A recent study out of Duke University shows that retinal cells called Müller glia play a key role in preventing the spread of age-related macular degeneration (AMD). Study authors believe their new finding will help scientists discover a novel cure for the common blinding disease in the near future.
Researchers involved in this study used stem cells from the umbilical cord (aka hUTC) in this rat trial. Injections of hUTC have already been shown to prevent retinal cell death in clinical trials, but doctors didn't know exactly why hUTC worked so well.
When they examined the eyes of rats injected with hUTC, scientists soon discovered the Müller glia played a key role preventing sight loss. Müller glia are often described as "tree-like" and play a critical role in building up synaptic connections between retinal cells.
Although many doctors focus on the death of photoreceptors like rods and cones when studying AMD, Duke researchers point out that this disease also affects the health of the synapses in the retina. When they observed rats that suffered retinitis pigmentosa, a genetic disease with similar symptoms to AMD, scientists found that Müller glia were sending out wrong signals.
Shortly after they injected these partially blind rats with hUTC, the rats' Müller glia started functioning properly again. In addition to the healthy Müller glia, rats treated with hUTC had a slower rate of photoreceptor death.
To further clarify their findings, Duke scientists also tested what happened when they removed an important gene from the Müller glia cells in healthy rats. Shortly after they took the gene out, researchers found that the rats started developing severe retinal problems. This proves Müller glia cells play a major role in the prevention of diseases like AMD and retinitis pigmentosa.
There are two main types of AMD: dry and wet. About nine out of ten cases of AMD are the dry form, which causes the retina to deteriorate over time. Although less common, wet AMD is far more severe and is caused by the leaking of retinal blood vessels.
Unfortunately, AMD doesn't present obvious symptoms until it has progressed into its later stages. These later visual symptoms include blurry vision and difficulty seeing at night. Doctors recommend everyone over the age of 40 to get at least one eye exam per year to keep tabs on diseases like AMD.
There's currently no cure for AMD, but there are many treatment strategies doctors can use to halt the disease's progression. These strategies include vitamin supplementation, diet changes, and laser surgery.
Sehwon Koh, a postdoc neurology student in the Duke University's School of Medicine, was the lead author of this study. A few other key study authors from Duke include William J. Chen, and Cagla Eroglu.
Besides Duke researchers, scientists from Cedars-Sinai Medical Center and Janssen Research and Development collaborated in this study.
Anyone interested in reading more about this research should pick up the latest copy of The Journal of Neuroscience. Scientists entitled this article, "Subretinal Human Umbilical Tissue-Derived Cell Transplantation Preserves Retinal Synaptic Connectivity and Attenuates Müller Glial Reactivity."