Factbox: How advanced is stem cell research?

HONG KONG (Reuters) - Desperate for a remedy, patients with incurable diseases are admitting themselves into hospitals from China and India to Mexico, Russia and Turkey for "stem cell therapies" that are backed by little or no scientific evidence and at best only experimental.

They pay thousands, even tens of thousands of dollars for treatments that are mostly advertised online, but come away with little or no improvement. Some die from them.

Below are some facts about stem cells and regenerative medicine, legitimate stem cell therapies that are approved and how to tell them apart from scams:

* What are stem cells and how is regenerative medicine supposed to help?

Stem cells are immature, master cells in the body that can grow into any kind of human cell or tissue. Experts are exploring how to use them to treat a variety of diseases and disorders, including cancer, diabetes and injuries.

* Are there any approved stem cell therapies around?

Bone marrow transplants for diseases such as leukemia and lymphoma have been proved to work. They are well-established clinical procedures.

In July, South Korea became the first country to approve the clinical use of adult stem cells to treat heart attack patients. But this procedure has not been vetted by independent experts nor has it been published in a scientific peer-reviewed journal.

* The Internet is rife with offers of stem cell therapies that claim to cure all kinds of diseases like diabetes, multiple sclerosis, arthritis, vision problems, Alzheimer's and Parkinson's disease and spinal cord injuries. How believable are they?

Many are not supported by robust, published evidence. Hospitals may offer experimental therapies for some diseases but they should be carried out within the framework of clinical trials that are approved by expert regulatory boards. Approval may only be given after they have shown to pass efficacy and safety tests as well as meeting ethical standards.

* What are the risks of undergoing stem cell therapies that are not approved?

No improvement, loss of money, developing complications and severe side effects, and possibly death.

* How can a patient tell a legitimate treatment from a scam?

Patients will not be asked large sums of money up front;

Patient should know exactly how treatment will be made, what stem cells will be used and where they are from;

Different stem cells are used for different diseases. Often, many different types of stem cells are needed for one procedure;

There will always be a risk and to be told that there will be no risk is suspicious;

Nobody should accept a therapy based on hearsay alone without at least part of the procedure validated by peer review;

Be wary if the clinic or hospital offers no post-therapy care.

Sources: International Society for Stem Cell Research, stem cell scientists

(Reporting by Tan Ee Lyn; Editing by Nick Macfie)