Stem cell interventions are offered at 570 clinics, with generally unproven treatments being marketed to consumers, found a recent study. Some ethical concerns include the following:

  • Patients are paying for stem cell treatments without sufficient data on safety and efficacy.
  • Clinics may not be able to properly administer informed consent due to conflict of interest.
  • Patients may not realize they’re being given experimental interventions.

Researchers recently identified 351 U.S. businesses engaged in direct-to-consumer marketing of stem cell interventions, being offered at 570 clinics.1 The clinics advertised treatments for neurological disorders, spinal cord injuries, heart disease, lung problems, eye injury and diseases, and other conditions.

“Although I realized the stem cell clinic industry in the U.S. had been growing, the sheer size surprised me,” says Paul Knoepfler, PhD, the study’s co-author and a stem cell expert at the University of California, Davis.

Knoepfler expected to find less than half the number of clinics selling non-FDA approved stem cell interventions to patients. “The size of this industry raises many practical and bioethical concerns,” he says.

The researchers found stem cell “hot spots” in California, Florida, Texas, Colorado, Arizona, and New York. They found at least one stem cell clinic operating in every state. “This is really a ubiquitous industry in the U.S.,” notes Knoepfler. “Based on this new research, we have to re-think how we use the phrase ‘stem cell tourism.’”

The researchers had been tracking stem cell clinics for a number of years, and recently noticed that the number had grown substantially. “But no data had been published based on a comprehensive analysis of this industry. That was a big gap to try to fill,” says Knoepfler.

Growing numbers of patients were asking the researchers for information about stem cell clinics. Most were interested in getting stem cells in the U.S. rather than abroad. “This raised concerns about patients being put at risk,” says Knoepfler.

No Sign of Crackdown

It is not ethically permissible to sell stem cell “treatments” to patients without data providing a reasonable expectation of both safety and efficacy, says Knoepfler. “Clinic medical providers have an inherent conflict of interest, since they are profiting from selling unproven stem cells to patients,” he adds. This also raises the concern over whether clinics can properly administer informed consent.

Knoepfler wonders if people paying for treatments at the clinics realize that they’re being given experimental interventions. “This goes against a long historical tradition of not charging people to be experimental subjects,” he explains. Some clinics also market stem cell treatments for pediatric conditions such as autism and cerebral palsy, which raises additional ethical concerns.

“I believe we will continue to see this industry grow, despite all the ethical concerns, until at some point either the FDA or the FTC crack down,” says Knoepfler. The FDA recently issued a warning letter to three co-owned clinics which offer unproven stem cell therapies for a range of diseases.2

“I don’t necessarily view the one warning letter as a clear sign of an impending FDA crackdown,” says Knoepfler. The FDA has only been issuing about one or less of such warning letters per year, despite there being nearly 600 stem cell clinics operating in the U.S. without FDA approval. “It’s not clear why these three clinics, out of hundreds, got warned,” he says.

A surge in malpractice lawsuits is another possibility. “If agencies do not take appropriate action, it is possible that litigation against certain clinics may serve as a deterrent to the growth of this industry,” says Knoepfler.

In 2015, the FDA published a draft guidance on stem cells.3 If implemented, these would result in fat stem cells — the most common stem cells used at clinics — being defined as drugs requiring premarket approval.

“That kind of regulatory change could have a major, positive impact by requiring more oversight and data before experimental cells go into patients,” says Knoepfler.


  1. Turner L, Knoepfler P. Selling stem cells in the USA: Assessing the direct-to-consumer industry. Cell Stem Cell 2016: 19(2);154–157.
  2. FDA. Irvine Stem Cell Treatment Center Warning Letter. Dec. 30, 2015. http://bit.ly/2fSzHYK.
  3. Draft guidances relating to the regulation of human cells, tissues, and cellular and tissue-based products. Notice of Proposed Rulemaking. 81 Federal Register 23664 (22 April 2016), pp. 23664-23666.


  • Paul Knoepfler, PhD, Department of Cell Biology and Human Anatomy, UC Davis School of Medicine. Phone: (916) 453-2289. Email: knoepfler@ucdavis.edu.