Snail that regrows its eyes could help restore human sight, find new study

A freshwater snail can regrow a complete camera-type eye in 30 days, prompting scientists to explore whether its Crispr-editable genetic toolkit could unlock future human eye regeneration

Losing vision due to injury or disease is usually permanent in humans. But a freshwater snail called the golden apple snail, which can regrow an entire, complex eye that is anatomically and genetically very similar to the human eye within a month, is giving new hope to medical researchers.

 

Scientists have found that this snail rebuilds a camera-type eye that closely resembles the human eye in both structure and genetic activity. The study titled A genetically tractable non-vertebrate system to study complete camera-type eye regeneration, published recently in Nature Communications, offers a new model for understanding how complex organs regenerate.

 

 

Led by Alice Accorsi, assistant professor of molecular and cellular biology at the University of California, Davis, and colleagues, the team shows that the snail’s regenerated eye mirrors the original in structure and gene activity. They have also developed gene-editing tools to manipulate the snail’s DNA, opening a powerful new window into how complex sensory organs regenerate.

What makes the golden apple snail a unique model for eye regeneration?

The golden apple snail (Pomacea canaliculata) is native to South America and is known for being resilient and highly adaptable. According to the study, it breeds quickly, produces many offspring, and thrives in controlled settings. It possesses a “camera-type” eye, which is the same general design found in humans and other vertebrates. That similarity gives scientists a rare opportunity to experiment with a simple, genetically manageable organism capable of regenerating a complex eye.

 

While regeneration in snails has been observed for centuries, this is the first time researchers have positioned such an organism as a modern genetic model for full eye regeneration.

What is a camera-type eye and why does it matter?

Camera-type eyes are among the most sophisticated types of eyes and include:

• A cornea for protection
• A lens to focus light
• A retina packed with light-sensitive photoreceptor cells
• An optic nerve connecting the eye to the brain

Humans, other vertebrates, squid, octopuses, some spiders, and certain snails share this design. 

How does the snail regrow a complete eye in 30 days?

According to the researchers, within 24 hours of losing an eye, the snail seals the wound, and undifferentiated cells (which have the capacity to differentiate into a variety of cell types, such as stem cells) then migrate to the injury site and begin multiplying. Over the next 10–15 days, these cells specialise into key structures such as the lens and retina. By around day 15, major components, including the optic nerve, are present.

 

By day 30, the eye appears structurally complete. However, gene expression analysis reveals that more than 1,000 genes remain differently regulated even after a month, suggesting that full molecular maturation continues beyond visible reconstruction.

 

The study also found that immediately after amputation, around 9,000 genes change their activity compared with a normal adult eye. After 28 days, 1,175 genes are still expressed at different levels in regenerated eyes. The study authors say that understanding which genes switch on, and when, is key to decoding how regeneration works.

 

One of the first genes the team investigated using Clustered Regularly Interspaced Short Palindromic Repeats (Crispr) and Crispr-associated protein 9 (Cas9), or simply the Crispr-Cas9 gene-editing system, was pax6.

 

According to researchers, Pax6 is often described as a “master control” gene for eye development across species. In humans, mice and fruit flies, it orchestrates early eye and brain formation.

 

When researchers disabled both copies of pax6 in snail embryos, the animals developed without eyes. That confirms its essential role in early eye formation in this species, too.

 

The next step is determining whether pax6 is also required for regeneration in adult snails. If so, it would strengthen the case that the same core genetic programme underlies both development and regrowth.

Could snail eye regeneration research help treat human blindness?

The researchers underlined that human eyes do not naturally regenerate. Damage to the retina or optic nerve typically leads to permanent vision loss. However, humans still possess many of the same developmental genes as the snail.

 

The working theory is that if regeneration fails in humans, it may be because certain genetic pathways are switched off or tightly suppressed after development. If scientists can identify and safely reactivate the right gene networks, regeneration might become possible.

 

This system is not a near-term therapy, as the research is still at an early stage. However, the study marks a turning point because, for decades, scientists lacked a genetically tractable non-vertebrate model capable of regenerating a full camera-type eye, and the apple snail fills that gap.

 

Scientists still need behavioural evidence to confirm whether regenerated snail eyes process visual information identically to the original eyes. Anatomically, all components are present, but functional testing is ongoing. Researchers also need to determine how these mechanisms can be translated safely into vertebrates.