I am both fascinated and horrified by this story from Guillaume Thierry in The Conversation. It definitely falls into the category of, just because you can, doesn’t mean you should.
And transplanting lab grown brains into animals is disgusting. It’s one thing to conduct experiments on tissue, it’s another to put that tissue into another living thing. That is both unethical and cruel.
I realise no amount of legislation or control will stop some motivated party exploring the many potentials of the technology. Perhaps they should also consider the possibility that lab grown brains might play a part in the Singularity.

For those who don’t know the Singularity is the point at which “technological growth becomes uncontrollable and irreversible, resulting in unfathomable changes to human civilization.”
The unfathomable changes could bring some kind of utopia. They could also bring judgment day, and Terminators dispatched to destroy us.
It’s sobering to think science fact is accelerating past science fiction.