Synovial joint-on-a-chip for modeling arthritis: progress, pitfalls, and potential

Therapeutic Potential of Adipose Mesenchymal Stem Cells for Synovial Regeneration: from In-Vitro Studies to Clinical Applications

Synovial joint disorders affect a substantial proportion of the global population, posing a significant challenge to the individual patient and global healthcare systems. Novel therapeutic strategies for resolving cartilage and synovial damage have recently been investigated. Adipose-derived mesenchymal stem cells (AD-MSCs) emerged as a potential cell-based therapy approach due to their accessibility, abundance, low immunogenicity, immunomodulatory effect, and tissue repair capability. The translation of AD-MSCs-based therapies from bench to clinical practice has shown promising results; with extensive evidence supporting their feasibility and efficacy for treating joint disorders. Despite their considerable potential, however, few AD-MSCs-based therapies have been approved for clinical application, primarily due to a lack of standardization and a poorly understood mechanism of action in vivo. The characterization of AD-MSCs from in vitro to in vivo models and eventually to clinical trials enables a comprehensive assessment of their therapeutic potential in synovial regeneration, bridging the gap between basic research and clinical application. The advantages and limitations collected from studies that delineate the effect of AD-MSCs on synovial cells will help researchers translate this cell-therapy approach from bench to clinical application. This review examines current models and applications of their therapeutic potential for synovial regeneration from in vitro studies to clinical trials. We also discuss the potential of cell-free therapy for joint disorders by means of extracellular vesicles.

Musculoskeletal organoids: An emerging toolkit for establishing personalized models of musculoskeletal disorders and developing regenerative therapies

Musculoskeletal (MSK) conditions are the primary cause of physical disability globally. These disorders are physically and mentally debilitating and severely impact the patients' quality of life. As the median age of the world's population increases, there has been an intensifying urgency of developing efficacious therapies for various orthopaedic conditions. Furthermore, the highly heterogeneous nature of MSK conditions calls for a personalized approach to studying disease mechanisms and developing regenerative treatments. Organoids have emerged as an advanced approach to generating functional tissue/organ mimics in vitro, which hold promise in MSK regeneration, disease modeling, and therapeutic development. Herein, we review the preparation, characterization, and application of various MSK organoids. We highlight the potential of patient-specific organoids in the development of personalized medicine and discuss the challenges and opportunities in the future development of MSK organoids. STATEMENT OF SIGNIFICANCE: Despite decades of research, translation of MSK research into clinical applications remains limited, partially attributed to our inadequate understanding of disease mechanisms. To advance therapeutic development, there are critical needs for MSK disease models with higher clinical relevance and predictive power. Additionally, engineered constructs that closely mimic the structural and functional features of native MSK tissues are highly desirable. MSK organoids have emerged as a promising approach to meet the above requirements. To unleash the full potential of MSK organoids necessitates a comprehensive understanding of their categories, construction, development, functions, applications, and challenges. This review aims to fulfill this crucial need, aiming to accelerate the clinical translation of MSK organoid platforms to benefit millions of patients afflicted with MSK conditions.

Latest developments of microphysiological systems (MPS) in aging-related and geriatric diseases research: A review

Aging is a gradual and irreversible process accompanied by the decline in tissue function and a significantly increased risk of various aging-related and geriatric diseases. Especially in the paradoxical context of accelerated global aging and the widespread emergence of pandemics, aging-related and geriatric diseases have become leading causes of individual mortality and disability, drawing increasing attention from researchers and investors alike. Despite the utility of current in vitro systems and in vivo animal models for studying aging, these approaches are limited by insurmountable inherent constraints. In response, microphysiological systems (MPS), leveraging advances in tissue engineering and microfluidics, have emerged as highly promising platforms. MPS are capable of replicating key features of the tissue microenvironment within microfabricated devices, offering biomimetic tissue culture conditions that enhance the in vitro simulation of intact or precise human body structure and function. This capability improves the predictability of clinical trial outcomes while reducing time and cost. In this review, we focus on recent advancements in MPS used to study age-related and geriatric diseases, with particular emphasis on the application of organoids and organ-on-a-chip technologies in understanding cardiovascular diseases, cerebrovascular diseases, neurodegenerative diseases, fibrotic diseases, locomotor and sensory degenerative disorders, and rare diseases. And we aim to provide readers with critical guidelines and an overview of examples for modeling age-related and geriatric diseases using MPS, exploring mechanisms, treatments, drug screening, and other subsequent applications, from a physiopathological perspective, emphasizing the characteristic of age-related and geriatric diseases and their established correlations with the aging process. We also discuss the limitations of current models and propose future directions for MPS in aging research, highlighting the potential of interdisciplinary approaches to address unresolved challenges in the field.

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.

Microfluidic chip-based co-culture system for modeling human joint inflammation in osteoarthritis research

Here we present a microfluidic model that allows for co-culture of human osteoblasts, chondrocytes, fibroblasts, and macrophages of both quiescent (M0) and pro-inflammatory (M1) phenotypes, maintaining initial viability of each cell type at 24 h of co-culture. We established healthy (M0-based) and diseased (M1-based) joint models within this system. An established disease model based on supplementation of IFN-γ and lipopolysaccharide in cell culture media was used to induce an M1 phenotype in macrophages to recapitulate inflammatory conditions found in Osteoarthritis. Cell viability was assessed using NucBlue™ Live and NucGreen™ Dead fluorescent stains, with mean viability of 83.9% ± 14% and 83.3% ± 12% for healthy and diseased models, respectively, compared with 93.3% ± 4% for cell in standard monoculture conditions. Cytotoxicity was assessed via a lactate dehydrogenase (LDH) assay and showed no measurable increase in lactate dehydrogenase release into the culture medium under co-culture conditions, indicating that neither model promotes a loss of cell membrane integrity due to cytotoxic effects. Cellular metabolic activity was assessed using a PrestoBlue™ assay and indicated increased cellular metabolic activity in co-culture, with levels 5.9 ± 3.2 times mean monolayer cell metabolic activity levels in the healthy joint model and 5.3 ± 3.4 times mean monolayer levels in the diseased model. Overall, these findings indicate that the multi-tissue nature of in vivo human joint conditions can be recapitulated by our microfluidic co-culture system at 24 h and thus this model serves as a promising tool for studying the pathophysiology of rheumatic diseases and testing potential therapeutics.

Constructing a 3D co-culture in vitro synovial tissue model for rheumatoid arthritis research

The development and exploration of highly effective drugs for rheumatoid arthritis remains an urgent necessity. However, current disease research models are no longer sufficient to meet the rapid development of high-throughput drug screening. In this study, bacterial cellulose simulating the structure of extracellular matrix was used as a 3D culture platform, and THP-1-derived M1 macrophages, representing the inflammatory component, human umbilical vein endothelial cells (HUVECs), simulating the vascular component, and rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs), embodying the synovial pathology, were co-cultured to simulate the pathological microenvironment in RA synovial tissues, and synovial organoids were constructed. Under three-dimensional (3D) culture conditions, there was a notable upregulation of fatty acid-binding protein 4 (FABP4) in polarized macrophages, and an enhancement of pathological phenotypes in HUVECs and RA-FLSs, mediated through the PI3K/AKT signaling pathway, including cell proliferation, migration, invasion and vascularization. Compared to planar cultures and 2D co-cultures, 3D synovial organoids not only exhibit a broader range of transcriptomic features characteristic of rheumatoid arthritis but also demonstrate increased drug resistance, likely due to the more complex and physiologically relevant cell-cell and cell-matrix interactions present in 3D environments. This model offers a promising path for personalized treatment, accelerating precision medicine in rheumatology.

Deciphering cartilage neuro-immune interactions and innervation profile through 3D engineered osteoarthritic micropathophysiological system

Osteoarthritis (OA) is an inflammatory musculoskeletal disorder that results in cartilage breakdown and alterations in the surrounding tissue microenvironment. Imbalances caused by inflammation and catabolic processes potentiate pathological nerves and blood vessels outgrowth toward damaged areas leading to pain in the patients. Yet, the precise mechanisms leading the nerve sprouting into the aneural cartilaginous tissue remain elusive. In this work, we aim to recapitulate in vitro the hallmarks of OA pathophysiology, including the sensory innervation profile, and provide a sensitive and reliable analytical tool to monitor the in vitro disease progression at microscale. Leveraging the use of patient-derived cells and bioengineering cutting-edge technologies, we engineered cartilage-like microtissues composed of primary human chondrocytes encapsulated in gelatin methacrylate hydrogel. Engineered constructs patterned inside microfluidic devices show the expression of cartilage markers, namely collagen type II, aggrecan, SOX-9 and glycosaminoglycans. Upon pro-inflammatory triggering, using primary human pro-inflammatory macrophage secretome, hallmarks of OA are recapitulated namely catabolic processes of human chondrocytes and the sensory innervation profile, supported by gene expression and functional assays. To monitor the OA micropathological system, a highly sensitive technology - EliChip™ - is presented to quantitively assess the molecular signature of cytokines and growth factors (interleukin 6 and nerve growth factor) produced from a single microfluidic chip. Herein, we report a miniaturized pathophysiological model and analytical tool to foster the neuro-immune interactions playing a role in cartilage-related disorders.

The Role of Thrombospondins in Osteoarthritis: from Molecular Mechanisms to Therapeutic Potential

Osteoarthritis (OA) is a prevalent chronic degenerative joint disorder characterized by cartilage degeneration, joint inflammation, and pain. The pathogenesis of OA still remains unclear. Among the various factors contributing to OA, the role of extracellular matrix (ECM) proteins, particularly thrombospondins (TSPs), has garnered significant attention. TSPs, a family of multifunctional extracellular matrix glycoproteins, are known to participate in numerous physiological and pathological processes, including cell adhesion, migration, differentiation, angiogenesis, and synaptogenesis through cell-cell and cell-matrix interactions. In this review, we provide a summary of the current understanding of TSP proteins in the pathogenesis of OA, including their effects on cartilage homeostasis, synovial inflammation, and subchondral bone remodeling and arthritic pain. We also review the evidence supporting the potential of TSP proteins as diagnostic biomarkers and therapeutic targets, with a focus on recent advances in cartilage regeneration, gene delivery therapy and pain management. Considering the multifaceted roles of TSP proteins in maintaining articular homeostasis, TSP proteins emerge as promising therapeutic targets for OA.

Single-cell RNA sequencing in autoimmune diseases: New insights and challenges

Autoimmune diseases involve a variety of cell types, yet the intricacies of their individual roles within molecular mechanisms and therapeutic strategies remain poorly understood. Single-cell RNA sequencing (scRNA-seq) offers detailed insights into transcriptional diversity at the single-cell level, significantly advancing research in autoimmune diseases. This article explores how scRNA-seq enhances the understanding of cellular heterogeneity and its potential applications in the etiology, diagnosis, treatment, and prognosis of autoimmune diseases. By revealing a comprehensive cellular landscape, scRNA-seq illuminates the functional regulation of different cell subtypes during disease progression. It aids in identifying diagnostic and prognostic markers, and analyzing cell communication networks to uncover potential therapeutic targets. Despite its valuable contributions, addressing the limitations of scRNA-seq is essential for making further advancements.

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.

Musculoskeletal Organs-on-Chips: An Emerging Platform for Studying the Nanotechnology-Biology Interface

Nanotechnology-based approaches are promising for the treatment of musculoskeletal (MSK) disorders, which present significant clinical burdens and challenges, but their clinical translation requires a deep understanding of the complex interplay between nanotechnology and MSK biology. Organ-on-a-chip (OoC) systems have emerged as an innovative and versatile microphysiological platform to replicate the dynamics of tissue microenvironment for studying nanotechnology-biology interactions. This review first covers recent advances and applications of MSK OoCs and their ability to mimic the biophysical and biochemical stimuli encountered by MSK tissues. Next, by integrating nanotechnology into MSK OoCs, cellular responses and tissue behaviors may be investigated by precisely controlling and manipulating the nanoscale environment. Analysis of MSK disease mechanisms, particularly bone, joint, and muscle tissue degeneration, and drug screening and development of personalized medicine may be greatly facilitated using MSK OoCs. Finally, future challenges and directions are outlined for the field, including advanced sensing technologies, integration of immune-active components, and enhancement of biomimetic functionality. By highlighting the emerging applications of MSK OoCs, this review aims to advance the understanding of the intricate nanotechnology-MSK biology interface and its significance in MSK disease management, and the development of innovative and personalized therapeutic and interventional strategies.

Development of a Microphysiological Cartilage-on-Chip Platform for Dynamic Biomechanical Stimulation of Three-Dimensional Encapsulated Chondrocytes in Agarose Hydrogels

Osteoarthritis (OA) is one of the most prevalent joint diseases globally, characterized by the progressive breakdown of articular cartilage, resulting in chronic pain, stiffness, and loss of joint function. Despite its significant socioeconomic impact, therapeutic options remain limited, largely due to an incomplete understanding of the molecular mechanisms driving cartilage degradation and OA pathogenesis. Recent advances in in vitro modeling have revolutionized joint tissue research, transitioning from simplistic two-dimensional cell cultures to sophisticated three-dimensional (3D) constructs that more accurately mimic the physiological microenvironment of native cartilage. Over the last decade, organ-on-chip technologies have emerged as transformative tools in tissue engineering, offering microphysiological platforms with precise control over biomechanical and biochemical stimuli. These platforms are providing novel insights into tissue responses and disease progression and are increasingly integrated into the early stages of drug screening and development. In this article, we present a detailed experimental protocol for constructing a cartilage-on-chip system capable of delivering controlled dynamic biomechanical stimulation to 3D-encapsulated chondrocytes in an agarose hydrogel matrix. Our protocol, optimized for both bovine and human chondrocytes, begins with Basic Protocol 1, detailing the preparation and injection of cell-laden hydrogels into the microdevice. Basic Protocol 2 describes the application of dynamic mechanical loading using a calibrated pressurized pump. Finally, Basic Protocols 3 and 4 focus on the retrieval of the hydrogel and RNA extraction for downstream molecular analyses. This platform represents a critical advancement for in vitro studies of cartilage biology, enabling more precise modeling of OA pathophysiology and evaluation of experimental therapeutics. © 2024 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Cartilage-on-chip injection Basic Protocol 2: Cartilage-on-chip actuation Basic Protocol 3: Cartilage-on-chip agarose hydrogel removal Basic Protocol 4: Preparation of cartilage-on-chip for RNA extraction.

Skeletal organoids

The skeletal system, composed of bones, muscles, joints, ligaments, and tendons, serves as the foundation for maintaining human posture, mobility, and overall biomechanical functionality. However, with ageing, chronic overuse, and acute injuries, conditions such as osteoarthritis, intervertebral disc degeneration, muscle atrophy, and ligament or tendon tears have become increasingly prevalent and pose serious clinical challenges. These disorders not only result in pain, functional loss, and a marked reduction in patients' quality of life but also impose substantial social and economic burdens. Current treatment modalities, including surgical intervention, pharmacotherapy, and physical rehabilitation, often do not effectively restore the functionality of damaged tissues and are associated with high recurrence rates and long-term complications, highlighting significant limitations in their efficacy. Thus, there is a strong demand to develop novel and more effective therapeutic and reparative strategies. Organoid technology, as a three-dimensional micro-tissue model, can replicate the structural and functional properties of native tissues in vitro, providing a novel platform for in-depth studies of disease mechanisms, optimisation of drug screening, and promotion of tissue regeneration. In recent years, substantial advancements have been made in the research of bone, muscle, and joint organoids, demonstrating their broad application potential in personalised and regenerative medicine. Nonetheless, a comprehensive review of current research on skeletal organoids is still lacking. Therefore, this article aims to present an overview of the definition and technological foundation of organoids, systematically summarise the progress in the construction and application of skeletal organoids, and explore future opportunities and challenges in this field, offering valuable insights and references for researchers.

Fibroblast-like synoviocytes preferentially induce terminal differentiation of IgD+ memory B cells instead of naïve B cells

Rheumatoid arthritis (RA) is a systemic autoimmune disease driven by highly active autoantibody-producing B cells. Activation of B cells is maintained within ectopic germinal centres found in affected joints. Fibroblast-like synoviocytes (FLS) present in inflamed joints support B-cell survival, activation, and differentiation. CD27+ memory B cells and naive B cells show very different responses to activation, particularly by CD40 ligand (CD40L). We show that FLS-dependent activation of human B cells is dependent on interleukin-6 (IL-6) and CD40L. FLS have been shown to activate both naive and memory B cells. Whether the activating potential of FLS is different for naive and memory B cells has not been investigated. Our results suggest that FLS-induced activation of B cells is dependent on IL-6 and CD40L. While FLS are able to induce plasma cell differentiation, isotype switching, and antibody production in memory B cells, the ability of FLS to activate naive B cells is significantly lower.

A point-of-research decision in synovial tissue engineering: Mesenchymal stromal cells, tissue derived fibroblast or CTGF-mediated mesenchymal-to-fibroblast transition

Rheumatoid arthritis (RA) and osteoarthritis (OA) are prevalent inflammatory joint diseases characterized by synovitis, cartilage, and bone destruction. Fibroblast-like synoviocytes (FLSs) of the synovial membrane are a decisive factor in arthritis, making them a target for future therapies. Developing novel strategies targeting FLSs requires advanced in vitro joint models that accurately replicate non-diseased joint tissue. This study aims to identify a cell source reflecting physiological synovial fibroblasts. Therefore, we newly compared the phenotype and metabolism of "healthy" knee-derived FLSs from patients with ligament injuries (trauma-FLSs) to mesenchymal stromal cells (MSCs), their native precursors. We differentiated MSCs into fibroblasts using connective tissue growth factor (CTGF) and compared selected protein and gene expression patterns to those obtained from trauma-FLSs and OA-FLSs. Based on these findings, we explored the potential of an MSC-derived synovial tissue model to simulate a chronic inflammatory response akin to that seen in arthritis. We have identified MSCs as a suitable cell source for synovial tissue engineering because, despite metabolic differences, they closely resemble human trauma-derived FLSs. CTGF-mediated differentiation of MSCs increased HAS2 expression, essential for hyaluronan synthesis. It showed protein expression patterns akin to OA-FLSs, including markers of ECM components and fibrosis, and enzymes leading to a shift in metabolism towards increased fatty acid oxidation. In general, cytokine stimulation of MSCs in a synovial tissue model induced pro-inflammatory and pro-angiogenic gene expression, hyperproliferation, and increased glucose consumption, reflecting cellular response in human arthritis. We conclude that MSCs can serve as a proxy to study physiological synovial processes and inflammatory responses. In addition, CTGF-mediated mesenchymal-to-fibroblast transition resembles OA-FLSs. Thus, we emphasize MSCs as a valuable cell source for tools in preclinical drug screening and their application in tissue engineering.

Integrin signalling in joint development, homeostasis and osteoarthritis

Integrins are key regulators of cell-matrix interactions during joint development and joint tissue homeostasis, as well as in the development of osteoarthritis (OA). The signalling cascades initiated by the interactions of integrins with a complex network of extracellular matrix (ECM) components and intracellular adaptor proteins orchestrate cellular responses necessary for maintaining joint tissue integrity. Dysregulated integrin signalling, triggered by matrix degradation products such as matrikines, disrupts this delicate balance, tipping the scales towards an environment conducive to OA pathogenesis. The interplay between integrin signalling and growth factor pathways further underscores the multifaceted nature of OA. Moreover, emerging insights into the role of endocytic trafficking in regulating integrin signalling add a new layer of complexity to the understanding of OA development. To harness the therapeutic potential of targeting integrins for mitigation of OA, comprehensive understanding of their molecular mechanisms across joint tissues is imperative. Ultimately, deciphering the complexities of integrin signalling will advance the ability to treat OA and alleviate its global burden.

4D bioprinting of programmed dynamic tissues

Setting time as the fourth dimension, 4D printing allows us to construct dynamic structures that can change their shape, property, or functionality over time under stimuli, leading to a wave of innovations in various fields. Recently, 4D printing of smart biomaterials, biological components, and living cells into dynamic living 3D constructs with 4D effects has led to an exciting field of 4D bioprinting. 4D bioprinting has gained increasing attention and is being applied to create programmed and dynamic cell-laden constructs such as bone, cartilage, and vasculature. This review presents an overview on 4D bioprinting for engineering dynamic tissues and organs, followed by a discussion on the approaches, bioprinting technologies, smart biomaterials and smart design, bioink requirements, and applications. While much progress has been achieved, 4D bioprinting as a complex process is facing challenges that need to be addressed by transdisciplinary strategies to unleash the full potential of this advanced biofabrication technology. Finally, we present future perspectives on the rapidly evolving field of 4D bioprinting, in view of its potential, increasingly important roles in the development of advanced dynamic tissues for basic research, pharmaceutics, and regenerative medicine.

Engineering Innervated Musculoskeletal Tissues for Regenerative Orthopedics and Disease Modeling

Musculoskeletal (MSK) disorders significantly burden patients and society, resulting in high healthcare costs and productivity loss. These disorders are the leading cause of physical disability, and their prevalence is expected to increase as sedentary lifestyles become common and the global population of the elderly increases. Proper innervation is critical to maintaining MSK function, and nerve damage or dysfunction underlies various MSK disorders, underscoring the potential of restoring nerve function in MSK disorder treatment. However, most MSK tissue engineering strategies have overlooked the significance of innervation. This review first expounds upon innervation in the MSK system and its importance in maintaining MSK homeostasis and functions. This will be followed by strategies for engineering MSK tissues that induce post-implantation in situ innervation or are pre-innervated. Subsequently, research progress in modeling MSK disorders using innervated MSK organoids and organs-on-chips (OoCs) is analyzed. Finally, the future development of engineering innervated MSK tissues to treat MSK disorders and recapitulate disease mechanisms is discussed. This review provides valuable insights into the underlying principles, engineering methods, and applications of innervated MSK tissues, paving the way for the development of targeted, efficacious therapies for various MSK conditions.

Advances in local drug delivery technologies for improved rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by an inflammatory microenvironment and cartilage erosion within the joint cavity. Currently, antirheumatic agents yield significant outcomes in RA treatment. However, their systemic administration is limited by inadequate drug retention in lesion areas and non-specific tissue distribution, reducing efficacy and increasing risks such as infection due to systemic immunosuppression. Development in local drug delivery technologies, such as nanostructure-based and scaffold-assisted delivery platforms, facilitate enhanced drug accumulation at the target site, controlled drug release, extended duration of the drug action, reduced both dosage and administration frequency, and ultimately improve therapeutic outcomes with minimized damage to healthy tissues. In this review, we introduced pathogenesis and clinically used therapeutic agents for RA, comprehensively summarized locally administered nanostructure-based and scaffold-assisted drug delivery systems, aiming at improving the therapeutic efficiency of RA by alleviating the inflammatory response, preventing bone erosion and promoting cartilage regeneration. In addition, the challenges and future prospects of local delivery for clinical translation in RA are discussed.

Application status and optimization suggestions of tumor organoids and CAR-T cell co-culture models

Tumor organoids, especially patient-derived organoids (PDOs) exhibit marked similarities in histopathological morphology, genomic alterations, and specific marker expression profiles to those of primary tumour tissues. They are applied in various fields including drug screening, gene editing, and identification of oncogenes. However, CAR-T therapy in the treatment of solid tumours is still at an exploratory stage. Tumour organoids offer unique advantages over other preclinical models commonly used for CAR-T therapy research, which the preservation of the biological characteristics of primary tumour tissue is critical for the study of early-stage solid tumour CAR-T therapies. Although some investigators have used this co-culture model to validate newly targeted CAR-T cells, optimise existing CAR-T cells and explore combination therapy strategies, there is still untapped potential in the co-culture models used today. This review introduces the current status of the application of tumour organoid and CAR-T cell co-culture models in recent years and commented on the limitations of the current co-cultivation model. Meanwhile, we compared the tumour organoid model with two pre-clinical models commonly used in CAR-T therapy research. Eventually, combined with the new progress of organoid technologies, optimization suggestions were proposed for the co-culture model from five perspectives: preserving or reconstructing the tumor microenvironment, systematization, vascularization, standardized culture procedures, and expanding the tumor organoids resource library, aimed at assisting related researchers to better utilize co-culture models.

Bioreactor Culture to Create Adipose Tissue from Human Mesenchymal Stromal Cells

Adipose tissue is a complex and multifaceted endocrine organ located throughout the body. The dysfunction of adipose tissue is known to induce a wide variety of comorbidities that can negatively impact one's health and quality of life. In addition to behavioral changes, drugs that target dysfunctional adipose tissue to treat associated diseases are clinically needed. Regarding drug-testing platforms, animal models are the most popular models, limited by known differences from humans in genetics and physiology. Two-dimensional and static three-dimensional (3D) cell cultures are also used. Still, these in vitro models with static culture fail to recapitulate the phenotype and function of adipocytes seen in vivo. To combat this, our lab has developed an adipose tissue microphysiological system. A perfusion bioreactor with dual-flow chambers is 3D printed, which enables individualized top and bottom medium flows after adipose tissues are inserted as a barrier. Human progenitor cells, such as human mesenchymal stem cells, are embedded within a gelatin scaffold and in situ adipogenic differentiation within the bioreactor. Medium flow is established via a syringe pump system, allowing in vivo-like conditions to be maintained. The novel bioreactor-cultured adipose tissues represent a versatile disease modeling and drug-testing system. Here, we present the step-by-step methods to generate the bioreactors and adipose tissues. We also show the process of collecting and analyzing samples. In addition, we highlight the critical steps that require particular attention in notes.

Curcuminoids-enriched extract and its cyclodextrin inclusion complexes ameliorates arthritis in complete Freund's adjuvant-induced arthritic mice via modulation of inflammatory biomarkers and suppression of oxidative stress markers

Curcuma longa extract and its marker curcuminoids have potential use in inflammatory conditions. However, curcuminoids solubility and bioavailability are major hindrances to their bioactivity. The current study investigated green extraction-based curcuminoids-enriched extract (CRE) prepared from C. longa and its cyclodextrin inclusion complexes, i.e., binary inclusion complexes (BC) and ternary inclusion complexes (TC), in complete Freund's adjuvant (CFA)-induced mice for their comparative anti-arthritic efficacy. CRE, BC, and TC (2.5 and 5 mg/kg) with the standard drug diclofenac sodium (13.5 mg/kg) were orally administered to mice for 4 weeks. Variations in body weight, hematological and biochemical parameters, along with gene expression analysis of arthritis biomarkers, were studied in animals. The histopathological analysis and radiographic examination of joints were also performed. CRE, BC and TC treatment significantly restored the arthritic index, histopathology and body weight changes. The concentration of C-reactive protein, rheumatoid factor and other liver function parameters were significantly recovered by curcuminoids formulations. The pro-inflammatory cytokines (NF-κB, COX-2, IL-6, IL-1β, and TNF-α) gene expression was considerably (p < 0.001) downregulated, while on the other side, the anti-inflammatory genes IL-4 and IL-10 were upregulated by the use of CRE and its complexes. The concentration of antioxidant enzymes was considerably (P < 0.001) recovered by CRE, BC and TC with marked decrease in lipid peroxidation, erosion of bone, inflammation of joints and pannus formation in comparison to arthritic control animals. Therefore, it is concluded that green CRE and its cyclodextrin formulations with enhanced solubility could be considered as an applicable therapeutic choice to treat chronic polyarthritis.

Organ-on-a-chip meets artificial intelligence in drug evaluation

Drug evaluation has always been an important area of research in the pharmaceutical industry. However, animal welfare protection and other shortcomings of traditional drug development models pose obstacles and challenges to drug evaluation. Organ-on-a-chip (OoC) technology, which simulates human organs on a chip of the physiological environment and functionality, and with high fidelity reproduction organ-level of physiology or pathophysiology, exhibits great promise for innovating the drug development pipeline. Meanwhile, the advancement in artificial intelligence (AI) provides more improvements for the design and data processing of OoCs. Here, we review the current progress that has been made to generate OoC platforms, and how human single and multi-OoCs have been used in applications, including drug testing, disease modeling, and personalized medicine. Moreover, we discuss issues facing the field, such as large data processing and reproducibility, and point to the integration of OoCs and AI in data analysis and automation, which is of great benefit in future drug evaluation. Finally, we look forward to the opportunities and challenges faced by the coupling of OoCs and AI. In summary, advancements in OoCs development, and future combinations with AI, will eventually break the current state of drug evaluation.

Bone/cartilage organoid on-chip: Construction strategy and application

The necessity of disease models for bone/cartilage related disorders is well-recognized, but the barrier between ex-vivo cell culture, animal models and the real human body has been pending for decades. The organoid-on-a-chip technique showed opportunity to revolutionize basic research and drug screening for diseases like osteoporosis and arthritis. The bone/cartilage organoid on-chip (BCoC) system is a novel platform of multi-tissue which faithfully emulate the essential elements, biologic functions and pathophysiological response under real circumstances. In this review, we propose the concept of BCoC platform, summarize the basic modules and current efforts to orchestrate them on a single microfluidic system. Current disease models, unsolved problems and future challenging are also discussed, the aim should be a deeper understanding of diseases, and ultimate realization of generic ex-vivo tools for further therapeutic strategies of pathological conditions.

Organoids as Innovative Models for Bone and Joint Diseases

Bone is one of the key components of the musculoskeletal system. Bone and joint disease are the fourth most widespread disease, in addition to cardiovascular disease, cancer, and diabetes, which seriously affect people's quality of life. Bone organoids seem to be a great model by which to promote the research method, which further could improve the treatment of bone and joint disease in the future. Here, we introduce the various bone and joint diseases and their biology, and the conditions of organoid culture, comparing the in vitro models among 2D, 3D, and organoids. We summarize the differing potential methods for culturing bone-related organoids from pluripotent stem cells, adult stem cells, or progenitor cells, and discuss the current and promising bone disease organoids for drug screening and precision medicine. Lastly, we discuss the challenges and difficulties encountered in the application of bone organoids and look to the future in order to present potential methods via which bone organoids might advance organoid construction and application.

Controlling Microenvironments with Organs-on-Chips for Osteoarthritis Modelling

Osteoarthritis (OA) remains a prevalent disease affecting more than 20% of the global population, resulting in morbidity and lower quality of life for patients. The study of OA pathophysiology remains predominantly in animal models due to the complexities of mimicking the physiological environment surrounding the joint tissue. Recent development in microfluidic organ-on-chip (OoC) systems have demonstrated various techniques to mimic and modulate tissue physiological environments. Adaptations of these techniques have demonstrated success in capturing a joint tissue's tissue physiology for studying the mechanism of OA. Adapting these techniques and strategies can help create human-specific in vitro models that recapitulate the cellular processes involved in OA. This review aims to comprehensively summarise various demonstrations of microfluidic platforms in mimicking joint microenvironments for future platform design iterations.

Osteoarthritis models: From animals to tissue engineering

Osteoarthritis (OA) is a chronic degenerative osteoarthropathy. Although it has been revealed that a variety of factors can cause or aggravate the symptoms of OA, the pathogenic mechanisms of OA remain unknown. Reliable OA models that accurately reflect human OA disease are crucial for studies on the pathogenic mechanism of OA and therapeutic drug evaluation. This review first demonstrated the importance of OA models by briefly introducing the OA pathological features and the current limitations in the pathogenesis and treatment of OA. Then, it mainly discusses the development of different OA models, including animal and engineered models, highlighting their advantages and disadvantages from the perspective of pathogenesis and pathology analysis. In particular, the state-of-the-art engineered models and their potential were emphasized, as they may represent the future direction in the development of OA models. Finally, the challenges in obtaining reliable OA models are also discussed, and possible future directions are outlined to shed some light on this area.

Composing On-Program Triggers and On-Demand Stimuli into Biosensor Drug Carriers in Drug Delivery Systems for Programmable Arthritis Therapy

Medication in arthritis therapies is complex because the inflammatory progression of rheumatoid arthritis (RA) and osteoarthritis (OA) is intertwined and influenced by one another. To address this problem, drug delivery systems (DDS) are composed of four independent exogenous triggers and four dependent endogenous stimuli that are controlled on program and induced on demand, respectively. However, the relationships between the mechanisms of endogenous stimuli and exogenous triggers with pathological alterations remain unclear, which results in a major obstacle in terms of clinical translation. Thus, the rationale for designing a guidance system for these mechanisms via their key irritant biosensors is in high demand. Many approaches have been applied, although successful clinical translations are still rare. Through this review, the status quo in historical development is highlighted in order to discuss the unsolved clinical difficulties such as infiltration, efficacy, drug clearance, and target localisation. Herein, we summarise and discuss the rational compositions of exogenous triggers and endogenous stimuli for programmable therapy. This advanced active pharmaceutical ingredient (API) implanted dose allows for several releases by remote controls for endogenous stimuli during lesion infections. This solves the multiple implantation and local toxic accumulation problems by using these flexible desired releases at the specified sites for arthritis therapies.