Vertebrate cell culture as an experimental approach - limitations and solutions.

Mammalian cell culture has provided the foundation for the incredible expansion of cell biology to uncover the 'inner life of the cell'. The protocols for propagating cells in the laboratory have their origins in the mid-20 century. At that time the focus was on creating cell culture media that kept cells viable and favoured replicative growth. To the extent that oxygen level was considered as an important parameter, it was in the context of ensuring that oxygen was not depleted; the idea that environmental oxygen levels could be toxic was not widely appreciated. We increasingly understand that media composition and oxygen levels have important effects on cellular functions and that maintaining physiologically relevant conditions is necessary to maintain in vivo behaviours. We also understand much about the impact of growing cells that function in a 3D environment in 2D adherent monolayers. In this review, we examine some of the issues affecting standard cell culture approaches and new solutions that address these issues to increase the physiological accuracy of the cellular environment. We have reached a threshold in cell biology in which we know enough about the problems and their solutions to inform useful adjustments to protocols moving forward. This will increase the accuracy and translatability of this reductionist approach to understanding cell behaviours.