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
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
"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."