Creating brain hybrids between different species has long been an ambitious goal for neuroscientific research. Now, a group of researchers in the US has taken an important step forward in this direction. As? By creating mice with rat neurons perfectly integrated into their olfactory system.
The discovery, published in the journal Cell (I link it to you here), opens new avenues for the study of neurodegenerative diseases and neurodevelopmental disorders.
Blastocyst complementation: the key to creating brain hybrids
The team, led by Kristin Baldwin, a professor of genetics and development at Columbia University, used a technique called complementation of the blastocyst to create these innovative cerebral hybrids.
What is it about? In practice, the researchers injected stamina cells rat pluripotent cells into mouse blastocysts, an early stage of embryonic development that occurs a few hours after fertilization.
The results? Surprising: Rat neurons have successfully integrated into almost the entire mouse brain. “You could see rat cells throughout almost the entire mouse brain. It was pretty surprising to us,” Baldwin said.
This tells us that there are few barriers to insertion, suggesting that many types of mouse neurons can be replaced by a similar rat neuron.
Kristin Baldwin
Mice that smell like a rat
To determine whether the rat neurons had been integrated into a functional neural circuit, the researchers genetically modified the mouse embryo to kill or inactivate its olfactory neurons. In this way, they could test whether the rat neurons had restored the animal's sense of smell.
The results exceeded expectations. Mice with rat neurons were able to locate a hidden cookie in their cages, demonstrating preserved olfactory functionality. However, mice that retained their olfactory neurons, even when silenced, were less successful than those whose neurons had disappeared during development.
Towards a better understanding of brain diseases
The creation of hybrid brains represents an important step forward in understanding the mechanisms underlying brain diseases and developing potential therapies. These innovative models will allow researchers to study many dynamics more closely. For example, how brain cells get sick or die.
Or how to repair and replace damaged parts of the brain.
While work is still needed to refine this technique and fully understand its implications, creating rat-mouse hybrids with functional neurons from both species is a significant achievement. I dare say decisive. This discovery lays the foundation for future advances in neuroscience research and offers hope for the development of new therapeutic approaches for brain diseases.
