A Purpose-Built System for Culturing Cells as In Vivo Mimetic 3D Structures

Abstract

Culturing cells in 3D is often considered to be significantly more difficult than culturing them in 2D. In practice, this is not the case: the situation is that equipment needed for 3D cell culture has not been optimised as much as equipment for 2D. Here we present a few key features which must be considered when designing 3D cell culture equipment. These include diffusion gradients, shear stress and time. Diffusion gradients are unavoidably introduced when cells are cultured as clusters. Perhaps the most important consequence of this is that the resulting hypoxia is a major driving force in the metabolic reprogramming. Most cells in tissues do not experience liquid shear stress and it should therefore be minimised. Time is the factor that is most often overlooked. Cells, irrespective of their origin, are damaged when cultures are initiated: they need time to recover. All of these features can be readily combined into a clinostat incubator and bioreactor. Surprisingly, growing cells in a clinostat system do not require specialised media, scaffolds, ECM substitutes or growth factors. This considerably facilitates the transition to 3D. Most importantly, cells growing this way mirror cells growing in vivo and are thus valuable for biomedical research.