Liver Acinus Dynamic Chip for Assessment of Drug-Induced Zonal Hepatotoxicity

Models for barrier understanding in health and disease in lab-on-a-chips

The maintenance of body homeostasis relies heavily on physiological barriers. Dysfunction of these barriers can lead to various pathological processes, including increased exposure to toxic materials and microorganisms. Various methods exist to investigate barrier function in vivo and in vitro. To investigate barrier function in a highly reproducible manner, ethically, and high throughput, researchers have turned to non-animal techniques and micro-scale technologies. In this comprehensive review, the authors summarize the current applications of organ-on-a-chip microfluidic devices in the study of physiological barriers. The review covers the blood-brain barrier, ocular barriers, dermal barrier, respiratory barriers, intestinal, hepatobiliary, and renal/bladder barriers under both healthy and pathological conditions. The article then briefly presents placental/vaginal, and tumour/multi-organ barriers in organ-on-a-chip devices. Finally, the review discusses Computational Fluid Dynamics in microfluidic systems that integrate biological barriers. This article provides a concise yet informative overview of the current state-of-the-art in barrier studies using microfluidic devices.

Construction of in vitro liver-on-a-chip models and application progress

The liver is the largest internal organ of the human body. It has a complex structure and function and plays a vital role in drug metabolism. In recent decades, extensive research has aimed to develop in vitro models that can simulate liver function to demonstrate changes in the physiological and pathological environment of the liver. Animal models and in vitro cell models are common, but the data obtained from animal models lack relevance when applied to humans, while cell models have limited predictive ability for metabolism and toxicity in humans. Recent advancements in tissue engineering, biomaterials, chip technology, and 3D bioprinting have provided opportunities for further research in in vitro models. Among them, liver-on-a-Chip (LOC) technology has made significant achievements in reproducing the in vivo behavior, physiological microenvironment, and metabolism of cells and organs. In this review, we discuss the development of LOC and its research progress in liver diseases, hepatotoxicity tests, and drug screening, as well as chip combinations. First, we review the structure and the physiological function of the liver. Then, we introduce the LOC technology, including general concepts, preparation materials, and methods. Finally, we review the application of LOC in disease modeling, hepatotoxicity tests, drug screening, and chip combinations, as well as the future challenges and directions of LOC.

Inhibition of 15-prostaglandin dehydrogenase attenuates acetaminophen-induced liver injury via suppression of apoptosis in liver endothelial cells

Hepatic microvascular disruption caused by injury to liver sinusoidal endothelial cells (LSECs) is an aggravating factor for drug-induced liver injury (DILI). It is suggested that prostaglandin E2 (PGE2) may be able to attenuate LSEC injury. However, it is also known that 15-keto PGE2, a metabolite of PGE2 produced by 15-prostaglandin dehydrogenase (15-PGDH) that is not a ligand of PGE2 receptors, suppresses inflammatory acute liver injury as a ligand of peroxisome proliferator-activated receptor γ. In this study, we aimed to understand whether 15-PGDH activity is essential for preventing DILI by suppressing hepatic microvascular disruption in a mouse model of acetaminophen (APAP)-induced liver injury. To inhibit 15-PGDH activity prior to APAP-induced LSEC injury, we administered the 15-PGDH inhibitor, SW033291, 1 h before and 3 h after APAP treatment. We observed that LSEC injury preceded hepatocellular injury in APAP administered mice. Hepatic endogenous PGE2 levels did not increase up till the initiation of LSEC injury but rather increased after hepatocellular injury. Moreover, hepatic 15-PGDH activity was downregulated in APAP-induced liver injury. The inhibition of 15-PGDH attenuated LSEC injury and subsequently hepatic injury by inhibiting apoptosis in APAP administered mice. Our in vitro studies also suggested that PGE2 inhibited APAP-induced apoptosis via the EP4/PI3K pathway in endothelial cells. Therefore, a decrease in 15-PGDH activity would be beneficial for preventing APAP-induced liver injury by attenuating LSEC injury.

Vascularized liver-on-a-chip model to investigate nicotine-induced dysfunction

The development of physiologically relevant in vitro systems for simulating disease onset and progression and predicting drug metabolism holds tremendous value in reducing drug discovery time and cost. However, many of these platforms lack accuracy in replicating the tissue architecture and multicellular interactions. By leveraging three-dimensional cell culture, biomimetic soft hydrogels, and engineered stimuli, in vitro models have continued to progress. Nonetheless, the incorporation of the microvasculature has been met with many challenges, specifically with the addition of parenchymal cell types. Here, a systematic approach to investigating the initial seeding density of endothelial cells and its effects on interconnected networks was taken and combined with hepatic spheroids to form a liver-on-a-chip model. Leveraging this system, nicotine's effects on microvasculature and hepatic function were investigated. The findings indicated that nicotine led to interrupted adherens junctions, decreased guanosine triphosphate cyclohydrolase 1 expression, impaired angiogenesis, and lowered barrier function, all key factors in endothelial dysfunction. With the combination of the optimized microvascular networks, a vascularized liver-on-a-chip was formed, providing functional xenobiotic metabolism and synthesis of both albumin and urea. This system provides insight into potential hepatotoxicity caused by various drugs and allows for assessing vascular dysfunction in a high throughput manner.

Evening primrose oil attenuates oxidative stress, inflammation, fibrosis, apoptosis, and ultrastructural alterations induced by metanil yellow in the liver of rat: a histological, immunohistochemical, and biochemical study

The food color metanil yellow (Myl) is hazardous to several body systems. Evening primrose oil (EPO) was reported to have anti-inflammatory and anti-oxidant properties. The present work investigated the impact of Myl on the hepatic structure and function of rats and evaluated the protective effect of EPO. Forty adult male rats were divided into four groups: control, EPO (5 g/kg/day), Myl (200 mg/kg/day), and EPO- Myl group. Myl significantly increased liver enzymes, advanced glycation end products (AGE), oxidative stress parameters, pro-inflammatory cytokines, nuclear factor kappa B (NF-κB), and inducible nitric oxide synthase (iNOS). Blood vessels in the liver were dilated and congested, with cellular infiltration around them and associated with fibrosis. The hepatocytes were vacuolated and had dark nuclei. The immunohistochemical expression of iNOS, glial fibrillary acidic protein (GFAP), and Bax was significantly elevated. Ultrastructurally, the hepatocytes showed lipid droplets, irregular condensed nuclei with widened perinuclear space, dilated rER, mitochondria with destructed cristae, and multiple vacuoles. Dilated congested blood sinusoids and collagen fiber bundles were seen between hepatocytes. Interestingly, these alterations were less pronounced in rats co-administrated with EPO and Myl. In conclusion, EPO can protect liver against the toxic effects of Myl due to its anti-inflammatory and anti-oxidant activities.

A ratiometric nanoprobe for the in vivo bioimaging of hypochlorous acid to detect drug-damaged liver and kidneys

As the organs responsible for toxin transformation and excretion in the body, damage to the liver and kidneys induced by inevitable drug toxicity is the main cause of acute liver and kidney injury. P-Acetamidophenol overdose leads hypochlorous acid (HClO) to accumulate in the mitochondria of tissues, ultimately resulting in acute liver and kidney injury in humans, despite its clinical use as an antipyretic medicine. Herein, we report an HClO-activatable self-assembling ratiometric nanoprobe NRH-800-PEG for screening the upregulation of HClO by colocalization in mitochondria while monitoring the changes in the endogenous HClO levels in cells with ratiometric signals. Furthermore, NRH-800-PEG was constructed to evaluate injury by fluorescence ratio imaging in the tissues of inflammatory mice. Our strategy offers a novel tool for assessing disease progression during drug-induced liver and kidney injury.