Japanese researchers from Gifu Pharmaceutical University and Gifu University have reported that a type of protein found in stem cells taken from adipose (fat) tissue can reverse and prevent age-related, light-induced retinal damage in mice. These results may lead to treatments for patients faced with permanent vision loss.
According to the work done by these two research teams led by Drs. Hideaki Hara and Kazuhiro Tsuruma, a single injection of fat-derived stem cells (ASCs) reduced the retinal damage induced by light exposure in mice. This study also discovered that when fat-derived stem cells were grown in culture with retinal cells, the stem cells prevented the retinal cells from suffering damage after exposure to hydrogen peroxide and visible light both in the culture and in the retinas of live mice.
Additionally, Hara and Tsuruma and their colleagues discovered a protein in fat-derived stem cells called “progranulin.” This protein, progranulin, seems to play a central role in protecting other cells from suffering light-induced eye damage.
In the retina, which lies at the back of the eye, excessive light exposure causes degeneration of the photoreceptor cells that respond to light. Several studies have suggested that a long-term history of exposure to light might be an important factor in the onset of age-related macular degeneration. Photoreceptor loss is the primary cause of blindness in particular eye-specific degenerative diseases such as age-related macular degeneration and retinitis pigmentosa.
“However, there are few effective therapeutic strategies for these diseases,” Hideaki Hara, Ph.D., R.Ph., and Kazuhiro Tsuruma, Ph.D., R.Ph.
“Recent studies have demonstrated that bone marrow-derived stem cells protect against central nervous system degeneration with limited results. Just like the bone marrow stem cells, ASCs also self-renew and have the ability to change, or differentiate, as they grow. But since they come from fat, they can be obtained more easily under local anesthesia and in large quantities.”
The fat tissue used in the study was taken from mice and processed in the laboratory to isolate the fat-based stem cells. Afterwards, those cells were tested with cultured mouse retinal cells, and they show a robust protective effect. These successes suggested to the team to test their theory on a live group of mice that had retinal damage after exposure to intense levels of light.
Five days after receiving injections of the fat-based stem cells, the animals were tested for photoreceptor degeneration and retinal dysfunction. The results showed the degeneration had been significantly inhibited.
“Progranulin was identified as a major secreted protein of ASCs, which showed protective effects against retinal damage in culture and in animal tests using mice,” Drs. Hara and Tsuruma said. “As such, it may be a potential target for the treatment of degenerative diseases of the retina such as age-related macular degeneration and retinitis pigmentosa. The ASCs reduced photoreceptor degeneration without engraftment, which is concordant with the results of previous studies using bone marrow stem cells.”
“This study, suggesting that the protein progranulin may play a pivotal role in protecting against retinal light-induced damage, points to the potential for new therapeutic approaches to degenerative diseases of the retina,” said, Anthony Atala, MD, editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine, where this work was published.