Tomoko Jomura

Long-term survival and functional maintenance of hepatocytes by using a microfabricated cell array

We developed a microfabricated cell array of hepatocyte spheroids that showed long-term viability and retained the properties of the parent hepatocytes. Fresh hepatocytes harvested from 8-week-old Wistar rats were cocultured with feeder cells to rapidly form hepatocyte spheroids; these cells retained the spheroidal formation for 42 days. We also evaluated the cellular functions of the hepatocytes such as albumin secretion and metabolic activity of cytochrome P450 (CYP). In spheroids in which hepatocytes were cocultured with feeder cells, these cellular functions were retained even after 42 days. Therefore, this novel coculture will be very useful not only for research on the mechanism and treatment of liver diseases but also for early prediction of hepatocyte toxicity in the pre-clinical phase of drug development.

Construction of Artificial Hepatic Lobule-Like Spheroids on a Three-Dimensional Culture Device:

One major purpose of cell culture is the reconstruction of physiological structures. Using bovine aortic epithelium cell line HH (JCRB0099) as feeder cells and rat primary hepatocytes, we constructed hepatic lobule-like spheroids on a cell array plate designed for three-dimensional (3D) culture. Microfabricated patterning of the cell array with poly(ethyleneglycol) brushes promotes the formation of spheroids at 100-μm diameter at 100-μm intervals. Our standard protocol is to seed with feeder HH cells and then seed with primary hepatic parenchymal cells. The composite cell spheroids thus obtained are called heterospheroids. Feeder cells that were attached to the plate migrated and encompassed the spheroidal hepatocyte mass. Electron microscopy revealed Disse space-like structures characterized by hepatocyte-rooted microvilli rooted between hepatocyte and feeder epithelial HH cells. Differentiated hepatic functions such as albumin synthesis and cytochrome P450 subfamily CYP3A activities were maintained for 28 days in the heterospheroid versus monospheroid and monolayer cultures. In addition, glucuronide conjugation activity was maintained at a high level in heterospheroids. These results indicate that structurally similar hepatic lobules were formed in a microfabricated cell array coculture system and that the culture conditions are beneficial for maintaining differentiated hepatic functions.

Preliminary Evaluation of Three-Dimensional Primary Human Hepatocyte Culture System for Assay of Drug-Metabolizing Enzyme-Inducing Potential

Drug-induced liver injury (DILI) is a common reason for withdrawal of candidate drugs from clinical trials, or of approved drugs from the market. DILI may be induced not only by intact parental drugs, but also by metabolites or intermediates, and therefore should be evaluated in the enzyme-induced state. Here, we present a protocol for assay of drug-metabolizing enzyme-inducing potential using three-dimensional (3D) primary cultures of human hepatocytes (hepatocyte spheroids). Hepatocyte spheroids could be used up to 21 d after seeding (pre-culture for 7 d and exposure to inducer for up to 14 d), based on preliminary evaluation of basal activities of CYP subtypes and mRNA expression of the corresponding transcription factor and xenobiotic receptors (aryl hydrocarbon receptor (AhR), constitutive androstane receptor (CAR) and pregnane X receptor (PXR)). After 2 d exposure of hepatocyte spheroids to omeprazole, phenobarbital and rifampicin (typical inducers of CYP1A2, 2B6 and 3A4, respectively), CYP1A2, 2B6 and 3A4 mRNA expression levels were significantly increased. The mRNA induction of CYP2B6 remained reasonably stable between days 2 and 14 of exposure to inducers, while induction of both CYP1A2 and 3A4 continued to increase up to day 14. These enzyme activities were all significantly increased compared with the control until day 14. Our findings indicate that our 3D hepatocyte spheroids system would be especially suitable for long-term testing of enzyme activity induction by drugs, either to predict or to verify clinical events.

Abstract 3838: Stem-like cell characteristics of cancer spheroids grown in a microfabricated cell array three-dimensional culture system Cell-ableTM Oncology.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Recently, the cell biology field has come to appreciate the dissimilarity between two- (2D) and three-dimensional (3D) environments in which cells routinely operate in vivo. Efficacy of most anti-cancer drugs have been evaluated in 2D environment but it must be desirable to evaluate it in 3D environment. We developed a novel 3D cell culture system named Cell-ableTM Oncology utilizing photo-sensitive materials that change to hydro-gel after UV irradiation and the optimized molecular design not to allow the cells adhere to the hydro-gel. In multi-well plates, the Cell-ableTM Oncology has type I collagen-coated cell-attaching areas on the each well surface, which are circle in 100 μm diameter and arrayed in every direction at 100 μm interval. Most cancer cells are able to attach these circles and grow to form spheroids of uniform size on the Cell-ableTM Oncology. In this study, we investigated the stem-like cell phenotypes of cancer spheroids formed on the Cell-ableTM Oncology in comparison with that of the 2D monolayer cells. Various cancer cell lines and patient-derived primary cancer cells proliferated and formed spheroids on the Cell-ableTM Oncology in serum-containing or serum-free media. In contrast to the 2D monolayer cells, the inside of the spheroids formed on the Cell-ableTM Oncology was hypoxic condition like in vivo tumor tissues in patients. The spheroids grown on the Cell-ableTM Oncology showed chemo-resistance against conventional chemotherapy, gemcitabine and paclitaxel compared with cells grown on collagen-coated 2D plates. The chemo-resistance of the spheroid cells was associated with high population of stem-kike cells (CD44high/CD24low) and high expression of mRNA for a stem cell marker, NANOG and an ABC transporter ABCG2. The combination of the Cell-ableTM Oncology and serum-free media showed the highest population of stem-like cells. These results indicate that the spheroids characterized by 3D structure formed on the ECM-coated surface and the hypoxic condition confer enriched the cancer stem-like cells. Thus, the spheroids on the Cell-ableTM Oncology could be suitable for research and development of drugs targeting cancer stem cells. The pharmacodynamic and pharmacokinetic studies using the cancer stem cell-rich spheroids could provide meaningful information relevant to clinical conditions. Citation Format: Koichi Yokota, Tomoko Jomura, Emiko Ozeki, Takeshi Ikeya. Stem-like cell characteristics of cancer spheroids grown in a microfabricated cell array three-dimensional culture system Cell-ableTM Oncology. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3838. doi:10.1158/1538-7445.AM2013-3838

Utility of human hepatocyte spheroids without feeder cells for evaluation of hepatotoxicity

We investigated the utility of three-dimensionally cultured hepatocytes (spheroids) without feeder cells (Sph(f-)) for the prediction of drug-induced liver injury (DILI) in humans. Sph(f-) and spheroids cultured on feeder cells (Sph(f+)) were exposed to the hepatotoxic drugs flutamide, diclofenac, isoniazid and chlorpromazine at various concentrations for 14 days, and albumin secretion and cumulative leakages of toxicity marker enzymes, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and γ-glutamyl transpeptidase (γ-GTP), were measured. The cumulative AST, LDH or γ-GTP leakages from Sph(f-) were similar to or greater than those from Sph(f+) for all drugs tested, although ALT leakages showed no consistent difference between Sph(f+) and Sph(f-). In the case of Sph(f-), significant correlations among all the toxicity markers except for γ-GTP were observed. As regards the drug concentrations causing 1.2-fold elevation of enzyme leakage (F1.2), no consistent difference between Sph(f+) and Sph(f-) was found, although several F1.2 values were undetermined, especially in Sph(f+). The IC50 of albumin secretion and F1.2 of AST leakage from Sph(f-) were equal to or lower than those of Sph(f+) for all the tested drugs. These results indicate that feeder cells might contribute to resistance to hepatotoxicity, suggesting DILI could be evaluated more accurately by using Sph(f-). We suggest that long-term exposure of Sph(f-) to drugs might be a versatile method to predict and reproduce clinical chronic toxicity, especially in response to repeated drug administration.