Tokyo, Sep 13 (IANS): Japanese researchers have successfully implanted lab-grown retinal tissue from induced pluripotent stem cells (iPS) into a woman in her 70s - the world's first recipient of stem cells.

In a two-hour procedure, a team of three eye specialists led by Yasuo Kurimoto of the Kobe City Medical Center General Hospital transplanted a 1.3 by 3.0 millimetre sheet of retinal pigment epithelium cells into an eye of the woman who was suffering from an age-related macular degeneration.

The procedure was performed at the Institute of Biomedical Research and Innovation Hospital, next to the RIKEN Center for Developmental Biology (CDB) where ophthalmologist Masayo Takahashi had developed and tested the cells.

Kurimoto performed the procedure in a mere four days after a health ministry committee gave Takahashi clearance for the human trials, the scientific journal Nature reported.

She took the patient's skin cells, converted them into iPS cells and then coaxed them to differentiate into retinal cells.

The patient experienced no effusive bleeding or other serious problems.

"The patient took on all the risks that came along with treatment and surgery. I have deep respect for the bravery she showed in resolving to go through with it," Kurimoto said in a statement.

Kurimoto also thanked Shinya Yamanaka, a stem-cell scientist at the Kyoto University "without whose discovery of iPS cells, this clinical research would not be possible".

Yamanaka shared the 2012 Nobel Prize in Physiology or Medicine for his work.

"We have taken a momentous first step toward regenerative medicine using iPS cells," Takahashi concluded.