The vast majority of cell culture models utilise non-physiological nutrient media developed more than 60 years ago. These cancer cells are typically cultured at near atmospheric oxygen concentrations (~18-21%), compared to tissue-relevant (~5-10%) and hypoxic (<1%) oxygen concentrations found in vivo. Cell lines are commonly maintained in 2D monoculture, which differs substantially from the 3D tumour microenvironment, with its complex mix of cell types, vasculature and dynamic gradients of nutrients, metabolites and oxygen. These differences raise important questions about how accurately conventional cell culture models reflect in vivo tumour biology and therapeutic responses.
More physiological media formulations (e.g. HPLM and Plasmax), reflecting nutrient concentrations present in human plasma, provide an opportunity to better model the complex in vivo nutrient environment. We have been utilising the physiological nutrient medium Plasmax to determine how nutrient availability alters the growth and metabolism of breast and prostate cancer cells. Using proteomics, metabolomics, ATAC-seq and systems microscopy, we have detected distinct molecular and metabolic states in prostate cancer cells depending solely on the medium they are cultured in. These studies have revealed specific metabolic vulnerabilities that are masked by the use of traditional media formulations, including androgen regulation of aspartate metabolism in castration-resistant prostate cancer.
The challenge now is to develop models that extend beyond nutrient composition to incorporate physiological oxygen levels, extracellular matrix scaffolds and include the multicellular 3D tumour environment. To do this, we are utilising patient-derived 3D tumour explant models to develop our Ex Vivo Clinical Trials Platform (EViCT). EViCT is housed in a physiological gas-controlled glovebox to precisely control oxygen levels and uses fluidics to provide a constant supply of nutrients, efficiently removing exported cellular waste products. We are currently evaluating EViCT as a platform for rapidly determining drug sensitivity/resistance in breast cancer patient samples.