Preparation: Cell Expansion and Contamination Control for Drug Discovery

The efficiency and consistency of your drug discovery program begins with the fundamentals of cell culture preparation. One of the core techniques involves contamination prevention in large-scale cell cultures, including passaging cells at scale. Innovative solutions for passaging allow you to practically eliminate contamination risks, streamline processes, and enhance your efficiency.

To accelerate your drug discovery program, we offer a portfolio that helps you improve productivity, ensure you are choosing the right candidates, and decrease your time to clinical trial.

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Stop contamination before it stops your drug discovery program

Contamination may take the form of bacteria, yeast, mold, chemicals, other biological agents, and/or cell line cross-contamination. It may affect the growth, morphology, and behavior of your cultured cells, and slow down your project. Contamination is one of the major challenges in any program involving cell culture.
 

Bacterial contamination

Bacteria are the most common contaminants. Typical tap water contains 100-1,000 CFU/100 mL of bacterial contamination, but the standard set by ASTM International is <10 CFU/100 mL for bacterial contamination in cell culture work. Bacterial contamination, unlike some other contaminants, is usually easily detectable because the culture will become cloudy or turbid and/or the color of the media will change, indicating a drop in pH. Bacteria are also readily visible under the microscope.

Despite the ease of detecting most bacterial contamination, it can still decrease your efficiency, since you might not notice it right away and might rely on this culture for an upcoming assay. Decontamination can also be expensive and time-consuming. 

To avoid bacterial contamination:

  • Water is your most important reagent, so be sure to use freshly produced ultrapure water for your stocks 
  • Take great care of your other reagents and use sterile filtration to eliminate any chance of contamination 
  • Be diligent with your sterile technique and use only sterile reagents
  • Beware of general lab stocks as monitoring contamination in those tends to be a challenge 

APPLICATION NOTE

Water is Life: Ultrapure Water in Cell Cultivation

Water is a major component of all cell culture media and is therefore needed to prepare media, buffers, and additives, and as well as to serve many ancillary functions, such as heating, cooling, cleaning and rinsing. Learn how ultrapure water improves the outcome of your cell culture experiments in this application note.

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APPLICATION NOTE

Preventing Cell Death: Ultrapure Water System Lowers Endotoxin Content Below Prescribed Limits

The presence of endotoxins can lead to cell death in mammalian cell cultures. For this reason, ultrapure media, i.e., ultrapure water, with levels proven to be below the limits must be used to manufacture biopharmaceuticals or to propagate cell lines or cell cultures. Read our application note to learn how the arium® pro VF ultrapure water system provides the highest quality, on-demand water that exceeds your requirements for endotoxin-free water.

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Tools to help you avoid bacterial contamination:

arium® mini Ultrapure Water System

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Sartolab Vacuum Filtration System

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Minisart Syringe Filter

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arium® pro Ultrapure Water System

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Mycoplasma contamination

Mycoplasma contamination is crafty because mycoplasma are small (0.15 µm-0.3 µm), have no cell wall, and have a flexible membrane. These flexible membranes and lack of a cell wall make mycoplasma difficult to detect using a microscope, and their small size allows them to proliferate to high concentration within mammalian cell culture without any noticeable turbidity or other change in cell culture appearance.

Contamination of your culture by mycoplasma may not be apparent until your cell line is lost.

Cross-contamination from other contaminated cells is one of the main sources of mycoplasma contamination. Elimination of mycoplasma contamination from a culture is almost impossible; it is resistant to most antibiotics and can survive liquid nitrogen without cryopreservation techniques, contaminating other cells stored in the same liquid nitrogen dewar. 

Using a mycoplasma-specific test on your cell cultures increases your efficiency; it allows you to know immediately if your cells are contaminated, preventing wasted time, reagents, and effort. Working with mycoplasma-free cultures increases the likelihood that the results you see at the bench will translate to the clinic.

Tools to help you detect mycoplasma in your cultures:

Microsart Mycoplasma Rapid Detection Kits

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Passaging cells

All cell cultures eventually need to be passaged or subcultured during cell expansion, regardless of whether they are adherent or nonadherent cells. Unfortunately, passaging presents a contamination challenge because the culture flask is opened, cells are handled, and new media and components are added. All of these steps increase the chance of introducing contaminants. Following proper aseptic technique, working quickly, and using the best tools and uncontaminated reagents will help reduce introduction of contaminants into your cell cultures.

Tools to reduce contaminants in your cultures:

Picus Electronic Pipette

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Midi Plus Pipetting Controller

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Sterile Filter Tips

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Tacta Mechanical Pipette

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Passage cells completely outside the hood: avoid introducing contaminants and improve efficiency

You can passage cells aseptically without ever needing to open a flask or enter a hood, with our innovative cell expansion system. To prevent contamination during passages outside the biosafety cabinet, this system combines tubing for aseptic fluid transfer and a filter cartridge for gas exchange in the cap pre-assembled on plastic Erlenmeyer shake flasks.

You will observe equivalent growth rates between our system, MYCAP CCX, and the traditional Erlenmeyer flasks. Media fill, inoculation, sampling, and transfer from flasks can all be done aseptically outside the biosafety cabinet by using tube welders or aseptic connectors.

These features allow you to reduce contamination risks, which means you can improve your efficiency by eliminating the use of back-up flasks and reducing redundant passages. You can also eliminate your use of a biosafety cabinet, thus lowering your operating costs and streamlining your operations. 

Tools for aseptic cell passaging:

MYCAP CCX Aseptic Cell Expansion System

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Improve the efficiency of your liquid handling to minimize damage during cryopreservation

Your cell lines are one of your most invaluable resources, but unfortunately, they are also fragile. Continuously cultured cell lines may be lost through senescence, contamination, and/or genetic drift in the population. You protect your cell lines by cryopreservation in liquid nitrogen. However, freezing and thawing processes are stressful to these fragile cells. Cells stored in liquid nitrogen are usually protected from the damaging effects through the use of cryoprotectants, such as DMSO or glycerol. Working quickly and using good technique is also critical to reduce the chance of damaging these invaluable cells.

The correct tools will help you work quickly and efficiently, while the wrong tools may slow you down and include the need for extra steps.

Your choice of pipette and pipette tip can make a difference when pipetting cells from the seed and working stocks of your established cell lines. Solutions containing cryoprotectants have lower surface tension than the aqueous cell culture media. For instance, the most commonly used cryoprotective, DMSO, has a surface tension of about 43 mN/m at 20◦C (water is 73 mN/m). Low surface tension means that liquid coats the pipette tip, making it difficult to pipette precisely. Using the right pipette tip, like low-retention tips with polished and treated surfaces, may help you ensure the correct ratio of cryoprotectant to cell suspension, thus decreasing the chance of cellular damage on freezing and thawing.
 

Tools to keep your cells alive during cryopreservation:

Tacta Mechanical Pipette

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Low-Retention Tips

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Picus Electronic Pipette

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Sterile Filter Tips

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