Lab-made mini-brains are sprouting their own blood vessels

In 2015, scientists at Brown University developed "mini-brains," models of living brains created from 3D cultures of neural cells. Like organs-on-chips, these models could help reduce our reliance on animal testing in the search for new treatments and drugs, and make early results more accurate. 

Now, the researchers have discovered something new about these mini-brains: the neural cells are growing their own blood vessels too, opening the door for better studies of stroke, Alzheimer's and concussion.

Each measuring less than a millimeter wide, Brown's mini-brains are created thousands at a time, grown from living rat neural cells. They can't think, but the neurons are electrically active, composed of several types of cells and arrange themselves in a natural three-dimensional structure. Serving as reliable models of the real thing, scientists can study how neural cells develop, and what effect injuries or drugs may have, without the need for animal testing.

But neurons are only part of the picture. Brains require blood, and until now, the mini-brains seemed unable to replicate the vascular system that feeds them. But as the researchers continued to work with the models, they noticed that about two thirds of their mini-brains had developed tangles of non-neural tissue, which further study indicated were blood vessels.