This has been a recurring theme for GEITP over the past 6 years: A Sprague-Dawley rat in 1999 is not necessarily the same Sprague-Dawley rat in 2o16. A cell culture line established in 2oo6 is not necessarily the same cell culture line in 2o16. The is a great example of Gene-Environment Interactions. The environment (animal room, diet, climate, cell culture conditions) constantly challenges the organism’s ability to survive and reproduce (or cells to divide). Biomedical scientists are often urged to check that their cell lines are not contaminated or mislabeled. But as a recent study (M. Allen et al. 2o16; Sci Transl Med 8, 354re3) demonstrates, and discussed in the attached editorial, any effort to authenticate a cell line is only as good as the reference standard against which the cells are compared.
A cell line that is widely used to study brain cancer does not match the cells used to create the line nearly 50 years ago, nor does it match the tumor from which it was purported to have been derived. In fact, no one is quite sure of the true origin of the cell line that is being distributed by most cell repositories.
Because few cell lines are ever verified against their primary-source material, “this paper is probably just the tip of the iceberg”, says Christopher Korch, a geneticist at the University of Colorado Denver. Many groups are trying to tackle the problem of misidentified cell lines to improve the reproducibility of research findings. This year, the US National Institutes of Health started requiring grant applicants to describe how they will authenticate their cell lines [see attached pdf: “grant guidelines”]. Also, journals such as Nature have begun to ask authors to check their cells against a database of 475 lines (and increasing all the time) that are known to be likely artifacts.
But no organizations have called for the kind of archival sleuthing that produced the new study. “It’s hard enough to get people to do the standard authentication,” says Leonard Freedman, president of the Global Biological Standards Institute, non-profit organization in Washington DC which has found that most life science researchers never authenticate their cells (L. P. Freedman et al. BioTechniques 59, 189–192; 2015). “This (archival sleuthing) is much more elaborate.”
The cell line in question is U87, established in 1966 at Uppsala University (Sweden), using tissue from a 44-year-old woman with a glioblastoma, a very aggressive brain cancer. U87 has since been used in countless investigations––which has resulted in ~2,000 scientific papers. The enthusiasm for U87 initially puzzled Bengt Westermark, a tumor biologist at Uppsala. As a graduate student in the 1970s, he studied eight different brain-cancer cell lines. U87 was “hopeless to work with”, he says, because it grew much more slowly than the others. Years later, Westermark got his hands on the version of U87 that is distributed by the American Type Culture Collection (ATCC), a cell repository in Manassas, Virginia. He could see from the cells’ growth properties that this U87 was clearly different from the cells that gave him so much grief in graduate school.
So, Westermark decided to do a formal comparison. Fortunately, Uppsala had preserved the tumor tissue that spawned the original cell line. This enabled Westermark’s team to verify identity of the archival U87 sample in their freezer. The researchers then used DNA-fingerprinting techniques to show that the ATCC’s U87 was different — and that it didn’t match any other cell line created at Uppsala.
They are still trying to find the source of Nature 8 Sept 2o16; 537: 149–150 [editorial]
As a grad student in the early seventies I was using restriction enzymes to fingerprint mitochondrial DNAs. We thought it would be interesting to compare chimp and human, so we purchased a chimp liver cell line from ATCC. Surprisingly, the “chimp” mtDNA was the same as HeLa cell mtDNA. Ditto for several of their other cell lines, presumably the result of sloppy cell culture techniques. Many of their exotic cell lines were just HeLa cells.