Reports of three cases in which elderly women went blind after receiving an experimental stem cell therapy at a Florida clinic should raise concern about the proliferation of similar centers across the country, where patients often are promised safe and effective care using unproven and potentially risky treatments, experts said Wednesday.

A paper describing the eye treatments, which were performed in 2015, was published Wednesday in the New England Journal of Medicine. At least two of the women sought to collect damages from the clinic that treated them in lawsuits that have since been settled.

Hundreds of clinics that market stem cell therapies directly to consumers have cropped up in the United States over the past few years, and California is a hot spot in the trend. The authors of the new paper said people seeking treatments at these clinics should consider what happened to the women in Florida a major red flag.

“It’s a terrible, terrible story. But if it helps raise awareness — boy, do we really need to get this story out there,” said Dr. Jeffrey Goldberg, a Stanford ophthalmologist who co-authored the paper with colleagues in Florida. “It’s an important opportunity to educate patients, to educate physicians, to engage the regulatory bodies — to make sure that we’re protecting people.”

The Florida cases come at a critical time for the U.S. stem cell industry, as federal officials, doctors, scientists and patient advocates try to come up with appropriate regulation of experimental therapies without tamping down research that has been heralded as potentially life-saving.

In the current climate, consumer stem cell clinics have flourished. There are roughly a dozen in the Bay Area, where they’re flanked by the locations of some of the nation’s most prominent stem cell scientists, UCSF and Stanford.

But the work that’s coming out of academic institutions is usually vastly different from what’s on offer at the clinics, which typically lack federal approval for the treatments they offer, stem cell experts said. And though California hasn’t seen cases of stem cell therapies gone horribly awry in a consumer clinic, it may just be a matter of time.

“The situation in Florida is disturbing on its own, but to me the bigger story is — whoa, how many people may be at risk across the country? And especially here in California, because our state has so many of these clinics,” said Paul Knoepfler, a UC Davis stem cell scientist who last summer published a report on the spread of the facilities.

“I see it as almost a public health crisis, with the number of clinics out there,” he said. “It’s probably in the tens of thousands of patients a year being treated. That’s a lot of people being given something that doesn’t have a lot of data to back it up.”

In the Florida cases, all three women had forms of macular degeneration, an age-related condition of the eye that causes the rods and cones that sense light and send visual cues to the brain to deteriorate and stop working entirely.

The condition eventually leads to blindness, but the three women, who ranged in age from 72 to 88, still had enough sight to live relatively normal lives — recognizing faces, reading with magnification, even driving. Still, fear of eventually going blind left them desperate for treatment, said Dr. Thomas Albini, an ophthalmologist at the University of Miami and co-author of the paper, who treated two of the women after they had the stem cell therapies.

At least two of the women found out about the stem cell treatment by looking at listings for clinical trials on a government website, clinicaltrials.gov. They later told doctors they believed they were participating in a clinical trial, but papers they signed showed that wasn’t the case. Clinical trials are subject to regulations and guidelines that demand certain safety protocols.

The trial that drew in the women is still listed online, though a note now says it was stopped “prior to enrollment” — meaning no one was ever treated as part of the trial. Each woman paid $5,000 for the procedure. Typically, patients do not pay to participate in clinical trials.

The treatment given to the women involved what are called “autologous adipose” stem cells, found in a person’s own fat tissue. The fat stem cells are a popular product at consumer clinics — promoted to treat everything from heart disease to diabetes and sexual dysfunction — because they’re so easy to obtain.

But there is little evidence these fat stem cells are effective for any of the conditions they’re marketed to treat. And almost none of that research is in treating eye conditions.

“There’s no doubt there are some stem cells in fat. As to whether they are the right cells to be put into the eye, that’s a different question,” said Abla Creasey, associate director for therapeutics at the California Institute for Regenerative Medicine, the state’s stem cell agency. “The misuse of stem cells in the wrong locations, using the wrong stem cells, is going to lead to bad outcomes.”

At the clinic, fat tissue was removed by liposuction from the women. In an on-site lab, the stem cells were prepared for injection into the patients’ eyes. All the patients had both eyes treated at once — something that would never happen in a clinical trial because of the risk of total blindness or other bad outcomes, doctors said.

Almost right away, the women experienced severe pain in their eyes and loss of vision. Within a year of treatment, all of the women were legally blind. One woman can’t sense light from dark or the motion of a hand waving in front of her face.

“I was angry; I was astonished. I was heartbroken to some degree,” said Albini, recalling his visits with the women. “When I heard about them, it was just baffling to me. I really didn’t know that clinics like this existed in the United States. I had patients who told me they were thinking about going to China, Mexico. But I didn’t know we had clinics doing this so close to home.”

The clinic where the women were treated wasn’t identified in the New England Journal of Medicine paper. But according to the clinical trial listing and lawsuits filed, the facility was run by U.S. Stem Cells in Sunrise, Fla. The clinic no longer offers eye therapies, but its website advertises treatments for neurological conditions, autoimmune disorders, diabetes, heart disease and orthopedic problems.

In a statement, the company said it has “successfully conducted” more than 7,000 stem cell procedures with “less than .01 percent adverse reactions.”

“We are unable to comment further on specific cases due to patient confidentiality or legal confidentiality obligations,” the company stated.

Albini said the U.S. Food and Drug Administration has opened an investigation into the company. FDA officials said they could not comment on or confirm ongoing investigations.

Beyond the tragedy of what the women endured, scientists said they fear cases like theirs could damage public support of, and faith in, the potential of stem cell science.

A few scientists are now studying stem cell treatments for macular degeneration, but using different kinds of stem cells, and only after years of lab research to back up their work.

“We don’t want to undercut the legitimate progress that’s being made,” Goldberg said. “These kinds of situations risk souring people’s enthusiasm. And the truth is, stem cells hold a lot of promise.”

Erin Allday is a San Francisco Chronicle staff writer. Email: eallday@sfchronicle.com

Resources

For information on how patients and their doctors can evaluate stem cell therapies and determine if a treatment or trial is appropriate for them, go to www.closerlookatstemcells.org.