Organoids are 3D assemblies of cells, containing multiple cell types, arranged in a similar structure to the modelled tissue, but on a micro-scale. Organoids represent a more physiologically relevant model of tissues than 2D and mono-culture systems. As organoids recapitulate tissue-specific features, they are used in the study of tissue development and maintenance, stem cell characteristics, cellular interactions, precision medicine, disease modelling and drug discovery. Due to long periods in culture, it is important that all growth factors for organoid culture give highly consistent biological activity. Where possible, consider replacing conditioned media with recombinant proteins such as high purity R-spondin 1 and noggin to improve reproducibility and scale-up.