Federal prosecutors say 57-year-old Fredda Branyon of Scottsdale, Ariz., knew that the stem cells were not created under Food and Drug Administration authority.
Investigators say Branyon, who formerly owned Global Laboratories LLC, sold the stem cells in Brownsville between April 2009 and February 2010, receiving about $300,000. Prosecutors believe the unapproved stem cells were used for medical procedures.
Branyon on Thursday pleaded guilty in Houston to introducing an unapproved new drug into interstate commerce. Branyon, who's free on bond, faces up to three years in prison and a $10,000 fine. Sentencing has been set for Nov. 18.
Details on the South Texas buyer have not been released as the investigation continues.