Sorting Made Simpler

Instruments for fluorescence-activated cell sorting were once uniformly bulky and required experts at core facilities to operate. But a new generation of smaller, cheaper sorters that have emerged in the past few years allows researchers to perform simple sorts on their own, often with only brief training.

The larger sorters are faster and can handle more colors, “but we didn’t need to sort with 10 colors,” says Blain. “We could get what we wanted with four colors,” and the smaller machines are still relatively fast, she said.

Managers of large core facilities are also feeling the draw. Smaller, less complex sorters “take a lot of pressure off our heavily used sorters,” says Aaron Rae, technical director of the pediatric flow-cytometry core at Emory University in Atlanta, Georgia. This has become useful as increasingly long, complex sorts of rare immune cell subsets have become possible. These compete for sorting time with popular simple sorts, such as ones using just green fluorescent protein (GFP).

Researchers increasingly are taking advantage of GFP-based cell sorting to isolate particular cell populations for sequencing or other further tests. Most recently, scientists making knockout cell lines using gene-editing CRISPR systems have started tagging their nucleases with GFP so they can sort out cells that are likely to have been successfully genetically engineered.

Small cell sorters are also attractive from a safety perspective: In recent years, cytometrists have become more aware of the danger of inhaling aerosolized droplets containing cells. Smaller sorters fit into standard biosafety cabinets or can be purchased with their own specially designed containment devices. Larger sorters can also be purchased with containment devices, but these are more expensive and can be “the size of a room,” said Rae.

Here, The Scientist profiles affordable, low-complexity sorters with a range of capabilities, costs, and required cell-sorting experience for operators.

BIO-RAD S3/S3E
Overview
The S3 cell sorter was first designed as the Avalon cell sorter at Propel Labs in Fort Collins, Colorado. Before its full commercial release, Bio-Rad of Hercules, California, acquired and renamed the machine, shipping the first S3 cell sorter in March 2013. In September 2014, the company released an additional version of the sorter called the S3e, in which the nozzle automatically realigns itself during daily start-up or after being swapped out for cleaning.

Pros

• The S3 is accessible to inexperienced users, says Ryan Duggan, technical director of the University of Chicago’s flow cytometry core facility. Users do need a basic understanding of flow cytometry but require little additional training to learn how to sort. Traditionally, sorting requires users to perform tricky tasks like aligning lasers and calculating various properties of the stream of cells and sheath fluid. S3 users need only load the machine with calibration beads, and it will automatically prepare itself to sort.
• Blain likes the S3’s intuitive, user-friendly software: “It’s not just all words and drop-down menus,” she says, praising in particular the “friendly little signs and warnings and gentle prods.”
• In contrast to many other sorters, the system that provides sheath fluid to encase the sample cells is internal, obviating the need for a cumbersome external fluidics cart.

Cons

• While it may be easy to use, “the S3 is very limited in the number of colors available,” says Dave Adams, manager of the BRCF Flow Cytometry Core at the University of Michigan. He opted for a less automated FACSJazz sorter (described below) instead. The S3/S3e can detect four colors, while competing machines can detect six to eight.
• The S3/S3e sorts into tubes and 8-well strips, but cannot sort onto 96-well plates.

SONY SH800
Overview
SONY SH800SONY BIOTECHNOLOGY INCTraditionally known for consumer electronics, the Japanese company Sony got into the cell-sorting business in 2010, when it acquired the flow cytometry company iCyt. Sony Biotechnology launched the SH800 in North America in late 2012.

Pros

• Like Bio-Rad’s S3, the SH800 gets rave reviews for its automated laser alignment, drop delay estimation, and other setup features. “I can now give [lab members] about a half-an-hour course in how to use the sorter, and they can basically use it by themselves,” says Peter Andersen, a postdoc studying cardiac development at Johns Hopkins University who operates an SH800 purchased specially for his lab. And once the sort gets going, the user can walk away.
• The SH800 also garners praise for its sleek software. “I learned how to use it in like five minutes,” says Emory’s Rae. He tested the machine recently and is considering purchasing one for his core facility.
• Unlike most sorters, the SH800 funnels cells through a disposable plastic microfluidic chip rather than through a ceramic nozzle. While ceramic nozzles for simplified sorters often come in just one size, the SH800 now offers chips with conduits of differing diameters, says Deena Soni, a global marketing manager at Sony. Someone might use a chip with a larger orifice and a relatively slow speed for tumor cells and one with a smaller orifice and a zippier sort speed for yeast.
• Disposable chips decrease contamination risk and cleaning time, allowing different types of samples to be run in quick succession.

Cons

• Some prospective SH800 users find the idea of having to constantly dispose of $35 flow chips annoying. “I feel like science is so wasteful anyways,” says Duggan. “This is another thing to use once and throw away.”

BD FACSJazz
Overview
BD FACSJazzCOURTESY OF BD BIOSCIENCES, A SEGMENT OF BD (BECTON, DICKINSON AND COMPANY)Launched in June 2012, the FACSJazz from BD Biosciences is a stripped-down version of the larger BD Influx, with some variables such as nozzle size and sheath pressure fixed to simplify operation.

Pros

• The FACSJazz will be familiar to anyone with experience using the BD Influx, making it an attractive choice for experienced core facility technicians.
• The FACSJazz has fluidics that can be easily removed and replaced all the way from the supply tank to the nozzle tip, making for easy cleaning. This feature was the biggest draw for Adams, whose core facility users needed to sort hazardous materials such as tuberculosis and encephalitis-infected cells and HIV-positive blood samples. It also makes the FACSJazz especially attractive to researchers hoping to sort cells for use in humans.

Cons

• The FACSJazz is much less automated than other small, relatively inexpensive sorters on the market, such as the S3/S3e and the SH800. Users must do some laser adjustment and calculate drop delay time, for instance. Florin Tuluc, who runs a small core facility at The Children’s Hospital of Philadelphia that acquired the sorter last May, has found that only highly motivated people can master it. “You really need to babysit the sorting,” he warns. Laura Escobar, who operates the instrument at the Achucarro Basque Center for Neuroscience in Spain, says that it is “not for someone with no experience in flow cytometry.”

CELLECTOR SCINDO XT
Overview
CELLECTOR SCINDO XTCOURTESY OF COLLECTERThe Scindo XT is a renamed and revamped version of the former Bay Bioscience JSAN JrSwift Cell sorter. San Diego-based biotech Cellector recently acquired intellectual property rights for Bay Bioscience’s cell sorting technology and officially launches the Scindo XT this month.

Pros

• The Scindo XT automatically aligns its lasers and calculates drop delay.
• The instrument achieves 8-color sorting at a lower cost than any other benchtop cell sorter.

Cons 

• The JSAN JrSwift never fully caught on in the U.S. Users will have to see if the Scindo XT lives up to its promise of enhanced features and increased U.S. company presence.

CYTONOME VIVA-G1
Overview
CYTONOME VIVA-G1COURTESY OF CYTONOMESeeing a recent uptick in interest for sorting cells expressing GFP, developers at Cytonome set out to develop an instrument optimized for sorting cells with that marker. The Cytonome Viva will launch this month.

Pros

• The Viva will sell for under $90,000, the lowest price offered for a cell sorter, according to Ruud Hulspas, Vice President of Scientific Affairs at Cytonome.
• The instrument is optimized for sorting cells tagged with GFP. Inexperienced users should be able to perform sorts automatically without adjusting settings.
• The Viva’s entire fluidic system is contained in the core machine, eliminating the need to find space for a fluidics cart. It also has a built-in tablet interface, so there’s no need to set up a separate computer monitor to interact with the software.

Cons

• The Viva currently performs only one-color cell sorting. Cytonome is developing versions of the instrument that will sort GFP in combination with other reporter genes, such as mCherry.
• The Viva cannot sort into welled plates.
• The instrument is untested in the marketplace.