Researchers have discovered an early-stage, experimental “living eye drop” that uses naturally occurring eye bacteria to support corneal wound healing.

The proof-of-concept study, published in Cell Reports,1 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 Associate Professor Anthony St. Leger, from the University of Pittsburgh School of Medicine in the United States.2

“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.

“What makes this exciting is that the system is modular,” Assoc Prof St. Leger explained. “We built it so you can swap in different genes – different cytokines, growth factors or other proteins – to tailor the therapy to specific eye diseases.”

Though promising, the technology is still in early development, with researchers noting that many steps must be completed before any clinical translation is possible, including developing built-in ‘off switches’ to safely and reliably remove or deactivate the engineered bacteria.

References available at mivision.com.au.