Radboud University researchers fear oncology, molecular biology, pharmacology, and other cell-centric medical research efforts are at risk due to verification that at least 30,000 studies published in 33,000 scientific journals included data derived from misidentified or contaminated cell lines

Many research findings that underpin the science behind various diagnostic technologies used regularly by clinical laboratories and anatomic pathology groups may not be valid. This is because a large number of published studies may have used misidentified or contaminated cell lines.

Biomedical scientists have known for a long time that many research papers exist containing reports on the wrong cells due to cell line misidentification. And yet, few studies have measured the true scope of the problem. Until now. Researchers at Radboud University in the Netherlands have determined that this problem may have influenced the findings of thousands of published research studies and upon which many other research studies were conducted.

Because clinical laboratories and anatomic pathology groups use assays and diagnostic tests that are developed as a result of these research studies, identifying how many published papers have inaccurate findings that cannot be duplicated would affect how and when it is appropriate for physicians to order certain medical laboratory tests and rely on the results.

Additionally, cancer research is based on cell line studies as well. Thus, it may prove necessary to restudy existing published findings and revise them as appropriate. In turn, these new findings might change how and when some cancer tests are ordered and the results interpreted.

Identifying Corrupted Published Data

Radboud researchers Serge P. J. M. Horbach, a doctoral student, and Willem Halffman, PhD, Associate Professor, Philosophy and Science Studies, used the Web of Science database to track down any scientific articles based on “known misidentified cell lines as listed by the International Cell Line Authentication Committee’s (ICLAC) Register of Misidentified Cell Lines,” according to an article in ScienceAlert.

“We considered a reference to this original article as a good proxy for the usage of a cell line,” the researchers noted in their study published in the journal PLOS ONE. “Since typically the original papers are focused on reporting the establishment of the cell line only.”

They focused on misidentified cell lines that were caused by HeLa cells, also known as “immortalized cells.” HeLa cells have been used in scientific research for decades. They were the first mass-producible cells that could be used in vitro, making them highly desirable for biomedical research.

However, the process of creating immortalized cells involves mutation, during which contamination can be introduced by other cells. Immortalized cells can be identified as one type of cell when in fact they are actually another type of cell.

Research scientists have been aware of this problem for about as long as immortalized cells have been in use. They attempt to take it into account when completing their analyses, though not always successfully.

The Radboud researchers found 32,655 records of primary literature based on contaminated cell lines. They then cross-referenced the ICLAC Register of Misidentified Cell Lines with a range of databases to determine if articles were available for each of the 451 cell lines listed on Table One of the ICLAC Register.

The databases they used included the:

With this information, they further researched published articles in the Web of Science database using cell line identifiers. They noted both primary literature and any citation report entries for each cell line.

The researchers noted in their published study, “As we only searched for cell lines known to be misidentified, this constitutes a conservative estimate of the scale of contamination in the primary literature. Moreover, to avoid false positives, we excluded several cell lines, such as the ones with non-unique identifiers or the cell lines for which verified stock is still in circulation.”

Their estimate for secondary contaminated literature based off primary articles is larger still. “In total, we can conservatively estimate the citations to the primary contaminated primary literature at over 500,000, excluding self-citations,” the authors noted in their PLOS ONE article. “Thereby leaving traces in a substantial share of the biomedical literature.” They concluded, “… the amount of research potentially building on false grounds remains worrisome.”

Impact of Contaminated Cell Lines on Research, Clinical Laboratory Communities

Many of the assays and diagnostic tests performed by clinical laboratories and pathology groups were developed using cell line research. Should further scrutiny into the ability to duplicate and verify study findings fail to produce positive outcomes, it might call into question the validity and appropriate use of these tests.

For the research community, these findings represent yet another call to promote accountability and define standards for verifying authenticity of cell lines to further strengthen research findings.

The Radboud researchers ranked the number of contaminated articles they discovered by research area. Top affected areas include:

  • Oncology
  • Molecular Biology
  • Pharmacology
  • Cell Biology
  • Immunology


The distribution of contaminated primary literature over the research areas as defined by Web of Science. Only the 25 most affected research areas are included. (Graphic copyright: PLOS ONE.)

Addressing the Problem of Cell Line Contamination and Misidentification

Adapting the ever-growing body of published medical literature to reflect the known misidentifications, as well as the possibility of invalid results, will be a major undertaking. Ultimately, resolving this problem could require changes to practices and procedures currently used by research facilities and medical laboratories.

While the cost to authenticate cell lines adds to the bottom line of research projects, the money spent on research that becomes invalidated by misidentified cell lines is far greater.

In a 2015 Retraction Watch article, Leonard P. Freeman, PhD, President, Global Biological Standards Institute, notes, “An NIH RePORT search identified 9,000 active projects using cell lines, totaling $3.7 billion. Required use of authentication techniques would affect over $900 million in research dollars annually.”

Additionally, failure to adapt authentication as a part of standard operations brings other consequences. “A 2004 survey reported that just one-third of laboratories authenticate their cell lines,” Freeman noted. “10 years later, a Sigma-Aldrich survey found that only 37% of respondents ‘validate the purity and identity before first use’ of cell lines. Understanding the existing barriers that prevent implementation of universal cell authentication is central to changing this sad state of affairs.”

Mixed Recommendations for Fixing Inaccurate Published Studies

Of course, none of this will change the vast body of archived literature that might contain errors due to misidentification. Recommendations for addressing this aspect of the problem vary. The Radboud study authors suggest posting notes on any previously published articles stating that misidentified cell lines were used.

However, in a STAT article, Ivan Oransky, MD, and Adam Marcus, Managing Editor, Gastroenterology and Endoscopy News, co-founders of Retraction Watch, recommend more severe measures. “When we polled readers of Retraction Watch last December about the issue, 55% said journals should correct papers known to describe contaminated or misidentified cell lines, and more than 40% said retraction was the right choice.”

Thanks to the Radboud study, as cell lines continue to power the innovations of modern biomedical research, concerns will surely increase surrounding cell-line authentication and research findings. For pathology groups and medical laboratories, staying abreast of these developments will work to ensure data validity and reduce reputation and liability concerns.

—Jon Stone


Related Information:

Over 30,000 Published Studies Could Be Wrong Due to Contaminated Cells

The Ghosts of HeLa: How Cell Line Misidentification Contaminates the Scientific Literature

The Economics of Reproducibility in Preclinical Research

Crosscontamination of Cells in Culture

Cell Authentication Survey Shows Little Progress in a Decade

Apparent HeLa Cell Contamination of Human Heteroploid Cell Lines

Some 30,000 Biomedical Publications Report on Misidentified Cells

Cell Line Misidentification: The Beginning of the End

Fixing Problems with Cell Lines

Thousands of Studies Used the Wrong Cells, and Journals Are Doing Nothing

We’re Wasting a Lot of Research Funding Using the Wrong Cell Lines. Here’s One Thing We Can Do

Misidentified and Contaminated Cell Lines Lead to Faulty Cancer Science, Experts Say

STR Analysis for Cell Line Authentication Gaining Traction in Research Community