Unregulated clinics worldwide are offering stem cell therapies that may not live up to the hype, and can worsen a patient’s health.

The injections of stem cells into his spine were supposed to help Jim Gass, 66, recover from a stroke he had six years ago.

Gass traveled to clinics in Mexico, China, and Argentina to undergo these unproven procedures. Including travel, he spent close to $300,000, according to a story in The New York Times.

After the final round of shots, he was able to walk better. But his hope for a full recovery was cut short. While on vacation in Thailand six months after his treatments, he developed low back pain and difficulty walking and standing.

Back in Boston, doctors at Brigham and Women’s Hospital did an MRI scan of his spine, and found a large mass filling the entire lower part of his spinal column.

Genetic testing revealed that the abnormal, primitive cells of the mass did not come from Gass, but from stem cells injected into his spine.

Radiation treatments seemed to slow the growth of the mass and improve Gass’ symptoms. But another scan done later in San Diego showed that the mass was growing again.

The doctors involved wrote about his case in a letter published June 22 in the New England Journal of Medicine.

Despite the outcome of this case, experts familiar with this kind of “stem cell tourism” say that some good may still come of it.

“It is a really sad case, but it’s good that it’s causing discussion around both the potential harm of these therapies and the lack of evidence regarding the benefits,” Timothy Caulfield, research director of the Health Law Institute at the University of Alberta, who wrote a recent commentary on stem cell hype, told Healthline.

Read more: Get the facts on stem cell research »

This is not the first time that stem cell treatments have led to bad outcomes such as tumors or lesions.

“There have been other reports of adverse events as a result of these kinds of therapies,” said Caulfield. “There have even been reports of adverse events when the procedure is less extreme — such as people getting stem cell therapy for anti-aging, anti-wrinkle procedures.”

Caulfield is quick to point out that “therapy” should be in quotes because — with the exception of a few approved treatments — the use of stem cells to treat illnesses has not reached the point where it is ready for widespread use in clinics.

“There are very few stem cell therapies that have been proven, at this point, to be efficacious,” said Caulfield. “Lots of exciting work is going on — they’re in clinical trials right now — but for most conditions we simply aren’t there yet.”

Although there are a few documented cases like Gass, many more may go unreported, resulting from treatments at unregulated stem cell clinics around the world.

“We don’t know exactly how many people are having these procedures,” Dr. Jaime Imitola, a neurologist and stem cell researcher at The Ohio State University Wexner Medical Center, who has written about the dangers of stem cell tourism and how to counsel patients, told Healthline.

“There are so many diseases that these clinics are often treating for — from diabetes to ALS —and some of these treatments may involve more risk than others,” Imitola said.

There’s a big difference in risk between taking cells from your own body and putting them back in your blood, and injecting foreign cells into your spine, as was done in Gass’ case.

Also, these clinics are not part of a clinical research program, so there are a lot of unknowns about what happens during the procedures.

“Are they actually using stem cells? How are they getting the stem cells into people?” said Caulfield. “Those are all open questions, because it is such an unregulated field.”

While Gass traveled outside the United States for injections, unproven stem cell therapies show up much closer to home.

A paper published online Thursday in the journal Cell Stem Cell found that at least 351 businesses in the United States are marketing stem cell therapies that have not gone through the rigorous clinical trial process, or been approved by the Food and Drug Administration (FDA).

These businesses marketed stem cells as treatment for a wide range of conditions from spinal cord injuries and immune system problems to heart disease or even cosmetic fixes.

Read more: Stem cell treatments offering hope for MS patients »

With few treatments available for many diseases, stem cell clinics step in to fill the void, many overhyping the actual research being done in this area.

“[Clinics] are leveraging excitement around legitimate stem cell research and the pop culture footprint — I’ll put it that way — of stem cells,” said Caulfield.

Some of this hype has been generated when high-profile athletes undergo stem cell therapy and see improvements, like Peyton Manning did in Germany for a neck injury.

The company that Gass contacted had been involved in the treatment of former NFL quarterback John Brodie.

These remarkable success stories offer people hope. But because they happened outside a clinical trial, it’s impossible to know if the athletes’ health would have improved on their own.

Imitola compares this to using acupuncture alongside proven treatments.

“If I give you acupuncture after a stem cell treatment, I cannot make the distinction whether what happens is a result of the acupuncture or the treatment,” said Imitola, “because this is not a clinical trial.”

Researchers, universities, and the media also have a hand in stem cell hype. The time element, in particular, can be misrepresented.

“I think that the scientific community really needs to be careful how they talk about stem cell research,” said Caulfield. “We did a study that showed, for example, that the time from doing basic research to getting into the clinic is often exaggerated when people talk about stem cell research. Our study found that it was often portrayed as if the research was going to be in the clinic in 5 to 10 years, or sooner, which is really, really fast. It creates unrealistic expectations.”

Read more: Stem cells as a possible treatment for rheumatoid arthritis »

Patients with spinal cord injuries or diseases are often anxious for new treatments to be approved quickly. But stem cell researchers have good reason to be cautious.

One characteristic that stem cells share with cancer cells is that they both multiply rapidly. This is why stem cell researchers have long been concerned that stem cells could form tumors.

That’s why there are so many years of testing in the lab, in animal models, and finally in clinical trials.

“It is unethical to offer a procedure or a drug that is unproven,” said Imitola.

When clinics skip ahead and offer treatments that have not been properly tested, they may end up hurting people instead of helping them.

“It’s interesting because [Gass’] case, and others, is generating a new disease, a new complication, an iatrogenic tumor,” said Imitola.

Of course, bad outcomes can happen during a clinical trial. But these are tracked, and clinical trials can be shut down if unforeseen side effects happen.

A recent stem cell clinical trial in Japan was stopped, “because when the researchers looked at whether the cells were ‘clean’ from a genetic point of view, the cells had some problems, some changes,” said Imitola, “So the researchers said, ‘We can’t do that, we can’t inject the cells.’”

Imitola recently co-authored a paper in JAMA Neurology calling on doctors to educate patients with neurological diseases about “stem cell tourism.”

But he admits that cases like Gass’ can serve as an even more effective warning.

“This patient, in particular, is important because he put a human face to this tragedy,” said Imitola. “We need more patients to come forward. Most likely, this is not an isolated case.”

Read more: Stem cell treatment for COPD »