One of the challenges facing drug makers is the eventuality of human trials. Obviously, there is some danger in that eventuality that requires a great deal of testing prior to that stage of the game. A team of researchers from both China and the USA have developed a way to 3D print cells onto a stack of electrodes that survive for up to 4 weeks while mimicking a biological neural network. Yes, a Mini-Me version of a functioning brain, minus all the cognition and blood flow stuff.

If you stop to think about it, drugs are just electricity because Chemistry is largely the study of what electrons are doing, where they are relative to one another, and how all of that impacts molecular motion. But I oversimplify for the sake of brevity. Given such a gross oversimplification of brain chemistry, it shouldn’t be hard to see that such a Mini-Me brain-on-a-stack-o-plates-in-a-Petri-dish would make for great fun when testing how chemical compounds will react in an environment that closely models neurons in the brain. The endgame of this technology is safer drugs that more precisely do their jobs.
The original research paper from which I swiped that cool picture can be found here.
Yu Song et al 2020 Biofabrication 12 035016