Dr. Michael J. Young, study leader and head of the Schepens Eye Research Institute's regenerative medicine center, along with Dr. Budd A. Tucker, an assistant professor of Ophthalmology at the University of Iowa, and a team of researchers, have used skin stem cells to regenerate parts of the retina in an effort to eventually treat diseases that lead to incurable blindness. 

Diseases like diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration affect millions of people around the world, causing irreparable blindness in most cases. When a person has one of these diseases, their retinal cells, or photoreceptors, start to die off. When photoreceptors die off, the eye loses the ability to capture light and send the information to the brain. It's also very difficult for photoreceptors to regenerate on their own. 

But now, researchers have found that induced pluripotent stem cells (iPSCs) from skin could regenerate areas of damaged retinas, improving vision function. IPSCs are capable of transforming into other cell types.

Young and Tucker harvested the skin cells from red fluorescent mice because the red tissue would be easy to track when transplanted into the eyes of "non-fluorescent diseased mice." A set of four transcription factors called Yamanaka transcription factors were used to signal the skin cells to become iPSCs, and with a little help from certain chemical aids, they became precursors of retinal cells, which are immature photoreceptors that can only mature once placed in the eye. 

A little over a month later, the cells were ready to be placed in the eyes of the mice with retinal-related diseases. During the transplant, electroretinography (ERG) was used to detect electrical activity, but it was nonexistent. Within a four to six week period, healthy retinal tissue formed in the appropriate area, and ERG showed that electrical activity was present once again within the retinal tissue. 

The results of the experiment showed that half of the amount of electrical activity found in normal retinal tissue was found in the mice with the stem cells. Also, a dark adaption test showed that the new photoreceptor cells were making connections with the rest of the retina, and could be stimulated by light.

"We are very excited about these results," said Tucker. "While other researchers have been successful in converting skin cells into induced pluripotent stem cells and subsequently into retinal neurons, we believe that this is the first time that this degree of retinal reconstruction and restoration of visual function has been detected."