Retinopathy, the loss of light sensing cells in the retina, is among the most common causes of blindness. Scientists from the North Texas Eye Research Institute found that they can partially restore light reception of blind mice with the help of re-programmed skin cells. They published their findings on April 15, 2020, in the scientific journal Nature.
Degeneration of light sensing cells (photoreceptors) can have many causes, from aging to disease, but almost always ends in complete, irreversible blindness. The most common causes are age-related macular degeneration, which afflicts 25-30 million people worldwide, and diabetic retinopathy, which globally affects 5 million people. Scientists from the USA report to having found a potential remedy for blindness. They treated embryonic skin cells from mice with chemicals, causing them to turn into cells that are very similar to photoreceptors.
Researchers often use the practice of cell reprogramming, but they copied the idea from nature, namely from stem cells. Stem cells are without a specific function, except producing new cells. These new cells only “learn” which cell type to become, from external cues in the form of chemicals. These molecules can tell a new cell to become a skin- or light-sensing cell. In the same way, researchers can use chemicals to trick cells in changing their identity.
After the researchers from Texas confirmed the identity of the cells they produced in the petri-dish, they transplanted them into the retina of lab-mice that suffered from retinal degradation. Within three weeks of the transplantation, six out of fourteen mice had partially restored vision. The animal’s pupils showed constriction upon light stimuli, even though to reduced extents than healthy mice. Furthermore, they were seeking dark spaces in their cages, their naturally preferred hiding spots. Mice with retinal degradation could not make out these areas.
After three months, the transplanted light sensing cells and their connections to neurons of the retina were still alive and functioning, indicating that the scientists achieved a long-lasting restoration of vision. As a next step, researchers need to conduct trials on human cells, to put this possible cure for many forms of blindness to the final test.
Mahato, B., Kaya, K. D., Fan, Y., Sumien, N., Shetty, R. A., Zhang, W., … & Mohanty, S. (2020). Pharmacologic fibroblast reprogramming into photoreceptors restores vision. Nature, 581(7806), 83-88.