Scientists have successfully implanted and integrated human brain cells into newborn rats, creating a new way to study complex psychiatric disorders such as schizophrenia (精神分裂症), and perhaps eventually test treatments.
Scientists can assemble small sections of human brain tissue made from stem cells in a special container. But in such a container, “neurons(神经元) don’t grow to the size, to which a human neuron in an actual human brain would grow,” said Sergiu Pasca, the study’s lead author from Stanford University. To overcome such restrictions, researchers implanted the groupings of human brain cells, called organoids, into the brains of young rats.
Human neurons have also been implanted into adult rats before, but an animal’s brain stops developing at a certain age, limiting how well implanted cells can integrate. “By transplanting them at these early stages, we found that these organoids can grow relatively large and receive nutrients, and they can cover about a third of a rat’s brain,” said Pasca.
To test how well the human neurons integrated with the rat brains and bodies, air was blown out across the animals’ whiskers, which prompted electrical activity in the human neurons. That showed that external stimulation of the rat’s body was processed by the human brain tissue.
The scientists then conducted another test in the opposite order. They implanted human brain cells which could respond to blue light, and then trained the rats to expect a “reward” of water from a pipe when blue light shone on the neurons via a cable in the animals’ brain. After two weeks, they found pulsing the blue light sent the rats scrambling to the pipe.
The team has now used the technique to show that organoids developed from patients with Timothy syndrome grow more slowly and display less electrical activity than those from healthy people.
Tara Spires-Jones, a professor at the University of Edinburgh’s UK Dementia Research Institute, said the work “has the potential to advance what we know about psychiatric disorders.”
【小题1】Why did scientists research on rats instead of the special container?| A．Because psychiatric disorders are too complex. |
| B．Because rats also suffer similar psychiatric illnesses. |
| C．Because it limits the growth of human brain neurons. |
| D．Because human brain neurons grow too quickly in it. |
| A．Rats’age has a significant influence on the research. |
| B．Human brain cells can’t be implanted into adult rats. |
| C．Rats’ brain won’t develop if they receive human neurons. |
| D．Human neurons can grow larger in adult rats’ brain than young rats’. |
| A．To train rats to respond to external stimulations. |
| B．To show similarities between rats and human tissues. |
| C．To confirm human brain cells could grow well in rats’ brains. |
| D．To check whether signals could be sent back to rats’ body. |
| A．It can advance more experiments on rats. |
| B．It can further our study of psychiatric illnesses. |
| C．It can provide some useful experimental methods. |
| D．It can promote our knowledge of human brain cells. |
