Microphysiological Platforms Research Articles

Barrier-free, open-top microfluidic chip for generating two distinct, interconnected 3D microvascular networks

Developing microphysiological cell culture platforms with a three-dimensional (3D) microenvironment has been a significant advancement from traditional monolayer cultures. Still, most of the current microphysiological platforms are limited in closed designs, i.e. are not accessible after 3D cell culture loading. Here, we report an open-top microfluidic chip which enables the generation of two sequentially loaded 3D cell cultures without physical barriers restricting the nurture, gas exchange and cellular communication. As a proof-of-concept, we demonstrated the formation of two 3D vasculatures, one in the upper and the other in the lower compartment, under three distinct flow conditions: asymmetric side-to-center, symmetric side-to-center and symmetric center-to-side. We used computational modelling to characterize initial flow pressures in cell culture compartments. We showed prominent vessel formation and branched vasculatures in upper and lower cell culture compartments with interconnecting, lumenized vessels with in vivo-relevant diameter in all flow conditions. With advanced image processing, we quantified and compared the overall vascular network volume and the total length formed in asymmetric side-to-center, symmetric side-to-center and symmetric center-to-side flow conditions. Our results indicate that the developed chip can house two distinct 3D cell cultures with merging vessels between compartments and by providing asymmetric side-to-center or symmetric center-to-side flow vascular morphogenesis is enhanced in terms of overall network length. The developed open-top microfluidic chip may find various applications in generation of tissue-specific 3D-3D co-cultures for studying cellular interactions in vascularized tissues and organs.

A Biomimetic Optical Cardiac Fibrosis-on-a-Chip for High-Throughput Anti-Fibrotic Drug Screening.

Cardiac fibrosis has emerged as the primary cause of morbidity, disability, and even mortality in numerous nations. In light of the advancements in precision medicine strategies, substantial attention has been directed toward the development of a practical and precise drug screening platform customized for individual patients. In this study, we introduce a biomimetic cardiac fibrosis-on-a-chip incorporating structural color hydrogels (SCHs) to enable optical high-throughput drug screening. By cocultivating a substantial proportion of cardiac fibroblasts (CFBs) with cardiomyocytes on the SCH, this biomimetic fibrotic microtissue successfully replicates the structural components and biomechanical properties associated with cardiac fibrosis. More importantly, the structural color shift observed in the SCH can be indicative of cardiac contraction and relaxation, making it a valuable tool for evaluating fibrosis progression. By incorporating such fibrotic microtissue into a microfluidic gradient chip, we develop a biomimetic optical cardiac fibrosis-on-a-chip platform that accurately and efficiently screens potential anti-fibrotic drugs. These characteristics suggest that this microphysiological platform possesses the capability to establish a preclinical framework for screening cardiac drugs, and may even contribute to the advancement of precision medicine.

Three-Dimensionally Printed Agarose Micromold Supports Scaffold-Free Mouse Ex Vivo Follicle Growth, Ovulation, and Luteinization.

Ex vivo follicle growth is an essential tool, enabling interrogation of folliculogenesis, ovulation, and luteinization. Though significant advancements have been made, existing follicle culture strategies can be technically challenging and laborious. In this study, we advanced the field through development of a custom agarose micromold, which enables scaffold-free follicle culture. We established an accessible and economical manufacturing method using 3D printing and silicone molding that generates biocompatible hydrogel molds without the risk of cytotoxicity from leachates. Each mold supports simultaneous culture of multiple multilayer secondary follicles in a single focal plane, allowing for constant timelapse monitoring and automated analysis. Mouse follicles cultured using this novel system exhibit significantly improved growth and ovulation outcomes with comparable survival, oocyte maturation, and hormone production profiles as established three-dimensional encapsulated in vitro follicle growth (eIVFG) systems. Additionally, follicles recapitulated aspects of in vivo ovulation physiology with respect to their architecture and spatial polarization, which has not been observed in eIVFG systems. This system offers simplicity, scalability, integration with morphokinetic analyses of follicle growth and ovulation, and compatibility with existing microphysiological platforms. This culture strategy has implications for fundamental follicle biology, fertility preservation strategies, reproductive toxicology, and contraceptive drug discovery.

A streamlined method to generate endothelial cells from human pluripotent stem cells via transient doxycycline-inducible ETV2 activation.

The development of reliable methods for producing functional endothelial cells (ECs) is crucial for progress in vascular biology and regenerative medicine. In this study, we present a streamlined and efficient methodology for the differentiation of human induced pluripotent stem cells (iPSCs) into induced ECs (iECs) that maintain the ability to undergo vasculogenesis in vitro and in vivo using a doxycycline-inducible system for the transient expression of the ETV2 transcription factor. This approach mitigates the limitations of direct transfection methods, such as mRNA-mediated differentiation, by simplifying the protocol and enhancing reproducibility across different stem cell lines. We detail the generation of iPSCs engineered for doxycycline-induced ETV2 expression and their subsequent differentiation into iECs, achieving over 90% efficiency within four days. Through both in vitro and in vivo assays, the functionality and phenotypic stability of the derived iECs were rigorously validated. Notably, these cells exhibit key endothelial markers and capabilities, including the formation of vascular networks in a microphysiological platform in vitro and in a subcutaneous mouse model. Furthermore, our results reveal a close transcriptional and proteomic alignment between the iECs generated via our method and primary ECs, confirming the biological relevance of the differentiated cells. The high efficiency and effectiveness of our induction methodology pave the way for broader application and accessibility of iPSC-derived ECs in scientific research, offering a valuable tool for investigating endothelial biology and for the development of EC-based therapies.

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.

Abstract 2797: Fusobacterium nucleatum antigens drive tumor-associated macrophage-like cells in an engineered oral squamous cell carcinoma on-a-chip

Abstract Oral squamous cell carcinoma (OSCC) is the sixth most prevalent cancer, representing 90% of all head and neck cancers. Oral cancers are expected to cause 11000 deaths in the US in 2023. OSCC comprises a complex microenvironment involving a 3D collagenous matrix, innate and adaptative immune cells, fibroblasts, and opportunistic microorganisms. Fusobacterium nucleatum, for instance, is related to OSCC development in different aspects, such as inducing epithelial-to-mesenchymal transition and coordinating the immunological response in the tumor microenvironment (TME). Although some advances were achieved in understanding the OSCC TME, there is an urge to develop advanced in vitro models to investigate the immunosuppressive role of opportunistic microorganisms in OSCCs. Offering a promising avenue for studying OSCCs, organs-on-a-chip serve as microphysiological platforms that closely emulate the complexities of biological tissues within the highly controllable microfluidic, cellular communication, and extracellular matrix. Here, we developed an OSCC on-a-chip to understand the immunomodulatory profile of F. nucleatum on macrophages in the TME. We cultivated oral squamous carcinoma cells in 3D in a collagen matrix (2.5 mg/mL) in a microfluidic device that has a central chamber (1mm in width) and two lateral channels connected by triangular pillars (space between pillars of 115 µm). Our tested groups were collagen matrix containing OSCC (5.105 cells/mL) in the presence or absence of heat-killed antigens (1.106 CFUs/mL) from F. nucleatum (ATCC 23726). F. nucleatum cells were integrated with collagen gels and oral squamous carcinoma cells for three days. On the fourth day, we added 2.103 THP-1 derived macrophages (differentiated with PMA 100 ng/mL) in the lateral channel to evaluate their chemoattraction to the 3D matrix in the presence or absence of F. nucleatum for 48 hours. We noticed a significantly higher number of macrophages invading the 3D matrices that had heat-killed antigens when compared to the groups containing just OSSCs. By immunofluorescence, we stained the cells with markers for M1 (CD86) and M2 (CD163) and observed a significantly lower number of CD86 and a higher number of CD163-positive cells in the F. nucleatum stimulated group. When cytokines and chemokines were measured from these chips by Luminex assay, we found that the presence of heat-killed bacteria upregulated TNF-α, MCP-1, IL-6, VEGF, and CCL5 significantly, showing that the presence of F.nucleatum might stimulate tumor-associated macrophages-like cells. These results enable us to understand how the early interactions between opportunistic microorganisms and the immune system modulate the suppression responses in the tumor microenvironment. Citation Format: Mauricio G. Sousa, Avathamsa Athirasala, May Anny A. Fraga, Dustin Higashi, Justin Merrit, Luiz Bertassoni. Fusobacterium nucleatum antigens drive tumor-associated macrophage-like cells in an engineered oral squamous cell carcinoma on-a-chip [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2797.

Abstract 533: Attenuating EZH2-mediated metastasis and tumor growth by pharmacological-based approaches using three-dimensional in vitro culture models

Abstract Triple Negative breast cancer (TNBC) accounts for 10-15% of all breast cancers where patients encounter poor clinical outcomes. Treatment modalities for TNBC are conventional cytotoxic chemotherapy and radiation leads to 35%-40% relapse within 5 years of diagnosis. There is a growing need for more effective targeted therapeutics to inhibit TNBC growth. The role of EZH2 in maintaining tumor growth and metastasis in TNBC is well documented. EZH2 promotes breast tumor-initiating cell expansion (BITC) and cancer progression by impairing the DNA damage repair process favoring activation of oncogenes. Despite the advancement in the discovery of inhibitors for EZH2 that attenuate its catalytic activity, resistance to these small molecules limits their use in solid tumors. The neurotransmitter dopamine via its D1 receptor activation in TNBC cell lines induces apoptosis and autophagy, as well as inhibits the invasion and regress in mammary tumors in vivo. Here we hypothesize that the presence of dopamine D1 receptor agonist (A77636) enhances the efficacy of EZH2 inhibitors (GSK126) to inhibit in vitro TNBC tumor growth and metastasis. To test the efficacy of the combination we employed a 3D culture system of MDA-MB-231 cells encapsulated in calcium-alginate microgels seeded from a microfluidic droplet generator. We also employed a 3D organ-on-chip-based microphysiological (MPS) platform (SynTumor) to study the effect of the drug combination on metastasis in vitro. The SynTumor MPS devices replicate the pathophysiological architecture of native vascularized breast tumors. The combination treatment enhanced a significant reduction of tumor spheroid diameter compared to the vehicle and indicated spheroid regression over treatment. Furthermore, the combination therapy induced necrosis and caused complete inhibition of EZH2 expression. The knockdown of EZH2 inhibited tumor spheroid formation and displayed cytoskeleton de-arrangement. In the microfluidic SynTumor model, circulating tumor cell numbers were reduced by half at 96 hrs after EZH2 combination treatment. Our data indicate that the combinatorial effect of DRD1 agonist and EZH2 inhibitor efficiently attenuates the EZH2-mediated in vitro tumor growth and metastasis (This work is supported by DOD: W81XWH2010065, for Eswar Shankar). Citation Format: xilal Rima, Gautam Sarathy, Chunyu Hu, Divya S. Patel, Deborah Ramsey, Lara Rizotto, Dario Palmeri, Gwen Fewell, Bhuvaneswari Ramaswamy, Eduardo Reátegu, Eswar Shankar. Attenuating EZH2-mediated metastasis and tumor growth by pharmacological-based approaches using three-dimensional in vitro culture models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 533.

Chitosan-Calcium Aluminate as a Cell-homing Scaffold: Its Bioactivity Testing in a Microphysiological Dental Pulp Platform.

In vitro models of the dental pulp microenvironment have been proposed for the assessment of biomaterials, to minimise animal use in operative dentistry. In this study, a scaffold/3-D dental pulp cell culture interface was created in a microchip, under simulated dental pulp pressure, to evaluate the cell-homing potential of a chitosan (CH) scaffold functionalised with calcium aluminate (the 'CHAlCa scaffold'). This microphysiological platform was cultured at a pressure of 15 cm H2O for up to 14 days; cell viability, migration and odontoblastic differentiation were then assessed. The CHAlCa scaffold exhibited intense chemotactic potential, causing cells to migrate from the 3-D culture to its surface, followed by infiltration into the macroporous structure of the scaffold. By contrast, the cells in the presence of the non-functionalised chitosan scaffold showed low cell migration and no cell infiltration. CHAlCa scaffold bioactivity was confirmed in dentin sialophosphoprotein-positive migrating cells, and odontoblastic markers were upregulated in 3-D culture. Finally, in situ mineralised matrix deposition by the cells was confirmed in an Alizarin Red-based assay, in which the CHAlCa and CH scaffolds were adapted to fit within dentin discs. More intense deposition of matrix was observed with the CHAlCa scaffold, as compared to the CH scaffold. In summary, we present an in vitro platform that provides a simple and reproducible model for selecting and developing innovative biomaterials through the assessment of their cell-homing potential. By using this platform, it was shown that the combination of calcium aluminate and chitosan has potential as an inductive biomaterial that can mediate dentin tissue regeneration during cell-homing therapies.

A microphysiological system for parallelized morphological and electrophysiological read-out of 3D neuronal cell culture.

Three-dimensional in vitro models in microfluidic systems are promising tools for studying cell biology, with complex models using multiple cell types combined with high resolution imaging. Neuronal models demand electrical readout of the activity of networks of single neurons, yet classical planar microelectrode arrays struggle to capture extracellular action potentials when neural soma are suspended distant from the microelectrodes. This study introduces sophisticated microfluidic microelectrode arrays, specifically tailored for electrophysiology of 3D neuronal cultures. Using multilayer photolithography of permanent epoxy photoresists, we developed devices having 12 independent culture modules in a convenient format. Each module has two adjacent compartments for hydrogel-based 3D cell culture, with tunnels allowing projection of neurites between compartments. Microelectrodes integrated in the tunnels record action potentials as they pass between the compartments. Mesh ceilings separate the compartments from overlying wells, allowing for simple cell seeding and later nutrient, gas and waste exchange and application of test substances. Using these devices, we have demonstrated 3D neuronal culture, including electrophysiological recording and live imaging. This microphysiological platform will enable high-throughput investigation of neuronal networks for investigation of neurological disorders, neural pharmacology and basic neuroscience. Further models could include cocultures representing multiple brain regions or innervation models of other organs.

A comparative approach to recapitulate intestinal physiological absorption in vitro, using a novel, modular and versatile MicroPhysiological platform

Not available.

Microphysiological Modeling of Gingival Tissues and Host-Material Interactions Using Gingiva-on-Chip.

Gingiva plays a crucial barrier role at the interface of teeth, tooth-supporting structures, microbiome, and external agents. To mimic this complex microenvironment, an in vitro microphysiological platform and biofabricated full-thickness gingival equivalents (gingiva-on-chip) within a vertically stacked microfluidic device is developed. This design allowed long-term and air-liquid interface culture, and host-material interactions under flow conditions. Compared to static cultures, dynamic cultures on-chip enabled the biofabrication of gingival equivalents with stable mucosal matrix, improved epithelial morphogenesis, and barrier features. Additionally, a diseased state with disrupted barrier function representative of gingival/oral mucosal ulcers is modeled. The apical flow feature is utilized to emulate the mechanical action of mouth rinse and integrate the assessment of host-material interactions and transmucosal permeation of oral-care formulations in both healthy and diseased states. Although the gingiva-on-chip cultures have thicker and more mature epithelium, the flow of oral-care formulations induced increased tissue disruption and cytotoxic features compared to static conditions. The realistic emulation of mouth rinsing action facilitated a more physiological assessment of mucosal irritation potential. Overall, this microphysiological system enables biofabrication of human gingiva equivalents in intact and ulcerated states, providing a miniaturized and integrated platform for downstream host-material and host-microbiome applications in gingival and oral mucosa research.

Microfluidic device with reconfigurable spatial temporal gradients reveals plastic astrocyte response to stroke and reperfusion.

As a leading cause of mortality and morbidity, stroke constitutes a significant global health burden. Ischemic stroke accounts for 80% of cases and occurs due to an arterial thrombus, which impedes cerebral blood flow and rapidly leads to cell death. As the most abundant cell type within the central nervous system, astrocytes play a critical role within the injured brain. We developed a novel microphysiological platform that permits the induction of spatiotemporally controlled nutrient gradients, allowing us to study astrocytic response during and after transient nutrient deprivation. Within 24 h of inducing starvation in the platform, nutrient deprivation led to multiple changes in astrocyte response, from metabolic perturbations to gene expression changes, and cell viability. Furthermore, we observed that nutrient restoration did not reverse the functional changes in astrocyte metabolism, which mirrors reperfusion injury observed in vivo. We also identified alterations in numerous glucose metabolism-associated genes, many of which remained upregulated or downregulated even after restoration of the nutrient supply. Together, these findings suggest that astrocyte activation during and after nutrient starvation induces plastic changes that may underpin persistent stroke-induced functional impairment. Overall, our innovative device presents interesting potential to be used in the development of new therapies to improve tissue repair and even cognitive recovery after stroke.

Microfluidic 3D platform to evaluate endothelial progenitor cell recruitment by bioactive materials

Most of the conventional in vitro models to test biomaterial-driven vascularization are too simplistic to recapitulate the complex interactions taking place in the actual cell microenvironment, which results in a poor prediction of the in vivo performance of the material. However, during the last decade, cell culture models based on microfluidic technology have allowed attaining unprecedented levels of tissue biomimicry. In this work, we propose a microfluidic-based 3D model to evaluate the effect of bioactive biomaterials capable of releasing signaling cues (such as ions or proteins) in the recruitment of endogenous endothelial progenitor cells, a key step in the vascularization process. The usability of the platform is demonstrated using experimentally-validated finite element models and migration and proliferation studies with rat endothelial progenitor cells (rEPCs) and bone marrow-derived rat mesenchymal stromal cells (BM-rMSCs). As a proof of concept of biomaterial evaluation, the response of rEPCs to an electrospun composite made of polylactic acid with calcium phosphates nanoparticles (PLA+CaP) was compared in a co-culture microenvironment with BM-rMSC to a regular PLA control. Our results show a significantly higher rEPCs migration and the upregulation of several pro-inflammatory and proangiogenic proteins in the case of the PLA+CaP. The effects of osteopontin (OPN) on the rEPCs migratory response were also studied using this platform, suggesting its important role in mediating their recruitment to a calcium-rich microenvironment. This new tool could be applied to screen the capacity of a variety of bioactive scaffolds to induce vascularization and accelerate the preclinical testing of biomaterials. Statement of significanceFor many years researchers have used neovascularization models to evaluate bioactive biomaterials both in vitro, with low predictive results due to their poor biomimicry and minimal control over cell cues such as spatiotemporal biomolecule signaling, and in vivo models, presenting drawbacks such as being highly costly, time-consuming, poor human extrapolation, and ethically controversial. We describe a compact microphysiological platform designed for the evaluation of proangiogenesis in biomaterials through the quantification of the level of sprouting in a mimicked endothelium able to react to gradients of biomaterial-released signals in a fibrin-based extracellular matrix. This model is a useful tool to perform preclinical trustworthy studies in tissue regeneration and to better understand the different elements involved in the complex process of vascularization.

The design basis and application in urology of the tumor-on-a-chip platform.

Clinical research has been desperately looking for effective treatments for tumors. As the molecular mechanisms of tumors have not been thoroughly defined, and the problem of anti-tumor drug resistance and clinical drug screening are not effective, new ways are currently needed to explore and improve. Given the limitations of traditional cell culture models and preclinical animal models, we review the recently developed tumor chip, a micro-physiological platform based on microfluidic technology that maximizes replication of the human TEM. Here, we focus on the design basis of the tumor microarray and its application in urology oncology, summarizing the challenges facing future development in the field. In conclusion, this review demonstrates the wide range and application of tumor chips and the potential of these systems for the future treatment and management of urological tumors.

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

An In Vitro Microfluidic Alveolus Model to Study Lung Biomechanics.

The gas exchange units of the lung, the alveoli, are mechanically active and undergo cyclic deformation during breathing. The epithelial cells that line the alveoli contribute to lung function by reducing surface tension via surfactant secretion, which is highly influenced by the breathing-associated mechanical cues. These spatially heterogeneous mechanical cues have been linked to several physiological and pathophysiological states. Here, we describe the development of a microfluidically assisted lung cell culture model that incorporates heterogeneous cyclic stretching to mimic alveolar respiratory motions. Employing this device, we have examined the effects of respiratory biomechanics (associated with breathing-like movements) and strain heterogeneity on alveolar epithelial cell functions. Furthermore, we have assessed the potential application of this platform to model altered matrix compliance associated with lung pathogenesis and ventilator-induced lung injury. Lung microphysiological platforms incorporating human cells and dynamic biomechanics could serve as an important tool to delineate the role of alveolar micromechanics in physiological and pathological outcomes in the lung.

Microfluidic systems for modeling human development.

The proper development and patterning of organs rely on concerted signaling events emanating from intracellular and extracellular molecular and biophysical cues. The ability to model and understand how these microenvironmental factors contribute to cell fate decisions and physiological processes is crucial for uncovering the biology and mechanisms of life. Recent advances in microfluidic systems have provided novel tools and strategies for studying aspects of human tissue and organ development in ways that have previously been challenging to explore ex vivo. Here, we discuss how microfluidic systems and organs-on-chips provide new ways to understand how extracellular signals affect cell differentiation, how cells interact with each other, and how different tissues and organs are formed for specialized functions. We also highlight key advancements in the field that are contributing to a broad understanding of human embryogenesis, organogenesis and physiology. We conclude by summarizing the key advantages of using dynamic microfluidic or microphysiological platforms to study intricate developmental processes that cannot be accurately modeled by using traditional tissue culture vessels. We also suggest some exciting prospects and potential future applications of these emerging technologies.

A multimodal 3D neuro-microphysiological system with neurite-trapping microelectrodes

Three-dimensional cell technologies as pre-clinical models are emerging tools for mimicking the structural and functional complexity of the nervous system. The accurate exploration of phenotypes in engineered 3D neuronal cultures, however, demands morphological, molecular and especially functional measurements. Particularly crucial is measurement of electrical activity of individual neurons with millisecond resolution. Current techniques rely on customized electrophysiological recording set-ups, characterized by limited throughput and poor integration with other readout modalities. Here we describe a novel approach, using multiwell glass microfluidic microelectrode arrays, allowing non-invasive electrical recording from engineered 3D neuronal cultures. We demonstrate parallelized studies with reference compounds, calcium imaging and optogenetic stimulation. Additionally, we show how microplate compatibility allows automated handling and high-content analysis of human induced pluripotent stem cell–derived neurons. This microphysiological platform opens up new avenues for high-throughput studies on the functional, morphological and molecular details of neurological diseases and their potential treatment by therapeutic compounds.

Liver microphysiological platforms for drug metabolism applications.

Drug development is a costly and lengthy process with low success rates. To improve the efficiency of drug development, there has been an increasing need in developing alternative methods able to eliminate toxic compounds early in the drug development pipeline. Drug metabolism plays a key role in determining the efficacy of a drug and its potential side effects. Since drug metabolism occurs mainly in the liver, liver cell‐based alternative engineering platforms have been growing in the last decade. Microphysiological liver cell‐based systems called liver‐on‐a‐chip platforms can better recapitulate the environment for human liver cells in laboratory settings and have the potential to reduce the number of animal models used in drug development by predicting the response of the liver to a drug in vitro. In this review, we discuss the liver microphysiological platforms from the perspective of drug metabolism studies. We highlight the stand‐alone liver‐on‐a‐chip platforms and multi‐organ systems integrating liver‐on‐a‐chip devices used for drug metabolism mimicry in vitro and review the state‐of‐the‐art platforms reported in the last few years. With the development of more robust and reproducible liver cell‐based microphysiological platforms, the drug development field has the potential of reducing the costs and lengths associated with currently existing drug testing methods.

Tissue-engineered vascular microphysiological platform to study immune modulation of xenograft rejection.

Most of the vascular platforms currently being studied are lab-on-a-chip types that mimic capillary networks and are applied for vascular response analysis in vitro. However, these platforms have a limitation in clearly assessing the physiological phenomena of native blood vessels compared to in vivo evaluation. Here, we developed a simply fabricable tissue-engineered vascular microphysiological platform (TEVMP) with a three-dimensional (3D) vascular structure similar to an artery that can be applied for ex vivo and in vivo evaluation. Furthermore, we applied the TEVMP as ex vivo and in vivo screening systems to evaluate the effect of human CD200 (hCD200) overexpression in porcine endothelial cells (PECs) on vascular xenogeneic immune responses. These screening systems, in contrast to 2D in vitro and cellular xenotransplantation in vivo models, clearly demonstrated that hCD200 overexpression effectively suppressed vascular xenograft rejection. The TEVMP has a high potential as a platform to assess various vascular-related responses.