Eric Gottwald

The three-dimensional cultivation of the carcinoma cell line HepG2 in a perfused chip system leads to a more differentiated phenotype of the cells compared to monolayer culture

We describe a polymer chip with a grid-like architecture that it is intended for the three-dimensional cultivation of cells with an active nutrient and gas supply. The chip is typically made from polymethyl methacrylate or polycarbonate but can also be manufactured from biodegradable polymers, such as poly(lactic-co-glycolic acid). Different designs of the chip can be realized. In this study, we evaluated a chip with 506 microcontainers of the size of 300 x 300 x 300 microm that are capable of housing up to 6 million cells, and its suitability as a tissue-specific culture system for the carcinoma cell line HepG2 instead of primary liver cells. Related to an earlier study, where we could show the principal suitability of the system for rat primary cells, we here investigated the systems suitability for the human carcinoma cell line HepG2. The carcinoma cells were used in two different types of chip-containing bioreactors. By confocal laser scanning microscopy, we could show that cellular integrity in the chip culture was maintained and that there were no signs of apoptosis as confirmed by the absence of K18 fragmentation. Gene expression analysis of some liver-specific genes revealed a significantly higher expression of the phase II metabolism genes uridine-diphosphate- glucosyl-transferase (UGT1A1) and glutathione-S-transferase (GSTpi1) as a marker. Therefore, we conclude that by using a three-dimensional instead of a conventional monolayer culture system, hepatocellular carcinoma cells display a phenotype that resembles more closely the tissue of origin.

Fabrication of Advanced Microcontainer Arrays for Perfused 3D Cell Culture in Microfluidic Bioreactors

The last 40 years have impressively shown that adding additional dimensionality makes an important difference in cell culture microenvironments. With this in mind, a variety of 3D microfluidic cell culture platforms have previously been fabricated using a broad spectrum of materials. One prominent example is the “3D-KITChip”, a polymer chip for 3D cell culture in form of an array of microcontainers provided with porous bottoms or walls to allow an active perfusion of the cells therein with cell culture medium within dedicated microfluidic bioreactors. In this chapter, the fabrication of the KITChip by different means of polymer micromolding is described as well as different methods to introduce porosity in the chips. Furthermore, various techniques to tailor the biophysicochemical microenvironment of the cells cultured in the containers of the KITChip are discussed. The end of the chapter deals with the integration of the chip into the bioreactors.