January 7, 2025
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Plant Photosynthetic Machinery Works Inside Hamster Cells
The transplanted chloroplasts lasted two days inside the animal cells – and began to work
The researchers transplanted algal chloroplasts into the cells of a Chinese hamster (Cricetulus griseus).
Juniors Bildarchiv GmbH/Alamy Stock Photo
Over a billion years ago a hungry cell swallowed a tiny blue-green algae. But instead of the former simply digesting the latter, the pair reached a remarkable evolutionary agreement. Now scientists are trying to engineer that miracle in a lab.
Report on a recent experiment in the year Proceedings of the Academy of Japan, Series B, the researchers transplanted the photosynthetic offspring of these algae, plant organelles called chloroplastsin hamster cells, where they converted light into energy, being active for at least two days.
In 2021, University of Tokyo biologist Sachihiro Matsunaga reported how sacoglossan sea slugs can do this. “steal” chloroplasts. they feed on the algae, feeding the energy needs of the slugs for weeks. His team wanted to recreate this mechanism in other animal cells.
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Scientists had previously tried to transfer plant chloroplasts into fungal cells, but the cell washing team destroyed the foreign organelles within hours. For their experiment, Matsunaga’s team harvested extremely tough chloroplasts from a red algae that grows in acidic hot springs and placed them in lab-grown hamster ovary cells.
A fluorescence image shows chloroplasts (magenta) has been successfully inserted into hamster cells, highlighting other characteristics of animal cells: the nuclei are in light blue and the organelles are in yellow-green.
Ryota Aoki et al.: “Incorporation of photosynthetically active algal chloroplasts into mammalian cells cultured for photosynthesis in animals.” Proceedings of the Academy of Japan, Series B, Volume 100, Number 9; 2024 (CC BY-NC-ND)
The team isolated chloroplasts from algal cells by centrifugation and gentle stirring. Instead of puncturing the membranes of host cells, as in previous work, the researchers adjusted the composition of the culture medium so that the animal cells engulfed the chloroplasts like amoebas, Matsunaga says, “mixing them with nutrients.”
Transplanted chloroplasts maintained their structure and showed successful electron transport, a crucial step in light processing, for two days before deteriorating. Previous attempts to transplant a chloroplast into a foreign cell worked within hours. “I was surprised that they were able to get that much mileage out of it,” says cell biologist Jef D. Boeke of the NYU Grossman School of Medicine.
Challenges remain: chloroplasts require a constant supply of cell proteins. “Animal cells, however, lack the necessary genes to make and transport these proteins, so chloroplasts would quickly break down without them,” says Werner Kühlbrandt, a structural biologist at the Max Planck Institute for Biophysics in Frankfurt. Like Boeke, he was not involved in the new study. Next, Matsunaga’s team plans to try inserting genes that maintain photosynthesis into animal cells to make them more compatible with the transplanted chloroplasts.
These types of transplants could someday help scientists make living materials, Boeke says, such as photosynthetic fungi or bacteria that can be used on rooftops to capture carbon dioxide from the atmosphere, or laboratory organoids that grow faster using the extra oxygen of a chloroplast. Solar-powered humans, of course, remain pure fantasy, Matsunaga says: “They would need the surface area of a tennis court covered in chloroplasts.”
