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Culturing Automation

Tue, 01/04/2011 - 9:11am
Jeffrey M. Perkel

Cell culture processes can be tedious and scream for automated alternatives, fortunately options exist that free up time and money throughout the lab.

As lab tasks go, perhaps none is more tedious than eukaryotic cell culture, a boring, laborious, and ergonomically irksome chore that is as constant as it is necessary. Cells are the sine qua non of modern biology, and many researchers devote literally hours every day to their care.

BST 1012 Cover ImageCounting and feeding, expanding and freezing—these tasks and more must be performed routinely by researchers toiling away in cramped quarters, generally in a dedicated cell culture room. The processes couldn't be simpler – just a bunch of liquid handling steps, really, albeit conducted under sterile conditions—and yet, in busy labs, and especially those devoted to biomanufacturing and drug development, they may comprise the full-time effort of several highly paid technicians. It is, in short, a process that practically cries out for automation.

Kevin Oldenburg, president of bioengineering firm MatriCal, who grew up on a dairy farm, likens traditional cell culture to milking cows. Just as cows must be milked daily, rain or shine, so too do cells. Cells don't care if it's the weekend or a holiday, or if it's snowing outside; they need looking after. "You never get a break," he says.

Catching A Break
Some researchers, though, do get a break. Firms like MatriCal and The Automation Partnership, Hamilton, and Tecan have developed integrated robotic systems that can passage and maintain multiple cell lines simultaneously, expand them as necessary, and prepare assay-ready plates on demand. Running in the hundreds of thousands of dollars, such systems are not for everyone. But for those facilities whose processes and throughput are in sync with their capital budgets, automated cell culture can liberate researchers from the cell culture hood, releasing them to tackle more intellectually stimulating tasks.

As Alison Rush, manufacturing manager at contract research organization Absorption Systems, explains, keeping lab techs engaged in cell culture isn't easy. "Finding the right person, who is going to do cell culture absolutely consistently day to day, is very challenging," she says. "Finding that person that is going to be with you for years, doing a job that is essentially pretty boring, but that you have to be very, very careful and rigorous about, that's asking a lot of a human being."

Rush knows of what she speaks. Though she doesn't use automated cell culture systems in her current position—the company's throughput and the nature of its cell culture processes argue against it, she says—Rush did use automation in her previous position. Prior to joining Absorption Systems in 2009, Rush managed the automated cell culture facility at Merck, a job she held for four or so years.

According to Rush, one of the chief advantages of automated culture is consistency; unlike people, robots never vary their routine. And that's important because, as simple as cell culture procedures can seem, no two people work precisely the same way. Take trypsinization, for instance. Researchers differ on such points as how much trypsin to add, how long they keep it on the cells, how many times they pipette the cell suspension up and down, how vigorously they pipette, and so on. Such minutiae can substantially affect the cells, and yet are almost never written down. "It's hands specific," Rush says. "There's a lot of subtleties that people just can't convey [in a protocol]."

Tecan Cellerity
Tecan’s Cellerity allows users to prepare cells for assays during off-office hours to be ready during working hours. (Source: Tecan)

Other advantages include fewer "lost assays"—cell-based experiments that fail either because of cell quality, contamination, or mistakes—and so-called "walk-away automation." That latter point addressed one key motivation for automating cell culture at Merck, Rush says: company scientists wanted to squeeze an extra day of assays into every week. Generally, she explains, because cells are plated a day before they are tested, assays cannot usually begin until Tuesday, because the cells only get plated on Monday. A robot, though, doesn't care if it's the weekend or not. "With automation you should be able to plate the cells on a Sunday. So you should be able to get an extra day's assays out of that," she says.

Rush says her facility employed a blend of automated systems, including both off-the-shelf and custom solutions. One of those, she says, was the CompacT SelecT from The Automation Partnership, a UK-based company that designs and builds lab automation. With a price tag of up to $1 million, the CompacT SelecT represents a significant investment. Yet it packs considerable functionality inside its 3-m2 footprint, including tissue culture incubators and agitators, cell counters and refrigerators, decappers, and of course, liquid-handling robots.

The CompacT SelecT can process and track up to 90 T-flasks per day, says product marketing director, Tim Ward. Given sufficient media and consumables, the system can passage and maintain a dozen or more adherent cell lines in multiple growth formats for months on end—all under aseptic conditions. It can also count those cells and use those data to guide seeding of new flasks; image flasks to assess confluency; and output cells in any of a variety of formats, from standard T-flasks and microtiter plates to bulk cell suspensions.

"I can't think of an example where we haven't been able, with a little bit of technology transfer, to get a cell to grow on the system," Ward says.

Available Alternatives
Other automated systems claim similar feature sets, though there are differences. Not all systems can accommodate the same variety of culture flasks, for instance. Whereas the CompacT SelecT can handle cells grown in such formats as standard culture T-flasks and multilayer "HYPERFlasks," Tecan's Cellerity exclusively uses SBS-formatted flasks, including six- and 24-well microtiter plates and the Corning RoboFlask. Some, including MatriCal's MACCS, can also handle suspension cells thanks to shaker modules that keep the cells aerated and suspended. Hamilton's 3D CellHOST splits the difference, growing adherent cells on magnetic microcarriers (Global Eukaryotic Microcarriers from Global Cell Solutions) in liquid suspension, thereby hugely increasing cellular yield while at the same time reducing incubator storage requirements. According to Daniel Caminada, senior product manager for cell biology at Hamilton, one 50-ml culture tube can yield 100 million CHO cells, the equivalent of about 10 T-75 culture flasks.

For those whose culture needs may change over time, the good news is that, in general, these systems are highly modular and configurable. Researchers can often upgrade components as needed to add, for instance, new pipetting capabilities and detection devices. MACCS can be configured to hold frozen cryovials for several days, thaw them out, and expand them; another module can sterilize the unit using vaporized hydrogen peroxide. The CompacT SelecT can be outfitted with the IncuCyte automated microscope from Essen, while Hamilton's systems can be souped up with a Roche Innovatis CellaVista or Genetix CloneSelect, a 96-channel pipetting head, as well as such deck modules as a shaker, heater, or cooler. "In this way, it is a living system," Caminada says.

Of course, there is a limit to upgradability, says Susanne Braum, senior market manager for cells and proteins at Tecan Liquid Handling – space on and around robotic systems is finite, and once it's filled, it's filled. "It is like a formula-1 car," she says: "There are limitations, but they are of physical nature."

Justifying the Expense
Automated cell culture systems originally were designed to accommodate the voracious cellular appetite of Big Pharma development pipelines. Yet the landscape has changed somewhat towards stem cell maintenance and regenerative medicine, says Ward—applications that could make these systems attractive to both academic core facilities and clinical labs.

Yet even within these niches, this level of automation isn't for everyone. Many researchers choose instead to automate pieces of the problem, such as liquid handling, cryopreservation (for instance, using TAP's Fill-It robot), and cell line generation (using the ClonaCell EasyPick platform, from Hamilton and STEMCELL Technologies). "There are a lot of systems you could put in a hood and just use them to plate cells," Rush notes. Full-blown automation makes the most sense for core labs or facilities that can anticipate consistently high usage of a number of cell lines, Ward says. "I think the tipping point is more about the nature of the research in the organization."

What's required is an assessment of return-on-investment. With a price tag of between $500,000 and $900,000, for instance, the MACCS makes the most financial sense if it can free up three or more highly paid technicians, says Oldenburg. "If you had four people doing cell culture continuously—eight hours a day, five-to-six days a week where people are having to come in on the weekends as well—I think you could justify it," he says. Assuming an annual salary of $70,000 per technician, if the system freed up three workers (leaving one to run the system) it could pay for itself in three or four years.

According to Rush, the first thing to think about when contemplating a purchase is throughput: how many cell lines will you be growing, and how many plates or cells will you need at once? Next, consider your lab space: do you have an area large enough to house an automated cell system?

Finally, and perhaps most importantly, give yourself (and those who ultimately control the purse strings) a reality check. Automated cell culture systems have many advantages, but they also have downsides. They're slower than a person, for one thing, and far less flexible. A lab tech might notice that trypsinization failed to dislodge most of the cells on a plate and respond accordingly, for instance, whereas a robot cannot. "That can be a little frustrating if people haven't worked with automation before," she says.

It's therefore important to go into such a capital purchase with realistic expectations. "The way you have to justify it is, it really is [about] quality."

This article was published in Bioscience Technology magazine: Vol. 34, No. 11, November/December, 2010, pp. 1, 12-13.

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