Impostor cells

Biomedical research uses immortal cell lines such as HeLa to test treatments and examine biological mechanisms. But sometimes those cell lines are not what everyone thought: they have been invaded.

HeLa V cells
National Institutes of Health (NIH), Public domain, via Wikimedia Commons

Biomedical research makes heavy use of immortal cell lines. Most human or other animal cells can only be cultivated in a lab for a very short period – beyond a few days, cells in a petri dish die. But there are some special cells that last longer. Because of a mutation, these cell lines can be cultivated and reproduced indefinitely. They are effectively immortal.

These immortal cell lines are absolutely invaluable for research purposes. Cultivated cells will survive long enough to answer any number of interesting questions: how do these cells work? How do they respond to specific medicines or treatments? There are cell lines from human skin, cell lines from internal organs, and cell lines from tumours and cancers. Jonas Salk, for example, developed the polio vaccine with help from an early immortal cell line.

The first and most famous immortal cell line came from a woman named Henrietta Lacks. She died in 1951, but the cell line taken from her cervical cancer (without her permission or consent) is still alive today and is used for research around the world. It’s a fascinating story in itself, so if you want to know more I recommend checking out Rebecca Skloot’s 2010 book The Immortal Life of Henrietta Lacks.

Today there are hundreds of immortal cell lines, representing all kinds of specific human (or animal) cells. They are grown and shared between labs worldwide. If you want to test a new treatment for melanoma, you might first test its effects on a melanoma cell line. This is an essential part of biomedical research. There’s just one snag: how sure are you that the cell line is actually melanoma?

Enter impostor cells. Sometimes, a cell line becomes contaminated with an outside cell. When the immortalised cell line is reproduced, the imposter cell is reproduced along with it. And, eventually, it might even take over. HeLa (Henrietta Lacks’ cell line) is a very common imposter cell. You think that you’re running a test on a melanoma cell, but it’s actually HeLa’s cervical adenocarcinoma instead. The cell line is contaminated and useless.

This is not inherently a problem – you just need to identify that a cell line is contaminated and replace it with a fresh one. But, up until very recently, much research did not test their cell lines for contamination. Their results might be partially or totally invalid, but they didn’t know it.

A few determined academics have been pushing for greater accountability in research: people like Christopher Korch (see the fifth link below) have been identifying contaminated cell lines and pushing for better testing of existing cell lines. Without this necessary quality check, hundreds of studies might be invalid thanks to these imposter cells.

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