Cells grown in vitro are traditionally grown as 2D monolayers, which are easy to set up and maintain. However, these are often mono-cultures (consisting of only one cell type), lack structural architecture due to the absence of extracellular matrix, and are flat with 50% of their surface exposed to tissue culture medium, rather being surrounded by other cells. Hence, 2D cell cultures are a poor approximation of tissues in living organisms.

Simple, highly-consistent and easy-to-use 3D models hold great promise to reduce the number of costly drug failures in clinical trials, provide a more realistic tumour models, and generally lead to more useful data and more relevant and successful research. There are a range of techniques to grow cells in 3D including spheroids and hydrogels. A scaffold is useful when cell-to-cell and cell-to-matrix contacts are important to cell morphology and behaviour, for cells that do not in nature form spheroids, where more cells are required for sensitive assays than can be grown in a spheroid and where diffusion of gases and proteins is desirable.