https://phys.org/news/2018-08-university-minnesota-breakthrough-d-spinal.html

"No one has been able to print those stem cells where they differentiate into active nerve cells using a 3-D printer," said Michael McAlpine, a U mechanical engineer who teamed up with Dr. Ann Parr, a neurosurgeon, to lead the research. "The cells have to survive the printing process."

The team recently reported a printing approach that allowed for 75 percent survival of neural progenitor cells, which are limited stem cells capable of producing brain cells. Results were published in Advanced Functional Materials, a prestigious technical journal. A university video demonstrates how the soft rubbery scaffold could be printed in layers along with hydrogel, a special ink that coats and preserves the stem cells.