What's Wrong With Growing Blobs of Brain Tissue?

Last week, Rusty Gage and colleagues at the Salk Institute announced that they had successfully transplanted lab-grown blobs of human brain tissue into mice. Gage’s team grew the blobs, known as brain organoids, from human stem cells. Once surgically implanted into rodent brains, the organoids continued growing, and their neurons formed connections with those of the surrounding brains. It was the first time such transplants had worked: Until now, organoids had only ever been grown in dishes.