Transplanted Eye Cells Restore Visual Function In Mice
Restoring vision with light-sensing cells transplanted into eyes.
Scientists have successfully transplanted light-sensing cells called photoreceptors directly into the eyes of mice and restored their visual function.
The achievement is based on a novel technology in which the cells are introduced at a particular stage in their development. It was carried out at the London Institute of Ophthalmology using a novel approach developed at the University of Michigan Kellogg Eye Center to tag rod precursor cells and prepare them for transplantation.
The team of scientists found that transplanted photoreceptor precursor cells survived and became integrated into the mouse retina-and that the technique succeeded because the cells were isolated when they had reached a certain level of maturity.
Rather than injecting undifferentiated and uncommitted stem cells into the retina in hopes they would develop into photoreceptors, researchers introduced cells at a somewhat later stage. These cells are referred to as "precursors": they are immature cells that are "programmed" to be, but have not yet become, functionally mature photoreceptors - - the light-sensitive cells in the retina that are essential for sight.
The findings, reported in the November 9 advance online issue of Nature, come from the collaborative research of Anand Swaroop, Ph.D., the Harold F. Falls Collegiate Professor of Ophthalmology and Visual Sciences at the University of Michigan Medical School, and Robin R. Ali, Ph.D., Professor, Division of Molecular Therapy at the Institute of Ophthalmology in London.
The technology represents a breakthrough in transplantation-based therapies for neuro-degenerative diseases. It suggests that scientists may need to introduce changes in stem cells in order for them to become highly specialized neurons.
Although the experiment has implications for human eye diseases that dim the sight of millions of people, Swaroop anticipates that several years of research using animal models and cell culture systems will still be needed before transplantation can be considered ready for testing in humans.
Restoring visual function in animals is an important advance, but the scientists caution that it shouldn't be considered the same as restoring vision in humans. The next wave of research will focus on characterizing the mechanisms that generate photoreceptor precursors from stem cells.