National Eye Institute-funded research at the University of Pittsburgh School of Medicine showed that an early-stage, experimental “living eye drop” that uses naturally occurring eye bacteria supports corneal wound healing.
The proof-of‑concept study, published today in Cell Reports, demonstrates that the harmless eye-dwelling microbe Corynebacterium mastitidis can be genetically modified to secrete an anti-inflammatory therapeutic that promotes healing following corneal injury in a mouse model.
“This is the first demonstration that a microbe that lives on the ocular surface could be engineered to deliver a therapeutic that improves eye health,” said senior author Anthony St. Leger, Ph.D., associate professor of ophthalmology and immunology at Pitt and the UPMC Vision Institute. “It opens the door to the idea of ‘living medicine’ for the eye—something you apply once, and it stays, protects and helps the tissue heal.”
Because tears continually wash medications away, treating ocular surface disease often requires multiple daily applications of eye drops. This can limit the effectiveness of therapies for conditions such as corneal abrasions or dry eye disease.
To explore an alternative delivery method, the Pitt team engineered C. mastitidis, a benign bacterium that naturally resides under the eyelid, to continuously secrete cytokine interleukin10 (IL10) – a small protein that regulates inflammation. In mice, corneas that were gently scratched and treated with the engineered bacteria healed faster than those treated with regular bacteria or saline. When the IL10 receptor was blocked, this benefit disappeared—confirming the therapeutic effect was IL10-dependent.
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