A new study where embryonic stem cells were turned into functioning neurons and successful implanted into the brains of laboratory mice represents a crucial step toward deploying customized cells to repair damaged or diseased brains.

Scientists from the University of Wisconsin who conducted the research described how they were able to turn blank slate human embryonic stem cells (hESC), turn them into neurons and implant them into the brains of laboratory mice.

"Whether hESC-derived neurons can fully integrate with and functionally regulate an existing neural network remains unknown," said lead author Jason P.Weick. "Here, we demonstrate that hESC-derived neurons receive unitary postsynaptic currents both in vitro and in vivo and adopt the rhythmic firing behavior of mouse cortical networks via synaptic integration."

Weick's team implanted the lab-created neurons into the hippocampus of adult mice and they found out that it successfully integrated by analyzing the tissues taken from the recipients.

"Optical stimulation of hESC-derived neurons expressing Channelrhodopsin-2 elicited both inhibitory and excitatory postsynaptic currents and triggered network bursting in mouse neurons. Furthermore, light stimulation of hESC-derived neurons transplanted to the hippocampus of adult mice triggered postsynaptic currents in host pyramidal neurons in acute slice preparations," they added.

"Thus, hESC-derived neurons can participate in and modulate neural network activity through functional synaptic integration, suggesting they are capable of contributing to neural network information processing both in vitro and in vivo," the researchers wrote in the study which was published in the journal Proceedings of the National Academy of Sciences (PNAS).

Specifically, the scientists were able to take embryonic stem cells, used them to create neurons and implanted them into the brains of a different type of living creature. Their study showed that the lab-created neurons were able to assimilate into a subject's brain and function as part of a complex system that affect locomotion, conversation, and even thinking.

"The big question was can these cells integrate in a functional way," said Weick. "We show for the first time that these transplanted cells can both listen and talk to surrounding neurons of the adult brain."

Aside from Weick, who is a scientist at the University of Wisconsin-Madison's Waisman Center, the study had Yan Liu and Su-Chun Zhang as associates.