Cell-based kinetic assays are a common component of pharmaceutical and academic research. Light is often used as an output for cell culture growth kinetics and as such, cell proliferation in 96-well plates is often measured in microplate readers. A challenge faced by some researchers is that maintaining an optimal environment for their cells often requires moving the cells between an incubator for growth and a microplate reader for measurement. While microplate readers are often equipped with temperature control capabilities, carbon dioxide and oxygen levels can still fluctuate, providing instabilities for the cultures. Furthermore, researchers often require a hypoxic environment to mimic the physiological conditions found in tissue. Carbon dioxide fluctuations in particular can therefore be disastrous for cell-based assays, since when carbon dioxide levels fall the bicarbonate-based pH buffering system in most growth media is upset, leading to a drop in pH which severely impacts cell viability.
An integrated gas regulator for automated, uninterrupted cell-based kinetic assays
Readers such as the Thermo Scientific Varioskan LUX multimode microplate reader can be equipped with an integrated gas module, offering a means of regulating carbon dioxide and oxygen levels during their cell-based kinetic assays. This means that researchers can regulate oxygen and carbon dioxide levels as well as temperature during their assay measurements, without removing their microplate cultures from the reader. This allows for full automation of assays and reduces the risk of varying the conditions the cultures are exposed to by opening equipment doors. What is more, that data can be collected continuously over long experiments without researchers needing to be constantly present at the instruments.
Testing the effects of the Integrated Gas Module
To test how important carbon dioxide regulation is for cell proliferation, scientists grew two microplates of HeLa S3 cells for 72 hours, one plate with gas regulation and another without. For the regulated plate, carbon dioxide partial pressure was maintained at 5% and cells proliferated well. In the unregulated plate, cells did not proliferate at any detectable level, demonstrating the importance of carbon dioxide levels for cell viability. The integrated gas module also records oxygen and carbon dioxide levels; carbon dioxide partial pressure fluctuated less than 0.1% during the entire experiment.
Now that gas regulation is can be integrated into a microplate reader, one of the final barriers to moving cell-based kinetic assays fully into the reader has been removed. This creates the ability for less assay variation and improved data through continuous acquisition, leading to better results.
Maximize your Cell-based Assay Research
For even more tips and techniques around cell-based assays, explore our on-demand webinar in the Cell Culture Cafe: From the hood to the microscope; Revolutionizing cell-based imaging.