Fluorescence-activated cell sorting (FACS)

Cell sorting is a common process used in life sciences. It involves the isolation of cell populations according to their cell sizes, density, and/or surface protein expression. This allows a homogenous population of cells to be studied. For example, the bone marrow consists of different types of cells but specific stem cells (e.g. mesenchymal stem cells) can be isolated through cell sorting.⠀
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One common method of cell sorting is the fluorescence-activated cell sorting (FACS). This utilizes fluorescence-associated antibodies specific to specific surface proteins. Cells with the surface protein will be bound with the antibody and fluoresce. These fluorescing cells are detected by a laser in the FACS, giving a quantitative analysis of the number of fluorescent cells. The cells will then be given a positive/negative charge depending on their fluorescence. These charged cells will be separated into their respective tubes through the negative/positive charged deflector respectively.⠀