Linda Smith turned to to find a research therapy for her osteoarthritis, only to be told by one company that she first had to pay $14,000 before she could participate in its study. (Heidi de Marco/Kaiser Health News)

Linda Smith learned last summer that she was losing significant cartilage in her knees, a consequence of a lifetime spent skiing, running and playing ultimate Frisbee.

Osteoarthritis was diagnosed, and she wanted to avoid surgery. So the 56-year-old Californian began looking for a research study that might offer an alternative. She scoured the government-run website, and focused on stem-cell therapy — a promising but unproven approach for her condition.

She thought she had scored with StemGenex Medical Group, a company in La Jolla, Calif., and called for more details about a study it was doing. The screener asked a long list of questions, then dropped a bomb: If Smith wanted in, she’d have to pay “associated” costs. Total charge: $14,000.

“I was outraged,” said Smith, a retired hospital administrator who knew enough about clinical studies to realize that the price tag was unusual. Most trials are free, and some even pay people to take part because of the possible risks and inconvenience involved.

But, maintained by the National Institutes of Health, says nothing about any charges to participants. The 16-year-old website is the most comprehensive such database publicly available in the United States, with listings for nearly 220,000 clinical studies in the United States and abroad. It does not independently vet those listings, however, or require trial sponsors to disclose potential costs.

The National Institutes of Health maintains the website but does not vet the nearly 220,000 studies listed on the site.

“I went back to [] and looked at the study again. It doesn’t say that patients are the funding source,” Smith said. The final affront was the screener’s suggestion that she could raise the $14,000 through an online GoFundMe campaign. “I was disappointed in the NIH. I thought, ‘Why are you letting this occur?’ ”

StemGenex denies that it charges people for enrolling in its clinical studies and maintains that the cost involved is only for the treatment being tested. A person’s actual research participation is separate, according to a company statement. Anyone who has undergone treatment is eligible to “voluntarily participate.”

The osteoarthritis study “is intended to be an observational study comparing two sets of data — before and after stem cell treatment,” Candace Henderson, vice president of operations, said in the statement. “The actual treatment is not part of the study protocol.”

Some ethicists and medical experts who share Smith’s concern say that is a false distinction. They say that if trial sponsors require participants to pay, the government website should let people know. Not doing so misleads consumers and makes a marketing tool for pay-to-play research, they argue.

The site’s lack of transparency is a growing concern, in part because of the surge in stem-cell research and in clinics offering unproven, high-priced treatments, said Leigh Turner, an associate professor at the University of Minnesota Center for Bioethics.

“It’s not just a handful of patients who are encountering these kind of so-called studies on and not just a handful of studies,” he said. “It is a bigger problem than that.”

Critics worry that some people seeking to participate in clinical trials may be desperately sick or in pain and vulnerable to requests for money they don’t have. These patients see the “.gov” domain and the NIH imprimatur as stamps of approval that mean the research is legitimate, they say.

“The average patient and even people in health care . . . kind of let their guard down when they’re in that database. It’s like, ‘If a trial is listed here, it must be okay,’ ” said Paul Knoepfler, an associate professor at the University of California at Davis School of Medicine who writes a blog about stem-cell research. “Most people don’t realize that creeping into that database are some trials whose main goal is to generate profit.”

Yet Rebecca Williams, the website’s assistant director, described it as primarily a clearinghouse and said that just because a study is included “does not necessarily mean an endorsement by the federal government.” relies heavily on the honor system and is not legally required to verify information provided by study sponsors, she said. Sponsors, whether pharmaceutical companies or universities, attest that the material they are submitting is complete and that their research complies with “all of the applicable regulations that may apply.”

When registering, they must provide a variety of details, including, in most cases, information about the committees that oversee the welfare and treatment of human subjects.

As to whether costs for study participants should be disclosed, “that’s a valid question,” said Williams, who holds a doctor of pharmacy degree and previously reviewed prescription drug advertising and promotion at the Food and Drug Administration.

“That has been information we don’t collect in a systematic way,” she said. Nor does NIH have any way to know whether a listing is essentially a for-profit study. Regardless, she added, it has no policy that would exclude them.

Williams pointed to the website’s disclaimer that the government is not liable for and does not “make any warranties” about information in the database. She also noted that the site suggests questions for consumers to ask, including, “Who will pay for my participation?”

The FDA regulates clinical trials of medications and medical devices and sets guidelines that determine when patients can be charged. But stem-cell studies, which often use patients’ cells to treat an array of conditions, can fall into a gray area, and what requires FDA approval is sometimes unclear or disputed.

StemGenex’s website acknowledges that its procedures are not FDA approved. At the same time, it says its studies are “registered through The National Institutes of Health which can be found at . . . By providing patients access to stem cell studies registered through The National Institutes of Health, patients now have the ability to choose treatment for osteoarthritis that focuses on both safety and efficacy,” the site says.

StemGenex further underscores the point in its site’s FAQ, noting that having studies registered on gives it a “significant advantage compared with treatment centers offering unregistered studies.”

Turner called those messages misleading because they suggest that NIH has vetted the studies. “In fact, nobody at the NIH or in our government has necessarily, or even likely, looked” at them, he said.

The company, which describes itself as “the [premier] leader in the United States for regenerative medicine,” says it offers “a concierge approach to treatment.” That includes covering the cost of patients’ hotel accommodations and a car service that “will be waiting for you at the airport baggage claim when you arrive.”

Its website also explains StemGenex’s procedure, in which dormant stem cells are harvested from a patient’s fat through “a mini-liposuction” and isolated from the fat. They are “activated with the patient’s growth factors,” then infused back into the individual. The stem cells “follow inflammatory signals from damaged tissues and have multiple ways of repairing these damaged areas.”

StemGenex says it invests revenue from its clinical trials “in innovation and research to further the development and advancement” of therapies. It has four other studies listed on the NIH website: for Parkinson’s disease, multiple sclerosis, rheumatoid arthritis and chronic obstructive pulmonary disease. In those cases, too, participants “are recruited from among patients who are having stem cell treatment,” Henderson said in the company statement.

Alison Bateman-House, a postdoctoral fellow in medical ethics at the New York University School of Medicine, takes a dim view of that reasoning:

“It’s unethical that these companies are saying, ‘Sure, come take part in our study, and by the way, we’re going to charge you for the privilege.’ ”

She and the other critics would like to see NIH reevaluate its position on what studies are allowed to post on the website and what detail must be included.

“It’s one of the best sources we have,” said Ken Getz of Tufts University, founder of the Center for Information and Study on Clinical Research Participation. “But there’s still room for misleading and incomplete information.”

For now, people such as Linda Smith may have to work harder to find cost-free trials. After months of searching, she eventually located a stem-cell trial that doesn’t charge for participation. In fact, she and the other enrollees receive $50 per visit to help cover mileage, parking and other expenses.

Kaiser Health News is a national health policy news service that is part of the nonpartisan Henry J. Kaiser Family Foundation.