bims-orenst 2021-09-19 papers

bims-orenst

Biomed News

on Organs-on-chips and engineered stem cell models

Issue of 2021–09–19
twenty-one papers selected by
Joram Mooiweer, University of Groningen

Intestinal Epithelium Tubules on a Chip.
Establishment of a Modular Anaerobic Human Intestine Chip.
Fabrication and Use of a Pumpless Microfluidic Lymphatic Vessel Chip.
Detailed Methodology to Establish a Synovium/Cartilage-on-a-Chip Model to Investigate the Process of Monocyte Extravasation.
Clinically Relevant Influenza Virus Evolution Reconstituted in a Human Lung Airway-on-a-Chip.
Organ-on-Chips for Studying Tissue Barriers: Standard Techniques and a Novel Method for Including Porous Membranes Within Microfluidic Devices.
Sorption of Neuropsychopharmaca in Microfluidic Materials for In Vitro Studies.
Generation of a Glomerular Filtration Barrier on a Glomerulus-on-a-Chip Platform.
Electromechanical Stimulation of 3D Cardiac Microtissues in a Heart-on-Chip Model.
Mechanical Induction of Osteoarthritis Traits in a Cartilage-on-a-Chip Model.
Isolation, Integration, and Culture of Human Mature Adipocytes Leveraging Organ-on-Chip Technology.
On-Chip Platelet Activation Assessment: Microfluidic Emulation of Shear Stress Profiles Induced by Mechanical Circulatory Support Devices.
Bile Duct-on-a-Chip.
A Human Neurovascular Unit On-a-Chip.
Biofabrication of 3D Human Muscle Model with Vascularization and Endomysium.
Modelling human liver fibrosis in the context of non-alcoholic steatohepatitis using a microphysiological system.
Human stem cell-based retina on chip as new translational model for validation of AAV retinal gene therapy vectors.
Welcome to the special issue on organs-on-chip from the guest editors.
An "occlusive thrombosis-on-a-chip" microfluidic device for investigating the effect of anti-thrombotic drugs.
Putting Science into Standards workshop on standards for organ-on-chip.
A Mesoscale 3D Culture System for Native and Engineered Biphasic Tissues: Application to the Osteochondral Unit.

Methods Mol Biol. 2022 ;2373 87-105

Intestinal Epithelium Tubules on a Chip.

Kinga Kosim, Iris Schilt, Henriëtte L Lanz, Paul Vulto, Dorota Kurek.

  The study of epithelial barrier properties in the human body is of paramount interest to a range of disciplines, including disease modeling, drug transport studies, toxicology, developmental biology, and regenerative biology. Current day in vitro studies largely rely on growing epithelial cells in a static environment on membrane cell culture inserts. With the advancement of microfluidic and organ-on-a-chip techniques it became possible to culture 3D intestinal tubules directly against an extracellular matrix (ECM) under flow and without the need for artificial membranes. Here we describe detailed protocols for culturing epithelial tubules in a high-throughput format, assessing their permeability and marker expression. The platform harbors 40 independent microfluidic chips in a microtiter plate format. The resulting 40 epithelial tubules are analyzed in parallel using a high-content microscopy. Protocols described here allow for adoption and routine application of microfluidic techniques by nonspecialized end-users.

Keywords:  Caco-2; Gut-on-a-chip; Intestinal model; Microfluidics; OrganoPlate; Phaseguides

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_6
Methods Mol Biol. 2022 ;2373 69-85

Establishment of a Modular Anaerobic Human Intestine Chip.

Sasan Jalili-Firoozinezhad, Amir Bein, Francesca S Gazzaniga, Cicely W Fadel, Richard Novak, Donald E Ingber.

  It is impossible to analyze human-specific host-microbiome interactions using animal models and existing in vitro methods fail to support survival of human cells in direct contact with complex living microbiota for extended times. Here we describe a protocol for culturing human organ-on-a-chip (Organ Chip) microfluidic devices lined by human patient-derived primary intestinal epithelium in the presence of a physiologically relevant transluminal hypoxia gradient that enables their coculture with hundreds of different living aerobic and anaerobic bacteria found within the human gut microbiome. This protocol can be adapted to provide different levels of oxygen tension to facilitate coculturing of microbiome from different regions of gastrointestinal tract, and the same system can be applied with any other type of Organ Chip. This method can help to provide further insight into the host-microbiome interactions that contribute to human health and disease, enable discovery of new microbiome-related diagnostics and therapeutics, and provide a novel approach to advanced personalized medicine.

Keywords:  Intestine; Microbiome; Microfluidic; Organ-on-a-Chip; Organoid; Oxygen gradients

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_5
Methods Mol Biol. 2022 ;2373 177-199

Fabrication and Use of a Pumpless Microfluidic Lymphatic Vessel Chip.

Parinaz Fathi, Mandy B Esch.

  Pumpless microfluidic systems are easy-to-use devices that can be used to culture cells that are sensitive to mechanical shear, such as lymphatic endothelial cells. However, previously developed pumpless systems either provide unidirectional shear where the cell culture medium is discarded, or bidirectional shear that produces endothelial cell cultures with disease characteristics. Here, we describe a PDMS-based system that produces cyclically rising and falling shear that is unidirectional, similar to what has been reported in lymphatic vessels. The system can recirculate cell culture medium, making it possible for proteins and growth factors produced by the cell culture to remain in circulation. In addition, we describe the custom-made rotating platform that we used to create this unique flow pattern. Using this rotating platform, the microfluidic device can be used to grow confluent layers of lymphatic endothelial cells under physiologically relevant growth conditions.

Keywords:  Endothelial lining; Endothelium; Gravity-driven flow; Lymph node; Lymphatic vessel; Organ-on-a-chip; Pumpless microfluidics; Rotating platform

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_11
Methods Mol Biol. 2022 ;2373 253-266

Detailed Methodology to Establish a Synovium/Cartilage-on-a-Chip Model to Investigate the Process of Monocyte Extravasation.

Silvia Palombella, Shima Salehi, Carlotta Mondadori, Giuseppe Talò, Valerio Sansone, Matteo Moretti, Silvia Lopa.

  Microfluidics allows for recapitulating organotypic environments in miniaturized cell culture platforms. This ability paves the way to the investigation of complex biological processes in a relevant milieu. Here we describe the protocols to generate an organotypic model including a vascularized compartment mimicking the synovial membrane and designed for the study of monocyte extravasation during osteoarthritis.

Keywords:  Cartilage; Extravasation; Microfluidics; Monocyte; Organ-on-a-chip; Synovium

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_15
Microbiol Spectr. 2021 Sep 15. e0025721

Clinically Relevant Influenza Virus Evolution Reconstituted in a Human Lung Airway-on-a-Chip.

Longlong Si, Haiqing Bai, Crystal Yuri Oh, Lei Jin, Rachelle Prantil-Baun, Donald E Ingber.

  Human-to-human transmission of viruses, such as influenza viruses and coronaviruses, can promote virus evolution and the emergence of new strains with increased potential for creating pandemics. Clinical studies analyzing how a particular type of virus progressively evolves new traits, such as resistance to antiviral therapies, as a result of passing between different human hosts are difficult to carry out because of the complexity, scale, and cost of the challenge. Here, we demonstrate that spontaneous evolution of influenza A virus through both mutation and gene reassortment can be reconstituted in vitro by sequentially passaging infected mucus droplets between multiple human lung airway-on-a-chip microfluidic culture devices (airway chips). Modeling human-to-human transmission of influenza virus infection on chips in the continued presence of the antiviral drugs amantadine or oseltamivir led to the spontaneous emergence of clinically prevalent resistance mutations, and strains that were resistant to both drugs were identified when they were administered in combination. In contrast, we found that nafamostat, an inhibitor targeting host serine proteases, did not induce viral resistance. This human preclinical model may be useful for studying viral evolution in vitro and identifying potential influenza virus variants before they appear in human populations, thereby enabling preemptive design of new and more effective vaccines and therapeutics. IMPORTANCE The rapid evolution of viruses, such as influenza viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is challenging the use and development of antivirals and vaccines. Studies of within-host viral evolution can contribute to our understanding of the evolutionary and epidemiological factors that shape viral global evolution as well as development of better antivirals and vaccines. However, little is known about how viral evolution of resistance to antivirals occurs clinically due to the lack of preclinical models that can faithfully model influenza infection in humans. Our study shows that influenza viral evolution through mutation or gene reassortment can be recapitulated in a human lung airway-on-a-chip (airway chip) microfluidic culture device that can faithfully recapitulate the influenza infection in vitro. This approach is useful for studying within-host viral evolution, evaluating viral drug resistance, and identifying potential influenza virus variants before they appear in human populations, thereby enabling the preemptive design of new and more effective vaccines and therapeutics.

Keywords:  drug resistance; gene reassortment; influenza virus; lung airway-on-a-chip; preclinical model; viral evolution

DOI:  https://doi.org/10.1128/Spectrum.00257-21
Methods Mol Biol. 2022 ;2373 21-38

Organ-on-Chips for Studying Tissue Barriers: Standard Techniques and a Novel Method for Including Porous Membranes Within Microfluidic Devices.

Mattia Ballerini, Mohammad Jouybar, Andrea Mainardi, Marco Rasponi, Giovanni Stefano Ugolini.

  A relevant number of organ-on-chips is aimed at modeling epithelial/endothelial interfaces between tissue compartments. These barriers help tissue function either by protecting (e.g., endothelial blood-brain barrier) or by orchestrating relevant molecular exchanges (e.g., lung alveolar interface) in human organs. Models of these biological systems are aimed at characterizing the transport of molecules, drugs or drug carriers through these specific barriers. Multilayer microdevices are particularly appealing to this goal and techniques for embedding porous membranes within organ-on-chips are therefore at the basis of the development and use of such systems. Here, we discuss and provide procedures for embedding porous membranes within multilayer organ-on-chips. We present standard techniques involving both custom-made polydimethylsiloxane (PDMS) membranes and commercially available plastic membranes. In addition, we present a novel method for fabricating and bonding PDMS porous membranes by using a cost-effective epoxy resin in place of microfabricated silicon wafers as master molds.

Keywords:  Microfluidics; Multilayer microdevices; Organ-on-chip; Porous membranes; Replica molding

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_2
ACS Appl Mater Interfaces. 2021 Sep 16.

Sorption of Neuropsychopharmaca in Microfluidic Materials for In Vitro Studies.

Thomas E Winkler, Anna Herland.

  Sorption (i.e., adsorption and absorption) of small-molecule compounds to polydimethylsiloxane (PDMS) is a widely acknowledged phenomenon. However, studies to date have largely been conducted under atypical conditions for microfluidic applications (lack of perfusion, lack of biological fluids, etc.), especially considering biological studies such as organs-on-chips where small-molecule sorption poses the largest concern. Here, we present an in-depth study of small-molecule sorption under relevant conditions for microphysiological systems, focusing on a standard geometry for biological barrier studies that find application in pharmacokinetics. We specifically assess the sorption of a broad compound panel including 15 neuropsychopharmaca at in vivo concentration levels. We consider devices constructed from PDMS as well as two material alternatives (off-stoichiometry thiol-ene-epoxy, or tape/polycarbonate laminates). Moreover, we study the much neglected impact of peristaltic pump tubing, an essential component of the recirculating systems required to achieve in vivo-like perfusion shear stresses. We find that the choice of the device material does not have a significant impact on the sorption behavior in our barrier-on-chip-type system. Our PDMS observations in particular suggest that excessive compound sorption observed in prior studies is not sufficiently described by compound hydrophobicity or other suggested predictors. Critically, we show that sorption by peristaltic tubing, including the commonly utilized PharMed BPT, dominates over device sorption even on an area-normalized basis, let alone at the typically much larger tubing surface areas. Our findings highlight the importance of validating compound dosages in organ-on-chip studies, as well as the need for considering tubing materials with equal or higher care than device materials.

Keywords:  materials; microfluidics; neuropsychopharmaca; non-specific binding; organs-on-chips

DOI:  https://doi.org/10.1021/acsami.1c07639
Methods Mol Biol. 2022 ;2373 121-131

Generation of a Glomerular Filtration Barrier on a Glomerulus-on-a-Chip Platform.

Laura Perin, Stefano Da Sacco.

  Despite an enormous investment of clinical and financial resources, chronic kidney disease (CKD) remains a global health threat. The lack of reliable in vitro systems that can efficiently mimic the renal and glomerular environment has hampered our ability to successfully develop novel and more renal specific drugs. Even though some success in generating in vitro tubule analogues and kidney organoids has been described, a major challenge remains for the in vitro assembly of the filtration unit of the kidney, the glomerulus. We have recently developed a novel glomerulus-on-a-chip system that mimics the characteristic and functionality of the glomerular filtration barrier, including its response to injury. This system recapitulates the functions and structure of the in vivo glomerulus, including permselectivity; indeed, we have confirmed free diffusion of insulin as well as impermeability to physiological concentrations of albumin. Exposure to nephrotoxic agents like puromycin aminonucleoside leads to a significant increase in albumin leakage. When exposed to sera from patients with anti-podocyte autoantibodies, the chip shows albumin leakage to an extent proportional to in vivo clinical data, phenomenon not observed with sera from either healthy controls, confirming functional response to injury. We describe here the detailed procedure to obtain a glomerulus-on-a-chip system that replicates both phenotypically and functionally the in vivo glomerular microenvironment.

Keywords:  Glomerular basement membrane; Glomerular endothelial cells; Glomerular filtration barrier; Glomerulus-on-a-chip; Kidney-on-a-chip; Permselectivity; Podocytes

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_8
Methods Mol Biol. 2022 ;2373 133-157

Electromechanical Stimulation of 3D Cardiac Microtissues in a Heart-on-Chip Model.

Roberta Visone, Paola Occhetta, Marco Rasponi.

  Modeling human cardiac tissues in vitro is essential to elucidate the biological mechanisms related to the heart physiopathology, possibly paving the way for new treatments. Organs-on-chips have emerged as innovative tools able to recreate tissue-specific microenvironments, guiding the development of miniaturized models and offering the opportunity to directly analyze functional readouts. Here we describe the fabrication and operational procedures for the development of a heart-on-chip model, reproducing cardiac biomimetic microenvironment. The device provides 3D cardiac microtissue with a synchronized electromechanical stimulation to support the tissue development. We additionally describe procedures for characterizing tissue evolution and functionality through immunofluorescence, real time qPCR, calcium imaging and microtissue contractility investigations.

Keywords:  Cardiac functionality; Electromechanical stimulation; Heart-on-chip

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_9
Methods Mol Biol. 2022 ;2373 231-251

Mechanical Induction of Osteoarthritis Traits in a Cartilage-on-a-Chip Model.

Andrea Mainardi, Paola Occhetta, Marco Rasponi.

  The present lack of effective therapies for osteoarthritis, the most diffused musculoskeletal disease, correlates with the absence of representative in vitro disease models. Microfabrication techniques and soft lithography allow the development of organs and tissues on chip with increased mimicry of human pathophysiology. Exploitation of polydimethylsiloxane elasticity, furthermore, permits to incorporate finely controlled mechanical actuators which are of the utmost importance in a faithful representation of the intrinsically active environment of musculoskeletal districts, to increase our comprehension of the disease onset and to successfully predict the response to pharmacological therapies. Here, we portray the fabrication and operational processes for the development of a cartilage-on-a-chip model. Additionally, we describe the methodologies to induce a phenotype reminiscent of osteoarthritis solely through hyperphysiological cyclic compression. The techniques to assess achievement of such features through immunofluorescence and gene expression are also detailed.

Keywords:  Cartilage-on-a-chip; Disease Modeling; Mechanical stimulation; Osteoarthritis

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_14
Methods Mol Biol. 2022 ;2373 297-313

Isolation, Integration, and Culture of Human Mature Adipocytes Leveraging Organ-on-Chip Technology.

Julia Rogal, Julia Roosz, Peter Loskill.

  Research on white adipose tissue (WAT), which constitutes one-fifth to one-half of the total body mass of a human's body, has gained more and more interest and attention in the era of "diabesity". In vitro research on mature human WAT is hampered by many challenges and, hence, a majority of WAT-related research is conducted using animal models as well as clinical observations and genome-wide association studies (GWAS), both featuring limitations in terms of translatability and potential for experimental interventions, respectively. Here, we describe methods to isolate primary mature human adipocytes from biopsies and to fabricate tailored organ-on-chip platforms for the long-term culture of WAT constructs.

Keywords:  Fat-on-chip; Microfluidics; Microphysiological systems; Organ-on-chip; Primary adipocytes; WAT-on-chip; White adipose tissue

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_18
Methods Mol Biol. 2022 ;2373 201-212

On-Chip Platelet Activation Assessment: Microfluidic Emulation of Shear Stress Profiles Induced by Mechanical Circulatory Support Devices.

Tatiana Mencarini, Silvia Bozzi, Alberto Redaelli.

  Mechanical circulatory support devices (MCSDs), although proved to be a pillar in the clinical setting of advanced heart failure, are afflicted by thromboembolic complications. Shear-mediated platelet activation has been recognized to drive thromboembolic events in patients implanted with MCSDs. Despite this, to date, a clinically reliable diagnostic test for assessing platelet response to stress stimuli is still missing. Here, we describe and apply the previously developed device thrombogenicity emulation methodology to the design of a microfluidic platform able to replicate shear stress profiles representative of MCSDs. The device-specific shear-mediated platelet activation is finally assessed by the platelet activity state assay, which measures real-time thrombin production, as a marker of platelet activation level. This technique can be employed to emulate the shear stress patterns of different MCSDs, such as mechanical heart valves, ventricular assist devices, and stents.

Keywords:  Mechanical circulatory support devices; Microfluidics; Platelet activation; Shear stress patterns; Thrombogenicity

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_12
Methods Mol Biol. 2022 ;2373 57-68

Bile Duct-on-a-Chip.

Yu Du, William J Polacheck, Rebecca G Wells.

  Cholangiopathies affect the biliary tree via various pathophysiological mechanisms. Research on biliary physiology and pathology, however, is hampered by a lack of physiologically relevant in vitro models. Conventional models, such as two-dimensional (2D) monolayers and organoids, fail to replicate the structural organization of the bile duct, and both the size of the duct and position of cells are difficult to manipulate in a controllable way. Here, we describe a bile duct-on-a-chip (BDOC) that phenocopies the open-ended tubular architecture of the bile duct in three dimensions which, when seeded with either a cholangiocyte cell line or primary cells, demonstrates barrier function similar to bile ducts in vivo. This device represents an in vitro platform to study the pathophysiology of the bile duct using cholangiocytes from a variety of sources.

Keywords:  3D cell culture; Bile duct epithelium; Biliary model; Cholangiopathy; Microfluidics; Organ-on-chip; Organotypic model

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_4
Methods Mol Biol. 2022 ;2373 107-119

A Human Neurovascular Unit On-a-Chip.

Sharon Wei Ling Lee, Renato Rogosic, Claudia Venturi, Manuela Teresa Raimondi, Andrea Pavesi, Giulia Adriani.

  Protection of the central nervous system (CNS) and cerebral homeostasis depend upon the blood-brain barrier (BBB) functions and permeability. BBB restrictive permeability hinders drug delivery for the treatment of several neurodegenerative diseases and brain tumors. Several in vivo animal models and in vitro systems have been developed to understand the BBB complex mechanisms and aid in the design of improved therapeutic strategies. However, there are still many limitations that should be addressed to achieve the structural and chemical environment of a human BBB. We developed a microfluidic-based model of the neurovascular unit. A monolayer of human cerebral endothelial cells (hCMEC-D3) was grown and cocultured with human brain microvascular pericytes (hBMVPC), and human induced pluripotent stem cells differentiated into astrocytes (hiPSC-AC) and neurons (hiPSC-N). To visualize the physiological morphology of each cell type, we used fluorescent cell-specific markers and confocal microscopy. Permeation of fluorescent solutes with different molecular weights was measured to demonstrate that the developed BBB was selectively permeable as a functional barrier.

Keywords:  Blood–brain barrier; Human induced pluripotent stem cells; Microfluidic; Neurovascular unit; Organotypic model

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_7
Methods Mol Biol. 2022 ;2373 213-230

Biofabrication of 3D Human Muscle Model with Vascularization and Endomysium.

Simone Bersini, Riccardo Francescato, Matteo Moretti.

  This protocol describes the biofabrication of 3D millimeter-scale human muscle units, embedding non-planar muscle fibers wrapped by fibroblasts-rich endomysium and intertwined with microvascular networks. Suspended muscle fibers are formed through the self-assembly of human myoblasts within cylindrical cavities generated in a sacrificial gelatin template cast in a 3D printed frame. Following myotube differentiation, muscle fibers are embedded in a 3D matrix containing endothelial cells and muscle-derived fibroblasts. The cellular complexity of the environment is instrumental to drive fibroblast migration towards muscle fibers and to induce the organ-specific differentiation of endothelial cells. This advanced 3D muscle model can be applied to analyze the biological mechanisms underlying specific muscle diseases which involve a complex remodeling of the muscle environment (e.g., muscular dystrophies and fibrosis) whereby the pathological interplay among different cell populations drives the onset and progression of the disease.

Keywords:  3D human muscle model; 3D printing; Duchenne muscular dystrophy; Endomysium; Endothelial cell; Fibrosis; Mesoscale; Organ specificity; Vasculature

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_13
Commun Biol. 2021 Sep 15. 4(1): 1080

Modelling human liver fibrosis in the context of non-alcoholic steatohepatitis using a microphysiological system.

Tomasz Kostrzewski, Sophie Snow, Anya Lindström Battle, Samantha Peel, Zahida Ahmad, Jayati Basak, Manasa Surakala, Aurelie Bornot, Julia Lindgren, Maria Ryaboshapkina, Maryam Clausen, Daniel Lindén, Christian Maass, Lucy May Young, Adam Corrigan, Lorna Ewart, David Hughes.

Non-alcoholic steatohepatitis (NASH) is a common form of chronic liver disease characterised by lipid accumulation, infiltration of immune cells, hepatocellular ballooning, collagen deposition and liver fibrosis. There is a high unmet need to develop treatments for NASH. We have investigated how liver fibrosis and features of advanced clinical disease can be modelled using an in vitro microphysiological system (MPS). The NASH MPS model comprises a co-culture of primary human liver cells, which were cultured in a variety of conditions including+/- excess sugar, fat, exogenous TGFβ or LPS. The transcriptomic, inflammatory and fibrotic phenotype of the model was characterised and compared using a system biology approach to identify conditions that mimic more advanced clinical disease. The transcriptomic profile of the model was shown to closely correlate with the profile of patient samples and the model displayed a quantifiable fibrotic phenotype. The effects of Obeticholic acid and Elafibranor, were evaluated in the model, as wells as the effects of dietary intervention, with all able to significantly reduce inflammatory and fibrosis markers. Overall, we demonstrate how the MPS NASH model can be used to model different aspects of clinical NASH but importantly demonstrate its ability to model advanced disease with a quantifiable fibrosis phenotype.

DOI: https://doi.org/10.1038/s42003-021-02616-x
Stem Cell Reports. 2021 Sep 14. pii: S2213-6711(21)00426-4. [Epub ahead of print]16(9): 2242-2256

Human stem cell-based retina on chip as new translational model for validation of AAV retinal gene therapy vectors.

Kevin Achberger, Madalena Cipriano, Matthias J Düchs, Christian Schön, Stefan Michelfelder, Birgit Stierstorfer, Thorsten Lamla, Stefan G Kauschke, Johanna Chuchuy, Julia Roosz, Lena Mesch, Virginia Cora, Selin Pars, Natalia Pashkovskaia, Serena Corti, Sophia-Marie Hartmann, Alexander Kleger, Sebastian Kreuz, Udo Maier, Stefan Liebau, Peter Loskill.

  Gene therapies using adeno-associated viruses (AAVs) are among the most promising strategies to treat or even cure hereditary and acquired retinal diseases. However, the development of new efficient AAV vectors is slow and costly, largely because of the lack of suitable non-clinical models. By faithfully recreating structure and function of human tissues, human induced pluripotent stem cell (iPSC)-derived retinal organoids could become an essential part of the test cascade addressing translational aspects. Organ-on-chip (OoC) technology further provides the capability to recapitulate microphysiological tissue environments as well as a precise control over structural and temporal parameters. By employing our recently developed retina on chip that merges organoid and OoC technology, we analyzed the efficacy, kinetics, and cell tropism of seven first- and second-generation AAV vectors. The presented data demonstrate the potential of iPSC-based OoC models as the next generation of screening platforms for future gene therapeutic studies.

Keywords:  AAV vectors; gene therapy; human iPSC; organ-on-chip; retina on chip; retinal organoids

DOI:  https://doi.org/10.1016/j.stemcr.2021.08.008
Stem Cell Reports. 2021 Sep 14. pii: S2213-6711(21)00431-8. [Epub ahead of print]16(9): 2029-2032

Welcome to the special issue on organs-on-chip from the guest editors.

Christine Mummery, Peter Loskill.

DOI: https://doi.org/10.1016/j.stemcr.2021.08.013
Lab Chip. 2021 Sep 15.

An "occlusive thrombosis-on-a-chip" microfluidic device for investigating the effect of anti-thrombotic drugs.

Jess Berry, François J Peaudecerf, Nicole A Masters, Keith B Neeves, Raymond E Goldstein, Matthew T Harper.

Cardiovascular disease remains one of the world's leading causes of death. Myocardial infarction (heart attack) is triggered by occlusion of coronary arteries by platelet-rich thrombi (clots). The development of new anti-platelet drugs to prevent myocardial infarction continues to be an active area of research and is dependent on accurately modelling the process of clot formation. Occlusive thrombi can be generated in vivo in a range of species, but these models are limited by variability and lack of relevance to human disease. Although in vitro models using human blood can overcome species-specific differences and improve translatability, many models do not generate occlusive thrombi. In those models that do achieve occlusion, time to occlusion is difficult to measure in an unbiased and objective manner. In this study we developed a simple and robust approach to determine occlusion time of a novel in vitro microfluidic assay. This highlighted the potential for occlusion to occur in thrombosis microfluidic devices through off-site coagulation, obscuring the effect of anti-platelet drugs. We therefore designed a novel occlusive thrombosis-on-a-chip microfluidic device that reliably generates occlusive thrombi at arterial shear rates by quenching downstream coagulation. We further validated our device and methods by using the approved anti-platelet drug, eptifibatide, recording a significant difference in the "time to occlude" in treated devices compared to control conditions. These results demonstrate that this device can be used to monitor the effect of antithrombotic drugs on time to occlude, and, for the first time, delivers this essential data in an unbiased and objective manner.

DOI: https://doi.org/10.1039/d1lc00347j
Stem Cell Reports. 2021 Sep 14. pii: S2213-6711(21)00376-3. [Epub ahead of print]16(9): 2076-2077

Putting Science into Standards workshop on standards for organ-on-chip.

Monica Piergiovanni, Ozlem Cangar, Sofia B Leite, Livia Mian, Andreas Jenet, Raffaella Corvi, Maurice Whelan, Fabio Taucer, Ashok Ganesh.

The European Commission Joint Research Centre and the European Standardization Organizations CEN and CENELEC organized the "Putting Science into Standards" workshop, focusing on organ-on-chip technologies. The workshop, held online on 28-29 April, 2021, aimed at identifying needs and priorities for standards development and suggesting possible ways forward.

DOI: https://doi.org/10.1016/j.stemcr.2021.07.010
Methods Mol Biol. 2022 ;2373 267-281

A Mesoscale 3D Culture System for Native and Engineered Biphasic Tissues: Application to the Osteochondral Unit.

Irene Chiesa, Roberto Di Gesù, Kalon J Overholt, Riccardo Gottardi.

  Interface tissues are functionally graded tissues characterized by a complex layered structure, which therefore present a great challenge to be reproduced and cultured in vitro. Here, we describe the design and operation of a 3D printed dual-chamber bioreactor as a culturing system for biphasic native or engineered osteochondral tissues. The bioreactor is designed to potentially accommodate a variety of interface tissues and enables the precise study of tissue crosstalk by creating two separate microenvironments while maintaining the tissue compartments in direct contact.

Keywords:  Bioreactor; Biphasic constructs; Crosstalk; Interface tissue engineering; Microphysiological system; Osteochondral junction; Paracrine signaling

DOI:  https://doi.org/10.1007/978-1-0716-1693-2_16