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Cultured cells are dramatically affected by the micro-environment in which they are grown. In this study, we have investigated whether HepG2 liver cells grown in three dimensional (3-D) cultures cope more effectively with the known cytotoxic agent, methotrexate, than their counterparts grown on traditional two dimensional (2-D) flat plastic surfaces. To enable 3-D growth of HepG2 cells in vitro , we cultured cells on 3-D porous polystyrene scaffolds previously developed in our laboratories. HepG2 cells grown in 3-D displayed excellent morphological characteristics and formed numerous bile canaliculi that were seldom seen in cultures grown on 2-D surfaces. The function of liver cells grown on 3-D supports was significantly enhanced compared to activity of cells grown on 2-D standard plasticware. Unlike their 2-D counterparts, 3-D cultures were less susceptible to lower concentrations of methotrexate. Cells grown in 3-D maintained their structural integrity, possessed greater viability, were less susceptible to cell death at higher levels of the cytotoxin compared to 2-D cultures, and appeared to respond to the drug in a manner more comparable to its known activity in vivo . Our results suggest that hepatotoxicity testing using 3-D cultures might be more likely to reflect true physiological responses to cytotoxic compounds than existing models that rely on 2-D culture systems. This technology has potential applications for toxicity testing and drug screening.

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A broad range of technologies have been developed to enable three dimensional (3D) cell culture. Few if any however are adaptable for routine everyday use in a straightforward and cost effective manner. Alvetex(®) is a rigid highly porous polystyrene scaffold designed specifically to enable routine 3D cell culture. The scaffold is engineered into thin membranes that fit into conventional cell culture plasticware. The material is inert and offers a polystyrene substrate familiar to cell biologists worldwide. The 3D geometry of the scaffold provides the environment in which cells grow, differentiate, and function to form close relationships with adjacent cells thus creating the equivalent of a thin tissue layer in vitro. This chapter introduces the features required by a technology that enables routine 3D cell culture. Using Alvetex(®) as a product that satisfies these requirements, its application is demonstrated for the growth of a recognised cell line. Procedures detailing the use of Alvetex(®) for 3D cell culture are provided. This is followed by a series of detailed methods describing ways to analyse such cultures including histological techniques, immunocytochemistry, and scanning electron microscopy. Examples of data generated from these methods are shown in the corresponding figures. Additional notes are also included where further information about certain procedures is required. The use of Alvetex(®) in combination with these methods will enable investigators to routinely produce complex 3D cultures to research the growth, differentiation, and function of cells in new ways.

Highly porous and permeable polymers are produced by polymerisation of the continuous phase of high internal phase emulsions (HIPEs). The morphology and properties of the resulting PolyHIPE materials can be varied, allowing the materials to be optimised for a variety of applications. Void diameter is controlled from 1 to around 100 μm by altering the HIPE stability. Surface areas greater than 700 m2g−1 can be achieved by replacing some of the monomer phase with non‐polymerisable solvent, in conjunction with a high crosslink density and the use of a surfactant mixture that limits Ostwald ripening. PolyHIPEs can be produced in a variety of physical forms including large monolithic slabs, rods and flat relatively thin membranes. The materials are currently under investigation for use as electrochemical sensor membrane substrates and as porous matrices for cell culture.