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Stem cell-derived β cells offer an alternative to primary islets for biomedical discoveries as well as a potential surrogate for islet transplantation. The expense and challenge of obtaining and maintaining functional stem cell-derived β cells calls for a need to develop better high-content and high-throughput culture systems. Microphysiological systems (MPS) are promising high-content in vitro platforms, but scaling for high-throughput screening and discoveries remain a challenge. Traditionally, simultaneous multiplexing of liquid handling and cell loading poses a challenge in the design of high-throughput MPS. Furthermore, although MPS for islet β culture/testing have been developed, studies on multi-day culture of stem-cell derived β cells in MPS have been limited. We present a scalable, multiplexed islet β MPS device that incorporates microfluidic gradient generators to parallelize fluid handling for culture and test conditions. We demonstrated the viability and functionality of the stem cell-derived enriched β clusters (eBCs) for a week, as assessed by the ∼2 fold insulin release by the clusters to glucose challenge. To show the scalable multiplexing for drug testing, we demonstrated the loss of stimulation index after long-term exposure to logarithmic concentration range of glybenclamide. The MPS cultured eBCs also confirmed a glycolytic bottleneck as inferred by insulin secretion responses to metabolites methyl succinate and glyceric acid. Thus, we present an innovative culture platform for eBCs with a balance of high-content and high-throughput characteristics. [ABSTRACT FROM AUTHOR]

Despite global efforts, it took 7 months between the proclamation of global SARS-CoV-2 pandemic and the first FDA-approved treatment for COVID-19. During this timeframe, clinicians focused their efforts on repurposing drugs, such as hydroxychloroquine (HCQ) or azithromycin (AZM) to treat hospitalized COVID-19 patients. While clinical trials are time-consuming, the exponential increase in hospitalizations compelled the FDA to grant an emergency use authorization for HCQ and AZM as treatment for COVID-19, although there was limited evidence of their combined efficacy and safety. The authorization was revoked 4 months later, giving rise to controversial political and scientific debates illustrating important challenges such as premature authorization of potentially ineffective or unsafe therapeutics, while diverting resources from screening of effective drugs. Here we report on a preclinical drug screening platform, a cardiac microphysiological system (MPS), to rapidly identify clinically relevant cardiac liabilities associated with HCQ and AZM. The cardiac MPS is a microfabricated fluidic system in which cardiomyocytes derived from human induced pluripotent stem cells self-arrange into a uniaxially beating tissue. The drug response was measured using outputs that correlate with clinical measurements such as action potential duration (proxy for clinical QT interval) and drug-biomarker pairing. The cardiac MPS predicted clinical arrhythmias associated with QT prolongation and rhythm instabilities in tissues treated with HCQ. We found no change in QT interval upon acute exposure to AZM, while still observing a significant increase in arrhythmic events. These results suggest that this MPS can not only predict arrhythmias, but it can also identify arrhythmias even when QT prolongation is absent. When exposed to HCQ and AZM polytherapy, this MPS faithfully reflected clinical findings, in that the combination of drugs synergistically increased QT interval when compared to single drug exposure, while not worsening the overall frequency of arrhythmic events. The high content cardiac MPS can rapidly evaluate the cardiac safety of potential therapeutics, ultimately accelerating patients' access to safe and effective treatments. [ABSTRACT FROM AUTHOR]

Only a handful of US Food and Drug Administration (FDA) Emergency Use Authorizations exist for drug and biologic therapeutics that treat severe acute respiratory syndrome‐coronavirus 2 (SARS‐CoV‐2) infection. Potential therapeutics include repurposed drugs, some with cardiac liabilities. We report on a chronic preclinical drug screening platform, a cardiac microphysiological system (MPS), to assess cardiotoxicity associated with repurposed hydroxychloroquine (HCQ) and azithromycin (AZM) polytherapy in a mock phase I safety clinical trial. The MPS contained human heart muscle derived from induced pluripotent stem cells. The effect of drug response was measured using outputs that correlate with clinical measurements, such as QT interval (action potential duration) and drug‐biomarker pairing. Chronic exposure (10 days) of heart muscle to HCQ alone elicited early afterdepolarizations and increased QT interval past 5 days. AZM alone elicited an increase in QT interval from day 7 onward, and arrhythmias were observed at days 8 and 10. Monotherapy results mimicked clinical trial outcomes. Upon chronic exposure to HCQ and AZM polytherapy, we observed an increase in QT interval on days 4–8. Interestingly, a decrease in arrhythmias and instabilities was observed in polytherapy relative to monotherapy, in concordance with published clinical trials. Biomarkers, most of them measurable in patients' serum, were identified for negative effects of monotherapy or polytherapy on tissue contractile function, morphology, and antioxidant protection. The cardiac MPS correctly predicted clinical arrhythmias associated with QT prolongation and rhythm instabilities. This high content system can help clinicians design their trials, rapidly project cardiac outcomes, and define new monitoring biomarkers to accelerate access of patients to safe coronavirus disease 2019 (COVID‐19) therapeutics. [ABSTRACT FROM AUTHOR]

Soft lithography techniques using polydimethylsiloxane (PDMS) are a cornerstone of microfluidic microdevices and emerging technologies such as microphysiological systems (MPS). Most of these systems employ hydrophobic small molecules during either stem cell differentiation, drug screening, or organoid development. However, due to PDMS's structure and hydrophobicity, lipophilic molecules are strongly absorbed creating unpredictable concentrations of mitogens, drugs, differentiation factors, and analytes, which is a major limitation in its use for biological applications. In this study, several catechol‐functionalized calix[4]arene based macrocyclic polyphenols (MPPs) are synthesized and coated on PDMS through a dip‐coating or flow through process. One molecule, MPP5cone, synthesized from catechol and resorcinol in its cone isomer form, increases the hydrophilicity of PDMS and drastically reduces the absorption of a number of hydrophobic drug surrogates, while preserving high oxygen permeability, good cell viability and function. However, simple rules of molecular absorption based on Log P are not observed, suggesting screening barrier coatings for PDMS with single probes is not sufficient. The coating procedure is easily translated to microfluidic devices by infusion through channels with a pump, and therefore should find use in applications where molecular absorption into PDMS is a significant problem. [ABSTRACT FROM AUTHOR]

The decrease in contractility in myocardium adjacent (border zone; BZ) to a myocardial infarction (MI) is correlated with an increase in reactive oxygen species (ROS). We hypothesized that injection of a thermoresponsive hydrogel, with ROS scavenging properties, into the MI would decrease ROS and improve BZ function. Fourteen sheep underwent antero‐apical MI. Seven sheep had a comb‐like copolymer synthesized from N‐isopropyl acrylamide (NIPAAm) and 1500 MW methoxy poly(ethylene glycol) methacrylate, (NIPAAm‐PEG1500), injected (20 × 0.5 mL) into the MI zone 40 min after MI (MI + NIPAAm‐PEG1500) and seven sheep were MI controls. Cardiac MRI was performed 2 weeks before and 6 weeks after MI + NIPAAm‐PEG1500. BZ wall thickness at end systole was significantly higher for MI + NIPAAm‐PEG1500 (12.32 ± 0.51 mm/m2 MI + NIPAAm‐PEG1500 vs. 9.88 ± 0.30 MI; p =.023). Demembranated muscle force development for BZ myocardium 6 weeks after MI was significantly higher for MI + NIPAAm‐PEG1500 (67.67 ± 2.61 mN/m2 MI + NIPAAm‐PEG1500 vs. 40.53 ± 1.04 MI; p <.0001) but not significantly different from remote myocardium or BZ or non‐operated controls. Levels of ROS in BZ tissue were significantly lower in the MI + NIPAAm‐PEG1500 treatment group (hydroxyl p =.0031; superoxide p =.0182). We conclude that infarct injection of the NIPAAm‐PEG1500 hydrogel with ROS scavenging properties decreased ROS and improved contractile protein function in the border zone 6 weeks after MI. [ABSTRACT FROM AUTHOR]

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) hold great potential for drug screening applications. However, their usefulness is limited by the relative immaturity of the cells' electrophysiological properties as compared to native cardiomyocytes in the adult human heart. In this work, we extend and improve on methodology to address this limitation, building on previously introduced computational procedures which predict drug effects for adult cells based on changes in optical measurements of action potentials and Ca2+ transients made in stem cell derived cardiac microtissues. This methodology quantifies ion channel changes through the inversion of data into a mathematical model, and maps this response to an adult phenotype through the assumption of functional invariance of fundamental intracellular and membrane channels during maturation. Here, we utilize an updated action potential model to represent both hiPSC-CMs and adult cardiomyocytes, apply an IC50-based model of dose-dependent drug effects, and introduce a continuation-based optimization algorithm for analysis of dose escalation measurements using five drugs with known effects. The improved methodology can identify drug induced changes more efficiently, and quantitate important metrics such as IC50 in line with published values. Consequently, the updated methodology is a step towards employing computational procedures to elucidate drug effects in adult cardiomyocytes for new drugs using stem cell-derived experimental tissues. [ABSTRACT FROM AUTHOR]

The development of various solid phase materials for central nervous system (CNS) culture including natural, semisynthetic, and fully synthetic materials are reviewed. Engineered materials containing natural and/or synthetic components of neural stem cells could find potential application for the treatment of neurodegenerative disorders and injuries of the CNS.

Cell therapy offers much promise for the treatment of ischemic diseases by augmenting tissue vasculogenesis. Matrix-assisted cell transplantation (MACT) has been proposed as a solution to enhance cell survival and integration with host tissue following transplantation. By designing semi synthetic matrices (sECM) with the correct physical and biochemical signals, encapsulated cells are directed towards a more angiogenic phenotype. In this review, we describe the choice of cells suitable for pro-angiogenic therapies, the properties that should be considered when designing sECM for transplantation and their relative importance. Pre-clinical models where MACT has been successfully applied to promote angiogenesis are reviewed to show the great potential of this strategy to treat ischemic conditions. Unlabelled Image [ABSTRACT FROM AUTHOR]