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A study led by Imperial College London in collaboration with a group from the University of Cambridge, researchers transplanted human brain cells into a mouse brain watched how they grew and connected to each other. This allowed the team to study the way human brain cells interact in a more natural environment than previously possible.
The team used the technique to model Down syndrome, using cells donated by two individuals with the condition, this approach could be used to study a range of brain conditions in the future, including schizophrenia, dementia or autism. The study describes how researchers saw differences in the brain cells from those with Down syndrome compared to brain cells from a person without the condition.
Although some of the connections formed between the brain cells from the individuals with Down syndrome were more stable and abundant, they communicated in a slightly less coordinated fashion. The results suggest the reduced coordinated activity and stability of connections in Down syndrome may be linked to cognitive function.
The transplantation of human brain cells has allowed monitoring the maturation over time, cells from Down syndrome individuals are not as active as normal cells at a crucial stage in their development, and this could have important implications for some of the symptoms of this condition.
The connections between brain cells, which enable them to talk to each other, is often the first thing to be damaged in conditions such as dementia and Parkinson’s. This happens long before the brain cells start to die. But the connections are so tiny, that no type of scanning tool available, such as MRI or PET scans, can see them. We used a revolutionary microscopy technique called in vivo 2-photon microscopy which allowed us to see not only individual live brain cells, but also the connections between them.
Researchers created human brain cells by reverse-engineering skin cells. This process involved taking a few skin cells from volunteers with Down syndrome, and then reprogramming them in the lab to form brain cells. They then engineered those neurons so their activity could be monitored. The human brain cells not only formed complex networks, but also started communicating in a way that was very similar to normal brain cells.