Apple Snail’s Regenerative Abilities Offer Hope for Human Vision Restoration
A groundbreaking new study reveals striking similarities between the eyes of humans and apple snails, offering a potential pathway toward regenerating damaged eye tissue and restoring vision. Published August 6 in Nature Communications, research led by Alice Accorsi, assistant professor of molecular and cellular biology at the University of California, Davis, demonstrates that the golden apple snail possesses remarkable regenerative capabilities that could hold the key to unlocking similar potential in humans.
The Unexpected Model: Why Apple Snails?
For decades, scientists have sought a robust model for studying complex organ regeneration. “Apple snails are an extraordinary organism,” Accorsi explained. “They provide a unique opportunity to study regeneration of complex sensory organs. Before this, we were missing a system for studying full eye regeneration.” The apple snail (Pomacea canaliculata), originally from South America and now an invasive species in many parts of the world, presents an ideal subject due to its resilience, rapid reproduction rate, and, crucially, its “camera-type” eye – the same type found in humans.
This isn’t the first time snails have been noted for their regenerative prowess; as far back as 1766, researchers observed garden snails regrowing entire heads. However, Accorsi’s work is the first to specifically leverage this ability for advanced regenerative research. “When I started reading about this, I was asking myself, why isn’t anybody already using snails to study regeneration?” she stated. “I think it’s because we just hadn’t found the perfect snail to study, until now.”
Camera-Type Eyes: A Shared Anatomy
Camera-type eyes, characterized by a cornea, lens, and retina containing millions of light-detecting photoreceptor cells, are known for producing high-resolution images. These eyes are found in vertebrates, some spiders, squid, octopi, and, surprisingly, certain snails. Accorsi’s team utilized dissections, microscopy, and genomic analysis to confirm that the apple snail’s eye shares significant anatomical and genetic similarities with the human eye.
“We did a lot of work to show that many genes that participate in human eye development are also present in the snail,” Accorsi said. “After regeneration, the morphology and gene expression of the new eye is pretty much identical to the original one.” This genetic overlap is a critical finding, suggesting that the mechanisms driving regeneration in snails may be applicable to humans.
The Regeneration Process: A Month-Long Transformation
The apple snail’s eye regeneration is a multi-phased process that takes approximately one month. Initially, the wound heals within 24 hours to prevent infection and fluid loss. Subsequently, unspecialized cells migrate to the site and begin to proliferate. Over roughly a week and a half, these cells differentiate and form the essential eye structures, including the lens and retina. By day 15 post-amputation, the optic nerve and all other eye structures are present, although continued maturation and growth occur for several weeks afterward.
While researchers haven’t definitively proven that the regenerated eyes provide the snails with functional vision, the anatomical structures necessary for image formation are present. “We still don’t have conclusive evidence that they can see images, but anatomically, they have all the components that are needed to form an image,” Accorsi noted. Her team is currently developing behavioral assays to assess the snails’ ability to process visual stimuli with their regenerated eyes.
Unlocking the Genetic Code with CRISPR-Cas9
To pinpoint the genes responsible for this remarkable regeneration, Accorsi’s team employed CRISPR-Cas9 gene editing technology. This allows them to manipulate the snail’s genome and observe the effects on regeneration. Initial investigations focused on the pax6 gene, known to be crucial for eye and brain development in humans, mice, and fruit flies.
The researchers discovered that apple snails, like other organisms, possess two copies of the pax6 gene. When both copies were deactivated in snail embryos, the snails developed without eyes, confirming pax6’s essential role in initial eye development. Accorsi is now investigating whether pax6 also plays a role in the regeneration process, and is also examining other eye-related genes.
“If we find a set of genes that are important for eye regeneration, and these genes are also present in vertebrates, in theory we could activate them to enable eye regeneration in humans,” Accorsi explained. This represents a significant step toward potentially treating vision loss caused by injury or disease.
The study involved contributions from Asmita Gattamraju of UC Davis, and Brenda Pardo, Eric Ross, Timothy J. Corbin, Melainia McClain, Kyle Weaver, Kym Delventhal, Jason A. Morrison, Mary Cathleen McKinney, Sean A. McKinney and Alejandro Sanchez Alvarado of the Stowers Institute for Medical Research. Accorsi conducted much of the research at the Stowers Institute before joining UC Davis in 2024. The research was funded by the Howard Hughes Medical Institute, the Society for Developmental Biology, the American Association for Anatomy and the Stowers Institute for Medical Research.
