Injecting Neurons into Rats Gives Mice the Ability to Smell Cookies, Despite Their Lack of Olfactory Function.

Rat cells grown in the brains of mice without a sense of smell have enabled them to acquire the sense of smell. This is the first time that one species has experienced the world through the sensory neurons of another species.

When cells of one species multiply within the body of another species, the resulting organism is known as an interspecies chimera. These have previously been used to study specific tissues, such as mice containing cells of the human immune system, to study disease responses. However, creating chimeras of other tissues, such as neural tissue, is more complex.

Researchers at the University of Texas Southwestern Medical Center previously bred mice with parts of rat brains transplanted into them. Now, another team of researchers has shown that this cross-species chimerism may confer the ability to smell in mice genetically modified to lack scent-sensing neurons.

christine baldwin The researchers at Columbia University in New York injected these engineered mouse embryos with rat stem cells. Once the embryos became adult mice, the researchers monitored neuronal activity. The researchers discovered that these animals have functional neural pathways for sensing odors, made up of both rat and mouse cells that can communicate directly with each other.

When researchers tested these mice's sense of smell by searching for hidden mini Oreo cookies, they found that the mice that received stem cell injections found the food more easily, as opposed to the same genetically modified mice. It turned out that it was possible. It wasn't a chimera.

“This is a huge opportunity for human health, allowing us to better understand how to create cell replacement therapies for humans,” Baldwin said. “We can also create models in mice and rats for diseases that affect long-lived organisms.”

The fact that rat cells were able to facilitate food exploration in mice, which normally don't have a sense of smell, is very impressive, he says. walter lowe at the University of Minnesota. “Now, it is not yet clear whether something similar to this can occur in even different species, but at least [this study] Shows what's happening in two relatively close species [in evolutionary terms]” he says.