Combining stem cell-derived hepatocytes with impedance sensing to better predict human drug toxicity

The cytotoxicity of gefitinib on patient‑derived induced pluripotent stem cells reflects gefitinib‑induced liver injury in the clinical setting

Gefitinib is a key drug used in the treatment of non-small cell lung cancer (NSCLC) with EGFR mutations. Gefitinib therapy is superior to conventional chemotherapy for the progression-free survival rate of patients with EGFR mutations. However, 10-26% of patients develop grade 3 or higher hepatotoxicity during gefitinib treatment; therefore, the development of preclinical tests for hepatotoxicity prior to clinical use is desirable. The present study evaluated the use of induced pluripotent stem cells (iPSCs) and iPSC-derived hepatocytes (iPSC-heps), as a platform for preclinical test development. Patient-derived iPSCs were generated by reprogramming peripheral blood mononuclear cells obtained from two groups of gefitinib-treated patients with severe hepatotoxicity [toxicity group (T group)] or mild hepatotoxicity [no clinical toxicity group (N group)]. To examine the hepatotoxicity, the iPSCs from both T and N groups were differentiated into hepatocytes to obtain iPSC-heps. Differentiation was confirmed by measuring the expression levels of hepatocyte markers, such as albumin or α-fetoprotein, via western blotting and quantitative PCR analyses. Cytotoxicity in iPSCs and iPSC-heps after gefitinib treatment was evaluated using a lactate dehydrogenase release assay. The gefitinib-induced cytotoxicity in iPSCs from the T group was significantly higher than that from the N group, whereas there were no significant differences between the groups of iPSC-heps. These results suggested that using iPSCs in preclinical assessment may be a good indicator for the prediction of gefitinib-induced cytotoxicity in clinical use.

Concepts, electrode configuration, characterization, and data analytics of electric and electrochemical microfluidic platforms: a review

Microfluidic cytometry (MC) and electrical impedance spectroscopy (EIS) are two important techniques in biomedical engineering. Microfluidic cytometry has been utilized in various fields such as stem cell differentiation and cancer metastasis studies, and provides a simple, label-free, real-time method for characterizing and monitoring cellular fates. The impedance microdevice, including impedance flow cytometry (IFC) and electrical impedance spectroscopy (EIS), is integrated into MC systems. IFC measures the impedance of individual cells as they flow through a microfluidic device, while EIS measures impedance changes during binding events on electrode regions. There have been significant efforts to improve and optimize these devices for both basic research and clinical applications, based on the concepts, electrode configurations, and cell fates. This review outlines the theoretical concepts, electrode engineering, and data analytics of these devices, and highlights future directions for development.

A HepG2 Cell-Based Biosensor That Uses Stainless Steel Electrodes for Hepatotoxin Detection

Humans are frequently exposed to environmental hepatotoxins, which can lead to liver failure. Biosensors may be the best candidate for the detection of hepatotoxins because of their high sensitivity and specificity, convenience, time-saving, low cost, and extremely low detection limit. To investigate suitability of HepG2 cells for biosensor use, different methods of adhesion on stainless steel surfaces were investigated, with three groups of experiments performed in vitro. Cytotoxicity assays, which include the resazurin assay, the neutral red assay (NR), and the Coomassie Brilliant Blue (CBB) assay, were used to determine the viability of HepG2 cells exposed to various concentrations of aflatoxin B1 (AFB1) and isoniazid (INH) in parallel. The viability of the HepG2 cells on the stainless steel surface was quantitatively and qualitatively examined with different microscopy techniques. A simple cell-based electrochemical biosensor was developed by evaluating the viability of the HepG2 cells on the stainless steel surface when exposed to various concentrations of AFB1 and INH by using electrochemical impedance spectroscopy (EIS). The results showed that HepG2 cells can adhere to the metal surface and could be used as part of the biosensor to determine simple hepatotoxic samples.

iPSC-Derived Hepatocytes as a Platform for Disease Modeling and Drug Discovery

The liver is one of the largest organs in the body and is responsible for a diverse repertoire of metabolic processes. Such processes include the secretion of serum proteins, carbohydrate and lipid metabolism, bile acid and urea synthesis, detoxification of drugs and metabolic waste products, and vitamin and carbohydrate storage. Currently, liver disease is one of the most prevalent causes of mortality in the USA with congenital liver defects contributing to a significant proportion of these deaths. Historically the study of liver disease has been hampered by a shortage of organ donors, the subsequent scarcity of healthy tissue, and the failure of animal models to fully recapitulate human liver function. In vitro culture of hepatocytes has also proven difficult because primary hepatocytes rapidly de-differentiate in culture. Recent advances in stem cell technology have facilitated the generation of induced pluripotent stem cells (iPSCs) from various somatic cell types from patients. Such cells can be differentiated to a liver cell fate, essentially providing a limitless supply of cells with hepatocyte characteristics that can mimic the pathophysiology of liver disease. Furthermore, development of the CRISPR-Cas9 system, as well as advancement of miniaturized differentiation platforms has facilitated the development of high throughput models for the investigation of hepatocyte differentiation and drug discovery. In this review, we will explore the latest advances in iPSC-based disease modeling and drug screening platforms and examine how this technology is being used to identify new pharmacological interventions, and to advance our understanding of liver development and mechanisms of disease. We will cover how iPSC technology is being used to develop predictive models for rare diseases and how information gained from large in vitro screening experiments can be used to directly inform clinical investigation.