So began WI-38, a strain of cells that has arguably helped to save more lives than any other created by researchers. Many of the experimental cell lines available at that time, such as the famous HeLa line, had been grown from cancers or were otherwise genetically abnormal. WI-38 cells became the first 'normal' human cells available in virtually unlimited quantities to scientists and to industry and, as a result, have become the most extensively described and studied normal human cells available to this day.

Vaccines made using WI-38 cells have immunized hundreds of millions of people against rubella, rabies, adenovirus, polio, measles, chickenpox and shingles. In the 1960s and 1970s, the cells helped epidemiologists to identify viral culprits in disease outbreaks. Their normality has made them valuable control cells for comparison with diseased ones. And at the Wistar Institute, as in labs and universities around the world, they remain a leading tool for probing the secrets of cellular ageing and cancer.