Key aspects for conception and construction of co-culture models of tumor-stroma interactions

Abstract

The tumor microenvironment is crucial in the initiation and progression of cancers. The interplay between cancer cells and the surrounding stroma shapes the tumor biology and dictates the response to cancer therapies. Consequently, a better understanding of the interactions between cancer cells and different components of the tumor microenvironment will drive progress in developing novel, effective, treatment strategies. Co-cultures can be used to study various aspects of these interactions in detail. This includes studies of paracrine relationships between cancer cells and stromal cells such as fibroblasts, endothelial cells, and immune cells, as well as the influence of physical and mechanical interactions with the extracellular matrix of the tumor microenvironment. The development of novel co-culture models to study the tumor microenvironment has progressed rapidly over recent years. Many of these models have already been shown to be powerful tools for further understanding of the pathophysiological role of the stroma and provide mechanistic insights into tumor-stromal interactions. Here we give a structured overview of different co-culture models that have been established to study tumor-stromal interactions and what we have learnt from these models. We also introduce a set of guidelines for generating and reporting co-culture experiments to facilitate experimental robustness and reproducibility.

Keywords: cancer associated fibroblasts; cell culture models; co-culture; organoid; tumor-stroma interactions.

FIGURE 1

Model of constituent components of the tumor microenvironment (TME). Cancer cells exist in a microenvironment containing multiple different cell types and a particular extracellular matrix context that together form the tumor. The interplay between all these components determines the biology of the tumor. These various components represent elements that can be incorporated into cell culture models of cancer cells to better replicate the in situ tumor microenvironment.

FIGURE 2

Technological sophistication of cell culture platforms. An overview of different cell culture technologies and the development of technical sophistication compared to biological complexity. Arrows represent typical model derivation routes.

FIGURE 3

Different physical model types for exploring co-cultures. A hierarchical overview of different physical arrangements of cells for exploring co-cultures with examples as referenced in the text. Dotted lines indicate that techniques/models are not mutually exclusive, where co-culture models may be constructed by combination of any of the approaches outlined.

FIGURE 4

Co-culture experimental versatility. A non-exhaustive selection of assays that can be performed with co-culture models. These assays can be used to determine what the effect of co-culturing cell types together is compared to mono-cultured counterparts to identify biologically relevant interactions and mechanisms. Arrows represent typical workflows. ECM, Extracellular matrix; EM, Electron microscopy; FACS, Fluorescence activated cell sorting; ICC, Immunocytochemistry; IF, Immunofluorescence; IHC, Immunohistochemistry; MS, Mass spectrometry.