A team of researchers in Japan says it has confirmed that transplants of corneal tissue derived from induced pluripotent stem cells, or iPS cells, are safe and effective.

The team led by Osaka University Professor Nishida Koji announced its findings on Monday.

iPS cells are created by reprogramming ordinary human cells and have the ability to develop into any type of cell.

Researchers transplanted iPS-derived sheet-like corneal tissues into four patients who were between the age of 30 years and up to 79 years old. Their eyesight had significantly deteriorated due to a disease of the cornea.

The team says none of the recipients had rejection or developed severe side effects one year after their transplants.
Three of them recovered eyesight to levels good enough to lead their daily lives without difficulties. The fourth recipient's cornea became transparent, but the results of vision tests varied.

Researchers say this method carries a lower risk of rejection than cornea from donors, and they are more transparent than cornea cell sheets made from mucus membrane from the mouth.

Professor Nishida hailed the findings as significant, and said the team wants to put its method into practical use soon so patients around the world can benefit.

The team aims to start a clinical trial next year at the earliest as a step toward obtaining government approval as a treatment.