A guest blog by Erin M. Hall, M.S., Genetica DNA Laboratories, Inc., Technical Leader
Do you use human cell lines in your research? I’m betting most of you just nodded “yes” to that question especially since you are reading this blog on “thecellculturedish.com”. Well, keep reading because this may be the most important blog you will ever read in your research career. It is estimated that 18-36% of all actively growing cell line cultures are misidentified and/or cross-contaminated with another cell line(1). For researchers, the consequences of this are that a significant number of the experimental data published in current and past journals are invalid. Millions of dollars are spent every year on wasted research and this is happening not just here in the United States but around the world as well.
Cell line misidentification and cross-contamination has been around for more than 50 years. It was finally brought to light in 1966 by Stanley Gartler, who reported that 19 supposedly independent human cell lines were in fact HeLa cells(2), which are known to be extremely robust and fast growing (even able to contaminate other cultures by aerosol droplets!). There was much resistance to his findings because scientists didn’t want to admit that the research done using those contaminated cell lines may be invalid. Walter Nelson-Rees was one scientist who didn’t want Gartler’s findings to be “swept under the rug”. Nelson-Rees highlighted the papers and the scientists who were publishing experimental data using misidentified cell lines and for this, in 1981, he lost his contract with the National Institutes of Health (NIH) because his behavior was deemed “unscientific”(3). From 1981 and on, misidentification went unchecked and even cell line repositories continued to distribute lines under their false names(3).
Specific cell culture practices may be aiding cell misidentification and cross-contamination, including the practice of assessing the phenotypic characteristics, such as protein expression, as a way to properly identify the cell population. It has been proven that phenotypic expression can change with an increased passage number or even with changes in growth medium or other cell culture conditions(4). The most popular modern way of assessing the correct identity of the cell line (“cell line authentication”) is to perform short tandem repeat (STR) DNA testing. The STR DNA profile of a human cell line is like a person’s fingerprint, it is unique to that individual. STR testing is now the “gold standard” of human identification testing and is routinely used by the FBI in profiling convicted offenders (CODIS).
Cell line misidentification and cross-contamination continues even today because the problem has not been properly brought to the attention of research scientists. We, as scientists, expect to use only the best reagents and supplies but the one aspect of the research that may be the most important, i.e. the cell line, is consistently overlooked. Without verifying the identity of the cell line before you start your experiments, every two months during active growth, and just prior to publication you may waste months, if not years, of research time and money. Think about the consequences of not authenticating your cell lines and do the right thing, not just for yourself but for the research community as a whole.
For more information on this topic, please check out Genetica DNA Laboratories’ informational website – www.celllineauthentication.com and the references listed below.
1. Editorial - Nature 457, 935-936 (2009).
2. Gartler, SM. Second Decennial Review Conference on Cell Tissue and Organ Culture: 167-195 (1967).
3. (ATCC SDO Workgroup ASN-0002. Cell line misidentification: the beginning of the end: 441- 448 (2010).
4. Kerrigan, L. Authentication of human cell-based products: the role of a new consensus standard: 255-260 (2011).