Organ-on-a-Chip Systems for Modeling Pathological Tissue Morphogenesis Associated with Fibrosis and Cancer

Cancer-on-chip: a breakthrough organ-on-a-chip technology in cancer cell modeling

Cancer remains one of the leading causes of death worldwide. The unclear molecular mechanisms and complex in vivo microenvironment of tumors make it difficult to clarify the nature of cancer and develop effective treatments. Therefore, the development of new methods to effectively treat cancer is urgently needed and of great importance. Organ-on-a-chip (OoC) systems could be the breakthrough technology sought by the pharmaceutical industry to address ever-increasing research and development costs. The past decade has seen significant advances in the spatial modeling of cancer therapeutics related to OoC technology, improving physiological exposition criteria. This article aims to summarize the latest achievements and research results of cancer cell treatment simulated in a 3D microenvironment using OoC technology. To this end, we will first discuss the OoC system in detail and then demonstrate the latest findings of the cancer cell treatment study by Ooc and how this technique can potentially optimize better modeling of the tumor. The prospects of OoC systems in the treatment of cancer cells and their advantages and limitations are also among the other points discussed in this study.

Cancer Patient-Derived Cell-Based Models: Applications and Challenges in Functional Precision Medicine

The field of oncology has witnessed remarkable progress in personalized cancer therapy. Functional precision medicine has emerged as a promising avenue for achieving superior treatment outcomes by integrating omics profiling and sensitivity testing of patient-derived cancer cells. This review paper provides an in-depth analysis of the evolution of cancer-directed drugs, resistance mechanisms, and the role of functional precision medicine platforms in revolutionizing individualized treatment strategies. Using two-dimensional (2D) and three-dimensional (3D) cell cultures, patient-derived xenograft (PDX) models, and advanced functional assays has significantly improved our understanding of tumor behavior and drug response. This progress will lead to identifying more effective treatments for more patients. Considering the limited eligibility of patients based on a genome-targeted approach for receiving targeted therapy, functional precision medicine provides unprecedented opportunities for customizing medical interventions according to individual patient traits and individual drug responses. This review delineates the current landscape, explores limitations, and presents future perspectives to inspire ongoing advancements in functional precision medicine for personalized cancer therapy.

Fibrosis-on-Chip: A Guide to Recapitulate the Essential Features of Fibrotic Disease

Fibrosis, which is primarily marked by excessive extracellular matrix (ECM) deposition, is a pathophysiological process associated with many disorders, which ultimately leads to organ dysfunction and poor patient outcomes. Despite the high prevalence of fibrosis, currently there exist few therapeutic options, and importantly, there is a paucity of in vitro models to accurately study fibrosis. This review discusses the multifaceted nature of fibrosis from the viewpoint of developing organ-on-chip (OoC) disease models, focusing on five key features: the ECM component, inflammation, mechanical cues, hypoxia, and vascularization. The potential of OoC technology is explored for better modeling these features in the context of studying fibrotic diseases and the interplay between various key features is emphasized. This paper reviews how organ-specific fibrotic diseases are modeled in OoC platforms, which elements are included in these existing models, and the avenues for novel research directions are highlighted. Finally, this review concludes with a perspective on how to address the current gap with respect to the inclusion of multiple features to yield more sophisticated and relevant models of fibrotic diseases in an OoC format.

Modelling and targeting mechanical forces in organ fibrosis

Few efficacious therapies exist for the treatment of fibrotic diseases, such as skin scarring, liver cirrhosis and pulmonary fibrosis, which is related to our limited understanding of the fundamental causes and mechanisms of fibrosis. Mechanical forces from cell-matrix interactions, cell-cell contact, fluid flow and other physical stimuli may play a central role in the initiation and propagation of fibrosis. In this Review, we highlight the mechanotransduction mechanisms by which various sources of physical force drive fibrotic disease processes, with an emphasis on central pathways that may be therapeutically targeted to prevent and reverse fibrosis. We then discuss engineered models of mechanotransduction in fibrosis, as well as molecular and biomaterials-based therapeutic approaches for limiting fibrosis and promoting regenerative healing phenotypes in various organs. Finally, we discuss challenges within fibrosis research that remain to be addressed and that may greatly benefit from next-generation bioengineered model systems.

Microphysiological systems as reliable drug discovery and evaluation tools: Evolution from innovation to maturity

Microphysiological systems (MPSs), also known as organ-on-chip or disease-on-chip, have recently emerged to reconstitute the in vivo cellular microenvironment of various organs and diseases on in vitro platforms. These microfluidics-based platforms are developed to provide reliable drug discovery and regulatory evaluation testbeds. Despite recent emergences and advances of various MPS platforms, their adoption of drug discovery and evaluation processes still lags. This delay is mainly due to a lack of rigorous standards with reproducibility and reliability, and practical difficulties to be adopted in pharmaceutical research and industry settings. This review discusses the current and potential use of MPS platforms in drug discovery processes while considering the context of several key steps during drug discovery processes, including target identification and validation, preclinical evaluation, and clinical trials. Opportunities and challenges are also discussed for the broader dissemination and adoption of MPSs in various drug discovery and regulatory evaluation steps. Addressing these challenges will transform long and expensive drug discovery and evaluation processes into more efficient discovery, screening, and approval of innovative drugs.

A biomimetic renal fibrosis progression model on-chip evaluates anti-fibrotic effects longitudinally in a dynamic fibrogenic niche

Although renal fibrosis can advance chronic kidney disease and progressively lead to end-stage renal failure, no effective anti-fibrotic drugs have been clinically approved. To aid drug development, we developed a biomimetic renal fibrosis progression model on-chip to evaluate anti-fibrotic effects of natural killer cell-derived extracellular vesicles and pirfenidone (PFD) across different fibrotic stages. First, the dynamic interplay between fibroblasts and kidney-derived extracellular matrix (ECM) resembling the fibrogenic niche on-chip demonstrated that myofibroblasts induced by stiff ECM in 3 days were reversed to fibroblasts by switching to soft ECM, which was within 2, but not 7 days. Second, PFD significantly down-regulated the expression of α-SMA in NRK-49F in medium ECM, as opposed to stiff ECM. Third, a study in rats showed that early administration of PFD significantly inhibited renal fibrosis in terms of the expression levels of α-SMA and YAP. Taken together, both on-chip and animal models indicate the importance of early anti-fibrotic intervention for checking the progression of renal fibrosis. Therefore, this renal fibrosis progression on-chip with a feature of recapitulating dynamic biochemical and biophysical cues can be readily used to assess anti-fibrotic candidates and to explore the tipping point when the fibrotic fate can be rescued for better medical intervention.

In Vivo and In Vitro Models to Study Liver Fibrosis: Mechanisms and Limitations

Liver fibrosis is a common result of liver injury owing to various kinds of chronic liver diseases. A deeper understanding of the pathophysiology of liver fibrosis and identifying potential therapeutic targets of liver fibrosis is important because liver fibrosis may progress to advanced liver diseases, such as cirrhosis and hepatocellular carcinoma. Despite numerous studies, the underlying mechanisms of liver fibrosis remain unclear. Mechanisms of the development and progression of liver fibrosis differ according to etiologies. Therefore, appropriate liver fibrosis models should be selected according to the purpose of the study and the type of underlying disease. Many in vivo animal and in vitro models have been developed to study liver fibrosis. However, there are no perfect preclinical models for liver fibrosis. In this review, we summarize the current in vivo and in vitro models for studying liver fibrosis and highlight emerging in vitro models, including organoids and liver-on-a-chip models. In addition, we discuss the mechanisms and limitations of each model.

Thinking in 3 dimensions: philosophies of the microenvironment in organoids and organs-on-chip

Organoids and organs-on-a-chip are currently the two major families of 3D advanced organotypic in vitro culture systems, aimed at reconstituting miniaturized models of physiological and pathological states of human organs. Both share the tenets of the so-called "three-dimensional thinking", a Systems Physiology approach focused on recapitulating the dynamic interactions between cells and their microenvironment. We first review the arguments underlying the "paradigm shift" toward three-dimensional thinking in the in vitro culture community. Then, through a historically informed account of the technical affordances and the epistemic commitments of these two approaches, we highlight how they embody two distinct experimental cultures. We finally argue that the current systematic effort for their integration requires not only innovative "synergistic" engineering solutions, but also conceptual integration between different perspectives on biological causality.

Experimental Workflow for Preclinical Studies of Human Antifibrotic Therapies

Chronic liver diseases accompanied by liver fibrosis have caused significant morbidity and mortality in the world with increasing prevalence. Nonetheless, there are no approved antifibrotic therapies. Although numerous preclinical studies showed satisfactory results in targeting fibrotic pathways, these animal studies have not led to success in humans. In this chapter, we summarize the experimental approaches currently available, including in vitro cell culture models, in vivo animal models, and new experimental tools relevant to humans, and discuss how we translate laboratory results to clinical trials. We will also address the obstacles in transitioning promising therapies from preclinical studies to human antifibrotic treatments.

New Approach Methodologies in Immunotoxicology: Challenges and Opportunities

To maintain the integrity of an organism, a well-functioning immune system is essential. Immunity is dynamic, with constant surveillance needed to determine whether to initiate an immune response or to not respond. Both inappropriate immunostimulation and decreased immune response can be harmful to the host. A reduced immune response can lead to high susceptibility to cancer or infections, whereas an increased immune response can be related to autoimmunity or hypersensitivity reactions. Animal testing has been the gold standard for hazard assessment in immunotoxicity but a lot of efforts are ongoing to develop non-animal-based test systems, and important successes have been achieved. The term "new approach methodologies" (NAMs) refer to the approaches which are not based on animal models. They are applied in hazard and risk assessment of chemicals and include approaches such as defined approaches for data interpretation and integrated approaches to testing and assessment. This review aims to summarize the available NAMs for immunotoxicity assessment, taking into consideration both inappropriate immunostimulation and immunosuppression, including implication for cancer development.

Engineering Natural and Recombinant Silks for Sustainable Biodevices

Silk fibroin (SF) is a structural protein derived from natural silkworm silks. Materials fabricated based on SF usually inherit extraordinary physical and biological properties, including high mechanical strength, toughness, optical transparency, tailorable biodegradability, and biocompatibility. Therefore, SF has attracted interest in the development of sustainable biodevices, especially for emergent bio-electronic technologies. To expand the function of current silk devices, the SF characteristic sequence has been used to synthesize recombinant silk proteins that benefit from SF and other functional peptides, such as stimuli-responsive elastin peptides. In addition to genetic engineering methods, innovated chemistry modification approaches and improved material processing techniques have also been developed for fabricating advanced silk materials with tailored chemical features and nanostructures. Herein, this review summarizes various methods to synthesize functional silk-based materials from different perspectives. This review also highlights the recent advances in the applications of natural and recombinant silks in tissue regeneration, soft robotics, and biosensors, using B. mori SF and silk-elastin-like proteins (SELPs) as examples.

Microfluidic Organ-on-a-Chip Devices for Liver Disease Modeling In Vitro

Mortality from liver disease conditions continues to be very high. As liver diseases manifest and progress silently, prompt measures after diagnosis are essential in the treatment of these conditions. Microfluidic organs-on-chip platforms have significant potential for the study of the pathophysiology of liver diseases in vitro. Different liver-on-a-chip microphysiological platforms have been reported to study cell-signaling pathways such as those activating stellate cells within liver diseases. Moreover, the drug efficacy for liver conditions might be evaluated on a cellular metabolic level. Here, we present a comprehensive review of microphysiological platforms used for modelling liver diseases. First, we briefly introduce the concept and importance of organs-on-a-chip in studying liver diseases in vitro, reflecting on existing reviews of healthy liver-on-a-chip platforms. Second, the techniques of cell cultures used in the microfluidic devices, including 2D, 3D, and spheroid cells, are explained. Next, the types of liver diseases (NAFLD, ALD, hepatitis infections, and drug injury) on-chip are explained for a further comprehensive overview of the design and methods of developing liver diseases in vitro. Finally, some challenges in design and existing solutions to them are reviewed.

Organ on Chip Technology to Model Cancer Growth and Metastasis

Organ on chip (OOC) has emerged as a major technological breakthrough and distinct model system revolutionizing biomedical research and drug discovery by recapitulating the crucial structural and functional complexity of human organs in vitro. OOC are rapidly emerging as powerful tools for oncology research. Indeed, Cancer on chip (COC) can ideally reproduce certain key aspects of the tumor microenvironment (TME), such as biochemical gradients and niche factors, dynamic cell-cell and cell-matrix interactions, and complex tissue structures composed of tumor and stromal cells. Here, we review the state of the art in COC models with a focus on the microphysiological systems that host multicellular 3D tissue engineering models and can help elucidate the complex biology of TME and cancer growth and progression. Finally, some examples of microengineered tumor models integrated with multi-organ microdevices to study disease progression in different tissues will be presented.

Recent Advances in Fluorescence Imaging of Pulmonary Fibrosis in Animal Models

Pulmonary fibrosis (PF) is a lung disease that may cause impaired gas exchange and respiratory failure while being difficult to treat. Rapid, sensitive, and accurate detection of lung tissue and cell changes is essential for the effective diagnosis and treatment of PF. Currently, the commonly-used high-resolution computed tomography (HRCT) imaging has been challenging to distinguish early PF from other pathological processes in the lung structure. Magnetic resonance imaging (MRI) using hyperpolarized gases is hampered by the higher cost to become a routine diagnostic tool. As a result, the development of new PF imaging technologies may be a promising solution. Here, we summarize and discuss recent advances in fluorescence imaging as a talented optical technique for the diagnosis and evaluation of PF, including collagen imaging, oxidative stress, inflammation, and PF-related biomarkers. The design strategies of the probes for fluorescence imaging (including multimodal imaging) of PF are briefly described, which can provide new ideas for the future PF-related imaging research. It is hoped that this review will promote the translation of fluorescence imaging into a clinically usable assay in PF.

Organs-on-a-chip models for biological research

We explore the utility of bioengineered human tissues-individually or connected into physiological units-for biological research. While much smaller and simpler than their native counterparts, these tissues are complex enough to approximate distinct tissue phenotypes: molecular, structural, and functional. Unlike organoids, which form spontaneously and recapitulate development, "organs-on-a-chip" are engineered to display some specific functions of whole organs. Looking back, we discuss the key developments of this emerging technology. Thinking forward, we focus on the challenges faced to fully establish, validate, and utilize the fidelity of these models for biological research.