Researchers from the Buck Institute have developed a method that restored long-term vision in blind mice. In their study published in the Cell Stem Cell journal, the blind mice were able to perceive light as far out as nine months after the injection of stem cells.
The new method allows the stem cells to survive in the body long enough to work. Currently, transplanting photoreceptors derived from human stem cells usually do not work because they get rejected by the body. Photoreceptors are specialized neurons in the retina that turns light into signals that get interpreted as sight.
The researchers determined that the mice that lack in immunodeficient IL2 receptor gamma (IL2rl), a specific immune cell receptor that rejects transplanted foreign cells experienced a longer-term survival of human embryonic stem cell. When the researchers observed the pupils’ response to light and examined the brains’ visual response centers, they found that the signals from the eye were going to the right areas.
“That finding gives us a lot of hope for patients, that we can create some sort of advantage for these stem cell therapies so it won’t be just a transient response when these cells are put in, but a sustained vision for a long time,” said study senior author Deepak Lamba, from Buck Institute for Research on Aging. “Even though the retina is often considered to be ‘immune privileged,’ we have found that we can’t ignore cell rejection when trying to transplant stem cells into the eye.”
Further research is still necessary, the researchers add. However, restoring vision in patients that suffer from diseases that affect the eyes, like macular degeneration, can be possible with the use of antibody that suppresses the immune receptor. “We can also potentially identify other small molecules or recombinant proteins to reduce this interleukin 2 receptor gamma activity in the body — even eye-specific immune responses — that might reduce cell rejection,” added Lamba. “Of course it is not validated yet, but now that we have a target, that is the future of how we can apply this work to humans.”