Athletes' use of stem cells and regenerative medicine is growing, according to The San Diego Union-Tribune.
Here are five insights:
1. Ice hockey player Gordie Howe and NFL quarterbacks Bart Starr and John Brodie are a few of the athletes receiving stem cells.
2. Last year, the FDA issued draft guidelines to clarify what types of human cell therapy it regulates. The guidelines accept most types of human cell therapy save for a few exceptions, including cells or tissues that are "minimally manipulated."
3. In January 2015, Paul Knoepfler, PhD, a stem cell researcher at the University of California in Davis, estimated more than 100 unauthorized stem cell clinics were operating in the United States. He increased that estimate to up to 200 later that year.
4. Hemacord was the first FDA-approved therapy researchers used as a stem cell treatment. The FDA cleared the therapy for use in 2011 and it contains blood-forming stem cells taken from umbilical-cord blood.
5. The comment period for all four FDA draft guidelines is open until Sep. 27, 2016.