Unproven stem cell therapies sold online could be dangerous and costly, say researchers who have launched a website to educate and protect patients.

"Many people are going into the hands of predators," Dr. Irving Weissman, director of the Stanford Institute for Stem Cell Biology and Regenerative Medicine, said in a release.

"They often mortgage their homes or borrow money to go abroad for these so-called treatments. They are away from their loved ones when they should have been together during the last months or years of their lives."

In Friday's issue of the journal Cell Stem Cell, Weissman warns of the potential risks to patients and describes practices and guidelines to assess the validity of internet claims, such as being wary of clinics that advertise results mainly through patient testimonials.

An internet search for stem cell therapies results in more than 200 companies that claim to grow stem cells, inject them back into the patient and cure almost any condition, Weissman said.

The International Society for Stem Cell Research's website includes questions to ask potential clinics, and users can submit a specific website for the society to investigate.

When a company or clinic is submitted for investigation, the society said it will evaluate whether a medical ethics committee is involved to protect the rights of a patient and whether the proposed treatment will be supervised by an official regulatory body such as the U.S. Food and Drug Administration.