Editing Flow cytometry (section)

== Cell sorting by flow cytometry ==
[[Cell sorting]] is a method to purify cell populations based on the presence or absence of specific physical characteristics.<ref name=":1" /><ref name=":3" /><ref name=":4">{{Cite web|url=https://www.the-scientist.com/how-it-works/fluorescence-activated-cell-sorter-49796|title=Fluorescence-Activated Cell Sorter|work=The Scientist | vauthors = Perkel J |date=July 19, 2004|access-date=2018-09-18}}</ref> In flow cytometers with sorting capabilities, the instrument detects cells using parameters including cell size, morphology, and protein expression, and then droplet technology to sort cells and recover the subsets for post-experimental use.<ref name=":1" /><ref name=":3" />

The first prototype sorter was built at the [[Los Alamos National Laboratory]] (LANL) in 1965 by physicist Mack J. Fulwyler by joining a Coulter volume sensor with the newly invented ink jet printer.<ref>{{Cite web|url=https://siarchives.si.edu/collections/siris_arc_217722|title=Record Unit 9554, The History of the Cell Sorter Interviews|date=1991|work=Smithsonian Institution Archives|access-date=2018-09-18|others=Fulwyler, Mack Jett. interviewee, Herzenberg, Leonard A. interviewee, Bach, Bruce Allen. interviewee, Krasnow, Mark A. interviewee, Mhatre, Nagesh S. interviewee|language=en}}</ref> Live cell cell sorter or fluorescence-activated cell sorter (FACS){{efn|1=The acronym FACS is [[trademark]]ed and owned by BD Biosciences-Immunocytometry Systems, a division of Becton-Dickinson, which licensed Stanford's patents.<ref name=":4"/><ref>{{Cite web|url=https://expertcytometry.com/12-flow-cytometry-terms-and-definitions-most-scientists-get-wrong/|title=12 Flow Cytometry Terms And Definitions Most Scientists Get Wrong | vauthors = Bushnell T |date=2016-05-04|work=Expert Cytometry|access-date=2018-09-18|language=en-US}}</ref>}} was generated by [[Leonard Herzenberg|Len Herzenberg]], who subsequently won the [[Kyoto Prize]] in 2006 for his seminal work.<ref>{{cite journal | vauthors = Julius MH, Masuda T, Herzenberg LA | title = Demonstration that antigen-binding cells are precursors of antibody-producing cells after purification with a fluorescence-activated cell sorter | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 69 | issue = 7 | pages = 1934–8 | date = July 1972 | pmid = 4114858 | pmc = 426835 | doi = 10.1073/pnas.69.7.1934 | bibcode = 1972PNAS...69.1934J | doi-access = free }}</ref>

[[File:Fluorescence Assisted Cell Sorting (FACS) B.jpg|thumb|upright=1.25|Cell Sorting Using Flow Cytometry and Droplet Technology|alt=]]Flow cytometry cell sorters have a collection system unlike flow cytometry analyzers. The collection process starts when a sample is injected into a stream of sheath fluid that passes through the flow cell and laser intercepts.<ref>{{Cite web|url=http://flowcytometry.utoronto.ca/cell-sorting/|title=Cell Sorting – Faculty of Medicine Flow Cytometry Facility|website=flowcytometry.utoronto.ca|language=en-US|access-date=2018-09-18}}</ref> The stream then carries the cell through a vibrating nozzle which generates droplets with most containing either one cell or no cells. An electrical charging ring is placed just at the point where the stream breaks into droplets and a [[electric charge|charge]] is placed on the ring based immediately prior to fluorescence intensity being measured; the opposite charge is trapped on the droplet as it breaks from the stream and the droplets are therefore charged. The charged droplets then fall through an [[electrostatic deflection]] system that diverts droplets into containers based on their charge. In some systems, the charge is applied directly to the stream, and the droplet breaking off retains charge of the same sign as the stream. The stream is then returned to neutral after the droplet breaks off. After collecting, these cells can be further cultured, manipulated, and studied.{{cn|date=April 2022}}