Scientists, particularly in biology, have faced a continuing embarrassment in recent years: Research results that cannot be proven a second time. By some estimates, more than half of all scientific studies may not be replicable, and billions of dollars are wasted every year on new research that relies on such unreliable studies.
Replicability is a key metric of trustworthiness. If scientists are diligently doing their jobs, why are other researchers not able to reproduce their work? A new study offers an embarrassing explanation: One in six researchers who use human cells in tests have been actually using the wrong cells.
The revelation comes from Amanda Capes-Davis of CellBank Australia (much like a blood bank, cell banks are stores for cell lines) and her colleagues, who meticulously analyzed studies from across the world that reported contamination of cell lines.
A cell line is a population of cells derived from a single cell, which contain the same genetic make up. Cell lines have become the workhorses of medical research, because they can be used in early testing before humans or animals are involved. Disturbingly, the contamination analysis showed that in 2010 some 360 of the cell lines studied were contaminated and by 2014 that number had increased to 438 cell lines. The results of medical studies using these cell lines are now simply worthless.
Most contaminations were within the same species—mixing up bladder cancer cells and breast cancer cells, for instance—but some did occur across species. For instance, a cell line called CDB for human astrocytoma was found to be made up of rat cells, AMDURII (human skin) was found to be pig cells; and ACCNS (human salivary gland carcinoma) was actually mouse cells.
Previous studies have shown that the rate of contamination in a particular cell bank can vary from 20% to 85% of all cell lines.
Leonard Freedman, president of the Global Biological Standards Institute, has previously proposed a solution to cutting out contaminated cell lines: Scientific journals must set better guidelines on studies involving cell lines; funding bodies must ensure only to fund projects that have stricter methods; and training of young scientists should improve to stop contamination from happening.
Of course, cell contamination is not the only factor in faulty research—reasons range from individual fraud to flawed institutional structure. So it’s impossible to guess what proportion of scientific studies might suddenly become replicable—and therefore reliable—if cell line contamination were completely eliminated.
But if there’s a chance we can improve fields like cancer research just by taking more care with cell samples, it’s certainly worth trying.