Grad Student Develops New Way to Study Optic Nerve Regeneration
Method could provide critical data to pursue whole-eye transplants.

In a study published in Scientific Reports, University of Miami Miller School of Medicine Ph.D. candidate Chloe Moulin, Daniel Pelaez, Ph.D., research associate professor of ophthalmology at Bascom Palmer Eye Institute, and colleagues showed that precision laser micro-optics offer an effective and repeatable way to study how optic nerves respond to injury and heal. This new method is already providing important insights into optic nerve regeneration.
“Our lab is part of a larger effort to develop whole-eye transplants, which could really benefit people with advanced macular degeneration, glaucoma, diabetic retinopathy or eye trauma,” said Moulin, a fourth-year graduate student and first author on the study. “Reconnecting the cut optic nerve is the most difficult part of the problem, but now we have a better way to study how other animals achieve nerve regeneration naturally.”
Tissue Regeneration: What Would Tadpoles Do?

Tissue regeneration may seem like science fiction, but it’s commonplace in the natural world. Lower vertebrates, plants and many other living things can readily regenerate. Researchers in the Pelaez Lab are studying this capability to understand how it works and possibly apply it to people.
“Humans and most other mammals can’t regenerate, but perhaps we can learn how it’s done,” said Dr. Pelaez, scientific director of the Dr. Nasser Al-Rashid Vision Research Center at Bascom Palmer and senior author on the paper. “We’ve been studying how tadpoles regenerate in the hope of applying that knowledge to human patients.”
Tadpoles are great models because they are small and transparent. The lab has also genetically engineered them to express green fluorescent protein in their optic and other nerves, making these structures glow to help visualize them. Moulin needed to perturb the optic nerves to set the stage for regeneration, but traditional methods weren’t working.
“The problem was that we couldn’t interfere with the optic nerve in a reproducible way,” said Moulin. “We needed a method that would work exactly the same way every single time.”
She turned to laser micro-optics, which can emit micrometer-size beams. The Miller School has a facility with a laser-equipped microscope Moulin optimized for the project. The laser provided the reproducibility she needed.
New Insights into New Optic Nerves
After the laser procedure, the green-glowing nerve cells can be easily tracked as they heal and regrow. Surprisingly, the nerves did not rely on immature stem cells to fuel regeneration.
“We know frog cells can differentiate to replace lost retinal neurons,” said Moulin. “But in our study, they don’t use that mechanism. They regenerate by preventing cell death. The surviving retinal ganglion cells send out new axons. This is exactly how people would have to regenerate after an eye transplant because we have no natural mechanisms to replace injured retinal neurons.”

The team also found tadpole optic nerves regrow haphazardly until they find their reconnection point in the brain. Once there, they send out signals for other axons to follow, ultimately restoring normal eyesight. The entire process takes around 14 days.
Though still finalizing her Ph.D., Moulin is already an established scientist who has co-authored 12 publications. And while Dr. Pelaez has worked with many gifted researchers, he has special praise for Moulin’s work ethic and results.
“Normally, developing a new model would be something a senior scientist would do, but Chloe established a highly accurate and reproducible method to study the cellular, physiological and molecular factors that drive central nervous system regeneration,” he said. “Understanding these mechanisms is going to be critical to reestablish optic nerve connections in higher vertebrates.”
Tags: Bascom Palmer Eye Institute, Dr. Daniel Pelaez, optic nerve regeneration, student research, whole eye transplant