Private clinics are performing unproven stem cell procedures on patients across Canada as the technology outpaces Health Canada's regulatory system.

"All cell therapies are considered drugs," a spokesperson for Health Canada told CBC News in an email. "This means that the distribution and use of these products would require authorization by Health Canada."

Yet none of the stem cell injections being offered by private clinics have been approved by Health Canada.

Stem cells are a unique category of human cells that can develop into a variety of specialized cells. Scientists are studying the possibility of using stem cells to regenerate organs and tissues, and to treat human diseases.

But it's still at the experimental stage. No stem cell therapies have been approved for human use, except the long established use of bone marrow transplants to treat blood disorders and cancer. There is also a stem cell product approved to treat complications from a childhood cancer treatment.

They are experimental. We don't know if they work, and we don't know how safe they are. - Dr. Duncan Stewart, Ontario Institute for Regenerative Medicine

CBC News went inside several private clinics to learn more about the stem cell treatments being offered to patients. In Toronto, we followed a woman who suffered from knee pain. She did an online search to find clinics that were offering stem cell treatments for various joint and muscle problems. After filling out a email form, she had an appointment with an orthopedic surgeon within days.

(CBC is withholding the identities of the patient and the doctor.)

CBC News identified almost two dozen private clinics in Quebec, Ontario, Alberta and British Columbia that are advertising stem cell injections directly to patients through internet sites.

The procedures only take an hour or so and are done in doctors' offices. The doctor extracts bone marrow or fat tissue from the patient, spins it in a centrifuge machine while the patient waits, and then injects the material into the patient's knee or hip or other parts of the body. The procedures are advertised to treat osteoarthritis and a variety of muscle, joint and sports injuries.

Watch our Stem Cell 101 explanation 0:27

The surgeon diagnosed our anonymous patient with osteoarthritis in one of her knees and told her that stem cells might help. His procedure would cost $3,500.

At another private clinic, a family doctor who also performs stem cell treatment told our patient that it would cost $3,000 for one knee and $3,500 for injections in both knees. (Our patient did not go through with the recommended procedure.)

The second doctor said the injections work 100 per cent of the time. Yet there is no good scientific evidence to support that claim.

"They are experimental," said Dr. Duncan Stewart of stem cell therapies. "We don't know if they work, and we don't know how safe they are."

Stewart is the scientific director of the Ontario Institute for Regenerative Medicine and is conducting clinical trials on the use of stem cells at the Ottawa Hospital.

Rick McGregor of Red Deer went to a private clinic in Alberta and paid $1,700 for stem cell injections in both knees, but he said there was no improvement.

"I waited the six months, and there might have been a little bit [of improvement], but it didn't last very long," he said.

Unproven stem cell therapies 'a mess'

"This is complex science. You can't just inject cells into a knee and hope it works," said Timothy Caulfield, a professor at the University of Alberta and a Canada research chair in health law and policy.

He has been studying the emergence of stem cell therapies over the last two decades.

"Marketing of unproven stem cell therapies is a big issue. It's a mess," he said.

Timothy Caulfield, a professor at the University of Alberta and a Canada research chair in health law and policy, says the marketing of unproven stem cell therapies to Canadians is 'a mess.' (Twitter)

So far, stem cell injections have not been tested in a blinded placebo controlled clinical trial. Still, patients and doctors insist that they have seen examples where the injections have relieved joint pain.

Adele Engel from Panorama, B.C., has travelled to the U.S. and spent more than $5,000 on two series of stem cell injections in her knees to treat osteoarthritis. She said she noticed some improvement and is considering having it done a third time.

"Well, I guess I'm getting a little bit greedy," she said.

She estimated the first procedure gave her a 50 per cent improvement in her knee.

"So, I was like, well, if I try it again, could I bump it up to maybe I could get a 60 per cent improvement and then could I bump it up even more."

Caulfield says there are a variety of explanations for patients like Engel reporting benefits.

"Placebo effect or regression to the mean," Caulfield said, referring to the phenomenon where conditions tend to improve on their own. "And you've got the cognitive bias that comes with having paid a lot of money for a service."

Scientists who are researching stem cells are concerned about the growing private stem cell industry.

"If a patient called me up to say they are thinking of getting the therapy from a practitioner offering it like this for a fee, I would say that I don't think that's wise," Stewart said.

"I don't think they know they are going to get any benefit. I think they are taking a potential risk, and all of these therapies should be offered within the context of a properly designed clinical trial."

Health Canada has not taken action

Stem cell injections seem to be falling between regulatory cracks. Health Canada is struggling with how to regulate this burgeoning practice. And none of the provincial colleges of physicians and surgeons, which regulate doctors, has a policy about them.

The equipment needed to harvest and process the cells is easily obtained from manufacturers and is a licensed medical device. But the cells that are extracted have not been approved for use in humans outside of an official clinical trial.

Health Canada told CBC News that cell therapies meet the definition of drugs under the Food and Drug Act.

"Health Canada approval is required before any cell therapy can be legally used on human patients," a Health Canada spokesperson said in an email.

But so far, the federal ministry has not taken any action to halt the growing stem cell industry.

Health Canada told CBC News it has contacted six clinics to request information on the procedures they are doing.

"Health Canada is currently assessing the information to determine whether the specific activities being conducted by the clinics are subject to the Food and Drug Regulations and whether these clinics are in compliance with federal regulatory requirements," the agency said.

Two clinics CBC news talked to that have received letters say they were asking for information but were not told to stop doing the procedures. CBC News has identified almost two dozen clinics that are advertising stem cell therapies online.

Theoretical risk of cancer

If stem cells do what they're hypothesized to do — spur cellular growth — then there is a theoretical risk that the cells can keep on growing. They could produce unwanted tissue, perhaps even cancerous tumours, according to Stewart.

The consent forms patients fill out for the clinical trials he's leading mention such risks.

"It is kind of scary because there is theoretical risk that there could be tumours that form," said Stewart.

"There is a theoretical risk of blood vessels forming where you don't want them to form — for instance, the back of the eye or other places, so all of these things could happen."

So, far there have been no reports of serious adverse effects from injections into knees or joints. But there is also no surveillance or official tracking for the clinics being performed at private clinics in Canada, so there is no way to track problems.

"This is a policy challenge around the world," said Caulfield.

In the U.S., where doctors are doing a broader range of unproven approaches, three women went blind from stem cell injections into their eyes to treat macular degeneration. The U.S. FDA has sent warning letters to two clinics so far and has said it will take a firmer regulatory approach to stem cell clinics.

In Australia, stem cell clinics are no longer allowed to advertise the procedures directly to patients.