Cell culture has become one of the most fundamental techniques for modeling biological systems, and is of increasing importance in the biotechnology and pharmaceutical sectors as well as an essential process in life science research labs. Though this technique is highly accessible, successful propagation of cells for stock expansion or modeling experiments can be plagued by contamination or other conditions that negatively impact cell viability. The common practice of sharing cells has led to well-published evidence of cross-contamination of cell stocks whose identity was previously unquestioned. Identifying both common and infrequent reasons why cells may fail to thrive can increase lab efficiency, enhance yield of cellular products, and ensure meaningful, reliable downstream data from in vitro models.
Extensive genetic testing by multiple cell repositories and other life science entities over more than two decades has revealed that cancer cell lines commonly used in research may be misidentified or cross-contaminated with other cell lines. Recent studies estimate misidentification may affect up to one third of all cell lines in use. These discoveries have the potential to call into question published findings about biological systems based on results from cell line models.
Factors leading to cell line misidentification/cross-contamination include:
Cell culture media and incubation conditions provide the ideal environment for cells, as well as bacterial, fungal, and viral contaminants. In addition to diligent adherence to aseptic culture technique, cultures must be regularly examined microscopically for evidence of bacterial and fungal intruders. Some microbial contaminants, however, evade visual detection.
According to studies by the US FDA, ATCC, and others, it’s estimated that up to 30% of all cultures are contaminated with mycoplasma. Reagents and kits designed for detection of mycoplasma are often based on PCR amplification, which can also be used to detect viral contaminants.
When cells die in culture or fail to attain confluency, adherent cells spontaneously detach, or cells clump in suspension, contamination with microorganisms must first be ruled out. Other factors that may cause poor cell health or behavior inconsistent with phenotype include
Appropriate equipment, reagents, and protocols are key to resolving unexpected cell culture outcomes.