Mouse eyes have been made to photosynthesize. Scientists in Japan transplanted tiny energy-producing structures from spinach cells into the eyes of living mice, and the foreign plant parts kept working inside animal tissue.
The experiment marks the first time that chloroplasts, the microscopic factories that let plants turn sunlight into energy, have functioned inside a living animal. The research was led by a team at the University of Tokyo and published in a peer-reviewed journal.
Spinach parts slipped into mouse retinas
The researchers extracted chloroplasts from spinach leaves and injected them into the retinas of mice. The chloroplasts survived inside the animal cells and began converting light into chemical energy, just as they do in plants. The team confirmed the transplanted organelles were active by measuring the energy molecules they produced.
Local scientists and ophthalmologists in Japan took notice because the work opens a new path for treating dry-eye disease, a condition that affects millions of people worldwide. In dry-eye disease, the cornea lacks enough moisture, and current treatments often fall short.
A possible fix for dry, damaged eyes
The Japanese team is now testing whether the photosynthetic spinach chloroplasts can help heal damaged corneas. The idea is that the chloroplasts could provide extra energy to eye cells that are struggling to repair themselves. Early results suggest the approach is safe in mice, but human trials remain years away.
For now, the finding stands as a proof of concept: plant cells can work inside animal bodies. The mice showed no signs of rejection or harm from the spinach transplants during the study period.
This is not science fiction. It is a laboratory result from a university in Tokyo, where researchers took a leaf from a grocery store vegetable and put it to work inside a living creature. Whether the technique will ever help a person see better or feel less dryness in their eyes depends on years more testing. But the fact that a mouse retina can run on sunlight, even a little, is a fact that changes what biologists thought was possible.
