The fantasy of transplanting neurons is pretty great. The possibilities are endless! Feeling like you need a leg up before your SAT? Maybe a dose of neurons could help form a few more pathways. Did a lot of binge drinking back in the day? Let's pump you full of healthy, new neurons to replace those ones you killed off with Jäger Bombs. Soon, we'll all be carrying around little vials of neurons like so much ibuprofen in our purses — kill a brain cell and replace it before it's even missed.
Of course, the real reason that neuron transplants are being experimented with is for far more serious conditions than your post-St. Patty's Day hangover. And let's get one thing straight before we continue: Neuron transplant is possible and has already been done. It's not as exciting as a brain transplant, but scientists and researchers are already experimenting with transplanting neuronal cells into a patient's brain.
Let's take one study, published in 2005, where stroke patients received transplants of human neuronal cells. Stroke victims, remember, are dealing with dead and damaged brain tissue, so they would benefit from neural regeneration or repair. The good news is that the transplantations seemed to work; no one had huge complications from receiving donor neurons. The other news: The results weren't exactly glowing. Basically, some people improved and some people didn't, and it's difficult to tell if the new neurons had much to do with it [source: Kondziolka et al]. Since the sample size was rather small (18 patients), it might take a larger-scale study to determine efficacy, but it does present limited good news for safety.
A 2011 study also confirmed that human neurons (in the form of embryonic stem cells) transplanted into mice could control the mice's native neurons. This is kind of a major deal, because it tells us that transplanted neurons can function like host neurons -- they can build connections and communicate with each other. Even more, the study showed that the transplanted neurons could signal to and regulate their hosts [source: Schubert]. That's pretty cool, because it gives an idea to what host cells are responding.
We are not only transplanting neurons, but we'll also probably pick up the pace in the next few years to get some more thorough answers about how best to go about improving our brain cell outcomes.