Would you read a story if this was the headline: New study raises questions about an experimental treatment that might not work and won't be ready for a long time." That description would apply to most medical studies that make the news but would be unlikely to generate the clicks, taps, likes and shares that propel a story through cyberspace and social media. What gets clicks? Words like "breakthrough," "groundbreaking," "game changer" and "lifesaver." Since the 1970s, the use of positive words in scientific abstracts increased by 880 per cent, according to a study last December in the British Medical Journal. And now, the world's stem cell scientists have been told to stop the hype. The International Society for Stem Cell Research (ISSCR) issued new guidelines last week that urge scientists to dial back their enthusiasm when talking publicly about their research. Because people are getting hurt. Last December, the Food and Drug Administration in the U.S. issued a warning letter to a U.S.-based company offering stem cell therapies for a range of diseases, including autism, multiple sclerosis and Parkinson's disease. And a U.K. newspaper claims its undercover investigation lead to the closure of a controversial clinic in Germany where a child died after having stem cells injected into his brain. "There is ... an industry already out there that is marketing unproven therapies directly to patients," said George Daley, a member of the ISSCR and a professor at Harvard Medical School. "It is part of the concern that has raised the alarm."