Scientists Look to Bridge Reproducibility Gap in Cell Culture

Bioscientists in Saudi Arabia are exploring why cell culture environments vary so much from each other and from conditions in the human body, making it difficult for experiments to be reproduced and validated by the larger scientific community. The work could lead to improved standards and protocols for cell culture experiments in the laboratory.

To evaluate what’s behind this “reproducibility crisis,” the team at King Abdullah University of Science and Technology constantly monitored three different cell types—human pluripotent stem cells, a cancer cell line, and a type of white blood cell—in a controlled incubator over a three-day period. Optical sensors were attached to some of the flasks belonging to each cell type to monitor changes in dissolved oxygen and carbon dioxide levels as the cells grew. Other flasks were removed every eight hours and then discarded after measuring cell growth rates and culture acidity.

The extent of changes that occurred in the cultures varied with cell type, but generally, as cell density increased, the amount of oxygen dissolved in the cell medium decreased and carbon dioxide increased. This in turn increased the acidity of the surrounding medium. The different extents to which these changes occurred in each cell type is likely due to differences in cell growth rates and metabolism. These changes affect cell processes.

“We were surprised to find the batch-cultured cell environments were many magnitudes different from their native environments in the human body,” says Ph.D. student Samhan Alsolami.

The team is now studying the functional consequences of cell culture environmental instability by analyzing gene expression and epigenetic and metabolic changes in cells grown under well-defined conditions.  “Scientists are still discovering the factors that contribute to maintaining an ideal cell culture environment in order to accurately mimic the human body,” says research scientist Shannon Klein. “But it’s not an easy task and requires parallel advances in technology and engineering,” she says.

Future research will aim to develop recommendations on how to improve culture conditions for different cell types. In the meantime, the researchers suggest that amendments to existing batch culture protocols, such as reducing cell density or adapting culture vessels, could help limit changes to within acceptable ranges. Commercially available systems could also be used to continuously dilute cultures with fresh medium or automatically add gasses or adjust medium acidity to maintain cellular environments.

The findings were published in Communications Biology.