The field of flow cytometry research has evolved significantly over the past 70 years. Here we take a look back at some of the most important achievements on the path to bigger, faster and better flow cytometry experiments. Microscopes (Early 1700s)
Antonie van Leeuwenhoek developed early simple microscopes using single-lens designs that achieved 300x magnification, popularizing the use of microscopes with researchers throughout Europe.
Light Scattering (1742)
Mikhail Lomonosov first discovered that particles in a suspension will scatter light in a method that can be used to determine the particles’ size and concentration.
Fluidics (1833)
Felix Savart demonstrated that a stream of liquid can be broken into regular droplets when vibrated at specific frequencies. Prototype Design (1934)
In the August 1934 issue of Science, a bacteriologist from Montreal Canada named Andrew Moldovan proposed a design for a photoelectric device to count individual cells moving through an illuminated capillary tube set on a microscope stage. Although his device was never built, it is now widely regarded as the first prototype design for the flow cytometer.
The First Cytometer (1947)
In 1947 Frank Gucker developed an electronic photometer to test smoke aerosols for agents of chemical and biological warfare. His device employed a Ford headlight as the source of illumination and a photomultiplier tube to amplify the incandescent light signal. By measuring the light scattering caused by chemical particles and bacterial spores, Gucker’s device pioneered many early technologies that would be incorporated into later cytometers.
Coulter Principle (1950’s)
In the early 1950s, electrical engineer Wallace Coulter discovered that particles pulled through an orifice in the presence of an electric current will produce a change in impedance that is proportional to the volume of the particle. This phenomenon, called the Coulter Principle, allows for the use of an electric field for counting and sizing dilute suspensions of particles or cells.
In 1953 Coulter was awarded U.S. patent #2,656,508 for the Means for Counting Particles Suspended in a Fluid. He soon partnered with brother Joseph Coulter to begin commercial production of a popular blood cell counting device called the Coulter Counter.
The Coulter Principle remains the basis for many modern flow cytometry and cell sorting platforms and is also used in a wide variety of other industrial technologies.
The First Cell Sorter (1965)
Mack Fulwyler invented the first cell sorter in 1963 at Los Alamos National Laboratory by combining automated cell-size analysis with a new fast ink-jet printing technology.
He discovered that cells suspended in a conducting fluid could be partitioned into fine droplets. After size analysis, a charge could be applied to the droplets containing the cells of interest, allowing those droplets to be pulled out of the stream by an electric field for collection and further study.
Fluwyler described his cell sorter and its ability to successfully sort mixtures of human and mouse blood cells in 1965.High-Speed Cell Sorting (1967)
In 1967, IBM engineer Louis Kamentsky designed a spectrophotometric device for sorting cervical cells based on multiple spectrophotometric properties at rates exceeding 500 cells per second. The drive for greater efficiency has continued over the years, as some modern cytometers may now be successfully run at speeds up to 50,000 cells per second.
Fluorescent Cytometry (1969)
Wolfgang Göhde developed the first fluorescence-based flow cytometer in 1968 at the University of Münster in Germany. This device, called the ICP 11, was commercialized by Partec through Phywe AG in Göttingen. However, absorption-based measurements remained more popular than fluorescence methods for some years.
FACS (Early 1970’s)
In 1972, a group at Stanford University led by Len Herzenberg developed and patented the first fluorescence-activated cell sorter (FACS). This new method for sorting individual cells based upon their specific light scattering and fluorescent characteristics revolutionized research in immunology and cancer biology. In 1974, Becton Dickinson, Inc. licensed the FACS technology from Stanford University and introduced the first commercial FACS cytometer, called the FACS-1.
Multi-Parameter (Late 1970’s)
By the late 1970’s, many researchers were analyzing and sorting cells by two different parameters. Coulter Electronics, Inc. then introduced the first flow cytometer with built-in multi-parameter capability, the Two-Parameter Sorter (TPS-1).
It Flows, by Any Other Name (1978)
The original name for the technology was “pulse spectro-cytophotometry”. Fortunately, a panel of researchers at the 1978 Conference of the American Engineering Foundation agreed to adopt the term “flow cytometry”.
Very High-Speed Genome Sorting (1987)
Researchers at the Lawrence Livermore National Laboratories (LLNL) were the first to use high-speed flow cytometer to sort human chromosomes as part of the Human Genome Project. In 1987 Joe Gray, Ger van den Engh and their colleagues at LLNL developed a high-speed cell sorter that could process fluorescent chromosomes at a rate of 20,000 per second, a rate 10x faster than previously possible.
In 1994, Cytomation introduced a commercial version, called the MoFlo®, which increased the sorting capabilities of commercially available sorters from 5,000 to 50,000 cells per second.OMIPs
Optimized Multicolor Immunofluorescence Panels (OMIPs) are peer-reviewed panels designed for fluorescent assays and published in Cytometry Part A. There are currently over 40 approved OMIPs, which serve as excellent starting points for new researchers designing experiments examining similar targets.
Panel Design Algorithms
As cytometers continue to allow for more channels and reagent suppliers continue to release new colors, multi-color panel design has grown increasingly complex. FluoroFinder has simplified panel design by allowing researchers to easily build panels for their specific cytometer parameters while visualizing fluorophores from any vendor catalog on a single SpectraViewer. As reagents are added to channels, the advanced panel design algorithm dynamically blocks channels that will be subject to excessive overlap, thereby significantly reducing both design time and errors.
Spectral Flow Cytometry
Improved optics, detectors, and computation allow for instruments that can perform spectral analysis in the sub-millisecond time frame, enabling complete fluorescence profiling of individual cells. Spectroscopy also allows for the delineation of fluorophores with overlapping spectral features, reducing the problem of spectral overlap or the need for compensation.
Imaging Flow Cytometry
Imaging flow cytometry (IFC) combines features of flow cytometry and fluorescent microscopy with advanced data-processing algorithms. IFC allows high-speed, multiparametric fluorescent and morphological analysis of thousands of cellular events via individual cell images. This enables researchers to identify targets at extremely low expression rates or even perform statistical analysis of subcellular protein distributions.
Transforming spectral information into images also provides a graphical means of mapping localized ionic, molecular, and protein-protein interactions.
IFC is now seeing a shift toward high-information-content analysis powered by new deep-learning algorithms.
