Researchers pinpoint a lack of best practices in mammalian cell culture

Reporting of biomedical studies on mammalian cells needs to be more standardized and elaborate, along with greater control and measurement of the environmental conditions of cell cultures. This would make the modeling of human physiology more accurate and contribute to the reproducibility of the study.

The study reveals the urgent need to report, measure, and control the environmental conditions of the media in which cells are cultured, which should improve how well scientists can repeat and reproduce experimental results. Image Credit: King Abdullah University of Science and Technology.

A group of King Abdullah University of Science and Technology (KAUST) researchers and co-workers in Saudi Arabia and the United States examined 810 randomly selected papers on mammalian cell lines. Less than 700 of those, comprising 1,749 individual cell culture experiments, contained relevant data on the environmental conditions of the media in which the cells were cultured.

The analysis indicates that a great deal has to be done to enhance the relevance and reproducibility of this kind of research.

Mammalian cell cultures are fundamental to manufacturing viral vaccines and other biotechnologies. They are used to study basic cell biology, replicate disease mechanisms and investigate the toxicity of novel drug compounds before they are tested on animals and humans.”

Shannon Klein, Marine Scientist, King Abdullah University of Science and Technology

Cells are cultured in controlled incubators in line with standard protocols. However, cells grow and “breathe” over time, exchanging gases with their surrounding environment. This impacts the local environment in which they grow and changes parameters like dissolved oxygen, culture acidity, and carbon dioxide. These variations may affect cell function and can make conditions distinct from those found in the living human body.

Our study highlights the extent to which scientists neglect to monitor and control cellular environments, as well as neglect to report the specific methodologies that allow them to reach their scientific conclusion.”

Shannon Klein, Marine Scientist, King Abdullah University of Science and Technology

For instance, the scientists identified that almost half of the papers examined failed to report the carbon dioxide and temperature settings of their cell cultures. Less than 10% notified the atmospheric oxygen levels in the incubator, and less than 0.01% reported the medium’s acidity. None of the papers reported on the dissolved oxygen or carbon dioxide in their media.

We were very surprised that researchers largely overlooked the maintenance of environmental factors, like culture acidity, at levels relevant to the physiological body over the full course of the cell cultures, despite it being well known that this is important for cell function.”

Samhan Alsolami, PhD Student, King Abdullah University of Science and Technology

The researchers headed by KAUST’s marine ecologist Carlos Duarte and stem cell biologist Mo Li in association with developmental biologist Juan Carlos Izpisua Belmonte from the Salk Institute, who is now a visiting professor at KAUST, suggest that biomedical scientists should create standard reporting, measuring, and control procedures along with using purpose-built instruments for controlling the culture environments of various cell types.

Scientific journals too should develop reporting standards while requiring satisfactory monitoring and control of dissolved oxygen, carbon dioxide, and culture medium acidity.

“Better reporting, measurement, and control of the environmental conditions of cell cultures should improve how well scientists can repeat and reproduce experimental results. More careful attention could drive new discoveries and increase the relevance of preclinical research to the human body,” adds Alsolami.