An international team of researchers may have found a way to eventually restore sight in humans with blindness caused by certain diseases.
Richard Kramer, study leader and professor of molecular and cell biology at the University of California – Berkeley, along with Dr. Russell Van Gelder, co-author from the Department of Ophthalmology at the University of Washington – Seattle and researchers from the University of Munich in Germany collaborated on the research.
The researchers discovered that a certain chemical, AAQ, is capable of temporarily restoring sight in mice. It does this by bringing light sensitive cells in the retina back to life.
In certain diseases, light sensitive cells in the retina die off. But AAQ acts as a photoswitch that attaches to protein ion channels on retinal cells, and when switched on by light, AAQ changes the flow of ions through these channels. The neurons are then activated, causing normally dead cells to be sensitive to light once again.
This method was tested out in mice that had genetic mutations, causing light sensitive cells in the retina to die within months after birth. Small amounts of AAQ were injected into the mice, and their sight was restored. They would avoid the light when being exposed to it, which is not typical of blind mice. However, the restoration was temporary.
Kramer hopes to keep working with the AAQ chemical and make it possible to give to humans at some point. There are better versions of AAQ in the making as we speak, which activate neurons for days rather than just hours. It aims to treat those with retinitis pigmentosa and age-related macular degeneration, which both result in the death of light sensitive cells in the retina.
“The advantage of this approach is that it is a simple chemical, which means that you can change the dosage, you can use it in combination with other therapies, or you can discontinue the therapy if you don’t like the results,” said Kramer. “As improved chemicals become available, you could offer them to patients. You can’t do that when you surgically implant a chip or after you genetically modify somebody.”
This study was published in the journal Neuron on July 26.