Multicellular tumor spheroids: an underestimated tool is catching up again

This review encompasses the most important advances in liver functions and hepatotoxicity and analyzes which mechanisms can be studied in vitro. In a complex architecture of nested, zonated lobules, the liver consists of approximately 80 % hepatocytes and 20 % non-parenchymal cells, the latter being involved in a secondary phase that may dramatically aggravate the initial damage. Hepatotoxicity, as well as hepatic metabolism, is controlled by a set of nuclear receptors (including PXR, CAR, HNF-4α, FXR, LXR, SHP, VDR and PPAR) and signaling pathways. When isolating liver cells, some pathways are activated, e.g., the RAS/MEK/ERK pathway, whereas others are silenced (e.g. HNF-4α), resulting in up- and downregulation of hundreds of genes. An understanding of these changes is crucial for a correct interpretation of in vitro data. The possibilities and limitations of the most useful liver in vitro systems are summarized, including three-dimensional culture techniques, co-cultures with non-parenchymal cells, hepatospheres, precision cut liver slices and the isolated perfused liver. Also discussed is how closely hepatoma, stem cell and iPS cell-derived hepatocyte-like-cells resemble real hepatocytes. Finally, a summary is given of the state of the art of liver in vitro and mathematical modeling systems that are currently used in the pharmaceutical industry with an emphasis on drug metabolism, prediction of clearance, drug interaction, transporter studies and hepatotoxicity. One key message is that despite our enthusiasm for in vitro systems, we must never lose sight of the in vivo situation. Although hepatocytes have been isolated for decades, the hunt for relevant alternative systems has only just begun.

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Recent advances in 2D and 3D in vitro systems using primary hepatocytes, alternative hepatocyte sources and non-parenchymal liver cells and their use in investigating mechanisms of hepatotoxicity, cell signaling and ADME.

In this review, we introduce two kinds of bio-related nanoarchitectonics, DNA nanoarchitectonics and cell-macromolecular nanoarchitectonics, both of which are basically controlled by chemical strategies. The former DNA-based approach would represent the precise nature of the nanoarchitectonics based on the strict or “digital” molecular recognition between nucleic bases. This part includes functionalization of single DNAs by chemical means, modification of the main-chain or side-chain bases to achieve stronger DNA binding, DNA aptamers and DNAzymes. It also includes programmable assemblies of DNAs (DNA Origami) and their applications for delivery of drugs to target sites in vivo, sensing in vivo, and selective labeling of biomaterials in cells and in animals. In contrast to the digital molecular recognition between nucleic bases, cell membrane assemblies and their interaction with macromolecules are achieved through rather generic and “analog” interactions such as hydrophobic effects and electrostatic forc...

Chemistry Can Make Strict and Fuzzy Controls for Bio-Systems: DNA Nanoarchitectonics and Cell-Macromolecular Nanoarchitectonics

Despite the tremendous hurdles presented by the complexity of the liver’s structure and function, advances in liver physiology, stem cell biology and reprogramming, and the engineering of tissues and devices are accelerating the development of cell-based therapies for treating liver disease and liver failure. This State of the Art Review discusses both the near- and long-term prospects for such cell-based therapies and the unique challenges for clinical translation.

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Cell and tissue engineering for liver disease

Introduction: For the past 30 years 2D-cell-based assay models have dominated preclinical cancer drug discovery efforts. 2D-cell-based models fail to predict in vivo efficacy, contributing to a lower success rate and higher cost required to translate an investigational new drug to clinical approval. Technological advances in 3D-cell culture models bridge the gap between 2D and in vivo models to improve upon the current success rates of cancer drug discovery. Areas covered: This review focuses on the multicellular tumor spheroid (MCTS), particularly how this model can be utilized for HTS drug discovery. We discuss the current technologies for uniform culture of MCTS suitable for HTS and detection methods utilized for assay development and drug screening. Expert opinion: Substantial hurdles remain before we reach the ultimate goal of robust HTS of large compound libraries with MCTS models. Specifically, we can group these challenges into three categories: MCTS growth, data collection, and data analysis. The...

http://www.protocol-online.org/forums/uploads/monthly_08_2012/msg-9402-0-19068300-1345636134.ipb

The multicellular tumor spheroid model for high-throughput cancer drug discovery

A spheroid array of fetal mouse liver cells, which comprise various immature cells, was constructed on a PEG-gel micropatterned surface and its hepatic activity and degree of differentiation induction were significantly upregulated by co-culture with nonparenchymal liver cells as feeder-cells.

Spheroid array of fetal mouse liver cells constructed on a PEG-gel micropatterned surface: upregulation of hepatic functions by co-culture with nonparenchymal liver cells

Graduate School of Pure and Applied Sciences, University of Tsukuba, Master’s School of Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Satellite Laboratory, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute of Materials Science (NIMS), University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan, Present address: Department of Life Sciences, Graduate School of Art and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 182-0006, Japan. nagasaki@nagalabo.jp

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Emiko Takahashi

Papers

Spheroid array of fetal mouse liver cells constructed on a PEG-gel micropatterned surface: upregulation of hepatic functions by co-culture with nonparenchymal liver cells

3D Cell Co-culture System on Hydrogel Micro-Patterned Surface Fabricated by Photolithography