perfusion culture systems
Cultures based on cell monolayers have the advantage of reducing tissue complexity to a minimum. However, the lack of normal physiological cell-matrix interactions leads the cell metabolism and gene expression towards a dedifferentiated state. Compared to a monolayer, three-dimensional cultures are associated with a higher cell density, and nutrient supply depends on diffusion through the extracellular matrix. This requires more exacting culture conditions which can be achieved using automated medium replacement in a perfusion culture system, thereby guaranteeing a stable concentration of nutrients, stable pH, and reduced risk of contamination.