Human neurons transplanted into a rat's brain influence its behaviour

Murugesu is a journalist by the name of jason arunn.

For the first time, human cells have been used to grow rats' brains. The technique of controlling rats can be used to test new drugs.

Stem cells have been grown in the lab to create mini models of the brain. They can be used to study the effects of drugs on human cells, but they don't have the complexity of real brain cells.

Sergiu Pasca says that researchers can manipulate the cells and see how they affect the animal.

This type of transplant has been done before in adult rats, but Pasca and his colleagues are the first to do it in rats that are just a few days old. The researchers hoped that the human neurons would be better integrated into the organs when they targeted the rats. The rats all had immune systems that were malfunctioning.

The human neuron was six times larger than it would have been if it had been in a dish. They grew to fill a third of the rat's brain and formed connections with rat cells.

The researchers used optogenetics to see if the human neurons could influence the rats.

The rats were given water each time the blue light was shone on them. The rats began licking in expectation of water after the team shone blue light on the neurons.

Some of the limitations of using organoids in drug testing can be overcome. It is difficult to link the activity of human brain cells in a petri dish with a behavior associated with a mental illness. Researchers can study human cells by implanting organoids into rats.

A couple of previous studies have used human brain organoids into rodents. Several state-of-the-art technologies have been used in the study by Pasca's group. They showed long-term growth and maturation, as well as synaptic integration and contribution to the behavior of those human cells.

Julia TCW at Boston University says that the research will expand neurological research in areas such as neurodevelopmental disorders, neuropsychiatric disorders, substance use disorders, neurogenerative disorders and many other diseases that disrupt brain circuits.

Many will question if manipulating rats in this way is ethical. Taimie Bryant is a professor of animal law at the University of California, Los Angeles. Rats consciousness as it is, without human manipulation, is rather remarkable and that damaging a rat's brain is indicative of an attitude towards nature that threatens human and non-human animals' prospects for continued life on Earth.

Nature is a journal.