Introduction
Automated cell screening in the biotechnology sector has become a fundamental driver of progress, enabling increased throughput and reducing reliance on labour-intensive workflows.
One of the main drivers behind this is the need for increased ‘speed to clinic’ - investors and CRO clients are placing heightened importance on shorter cell line development times and the production of consistently high quality recombinant products. As a result, various companies are developing automation strategies in order to meet these demands. However, caution should be exercised when choosing an automation system, as not all solutions are created equal. Here we take a look at what to look out for to ensure safe and successful cell line development.
Why automate?
Automation generates high quality, reproducible results, streamlining the
workflow with the added benefit of freeing laboratory staff from manual
repetitive steps.
There are various processes in cell line development that are particularly labour-intensive. For example, transfection (gene knock in or knock out), which is a random process, can often create a major bottleneck. It is both time and labour intensive as multiple screens and selection panels are needed to ensure the best clones are identified. Cell maintenance and cell line stability are also time-consuming processes. The highest performing clones need to be selected, cultured and expanded through a range of volumes to achieve cell yields that can be moved on to systems for further development. By automating cell line development, researchers can significantly streamline the workflow, speeding up these processes. This not only saves time and money but also helps to eliminate human error and liberates operator resources. The most well-designed and comprehensive enclosed automation systems can safely and accurately perform a wide range of tasks covering the entire cell line development workflow:
Cell seeding • dispensing cells into primary culture plates • maintaining cell lines in water baths to avoid temperature shocking • dilutions to required cell concentration with fresh media Addition of growth supplements or inhibitors Automated incubation • controlled CO2 and temperature Confluence measurement • check cell growth and clones • automatic clone selection based on operator set growth parameters | Clone selection and cell maintenance Transfection of cells • both chemical and viral transfection Clone selection • stripping of adherent cell lines • centrifugation of cells • transfer to expansion plates and fresh media Lead optimisation and target identification Phenotypic screening of suspension cells Clone selection for antibody production Hit picking |
Such comprehensive automation solutions normally consist of robotic plate handlers, microplate stores, incubators and laboratory instruments controlled by scheduling software. These are housed in an enclosed system also known as a workcell that importantly monitors and controls the internal sterile environment.
So, what do you need to look for when selecting an automation system and provider for cell line development? It is clearly important to select a provider with the freedom to install the best equipment to complete the tasks at hand, however it is also important to ensure that the both the system and system provider are equipped to meet safety requirements as well as complying with the most up-to-date standards.
Figure 1: A sterile workcell is vital for automated cell screening.
PAA’s S-CELTM Laboratory Automated Workcells are ETLus certified and provide full system laminar air flow across the whole system to maintain sterility and protect your assay.
Top priority – safety
Possibly the most important consideration when looking at automating cell
line development is safety. This is two-fold; protection for the cell lines and
protection for operators.
Developing and maintaining cell cultures in a stable and sterile environment is of paramount
importance in order to protect samples, and in turn increases overall success. Cell lines are
extremely fragile and susceptible to contamination which can be catastrophic in terms of both
time and money. They must have adequate environmental protection at all times in automation system enclosures. To ensure this, workcells must meet class II type requirements.
Why is it important to choose a workcell that meets class II type requirements rather than
biosafety level (BSL)-2? It should be noted that BSL-2 is a specification of a laboratory. Therefore, a system labelled as BSL-2 offers the same level of protection as if the user is performing the experiment on an open bench. In contrast, a workcell with a class II type classification provides the same level of protection as if the scientist were working inside a biological safety cabinet – which is significantly safer for both the operator and the product.
If the workflow involves cells of human origin, there is also a strong requirement to protect
operators. Although cell lines should be pure, there remains a risk that various infectious
agents can be carried by the cell lines that could be deleterious to human health. Although
the requirement to protect operators is not currently fully implemented in various laboratories
using open class II hoods, it is gradually becoming more enforced and should be taken into
consideration when automating the process.
Another reason to be vigilant about operator protection is transfection. There are various
methods to insert an identifiable segment of DNA into the genome of a cell. This can be done
chemically or via electroporation, but perhaps the simplest and most popular method is using
viral vectors that have been edited with CRISPR/ Cas9 or an equivalent technology. The modified virus can then be used to infect the cell, delivering the desired segment of DNA into the cellular genome.
The potential problem here is that the most effective viruses are the ones that rapidly react
to protect themselves and are therefore often highly infectious, examples being Hep B, HIV or influenza virus. It is therefore clearly very important to protect operators against exposure to these biological agents, due to the risk of aerosol dispersion during dispensing or via a dropped plate.
Airflows inside the workcell and through the access doors and windows must be considered
to prevent contaminated air being pulled from the system by the lab air conditioning, or
contamination being drawn through large, full height doors. Careful consideration of the location of equipment inside the system is also important. This is because instrumentation can disrupt the laminar air flow, potentially causing stagnant pockets of air - not ideal if these form over an unlidded sample plate.
PAA automated systems are designed to provide full protection through the entry portals.
When opened, the system monitors and adjusts the airflow continuously to ensure protection is maintained while ensuring noise levels are minimised providing a comfortable environment for the scientists working in the lab.
Figure 2: Safety is of paramount importance when automating cell line development.
PAA’s S-CELTM Laboratory Automated Workcells provide both operator and sample protection.
Safe but flexible – a system with the user in mind
It is important therefore, to select and install an automation system that
will provide both operator and product protection.
However, a system also needs to be easy to work with. Inevitably, there will be the need to access instruments inside the workcell when cells are in situ - for example to replace a seal on a plate sealer or reagents for a dispenser, or even just to add sample plates or additional labware. So there has to be adequate protection in place for this.
For example, it is not uncommon during cell line development for cells to be incubated for a
month to six weeks to achieve the required outcome. During this time the cells are continually
cultured, taken out of the incubator, reformatted, expanded, and returned to the incubator
for continued growth. There is clearly a constant requirement to replenish consumables and
reagents within the workcell, which in turn increases the risk of contamination, resulting in the potential loss of six weeks’ worth of work and perhaps significant clones. Any potential sources of contamination must therefore be avoided. A workcell must also be safe, flexible enough to fit around a particular workflow and easy to use.
PAA’s S-CEL workcells are good examples of a comprehensive and flexible automation solution that accommodates integrated laboratory automation applications - designed to ensure the utmost safety for cell lines and operators without compromise. The S-CEL enables an enclosure door to be opened without compromising the internal environment. A sensor detects when one of the doors is opened and the downflow of air is automatically increased, providing protection of the internal environment. This enables an operator to access instruments inside the system without risking contamination.
Another key feature that delivers not only safety but flexibility in this automation workcell is a
recirculating laminar flow system (Figure 1 & 3). This draws in air from outside and recirculates it round the enclosure, passing through triple HEPA filters which provide class II type protection in accordance with BS EN12469-2000. The air is cleansed via another HEPA filter and exhausted approximately two and a half meters up, providing additional assurance that it is not vented onto operators. The alternative to such a system would be a ducted cabinet which is plugged in to an existing air extraction system within the building. However, this can be very restricting as the automation workcell therefore has to be sited in a particular place to have access to the infrastructure. A recirculation system is much more flexible as it can be sited anywhere in the laboratory as long as the ceiling is high enough.
As well as being safe and flexible it is also worth bearing in mind that the system should be easy to use. A good system provider will have user-friendly scheduling software with an intuitive interface, and will have considered the workflow as part of the system build, ensuring easy access to instrumentation.
Figure 3: PAA’s S-CELTM employs a recirculation system and maintains internal environment protection when a door is opened. This design delivers the utmost in safety and allows the workcell to be situated in any space large enough to accommodate it.
Complying with standards
Another important consideration when choosing an automation system
for cell line development is compliance with standards.
A good automation system provider will test their systems to BS EN12469-2000 to achieve a
class II type classification. Part of this standard dictates that these enclosures should produce a laminar airflow across the deck of the workcell. However, it is important to note that while an empty workcell may achieve this, the addition of robots and instrumentation will disrupt this significantly, so it is important to select an automation system provider which understands this and tests its systems accordingly.
PAA’s automation systems are tested to BS EN 12469-2000 by measuring various air velocities, particle counting and tracer visualisation to meet class II type requirements. The systems are also certified by a nationally recognised test laboratory (NRTL) in the US - ETLus. Stacked equipment in a system can result in poor airflows and stagnant areas – therefore PAA systems are tested with smoke trace profiling, and for cleanliness using particle counting around the system.
As discussed, when working with live cells, it is of paramount importance to avoid contamination and cleanliness must be maintained within the workcell. Therefore, equipment layouts must consider maintenance of equipment and spill points etc. When working with multiple cell lines, the ability to chemically deep clean the system is critical. UV sterility offers minimal effectiveness within large automation systems due to the wavelength of UV compared to the size of the system and associated shadow effects. For this reason, PAA systems are supplied and installed to allow for vaporised hydrogen peroxide cleansing and are currently the only systems on the market capable of this.
Summary
Automating cell line development can make an enormous difference to laboratory workflows, speeding up processes, increasing reliability and reproducibility, while also saving time and money.
When selecting an appropriate automation system, safety, compliance with standards,
flexibility and ease of use should all be considered. A good solution provider will
understand these requirements and have the necessary expertise and experience to
guide the creation and installation of the best automation solution possible for the
required workflow. PAA are well placed to meet these requirements by providing forward
looking flexible automation platforms that produce consistent high product quality.
PAA’s S-CEL robotic workcells provide:
• Class II type enclosures – recirculating HEPA filtration
• Portal access without contamination – increased airflow over open portal
• NRTL certification for US
• Configurable sizes to fit the required instrumentation
• Advanced safety system – interlocked and sealed doors for easy access
• ‘Vendor neutral’ approach, enabling the best instrumentation for the workflow
• Advanced scheduling and control software that allows the widest range of robots and
instruments to be incorporated into the workcell
• Instrument slides for easy access to reagent replenishment
• Connect system enables instruments to be easily added when required.
Comments