Retina Stem Cell Therapy Restores Vision in Animal Models

Bo Chen, PhD

Mount Sinai researchers have made history with the first recorded restoration of vision in animal models through the activation of retinal stem cells.

In a newly published study observing the reactivation of critical cells in mouse models to regain their vision, researchers from the Ocular Stem Cell Program at the Icahn School of Medicine at Mount Sinai have found indications that ophthalmic diseases such as macular degeneration (MD) or retinitis pigmentosa—previously believed to be irreversible—can be reversed.

The discovery is in due part to zebrafish.

The class of freshwater fish are capable of repairing retina damage within a few days through their cellular makeup, lead investigator Bo Chen, PhD, associate professor of Ophthalmology and Director of the Ocular Stem Cell Program, told MD Magazine®.

Müller glial cells (MGs), a source of retinal stem cells capable of rebuilding damaged retinal neurons, are what makes zebrafish capable of restoring vision. Unfortunately, MGs in mammals do not possess regenerative capabilities once photoreceptors are lost. The “basic machinery” by which retinal regeneration would occur still exists in humans, Chen said, but the process is somehow dormant.

“We lost the regenerative capability,” Chen said. “We have been very interested in this phenomenon.”

In an effort to reprogram MGs into blind mouse models, investigators conducted a two-step gene transfer in which they activated dormant stem cells, then aided other stem cells in developing into rod photoreceptor cells—the most abundant cell type in the retina which first aid the retina in sensing light.

The rod photoreceptor cells transmit to other retina cells, which eventually send signals to the brain and allow for actual sight. In their investigation, the team found that new rod photoreceptors were actually generated and integrated into the existing retinal structure—not just remaining isolated and dormant. There were no found differences between these new cells and previous, real rod photoreceptors cells.

In 4-6 weeks following the procedure, observed mice were capable of sensing light again and regained their vision. However, the vision restoration was not whole, and investigators are anticipating further studies will be needed to improve the degree of restoration.

That said, Chen anticipates it could lead to “extraordinary opportunities” in future human stem cell eye care.

“If this works, this could transform the way we treat patients with retinal disease and possibly learn how to cure other types of eye disease like glaucoma,” Chen said.

The next round of investigations will focus on whether the transfer tools used in mouse models are feasible for human tissue, Chen said. He projected that human stem cell therapy—though particularly prominent in current ophthalmic research—is still about a decade away from marketed use.

“This type of therapeutic treatment is very generous,” Chen said. “A lot of retina conditions are caused by genetic disease. Restarting the regeneration is being able to correct those problems.”