Clinics that offer to "bank" stem cells from the umbilical cords of newborns for use later in life when illness strikes are fraudsters, a top U.S. scientist said.

Clinics in many countries allow parents to deposit stem cells from their neonate's umbilical cord with a view to using the cells to cure major illnesses that could occur later in life.

In Thailand, for example, parents pay in the region of 3,600 dollars to make a deposit in a stem cell bank, thinking they are taking out a sort of health insurance for their child.

But Irving Weissman, director of the Institute of Stem Cell Biology and Regenerative Medicine at Stanford University in California, said the well-meaning parents were being fleeced by the stem cell bankers.

"Umbilical cords contain blood-forming stem cells at a level that would maintain the blood-forming capacity of a very young child," Weissman told reporters at the annual meeting of the American Association for the Advancement of Science (AAAS).

"They could also have derived mesenchymal cells — fiberglass-like cells that have a very limited capacity to make scar, bone, fat — but they don't make brain, they don't make blood, they don't make heart, they don't make skeletal muscle, despite what various people claim," he said.

Weissman said these "unproven stem cell therapeutic clinicians" tend to set up shop in countries with poor medical regulations, but AFP found websites for umbilical cord stem cell banks in European Union member states and in the United States.

"They do the therapies, then they let the patients go on their own, short of maybe 50-150,000 dollars for a therapy that has no chance — taken away from a family that needs them when they have an incurable disease," Weissman said.

"It is wrong."

The International Stem Cell Society is due to issue a report in April about unproven stem cell therapies such as banking a baby's umbilical cord blood for future use.