Stem cells can become any other part of the body - from nerve to bone to skin - and are touted as the future of medicine.

Researchers in Japan will use the cells to attempt to treat a form of blindness - age-related macular degeneration.

The announcement was described as "a major step forward" for research in the field.

There are already trials taking place using stem cells taken from embryos. But this is ethically controversial and the cells will not match a patient's own tissues, so there is a risk of rejection.

Induced pluripotent stem cells, however, are made by coaxing a sample of the patient's skin to become stem cells, so there should be no risk of rejection.

Japan's health minister, Norihisa Tamura, has ruled that the cells can now be tested in patients.

The trial will by run by the Riken Center for Developmental Biology and the Institute of Biomedical Research and Innovation Hospital in Kobe.

Initially, six patients will receive transplants of cells to see if the procedure can restore their damaged vision.

Prof Chris Mason, an expert on regenerative medicine at University College London said: "This was expected, but it's obviously a major step forward.

"They are beneficial for two main reasons. One, they are from the patients themselves so the chance of rejection is greatly reduced and there are the ethical considerations - they do not have the baggage which comes with embryonic stem cells.

"On the down side we are a decade behind on the science. Induced pluripotent stem cells were discovered much later, so we're behind on the safety."

In 2012, Prof Shinya Yamanaka shared the Nobel prize for medicine or physiology for his discovery that adult human tissue could be coaxed back into a stem cell state.