Scientists routinely use standard microscopes to inspect cell cultures for performance, cell growth and culture contamination. This method does provide a certain level of confidence as to the quality of the cell culture. However, is this enough to produce reproducible, reliable and relevant data? According to the guidelines for Good Cell Culture Practice (GCCP) there is much more to the maintenance of a high standard in cell culture necessary to ensure reproducibility, credibility, acceptance, and proper application of any results produced1.
1) Gerhard Gstraunthaler (2010) Altex 27, Special Issue; 141-146
Different aspects of cell culture monitoring
Good Cell Culture Practice requires that reports of cell culture experiments include a basic and detailed description of the cultured cells, describing the origin and mode of culture initiation, the source and the morphology of the cell culture and its differentiation state. Morphology, gene expression, growth rates, viability, and adherence to matrices can all be used to describe the phenotype and differentiation stage of a cell line. Using time-lapse microscopy as well as automatic growth curve recording can help document morphology and the growth and motility behaviour of a cell culture. Finally, cell lines should be identified and authenticated using karyotyping, DNA analysis, fingerprinting or tests for cross-contamination.
The composition of culture media, the nature of culture vessels and culture matrices, and the subculture procedure are known to have a significant impact on cell culture and should be standardized wherever possible. Defining standard operating procedures (SOPs) for cell culture helps to reduce the variables affecting cell culture performance and assay results. Subculture details, such as culture confluency at the time of splitting, seeding density and total number of passages, should be precisely defined.
However, even a standardized cell culture experiences variation as a biological system. For example, primary cell systems such as patient derived materials may vary widely in proliferation behavior. Additionally, cell culture performance is highly user dependent and requires a certain degree of expertise to achieve consistency in cell cultures. Regardless of these challenges, standardized cell culture is of great importance as the condition of a cell culture may have a significant influence on the downstream experiment results obtained using the cultured cells.
Microscopes, small enough to fit inside a cell culture incubator and at the same time offering live cell imaging and time-lapse recording functionalities can help monitoring cell cultures. Automatic cell confluency determination provided by some microscopes can reduce operator dependent variations in cell culture handling. Unfortunately, most microscopes are not suited to be operated inside an incubator, or they are too big to be used for or too valuable to be blocked by cell culture monitoring applications.