This month the US Food and Drug Administration will convene a public hearing on a set of draft guidances related to the oversight of stem cell therapy. These guidances are intended to clarify the criteria used by the FDA to determine which products derived from human cells or tissues fall under its jurisdiction—and which do not. If finalized in their present form, they should bring back onto the grid many stem cell clinics that currently evade oversight. But tightening regulation can only go so far. To better protect patients, we need mechanisms to engage with those undergoing unlicensed procedures in stem cell clinics so that their experiences can be brought into the public domain.

Just how widespread direct-to-consumer stem cell marketing efforts have become was clarified over the summer in two reports. One survey of the US market (Cell Stem Cell 19, 154–157, 2016) identified 351 stem cell businesses at 570 locations (up from around 100 clinics a couple of years ago). Much of that rapid growth has come from chains of stem cell franchising clinics touting the use of adipose-derived stem cells as cosmetic or 'anti-aging' remedies; other businesses overtly sell stem cells as 'cure-all' therapies to desperate patients with such diseases as amyotrophic lateral sclerosis (ALS), multiple sclerosis, Parkinson's, and even muscular dystrophy and autism.

A second study (Cell Stem Cell 19, 158–162, 2016) provides a global snapshot of stem cell businesses, suggesting growth is greatest in “countries that tend to have more stringent regulatory infrastructures governing health products and medical practice”: in other words, places like the United States, the United Kingdom, Australia and Germany. This goes against conventional thinking that these businesses operate in 'off-shore' locations (such as the Cayman Islands or Belize) or in emerging economies (such as Mexico, India, China, Russia or Thailand) where regulations are lax.

Stem cell clinics are now part of the economic mainstream. And given the size of this global cottage industry, tens of thousands of patients are being experimented on every year. That is a huge cohort of patients to expose to unapproved, unregulated procedures—a cohort for which we gather virtually no clinical data.

The practice is ethically dubious because many patients turn to stem cell clinics as a last resort when all other therapies have failed. They may spend their life savings or children's college funds doing so. And they may not fully understand the risk they are taking because clinics fail to provide sufficient information about their products—or, worse, exaggerate their claims using glowing testimonials.

In the United States, complaints about false advertising can be brought to the US Federal Trade Commission (FTC). And indeed, the FTC could play a greater role in clamping down on rogue clinics. But most stem cell businesses avoid the FTC and operate outside FDA oversight. They can do this because their products are not 'drugs' and their physicians, who are already licensed by state medical boards, transplant stem cells under 'the practice of medicine'.

The FDA begs to differ. Under the Federal Food, Drug and Cosmetic Act and the Public Health Service Act, it has legal authority to regulate human stem cells and clinics that sell them, albeit with exceptions under so-called 'section 316'. It is these 316 exceptions that are the subject of the FDA draft guidances (http://bit.ly/2bKAcmA).

One 316 exception is for cell therapies that are 'minimally manipulated'—cells that have undergone only minor handling via processes such as purification, centrifugation, washing, preservation or storage. Although clinics argue that their products fall under this definition, the new guidances clarify many stem cell clinic procedures that involve more manipulation and therefore require oversight. Another 316 exception is 'homologous use': if a stem cell product's clinical use is congruent with the original tissue source, it requires no FDA oversight; thus, a hematopoietic stem cell transplant for a blood disorder is a homologous use, whereas application of the same cells to treat a neurological condition is a nonhomologous use. The new guidances clarify which stem cell clinic procedures are nonhomologous uses.

The clinics argue that these changes overstep the mark and involve the FDA when what the stem cell sector really needs is further deregulation to promote innovation. But there are enough tragic stories in the newspapers and the literature (New Engl. J. Med. 375, 196–198, 2016) to tell us that these modest changes to regulation make sense.

The larger point is that an industry shrouded by secrecy helps unscrupulous clinics exploit patients.

If we want to promote greater transparency and create a market for information about the best private stem cell clinics—and the worst—a place to start might be a service like PatientsLikeMe. This web-based social networking site is able to capture patient-reported data. A brief glance at the site's entries for 'stem cell transplants' reveals how patient-reported data clearly differentiates outcomes in different indications: bone marrow transplants for multiple myeloma patients receive overwhelmingly positive outcomes; the hodgepodge of stem cell approaches for ALS do not.

The problem is that too few patients from stem cell clinics sign up. The few patients undergoing stem cell therapy who experience positive, short-lived benefit often become vocal advocates. But the majority of patients who receive no benefit are stigmatized and disinclined to report their experience. And the small number who experience serious adverse events often choose to remain silent or end up in malpractice suits, newspaper stories or journal articles.

We need to find incentives that encourage more patients to come forward and report their experiences. Regulators, physicians, patients and indeed the stem cell clinics themselves need more information on what works better, what doesn't work at all, and which clinics do a better job. Putting patients back on the grid will be key to achieving this goal.