New york: In an experiment at the SUNY Upstate Medical University, in Syracuse, NY researchers have grown frog eyes from stem cells.

Researcher Michael Zuber and his colleagues took the cells from frog eggs.Then got them to become eyes, by genetically modifying them, inserting transcription factors (proteins that trigger expression of other genes) which are known to regulate eye growth and development.

The scientists then implanted the cells into tadpoles missing an eye. The cells properly developed and differentiated into all seven types of retinal cells and appeared to have the proper structure. Additionally the new eye attached properly to the brain. In swimming tests the eye was shown to be working as implanted tadpoles only swam to the white side of the tank (normal behavior), while blind ones would also swim to the black side of the tank.

Would the technique work on mammals? The answer is maybe — frogs naturally have a much easier type regrowing tissues than humans, in fact they can be triggered to regrow legs and many amphibians can regrow lost tails. Triggering proper differentiation in mammals is much more complex.

Nonetheless, Professor Zuber hopes that chemicals will be found from the research that can activate transcription factors in humans. Even if a full eye could not be grown, this could help people with retinal disorders regenerate ocular tissue.

In a separate, but perhaps equally intriguing study performed by Sujeong Jang of Chonnam National University, in South Korea, and his colleagues, the researchers were able to restore the hearing of deaf guinea pigs by implanting them with human neural stem cells obtained from human bone marrow.