A series of damning documents seen by Nature expose deep concerns over the safety and efficacy of the controversial stem-cell therapy promoted by Italy’s Stamina Foundation. The leaked papers reveal the true nature of the processes involved, long withheld by Stamina’s president, Davide Vannoni.

Other disclosures show that the successes claimed by Stamina for its treatments have been over-stated. And, in an unexpected twist, top Italian scientists are dissociating themselves from an influential Miami-based clinician over his apparent support for the foundation.