A recent study published by Horbach and Halffmann (2017) reports on the number of ‘contaminated’ papers in scientific literature in which misidentified cell lines are used. The number of articles referring to misidentified cell lines is still increasing and a ‘fair and reasonable notifications system’ is therefore required to raise awareness of this issue.
Many articles in life science research continue to be published in which misidentified cell lines have been used, adding to concerns regarding errors, false conclusions and irreproducibility. No exact numbers are known, but estimates have shown that between one fifth and one third of all cell lines are misidentified. These estimates prove the importance of obtaining cell lines from a trusted supplier with a reputation for authenticity. Attempts have been made to find solutions to the issue of misidentification. For example, researchers may use genotypic identification via short tandem repeats (STR Profiling) to verify cell line identity prior to publication. Indeed, this is becoming a mandatory requirement of both funding bodies and publishers.
A recently published study by Horbach and Halffmann (2017) predicts that even if all future misidentifications are eradicated, the ‘contaminated’ articles already published will continue to affect research for years to come. The authors used the International Cell Line Authentication Committee's (ICLAC) Database of Cross-Contaminated or Misidentified Cell Lines, and searched for scientific literature based on misidentified cell lines from this list using the Web of Science. Nearly 33,000 articles were found to have reported on cell lines now proven to be misidentified. This number is a conservative estimation as it only accounts for known misidentifications. 'Contaminated' primary literature makes up approximately 0.8% of all cell based literature (4.5-5 million articles), and 'contaminated' secondary literature makes up approximately 10%. The article discusses three case studies; ALVA-31, Thymic cell lines, and JCA-1, each line being randomly selected from the ICLAC misidentified cell line database. These case studies show that misidentified cell lines were still being used in 2016 despite being listed as misidentified, thus showing that despite attempted solutions, misidentified cell lines still have an impact on modern research.
The fastest growth in the number of misidentified cell lines occurred between 1985 and 2000, starting after the report on large scale HeLa contamination and ending just before the introduction of STR profiling to authenticate cell lines. Since the use of STR profiling, the growth of the number of published articles on misidentified cell lines has decreased. The article appeals for a system to highlight ‘contaminated’ articles to users and readers to ensure that these articles are considered with appropriate care in order to help avoid the inappropriate use of misidentified lines.
One way to guarantee the use of correctly identified cell lines is to obtain them from a reputable source for authenticated cell lines. Not doing this opens the risk of using a misidentified cell lines, and in turn the risk of errors, false conclusion, and irreproducibility.
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