An introduction to mammalian cell culture

Cells isolated from animal tissues can be expanded in culture for use as a research tool, for the production of virus vaccines and various therapeutic proteins, and to generate functional cells or tissue analogues for regenerative medicine. Mammalian cells can be made to produce vaccines through viral infection, and therapeutic proteins through genetic engineering. Many of these medicines are necessary for patients who either lack the normal form of a protein or cannot produce it in sufficient quantity. A first step in cell isolation is to explant a tissue in a physical and chemical environment suitable for those cells to survive and proliferate. A permissive environment for cell growth requires a complex mixture of nutrients, including sugars, amino acids, vitamins, minerals, and growth factors such as insulin. After attachment, cells grow and expand onto empty surfaces until the entire surface is covered in a layer that is one cell thick. At this point, they stop dividing and reach a state called contact inhibition. Next, an enzyme is used to degrade the proteins that ?glue? the cells to the surface, thereby releasing the cells into solution. Once detached, the cells can be transferred to a culture vessel with a larger surface area to resume growth. This cycle of attachment, cell expansion, and detachment can repeat many times, with each cycle comprised of multiple cell divisions. However, because they can be cultured forever, cell lines can be genetically engineered to produce a product in virtually unlimited quantities.