In the last ten years researchers have managed to create replicas of human organs from stem cells. These organs are actually scaled down organs, they are called organoids to distinguish them from the real thing, having some of the characteristics, including structure, of the real organ. These similarities make the organoids very interesting since they provide a (3d) model of the real thing that can be used for studying both how that organ (with respect to a specific characteristics) works and to test the reaction of that organ to drugs.
So far organoids mimicking lungs, gut, liver and even neural cells have been developed. However, no brain organoid was available so far.
No longer so. Researches at the UC San Diego school of medicine have announced the development of a brain organoids mimicking human cortex.
They did something more. They have been able to find a more effective method to create organoids. The current process is cumbersome, requiring the re-programming of fibroblasts into induced pluripotent stem cells (iPSCs). In the case of brain organoids you need to re-program many of them (because you need many different kinds of cells) which makes the whole even more complex.
The new method support the simultaneous creation of hundreds of iPSCs.
The created brain organoids have been used to get the first experimental proof that the Zika virus can cause severe birth defects, to repurpose existing HIV drugs to fight a rare neurological disorder and to create a Neanderthalised mini-brain.
Organoids, brain organoids, are tools to increase our understanding and to create labs on a dish to experiment with them. They are not real replica of an organ. We cannot push the envelop of an organoid to build the real organ, a real brain and dream of transplanting it to fix a defective organ.
However, they can provide an experimental understanding of how we could (in a future) work on the real organ to fix it. It might take 100 more years (or we, as human kind might never get there) but these researches have the potential to augment our organs in the future, to get better brains. Whether this would be desirable or not is a completely different story.