A new set of implants could help improve the vision of those impacted by dry age-related macular degeneration (AMD), a progressive blinding disease caused by the loss of the retinal pigment epithelium (RPE) of the eye.
A team from the University of California Santa Barbara (UCSB) has conducted the first in-human phase I clinical trial for dry AMD, where four patients received implants consisting of human embryonic stem cell-derived RPE, which supports the light-sensitive photoreceptor cells crucial to vision.
In the trial, the participants had advanced AMD with geography atrophy—considered a late stage in dry AMD—and poor visual abilities. None of the implanted eyes showed progression of vision loss and the implant improved the vision of one of the four participants. Two patients’ implants demonstrated improved fixation.
“Our goal is to implant healthy RPE to revive remaining photoreceptors and prevent any further loss of these light-sensing cells,” Dennis Clegg, who holds the Wilcox Family Chair in Biomedicine at UCSB and is co-director of the campus’s Center for Stem Cell Biology and Engineering, said in a statement. “Eventually, we would like to be able to provide implants at an earlier stage to prevent patients from losing photoreceptors in the first place.”
The implant—dubbed the California Project to Cure Blindness-Retinal Pigment Epithelium 1 (CPCB-RPE1)—consists of a polarized monolayer of human embryonic stem cell–derived RPE (hESC-RPE) on an ultrathin, synthetic parylene substrate designed to mimic Bruch’s membrane.
“Using advanced imaging methods, doctors can see evidence of integration between the implanted RPE and the host photoreceptors,” said Clegg, who is also co-director of the California Project to Cure Blindness, a collaborative effort aimed at advancing stem cell-based therapy for AMD.
In dry AMD, the RPE support cells in the macula become dysfunctional and die, causing the light-sensitive photoreceptors to begin to die as well. This causes the loss of clear vision in the direct line of sight while the surrounding vision remains unaffected.
A phase 1/2A trial is being conducted at the University of Southern California Roski Eye Institute at the campus’s Keck School of Medicine. The trial is ongoing and the team continues to analyze more patients.
AMD affects more than 1.75 million people in the U.S., with the number expected to increase to nearly three million by 2020 as the population continues to age. Between 80 and 90 percent of the cases in the U.S. are the dry version of the condition.
Other participating institutions include the California Institute of Technology, City of Hope National Medical Center, CamTek LLC and Regenerative Patch Technologies, Inc. Additional funding was provided by the California Institute for Regenerative Medicine and the Garland Initiative for Vision at UCSB.
The study was published in Science Translational Medicine.