What are the two systems for growing cells in culture?

The two basic systems used for growing cells are adherent culture and suspension culture.

• Adherent culture: Cell are grown as monolayers on an artificial substrate. This type of cell line is appropriate for most cell types, including primary cultures. Vessels need to be tissue-culture treated and cells are dissociated enzymatically or mechanically from the vessel. Growth is limited by the surface area, which may limit product yields.
• Suspension culture: For cell lines that are adapted for suspension culture, cells are free-floating in the culture medium. Tissue-culture treatment is not required for the culture vessels, but agitation is needed for adequate gas exchange. Growth is limited by concentration of cells in the medium, which allows easy scale-up.