Scientists grow 'embryonic eye' in test tube

By Richard Alleyne, Science Correspondent,  6 Apr 2011

Eye transplants to cure blindness have taken a step closer after scientists managed to 'grow' a retina in the laboratory for the first time. Researchers were amazed when stem cells in a test tube spontaneously organised themselves into a complex structure that resembles the developing embryonic eye.

The surprising development could lead eventually to whole retinas being cultured and then transplanted, restoring sight in the blind and visually impaired. The team from the Institute of Physical and Chemical Research in Japan, first cultivated embryonic stem cells in a test tube and then added proteins to trigger them into developing.

They hoped that they would form a recognisable organ but were still stunned when over 10 days they clustered together and began to grow the "optical cup" of a retina.Tests showed that the cells were functioning normally and were capable of communicating with each other.

The research was done on mouse eyes, but there is no reason why a similar technique would not work on humans, said the experts.They hope that within 10 years to be able to start clinical trials on retina implants.

"This is an absolutely stunning achievement," said Professor Robin Ali, an ophthalmologist at University College London."It is a landmark not just for the retina but for regenerative medicine as a whole."

More than a million people in Britain suffer from vision problems caused by a damaged or malfunctioning retinas. The retina is the "business end" of the eye, where nerve cells convert light into electrical and chemical signals that are sent to the brain down the optic nerve. If it is not working then the eye is useless.

Professor Yoshiki Sasai, lead author said: "What we've been able to do in this study is resolve a nearly century-old problem in embryology, by showing that retinal precursors have the inherent ability to give rise to the complex structure of the optic cup."

His team, who filmed the technique as it unfolded, grew floating clusters of the mouse cells in a special tissue culture in the laboratory that had previously been successfully used to make a variety of brain cells.

By adding particular proteins they were able to get the cells to build a three dimensional layered structure reminiscent of the optic cup within 10 days.The retinal neurons ultimately organised into a six-layer structure closely resembling that of a retina shortly after birth.

This could eventually lead to treatments aimed at repairing the eyes of people with conditions that limit or destroy their sight. Potential applications include regenerative medicine approaches to the treatment of progressive genetic disorders such as retinitis pigmentosa.

Prof Ali, who reviewed the research published in Nature, said: "For the first time, we see unfolding in real time the beautiful events that shape the early stages of mammalian eye development. "But even more remarkable is that these are not recordings from live animals, but of self-organising 3-D cultures of embryonic stem cells."