After being transplanted into rats, human brain organoids develop.
Human brain organoids implanted in rats might be utilized to research neuropsychiatric illnesses in vivo. Stanford University researchers were able to develop human organoid neurons in the somatosensory cortex of the animal’s brain and integrate them into its neural circuitry.
The transplanted neurons’ morphological and physiological features were enhanced as a result of the integration. Human cells retained their identity when compared to organoids in a Petri dish, and they adjusted the rat’s acquired behavior through stimulation and reward studies.
Researchers have successfully transplanted human neurons into the brains of young rats for the first time, they report today (October 12) in Nature. Human cells made connections with rat neurons and could be utilized to affect the behavior of the rats.
According to Yun Li, a molecular geneticist at the University of Toronto who was not involved in the research, “The fact that they were successful in many of these studies is extremely remarkable.”
Scientists have constructed models called organoids to do human cell experiments, particularly when researching the effects of specific medications. Organoids are microscopic structures generated from stem cells that imitate the human brain or other organs. They do, however,
Scientists implanted human cerebral organoids into the brains of days-old rat pups whose immune systems had been suppressed so that the human cells would not be rejected.
The researchers believed that by utilizing young rats rather than adults, the cells would integrate more seamlessly and make more connections in the rodents’ brains. They find that the human neurons grew well, becoming six times bigger than neurons generated in a dish and making synapses with rat neurons.
“They’re simply extremely enormous,” says Stanford University neurologist and main author Sergiu Pasca. “The cells have simply advanced to the next stage of development.”
To see if the transplanted human neurons affected the behavior of the young rats, Pasca and his colleagues genetically changed the human cells using optogenetics, a technology that allows cells to respond to light.
When they gave the rats water, they utilized a fiber optic wire to shine a blue light on the rat-integrated human neurons. The rats quickly learned to identify the light’s rays with water, and after just two weeks, they began to lick in anticipation of drinking when the light was shined.
Rat behavior is influenced by human brain organoids.
Human tissue mimicking the cortex of the brain may be produced in vitro from stem cells. This tissue can grow, integrate into neural networks, and alter behavior after being transplanted into a developing rat brain.
Barbara Treutlein and J. Gray Camp
Scientists all across the globe were enthralled when it was discovered that pluripotent stem cells originating from the skin could be encouraged to grow into intricate 3D neural tissues1,2. These primitive in vitro structures, known as organoids, heralded a new era in human brain research3,4.
There are currently protocols for creating organoids that resemble many areas of the brain5, but one important challenge is that neural organoid tissues fail to grow adequately in vitro. Nature Writing,
Brain-like human tissue placed in rat brains impacted the animals’ behavior in a fresh experiment.
Stanford University researchers launched an ambitious experiment by creating small, simpler replicas of the human brain from stem cells in a lab, then injecting that tissue into the brains of newborn rats.
Their findings, published in the journal Nature on Wednesday, demonstrated that the brain-like human tissue merged with the rat tissue and then matured.
These brain cells appeared to alter the rats’ behavior.
The human tissue was injected into the rats’ somatosensory cortexes, which receive and process sensory information such as touch or pain. After about two weeks of training, the rats began to lick the spout in search of water whenever the water was turned off.
Human neurons were activated by researchers (they did this using blue light lasers). The researchers then prodded the rats’ whiskers with a puff of air and then studied how the human neurons responded.
“We discovered that when we activated the whiskers, human neurons responded remarkably fast. Indeed, more than 70% of human neurons are engaged in some form of activity within a second or so of stimulation, indicating that they are most likely connected
“Sergiu Pașca, a Stanford professor of psychiatry and behavioral sciences and one of the study’s authors, stated during a conference call with reporters.
“Human neurons become part of the rat circuitry,” Pașca explained, adding that under a microscope, the neurons were “sparkling with electrical activity.”
The rats showed no evidence of health problems such as convulsions or epilepsy, which the researchers were concerned about. One year following the transplants, more than 70% of the patients were still alive.
The research is the most recent effort to transplant human cells into animals. This area of scientific investigation began decades ago, and some previous attempts were successful: In 2006,
developmental biologist Ali Brivanlou and a team of researchers from Rockefeller University demonstrated that human embryos may be grown in mouse tissue. Then, in 2013, a team of Belgian scientists implanted human neurons into newborn mice, resulting in functioning brain circuits.
Is it possible to transplant part of a brain?
The response is that, unlike the preceding situations, this type of transplant is not now viable and has no objective reason to believe that it will ever be. When severed, central nervous system tissue, including brain and spinal cord tissue, does not regain function.
Can a human get a new brain?
Transplants from one head to another, on the other hand, are highly improbable to occur. Given what we know about memory and personality (not to mention the immune system), it is nearly certain that one individual will never be able to receive a “mind transplant” from another.
Can memory be transplanted?
For decades, memory transfer has been at the core of science fiction, but it’s becoming more science fact. A team of researchers successfully transplanted memories by transferring RNA, a type of genetic information, from one snail to another. The snails were taught how to defend themselves.
Can a brain survive without a body?
It is feasible to maintain an isolated brain alive for a short period of time. Many specialists avoid this predicament for ethical and practical reasons. In the early 1990s, scientists maintained a mammalian brain alive outside its body for around eight hours.
Human Cells Grown in the Lab Form Working Circuits in Rat Brains
Scientists should be able to build new live models for a wide range of neurodevelopmental problems, including at least some kinds of autism spectrum disorder, using this technology.
The models would be equally as useful for neuroscientific lab investigations as present animal models, but they would be superior substitutes for human illnesses since they would be made out of genuine human cells in working brain circuits. They may be great targets for contemporary neuroscience technologies that are too intrusive for use in human brains.
Sergiu Paşca stands in front of a rack of equipment at his lab at Stanford University.
Q&A
Human Brains Are Difficult to Study. He cultivates useful substitutes.
12 OCTOBER 2022
The study also opens a new chapter in the usage of neuronal organoids. Biologists found nearly 15 years ago that human stem cells could self-organize and develop into little spheres that housed several types of cells and resembled brain tissue.
These organoids provided a unique perspective on the actions of brain cells, although the view had limitations. While neurons in a dish can connect and interact electrically, they cannot form fully functioning circuits or achieve the full development and computational prowess of healthy neurons in their native environment, the brain.
Several research groups demonstrated years ago that human brain organoids may be implanted into the brains of adult rats and thrive. However, new research indicates that Read