A first-in-human trial using adult retinal stem cells for advanced dry macular degeneration showed the treatment was safe and unexpectedly improved vision. Credit: Shutterstock
In a first-in-human phase 1/2a clinical trial, researchers used adult stem cells to help restore vision in people with age-related macular degeneration.
In the United States, age-related macular degeneration (AMD) stands as one of the primary causes of permanent vision loss among adults aged 60 and older.
The disease affects the macula, the central region of the retina that enables sharp, detailed, and color vision. When this area deteriorates, central vision becomes blurred or lost, while peripheral vision remains intact.
An estimated 20 million adults in the United States live with some form of AMD. While the condition does not impact peripheral vision, it severely limits the ability to see objects directly ahead.
Current therapies can slow disease progression but are unable to restore lost sight.
Using adult stem cells to target retinal cell loss
In research published in Cell Stem Cell, scientists tested retinal pigment epithelial (RPE) stem cells derived from adult postmortem eye tissue in a phase 1/2a clinical trial. These early trials focus primarily on determining the safety of a new treatment.
AMD occurs in two main forms: dry and wet.
Over 90% of patients are affected by the dry form, which results from dysfunction and eventual death of RPE cells.
Credit: Jacob Dwyer, Justine Ross, Michigan Medicine
In the early stages of AMD, these cells do not function properly. In late stages, they die and do not regenerate.
As the disease progresses, several areas inside the central eye lose these cells.
Testing safety and early outcomes in patients
In the current study, patients with advanced dry AMD received transplanted stem cells, originally isolated from eye-bank tissues. These adult stem cells were specialized and could only develop into retinal pigment epithelial cells.
Six patients received the lowest dose of transplanted stem cells (50,000 cells) through a surgical eye procedure.
In all of them, the treatment was safe and did not cause serious inflammation or tumor formation.
The participants also experienced improved vision in the transplanted eye; the non-transplanted eye did not have these improvements, hinting that the approach could provide a new therapeutic avenue. “Although we were pleased with the safety data, the exciting part was that their vision was also improving,” said Rajesh C. Rao, M.D., Leonard G. Miller Professor of Ophthalmology & Visual Sciences, and an associate professor of pathology and human genetics.
Promising early results and next steps
“We were surprised by the magnitude of vision gain in the most severely affected patients who received the adult stem cell-derived RPE transplants. This level of vision gain has not been seen in this group of patients with advanced dry AMD.”
When tested with an eye chart, the participants in the low-dose group were able to see 21 more letters after a year.
The team is now following the 12 other patients who received medium and high doses of 150,000 and 250,000 cells.
If no safety concerns arise, the research team will proceed with the next phases of the clinical trial.
“We are grateful to all our participants who are allowing to better understand whether this intervention is safe enough to be a future therapy,” Rao said.
“These kinds of NIH-funded studies can help us offer advanced treatments in the field of regenerative medicine, and we are happy we can offer this first-in-human, cutting-edge clinical trial at the University of Michigan.”
Reference: “Safety and tolerability of RPESC-RPE transplantation in patients with dry age-related macular degeneration: Low-dose clinical outcomes” by Rajesh C. Rao, Brigitte L. Arduini, Susan Borden, Dhruv Sareen, Clive Svendsen, Paul Lee, Charles Ryan, Shilpa Kodati, Caroline Nyaiburi, Keith Wolsieffer, Eric Oh, Shuna Park, Glenna Ford, Keith Dionne, Sally Temple and Jeffrey Stern, 16 September 2025, Cell Stem Cell.
DOI: 10.1016/j.stem.2025.08.012
Funding: Luxa Biotechnology, NIH/National Eye Institute
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