The Scientist spoke with Westermark about his team’s latest analysis of U87MG, which was published in Science Translational Medicine today (August 31).
The Scientist: What led you to question the purity of the cell line?
Westermark: Out of the cell lines I studied in my thesis, U87 was the worst. It was really very difficult to handle. It grew very slowly—large, flat cells that had a long doubling time. They were always lagging behind in my studies. [Years later] I noticed that people loved this cell line. There came many publications on this cell line. I started to question why, because I hated this cell line. Very slowly, the suspicion came that maybe it is not U87. Maybe it is something else. At last, we attacked the problem by genetic profiling.
TS: You compared genotypes of your U87MG to those of a commercially available cell line from ATCC. How similar were these two, if at all?
Westermark: Completely different! The vast majority of the STRs [short tandem repeats] was different. I think it was 14 out of 16. Completely different. [The commercially available cells are] from another individual, I would say.
TS: Were you able to figure out at what point the contamination occurred?
Westermark: No, we don’t know that. . . .We went through all the cell lines that were established before and after they were sent to the United States. The mix-up is not at Uppsala, it’s somewhere else. The ATCC cell line is a very nice cell line. I understand why people have used it.
TS: What do you know about the cell line ATCC is distributing under the name U87MG?
Westermark: What we did was make an RNA expression profile. It’s most similar to cells derived from central nervous system. The suspicion is it is really a glioblastoma cell line. If you look into the literature you can also find people have found markers that are completely consistent with a GBM [glioblastoma multiforme] phenotype and also mutations consistent with a GBM phenotype.
TS: What should be done with regard to the hundreds of publications that include “U87MG?” Should researchers go back and correct them or move forward?
Westermark: I think we should move forward. And whenever we pick up one of these papers we should know this limitation, which may be completely [irrelevant] for many publications. Move forward, don’t despair. When it comes to human GBMs, use these new types of cell lines [that are grown in serum-free neural stem cell medium, which retains tumor phenotypes]. This is the path we are taking in our laboratory. . . . Ninety-five percent of what we are doing is based on these new types of cell lines. We have in our lab over 100 such cell lines that are well-annotated, we know where they come from, we have patient data and blood samples. We really know what we’re working on.