Monday, November 19, 2012

First steps to a functioning brain transplant

One of the hardest tissue types to replace is that of the nervous system. Individual cells, called neurons, are hard to acquire and even harder to grow new in the body. Being able to provide our central nervous system, especially our brain, with fresh neurons may be a way to counter neurodegenerative diseases such as Alzheimer's or Parkinson's. Scientists have already shown capable of growing neurons from stem cells, but a recent study has now provided a way to actually make them functional after transplantation, which is a big step forward towards regrowing parts of the brain.

Growing tissues of your choice is one thing, but integrating them with existing tissue in the body is much harder. That is why integrating custom-made neurons in the brain is something that has gathered a lot of scientific interest, as the ability to grow such tissue in the lab has already been possible for years. And getting the lab-grown brain cells to work on a functional level is exactly what scientists from Sanford-Burnham research institute have achieved.

In order to get the artificially produced neurons to function properly after transplantation, the scientists transformed human embryonic stem cells into the cells they needed. While transforming such stem cells is not that hard anymore, the scientists needed something extra to get them to work in the brain. They found the answer using light, by so-called optogenetic stimulation. This technique switches genes on and off by simply using light. By turning on the required genes, the modified neurons appeared functional after transplantation. It is not the first time light stimulation has been shown to be beneficial for the creation of artificial tissue.

By measuring the electrical signals flowing through the brain and the previously transplanted neurons, the scientists showed that their creations are indeed functional. Not only did they find the presence of electric activity, but they also showed that the transplants were able to stimulate neighbouring neurons. That is why it appears as if the transplanted neurons are able to cooperate with existing tissue, which is of course necessary if we want to replace brain cells that have either died or are dysfunctional. This should eventually lead to fully-fledged brain transplants, ready to counter those diseases that impair brain function.

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