FDA Commissioner Scott Gottlieb announced moves to crack down on illicit marketers of stem-cell therapies while also pledging to foster ethical innovation in the field.

“There are a small number of unscrupulous actors who have seized on the clinical promise of regenerative medicine, while exploiting the uncertainty, in order to make deceptive, and sometimes corrupt, assurances to patients based on unproven and, in some cases, dangerously dubious products,” Gottlieb said.

The FDA announced two enforcement actions against companies offering stem-cell therapies. The agency issued a warning letter to US Stem Cell Clinic in Sunrise, Florida and directed the seizure by U.S. marshals of smallpox vaccine from StemImmune of San Diego. Gottlieb said the FDA would set up a working group to go after unscrupulous stem cell clinics.