Pollution of Biomedical Journals
Serious concern exists with regard to the extent of pollution of scientific journals
that unwittingly publish results of biomedical research based on the use of
misidentified and/or cross-contaminated cell lines. Although it is virtually
impossible to accurately measure the extent of pollution and its harmful effect, we
can analyze the tip of the iceberg and logically deduce some important information
about the hidden danger and its potential for harm. While reviewing data for
possible impact, be mindful that there are tens of thousands of cell lines in use.
There are over 3500 cell lines in the ATCC repository, thousands of others in other
major repositories, and more than 10,000 cancer cell lines in private holdings.
One approach that confirms that the literature is highly contaminated entails
analyses of data bases, such as PubMed, for research articles based on the use of cell
lines that are widely known to be misidentified or cross-contaminated (except to the
authors and peer reviewers of grant applications and journal manuscripts). Some of
these “bad actors” date back to Gartler’s original research (1966), that revealed
more than forty years ago, that some cultures were over-run by the HeLa cell line
and no longer showed signs of the original cell line. Among misidentified cell lines
there are some that were elevated to the status of model cell because of their
presumed origin and some of the phenotypic properties they expressed. Among
them were the following cell lines over-run by HeLa: KB, purported to be an
oropharyngeal human cancer cell; Hep-2, purported to be a human laryngeal
cancer cell; Chang liver, purported to be a normal human liver cell; WISH, a cell
line purported to be a human amnion cell line; and Int-407, a putative intestinal cell
line. A PubMed search (by Nardone and Padilla, unpublished) covering the years
2001 through 2006 uncovered 1963 citations based on at least one of these 5 “false”
cell lines. The statistics summarized in Table 1 show no reduction in the frequency
of the erroneous use of these cell lines between 2001 and 2006; indeed, the number
of citations in 2006 was almost double the citation number for 2001. These numbers
support the reports of Masters (2005) and Buehring et al (2004) who conducted
similar studies. When Nardone and Padilla (2008) surveyed the data base for
“false” reports of the “infamous five” cell lines in 14 journals for the years 2004
through 2006, 54 citations were retrieved. Of the 54 citations, 30 were published in
the Proceedings of the National Academy of Sciences. We cannot conclude that this
journal was more lax in its peer review than the others; our studies did not delve
into the total number of published articles. Also, we did not strive to identify other
“false” cell lines. What can be concluded, however, is that the problem is widely
distributed and it extends to the high and mighty. Remember, manuscripts accepted
for publication in PNAS must be submitted by a member of this prestigious group
or endorsed by a member!
It is also logical to assume that if the frequency of misidentified and crosscontaminated cell lines is about 15-20% (a conservative estimate) then the frequency
of research articles based on the use of cultured cells should have a frequency
somewhat related to that frequency. Very few studies have provided quantitative
information. The German cell culture repository (DSMZ) has examined hundreds of
submitted cell lines and its staff has reported the following. In 1999, MacLeod et al
reported that 18% of the new cell lines submitted were false and 29% of the
originators depositing cell lines had submitted at least one false culture. Another
survey dealing with hematopoietic cell lines found that 45 of 326 submissions
(17.9%) were cross-contaminated (Drexler et al, 1999). Masters et al (2001) reported
the outcome of a cooperative DNA profiling study by the ATCC, the DMSZ, and
JCRB (the Japanese Cell Research Bank). Thirty-six percent cross-contamination
was found.
It is apparent that the owners and editors of journals that publish outcomes of cell
culture- based research, must undertake special action in order to reduce the
publication of misleading and wasteful articles. This can be achieved by announcing
that papers which present no evidence of cell line authentication and
characterization will not be accepted. It also requires that peer reviewers be
properly informed of existing criteria that should be met by the author and enforced
by the reviewer. We hope that the cell authentication initiative I have undertaken
will lead to a profession-wide consensus with journals and funding agencies
adopting a zero tolerance policy: no cell line authentication/no publication; no cell
line authentication/no grant. Such a policy would not be an unusually difficult
burden for scientists to carry. More importantly, it would ensure uniform
compliance and protect the underpinnings of good scientific research
(Nardone, 2007).
Literature Cited
Buehring, G., Eby, A., and Eby, M. 2004. Cell line cross-contamination: How aware
are mammalian cell culturists of the problem and how to monitor it. In Vitro Cell
Dev. Biol. Animal 40: 211-215.
Drexler, H., Dirks, W., and MacLeod,R. 1999. False human hematopoietic cell
lines;cross-contamionations and misrepresentations. Leukemia 13:1601-16067.
Gartler, S. 1966. Genetic markers as tracers in cell culture. Nat. Cancer Inst. Mono.
265:167-195.
MacLeod, R., Dirks, W., Matsuo, Y., Kaufman, M., Milch, H., and Drexler, H.
Widespread intraspecies cross-contamination of human tumor cell lines arising at
source. Int. J. Cancer 83:555-563.
Masters, J., Thomson,J., Daly-Burns B., Reid, Y., Dirks, W., Packer, P., Toji, L.,
Ohno, T., Tanabe, H., Arlett, C., Kelland, L., Harrison, M., Vermani, A., Ward, T.,
Ayres, K., and Debenham, P. 2001. Short tandem repeat profiling provides an
international reference standard for human cell lines. Proc. Natl. Acad. Sci. 98:
8012-8017.
Masters, J. 2005. Report presented at the Annual Meeting of the Society for in Vitro
Biology.
Nardone, R. M. 2007. Eradication of cross-contaminated cell lines: A call for action.
Cell Biol. and Toxicol., May 24, 2007. Epub ahead of print PMID 17522957.
Nardone, R. and Padilla, V. 2008. A PubMed search for misidentified cell lines,
2001-2006: Five cell lines and fourteen journals. Personal communication.
Roland M. Nardone
nardone@cua.edu
http://cellid.cua.edu
Table 1. Use of 12 False Cell Lines*: A PubMed Search, 2001-2006.
Year
Number of Articles
2001
2002
2003
2004
2005
2006
203
297
323
376
386
378
*Esophageal carcinoma ,squamous carcinoma, TE-7, TE-2, TE-3, TE-12, TE-13,
Chang liver, Int-407, WISH, Hep-2, KB.
Table 2. Use of Five False “Model” Cell Lines: A PubMed Search, 2001-2006.
Year
Chang Liver
Int-407
WISH
Hep-2
KB
2001
2002
2003
2004
2005
2006
7
8
10
12
8
18
8
6
10
8
9
9
9
14
6
10
8
9
35
65
99
111
89
101
74
114
99
122
118
109