Most primary cells isolated from an organism can be kept alive for a period of time but will eventually stop dividing due to senesce. However, a cell line can be transformed and immortalised, which means it acquires the ability to proliferate indefinitely. Many types of tumour cells acquire this ability naturally and can be cultured indefinitely once taken into culture. Transformed non-cancer cells acquire the same capability. When cells are grown in culture, they proliferate on the surface of a plate covered in media (adherent cells) or may be suspended in the media directly (suspension cultures). For example, many types of blood cells can only be grown in suspension culture whilst cells which would naturally be closely packed together (e.g., in different organs and tissues such as liver, kidney or brain cells for example) will naturally connect to a surface especially one coated in collagen resembling connective tissue.
In addition to providing a model to study a particular natural cell type, cells in tissue culture can also be genetically modified and/or treated with xenobiotics to investigate basic biological functions at the molecular level. Genetically modifying a cell line (e.g., deleting or over-expressing a specific gene for example) can be achieved via transfection or transduction which involves the introduction of foreign DNA into the cell and can be used to study the effects of a specific gene in a cellular environment. Treating cells with drugs can also be used to explore bioactivity and manipulate cellular functions to study their effects.
The versatility of tissue culture in providing a well-controlled tissue-specific model to study and explore the effects of specific genetic changes and drug interactions, makes tissue culture an extremely useful research tool.
