Japan team creates ‘planimal’ hybrid plant-animal cells in world first

A Japanese team said that it has become the first in the world to create hybrid plant-animal cells, dubbed “planimal” cells, by fusing a unicellular alga called Cyanidioschyzon merolae into cultured animal cells.

According to the team from the University of Tokyo, the Institute of Science Tokyo, Kindai University and others, all of C. merolae’s DNA was integrated into the animal cells’ chromosomes.

But the hybrid cells were, in terms of function, animal cells because C. merolae’s DNA was suppressed and chloroplasts, which conduct photosynthesis, were degraded during fusion.

“We hope to introduce chloroplasts and activate C. merolae genes to generate oxygen through photosynthesis,” said Sachihiro Matsunaga, professor at the University of Tokyo’s Graduate School of Frontier Sciences.

The team’s findings were published in the international journal Nature Communications.

Matsunaga had been working on the production of planimal cells since he proposed the creation of such a hybrid in 2018.

If cells that produce useful animal and plant proteins can be cultured in large quantities using photosynthesis, it could provide a new means of producing drugs and cultured meat. In this experiment, the cultured animal cells were derived from Chinese hamster ovaries, which are used to produce drugs and other products.

While plant cells have walls outside the cell membrane, C. merolae has no cell walls because it is primitive. In addition, its genome is very small.

Matsunaga and other members of the team fused C. merolae into cultured animal cells using a conventional method involving polyethylene glycol, in order to put the alga’s DNA into the animal cell nucleus.

Although the success rate was low, they produced planimal cells in which all of the alga’s DNA was integrated into the animal cells’ chromosomes.

The integrated DNA was frozen by a mechanism called methylation, acting as an “off” switch for gene expression. Like ordinary cultured animal cells, the planimal cells continued to divide and multiply for more than 150 generations.