Cell Sorters / Cell Sorting Instruments

In the late 1960s, the Fluorescence Activated Cell Sorter (FACS) was invented by Herzenberg and others, allowing the sorting and collection of viable cells from a heterogenous mixture by flow cytometry. It has since led to many biomedical research advancements such as in the functional determinations of unique cell types in the blood and tissues. To begin sorting, a cell suspension flows into a narrow stream of individual particles to be analyzed by one or more lasers. Cells then pass through a nozzle tip, from which they are separated into individual droplets. Droplets containing cells that meet the sort criteria are applied an electric charge, and are then sorted as they pass between constantly charged deflecting plates. As with flow cytometry, cells can be identified by parameters such as forward-scattered light (FSC), side-scattered light (SSC) as well as specific fluorescent emissions from antibodies, tags, and probes. Many cell sorters now come with features such as temperature control, automated startup and cleanup, multiple lasers, and options for biosafety.

Magnetic-activated cell sorting (MACS) is an alternative cell sorting method that utilizes magnetic particles rather than fluorescence. This application has become widely used, especially in separating and isolating cells from blood samples. Magnetic nanoparticles attached to specific antibodies are bound to cells. Cells expressing an antigen of interest can then be immobilized onto a magnetic column and washed out onto a separate collection tube (positive selection). Alternatively, the cells of interest may be lacking the specified antigens, and instead are collected in the unbound fraction (negative selection). Magnetic cell sorting instruments allow for the automated and parallel processing of magnetic-labeled cells for better productivity and reproducibility.