An eye implant made of a thin sheet of human embryonic stem cells might be an effective treatment for a common form of vision loss. Researchers at the University of Southern California grew stem-cell membranes in a sterile lab for a month and then inserted them into the eyes of four people with “dry” macular degeneration, the leading cause of blindness in developed countries. An estimated 196 million people worldwide will have some form of macular degeneration by 2020. People with the dry type suffer from a progressive thinning of the retinal pigment epithelium, a layer of cells that support and nourish the light-sensing photoreceptors. Without this vital layer, which the implant is intended to replace, the photoreceptor cells also die off, and people slowly lose their eyesight. Researchers monitored the four patients over the course of a year, and found that their eyesight didn’t decline. The study was meant to test the safety of the implant, so only patients with very advanced macular degeneration were included. Because of that, study author Amir Kashani says, he didn’t expect an improvement in vision. “But after surgery, one patient could read 17 more letters on an eye chart than before surgery,” he says. Two patients were also able to focus their gaze better than before. The results appear today in the journal Science Translational Medicine. Kashani thinks the implant will be more effective for people in earlier stages of the disease. When stem cells were first extracted from human embryos 20 years ago, scientists marveled at their ability to change into any type of cell in the body and thought they would soon be used to treat all types of diseases, from eye disorders to diabetes. But that dream has yet to be realized. There are no embryonic stem-cell treatments approved by the US Food and Drug Administration, and most human studies of such therapies have shown unremarkable results.
An eye implant made from human embryonic stem cells could treat a common cause of blindness. Researchers at the University of California inserted stem-cell membranes into the eyes of four people with advanced dry macular degeneration, a leading cause of blindness. During a year, their eyesight either grew no worse or improved slightly. Researchers at the Moorfields Eye Hospital in London have developed a similar stem-cell patch for patients with the wet form of macular degeneration. However, both studies were small, with no control groups, and the US Food and Drug Administration has yet to approve embryonic stem-cell treatments.