cancer. From our perspective, the TMOC platform necessitates enhanced integration with tissue engineering techniques and microphysiological environments before it can evolve into a more refined preclinical model for cancer research.

Reversible bonding in thermoplastic elastomer microfluidic platforms for harvestable 3D microvessel networks

Transplantable ready-made microvessels have therapeutic potential for tissue regeneration and cell replacement therapy. Inspired by the natural rapid angiogenic sprouting of microvessels in vivo, engineered injectable 3D microvessel networks are created using thermoplastic elastomer (TPE) microfluidic devices. The TPE material used here is flexible, optically transparent, and can be robustly yet reversibly bonded to a variety of plastic substrates, making it a versatile choice for microfluidic device fabrication because it overcomes the weak self-adhesion properties and limited manufacturing options of poly(dimethylsiloxane) (PDMS). By leveraging the reversible bonding characteristics of TPE material templates, we present their utility as an organ-on-a-chip platform for forming and handling microvessel networks, and demonstrate their potential for animal-free tissue generation and transplantation in clinical applications. We first show that TPE-based devices have nearly 6-fold higher bonding strength during the cell culture step compared to PDMS-based devices while simultaneously maintaining a full reversible bond to (PS) culture plates, which are widely used for biological cell studies. We also demonstrate the successful generation of perfusable and interconnected 3D microvessel networks using TPE-PS microfluidic devices on both single and multi-vessel loading platforms. Importantly, after removing the TPE slab, microvessel networks remain intact on the PS substrate without any structural damage and can be effectively harvested following gel digestion. The TPE-based organ-on-a-chip platform offers substantial advantages by facilitating the harvesting procedure and maintaining the integrity of microfluidic-engineered microvessels for transplant. To the best of our knowledge, our TPE-based reversible bonding approach marks the first confirmation of successful retrieval of organ-specific vessel segments from the reversibly-bonded TPE microfluidic platform. We anticipate that the method will find applications in organ-on-a-chip and microphysiological system research, particularly in tissue analysis and vessel engraftment, where flexible and reversible bonding can be utilized.

Emerging microfluidic gut-on-a-chip systems for drug development

The gut is a vital organ that is central to the absorption and metabolic processing of orally administered drugs. While there have been many models developed with the goal of studying the absorption of drugs in the gut, these models fail to adequately recapitulate the diverse, complex gastrointestinal microenvironment. The recent emergence of microfluidic organ-on-a-chip technologies has provided a novel means of modeling the gut, yielding radical new insights into the structure of the gut and the mechanisms through which it shapes disease, with key implications for biomedical developmental efforts. Such organ-on-a-chip technologies have been demonstrated to exhibit greater cost-effectiveness, fewer ethical concerns, and a better ability to address inter-species differences in traditional animal models in the context of drug development. The present review offers an overview of recent developments in the reconstruction of gut structure and function in vitro using microfluidic gut-on-a-chip (GOC) systems, together with a discussion of the potential applications of these platforms in the context of drug development and the challenges and future prospects associated with this technology. STATEMENT OF SIGNIFICANCE: This paper outlines the characteristics of the different cell types most frequently used to construct microfluidic gut-on-a-chip models and the microfluidic devices employed for the study of drug absorption. And the applications of gut-related multichip coupling and disease modelling in the context of drug development is systematically reviewed. With the detailed summarization of microfluidic chip-based gut models and discussion of the prospective directions for practical application, this review will provide insights to the innovative design and application of microfluidic gut-on-a-chip for drug development.

Genome-wide pan-GPCR cell libraries accelerate drug discovery

G protein-coupled receptors (GPCRs) are pivotal in mediating diverse physiological and pathological processes, rendering them promising targets for drug discovery. GPCRs account for about 40% of FDA-approved drugs, representing the most successful drug targets. However, only approximately 15% of the 800 human GPCRs are targeted by market drugs, leaving numerous opportunities for drug discovery among the remaining receptors. Cell expression systems play crucial roles in the GPCR drug discovery field, including novel target identification, structural and functional characterization, potential ligand screening, signal pathway elucidation, and drug safety evaluation. Here, we discuss the principles, applications, and limitations of widely used cell expression systems in GPCR-targeted drug discovery, GPCR function investigation, signal pathway characterization, and pharmacological property studies. We also propose three strategies for constructing genome-wide pan-GPCR cell libraries, which will provide a powerful platform for GPCR ligand screening, and facilitate the study of GPCR mechanisms and drug safety evaluation, ultimately accelerating the process of GPCR-targeted drug discovery.

Brain-on-a-chip: an emerging platform for studying the nanotechnology-biology interface for neurodegenerative disorders

Neurological disorders have for a long time been a global challenge dismissed by drug companies, especially due to the low efficiency of most therapeutic compounds to cross the brain capillary wall, that forms the blood-brain barrier (BBB) and reach the brain. This has boosted an incessant search for novel carriers and methodologies to drive these compounds throughout the BBB. However, it remains a challenge to artificially mimic the physiology and function of the human BBB, allowing a reliable, reproducible and throughput screening of these rapidly growing technologies and nanoformulations (NFs). To surpass these challenges, brain-on-a-chip (BoC) - advanced microphysiological platforms that emulate key features of the brain composition and functionality, with the potential to emulate pathophysiological signatures of neurological disorders, are emerging as a microfluidic tool to screen new brain-targeting drugs, investigate neuropathogenesis and reach personalized medicine. In this review, the advance of BoC as a bioengineered screening tool of new brain-targeting drugs and NFs, enabling to decipher the intricate nanotechnology-biology interface is discussed. Firstly, the main challenges to model the brain are outlined, then, examples of BoC platforms to recapitulate the neurodegenerative diseases and screen NFs are summarized, emphasizing the current most promising nanotechnological-based drug delivery strategies and lastly, the integration of high-throughput screening biosensing systems as possible cutting-edge technologies for an end-use perspective is discussed as future perspective.

Microfluidic systems for modeling digestive cancer: a review of recent progress

Purpose. This review aims to highlight current improvements in microfluidic devices designed for digestive cancer simulation. The review emphasizes the use of multicellular 3D tissue engineering models to understand the complicated biology of the tumor microenvironment (TME) and cancer progression. The purpose is to develop oncology research and improve digestive cancer patients' lives.Methods. This review analyzes recent research on microfluidic devices for mimicking digestive cancer. It uses tissue-engineered microfluidic devices, notably organs on a chip (OOC), to simulate human organ function in the lab. Cell cultivation on modern three-dimensional hydrogel platforms allows precise geometry, biological components, and physiological qualities. The review analyzes novel methodologies, key findings, and technical progress to explain this field's advances.Results. This study discusses current advances in microfluidic devices for mimicking digestive cancer. Micro physiological systems with multicellular 3D tissue engineering models are emphasized. These systems capture complex biochemical gradients, niche variables, and dynamic cell-cell interactions in the tumor microenvironment (TME). These models reveal stomach cancer biology and progression by duplicating the TME. Recent discoveries and technology advances have improved our understanding of gut cancer biology, as shown in the review.Conclusion. Microfluidic systems play a crucial role in modeling digestive cancer and furthering oncology research. These platforms could transform drug development and treatment by revealing the complex biology of the tumor microenvironment and cancer progression. The review provides a complete summary of recent advances and suggests future research for field professionals. The review's major goal is to further medical research and improve digestive cancer patients' lives.

Know your molecule: pharmacological characterization of drug candidates to enhance efficacy and reduce late-stage attrition

Despite advances in chemical, computational and biological sciences, the rate of attrition of drug candidates in clinical development is still high. A key point in the small-molecule discovery process that could provide opportunities to help address this challenge is the pharmacological characterization of hit and lead compounds, culminating in the selection of a drug candidate. Deeper characterization is increasingly important, because the 'quality' of drug efficacy, at least for G protein-coupled receptors (GPCRs), is now understood to be much more than activation of commonly evaluated pathways such as cAMP signalling, with many more 'efficacies' of ligands that could be harnessed therapeutically. Such characterization is being enabled by novel assays to characterize the complex behaviour of GPCRs, such as biased signalling and allosteric modulation, as well as advances in structural biology, such as cryo-electron microscopy. This article discusses key factors in the assessments of the pharmacology of hit and lead compounds in the context of GPCRs as a target class, highlighting opportunities to identify drug candidates with the potential to address limitations of current therapies and to improve the probability of them succeeding in clinical development.

Inhibition of Transmural Inflammation in Crohn's Disease by Orally Administered Tumor Necrosis Factor-Alpha Deoxyribozymes-Loaded Pyroptosis Nanoinhibitors

Crohn's disease (CD) is a refractory chronic inflammatory bowel disease (IBD) with unknown etiology. Transmural inflammation, involving the intestine and mesentery, represents a characteristic pathological feature of CD and serves as a critical contributor to its intractability. Here, this study describes an oral pyroptosis nanoinhibitor loaded with tumor necrosis factor-α (TNF-α) deoxyribozymes (DNAzymes) (DNAzymes@degradable silicon nanoparticles@Mannose, Dz@MDSN), which can target macrophages at the site of inflammation and respond to reactive oxygen species (ROS) to release drugs. Dz@MDSN can not only break the inflammatory cycle in macrophages by degrading TNF-α mRNA but also reduce the production of ROS mainly from macrophages. Moreover, Dz@MDSN inhibits excessive pyroptosis in epithelial cells through ROS clearance, thereby repairing the intestinal barrier and reducing the translocation of intestinal bacteria to the mesentery. Consequently, these combined actions synergistically contribute to the suppression of inflammation within both the intestine and the mesentery. This study likely represents the first successful attempt in the field of utilizing nanomaterials to achieve transmural healing for CD, which also provides a promising treatment strategy for CD patients.

Neuroinflammation-on-a-chip for multiple sclerosis research: a narrative review

Introduction

Multiple sclerosis (MS) is a chronic inflammatory condition that impacts the central nervous system. It is distinguished by processes like demyelination, gliosis, neuro-axonal harm, and inflammation. The prevailing theory suggests that MS originates from an immune response directed against the body's own antigens within the central nervous system.

Aim

The main aim of this research paper "Neuroinflammation-on-a-Chip" for studying multiple sclerosis is to enhance our comprehension of MS development, demonstrate the application of cutting-edge technology, and potentially provide valuable insights for therapeutic approaches.

Methods

The available literature for this Narrative Review was searched on various bibliographic databases, PubMed, NCBI, and many other medical references using an individually verified, prespecified approach. Studies regarding the significance of MS and its neuroinflammatory pathogenesis in addition to the development and optimization of neuroinflammatory-on-a-chip and the advancement in innovations in this field have been reviewed in this research for a better understanding of "Neuroinflammation-on-a-chip for multiple sclerosis". The level of evidence of the included studies was considered as per the Centre for Evidence-Based Medicine recommendations.

Results

Several studies have indicated that the brain-chip model closely mimics cortical brain tissue compared to commonly used conventional cell culture methods like the Transwell culture system. Additionally, these studies have clearly demonstrated that further research using brain chips has the potential to enhance our understanding of the molecular mechanisms and roles of blood-brain barrier (BBB) transporters in both normal and disease conditions.

Conclusion

Understanding neuroinflammation processes remains essential to establish new MS treatments approaches. The utilization of brain chips promises to advance our understanding of the molecular processes involving BBB transporters, both in normal and diseased states. Further research needs to be addressed in order to enhance the performance and understanding of neuroinflammation on a chip, hence aiming to provide more effective treatments for all CNS diseases.

Tailoring epilepsy treatment: personalized micro-physiological systems illuminate individual drug responses

Introduction

Approximately 50 million people worldwide have epilepsy, with many not achieving seizure freedom. Organ-on-chip technology, which mimics organ-level physiology, could revolutionize drug development for epilepsy by replacing animal models in preclinical studies. The authors' goal is to determine if customized micro-physiological systems can lead to tailored drug treatments for epileptic patients.

Materials and methods

A comprehensive literature search was conducted utilizing various databases, including PubMed, Ebscohost, Medline, and the National Library of Medicine, using a predetermined search strategy. The authors focused on articles that addressed the role of personalized micro-physiological systems in individual drug responses and articles that discussed different types of epilepsy, diagnosis, and current treatment options. Additionally, articles that explored the components and design considerations of micro-physiological systems were reviewed to identify challenges and opportunities in drug development for challenging epilepsy cases.

Results

The micro-physiological system offers a more accurate and cost-effective alternative to traditional models for assessing drug effects, toxicities, and disease mechanisms. Nevertheless, designing patient-specific models presents critical considerations, including the integration of analytical biosensors and patient-derived cells, while addressing regulatory, material, and biological complexities. Material selection, standardization, integration of vascular systems, cost efficiency, real-time monitoring, and ethical considerations are also crucial to the successful use of this technology in drug development.

Conclusion

The future of organ-on-chip technology holds great promise, with the potential to integrate artificial intelligence and machine learning for personalized treatment of epileptic patients.

Lymph Node-on-Chip Technology: Cutting-Edge Advances in Immune Microenvironment Simulation

Organ-on-a-chip technology is attracting growing interest across various domains as a crucial platform for drug screening and testing and is set to play a significant role in precision medicine research. Lymph nodes, being intricately structured organs essential for the body's adaptive immune responses to antigens and foreign particles, are pivotal in assessing the immunotoxicity of novel pharmaceuticals. Significant progress has been made in research on the structure and function of the lymphatic system. However, there is still an urgent need to develop prospective tools and techniques to delve deeper into its role in various diseases' pathological and physiological processes and to develop corresponding immunotherapeutic therapies. Organ chips can accurately reproduce the specific functional areas in lymph nodes to better simulate the complex microstructure of lymph nodes and the interactions between different immune cells, which is convenient for studying specific biological processes. This paper reviews existing lymph node chips and their design approaches. It discusses the applications of the above systems in modeling immune cell motility, cell-cell interactions, vaccine responses, drug testing, and cancer research. Finally, we summarize the challenges that current research faces in terms of structure, cell source, and extracellular matrix simulation of lymph nodes, and we provide an outlook on the future direction of integrated immune system chips.

Advances in the Model Structure of In Vitro Vascularized Organ-on-a-Chip

Microvasculature plays a crucial role in human physiology and is closely related to various human diseases. Building in vitro vascular networks is essential for studying vascular tissue behavior with repeatable morphology and signaling conditions. Engineered 3D microvascular network models, developed through advanced microfluidic-based techniques, provide accurate and reproducible platforms for studying the microvasculature in vitro, an essential component for designing organ-on-chips to achieve greater biological relevance. By optimizing the microstructure of microfluidic devices to closely mimic the in vivo microenvironment, organ-specific models with healthy and pathological microvascular tissues can be created. This review summarizes recent advancements in in vitro strategies for constructing microvascular tissue and microfluidic devices. It discusses the static vascularization chips' classification, structural characteristics, and the various techniques used to build them: growing blood vessels on chips can be either static or dynamic, and in vitro blood vessels can be grown in microchannels, elastic membranes, and hydrogels. Finally, the paper discusses the application scenarios and key technical issues of existing vascularization chips. It also explores the potential for a novel organoid chip vascularization approach that combines organoids and organ chips to generate better vascularization chips.

Allogeneic bone marrow mesenchymal stem cell-derived exosomes alleviate human hypoxic AKI-on-a-Chip within a tight treatment window

BACKGROUND

Acute hypoxic proximal tubule (PT) injury and subsequent maladaptive repair present high mortality and increased risk of acute kidney injury (AKI) - chronic kidney disease (CKD) transition. Human bone marrow mesenchymal stem cell-derived exosomes (hBMMSC-Exos) as potential cell therapeutics can be translated into clinics if drawbacks on safety and efficacy are clarified. Here, we determined the real-time effective dose and treatment window of allogeneic hBMMSC-Exos, evaluated their performance on the structural and functional integrity of 3D microfluidic acute hypoxic PT injury platform.

METHODS

hBMMSC-Exos were isolated and characterized. Real-time impedance-based cell proliferation analysis (RTCA) determined the effective dose and treatment window for acute hypoxic PT injury. A 2-lane 3D gravity-driven microfluidic platform was set to mimic PT in vitro. ZO-1, acetylated α-tubulin immunolabelling, and permeability index assessed structural; cell proliferation by WST-1 measured functional integrity of PT.

RESULTS

hBMMSC-Exos induced PT proliferation with ED50 of 172,582 µg/ml at the 26th hour. Hypoxia significantly decreased ZO-1, increased permeability index, and decreased cell proliferation rate on 24-48 h in the microfluidic platform. hBMMSC-Exos reinforced polarity by a 1.72-fold increase in ZO-1, restored permeability by 20/45-fold against 20/155 kDa dextran and increased epithelial proliferation 3-fold compared to control.

CONCLUSIONS

The real-time potency assay and 3D gravity-driven microfluidic acute hypoxic PT injury platform precisely demonstrated the therapeutic performance window of allogeneic hBMMSC-Exos on ischemic AKI based on structural and functional cellular data. The novel standardized, non-invasive two-step system validates the cell-based personalized theragnostic tool in a real-time physiological microenvironment prior to safe and efficient clinical usage in nephrology.

Microphysiological systems for human aging research

Recent advances in microphysiological systems (MPS), also known as organs-on-a-chip (OoC), enable the recapitulation of more complex organ and tissue functions on a smaller scale in vitro. MPS therefore provide the potential to better understand human diseases and physiology. To date, numerous MPS platforms have been developed for various tissues and organs, including the heart, liver, kidney, blood vessels, muscle, and adipose tissue. However, only a few studies have explored using MPS platforms to unravel the effects of aging on human physiology and the pathogenesis of age-related diseases. Age is one of the risk factors for many diseases, and enormous interest has been devoted to aging research. As such, a human MPS aging model could provide a more predictive tool to understand the molecular and cellular mechanisms underlying human aging and age-related diseases. These models can also be used to evaluate preclinical drugs for age-related diseases and translate them into clinical settings. Here, we provide a review on the application of MPS in aging research. First, we offer an overview of the molecular, cellular, and physiological changes with age in several tissues or organs. Next, we discuss previous aging models and the current state of MPS for studying human aging and age-related conditions. Lastly, we address the limitations of current MPS and present future directions on the potential of MPS platforms for human aging research.

Organoids and organoids-on-a-chip as the new testing strategies for environmental toxicology-applications & advantages

An increasing number of harmful environmental factors are causing serious impacts on human health, and there is an urgent need to accurately identify the toxic effects and mechanisms of these harmful environmental factors. However, traditional toxicity test methods (e.g., animal models and cell lines) often fail to provide accurate results. Fortunately, organoids differentiated from stem cells can more accurately, sensitively and specifically reflect the effects of harmful environmental factors on the human body. They are also suitable for specific studies and are frequently used in environmental toxicology nowadays. As a combination of organoids and organ-on-a-chip technology, organoids-on-a-chip has great potential in environmental toxicology. It is more controllable to the physicochemical microenvironment and is not easy to be contaminated. It has higher homogeneity in the size and shape of organoids. In addition, it can achieve vascularization and exchange the nutrients and metabolic wastes in time. Multi-organoids-chip can also simulate the interactions of different organs. These advantages can facilitate better function and maturity of organoids, which can also make up for the shortcomings of common organoids to a certain extent. This review firstly discussed the limitations of traditional toxicology testing platforms, leading to the introduction of new platforms: organoids and organoids-on-a-chip. Next, the applications of different organoids and organoids-on-a-chip in environmental toxicology were summarized and prospected. Since the advantages of the new platforms have not been sufficiently considered in previous literature, we particularly emphasized them. Finally, this review also summarized the opportunities and challenges faced by organoids and organoids-on-a-chip, with the expectation that readers will gain a deeper understanding of their value in the field of environmental toxicology.

Advances in microfluidic chips targeting toxic aggregation proteins for neurodegenerative diseases

Neurodegenerative diseases (NDs) are characterized by nervous system damage, often influenced by genetic and aging factors. Pathological analysis frequently reveals the presence of aggregated toxic proteins. The intricate and poorly understood origins of these diseases have hindered progress in early diagnosis and drug development. The development of novel in-vitro and in-vivo models could enhance our comprehension of ND mechanisms and facilitate clinical treatment advancements. Microfluidic chips are employed to establish three-dimensional culture conditions, replicating the human ecological niche and creating a microenvironment conducive to neuronal cell survival. The incorporation of mechatronic controls unifies the chip, cells, and culture medium optimizing living conditions for the cells. This study provides a comprehensive overview of microfluidic chip applications in drug and biomarker screening for neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, and amyotrophic lateral sclerosis. Our Lab-on-a-Chip system releases toxic proteins to simulate the pathological characteristics of neurodegenerative diseases, encompassing β-amyloid, α-synuclein, huntingtin, TAR DNA-binding protein 43, and Myelin Basic Protein. Investigating molecular and cellular interactions in vitro can enhance our understanding of disease mechanisms while minimizing harmful protein levels and can aid in screening potential therapeutic agents. We anticipate that our research will promote the utilization of microfluidic chips in both fundamental research and clinical applications for neurodegenerative diseases.

Trends in Photopolymerizable Bioinks for 3D Bioprinting of Tumor Models

Three-dimensional (3D) bioprinting technologies involving photopolymerizable bioinks (PBs) have attracted enormous attention in recent times owing to their ability to recreate complex structures with high resolution, mechanical stability, and favorable printing conditions that are suited for encapsulating cells. 3D bioprinted tissue constructs involving PBs can offer better insights into the tumor microenvironment and offer platforms for drug screening to advance cancer research. These bioinks enable the incorporation of physiologically relevant cell densities, tissue-mimetic stiffness, and vascularized channels and biochemical gradients in the 3D tumor models, unlike conventional two-dimensional (2D) cultures or other 3D scaffold fabrication technologies. In this perspective, we present the emerging techniques of 3D bioprinting using PBs in the context of cancer research, with a specific focus on the efforts to recapitulate the complexity of the tumor microenvironment. We describe printing approaches and various PB formulations compatible with these techniques along with recent attempts to bioprint 3D tumor models for studying migration and metastasis, cell-cell interactions, cell-extracellular matrix interactions, and drug screening relevant to cancer. We discuss the limitations and identify unexplored opportunities in this field for clinical and commercial translation of these emerging technologies.