The lab-grown brain consists of both human nerve cells that can communicate with each other and the glial cells that feed them. "The most important brain regions are all there," announced Rene Anand, a researcher at Ohio State University, at a conference in Florida, as if this were nothing out of the ordinary.

Also extraordinary is the fact that the researchers used human skin cells to grow the brain in its jar. Through a process known as "reprogramming," the cells rejuvenate themselves as more versatile stem cells, or induced Pluripotent Stem Cell (iPS cells) that can then be manipulated to further transform into other cell types. Stem cell research labs all over the world have been using this technique since 2007.

Today in many labs it's standard practice to grow nerve cells from these reprogrammed cells. The cells generally grow in thin stalks that look like grass, covered by a broth of nutrients.

Brains and bioreactors

Viennese researchers first succeeded in programming stem cells to knit together to form a brain-like tissue in 2013.

The team, headed by Jürgen Knoblich, a native of Bavaria and the head of the research team at the Institute for Molecular Biotechnology in Vienna, and Madeline Lancaster of Cambridge University, fed the reprogrammed cells nerve growth nutrients and developed a specialized glass container with an automatic stirrer called a bioreactor.

"This way we can just let the cells sit, and if conditions are right, they organize themselves," Knoblich said.

Dozens of labs adopted Knoblich and Lancaster's methods after they introduced their new technique in "Nature" magazine.

Knoblich estimates that there are probably a hundred tiny brains growing in labs all over the world today.

Only as big as a pea

In order for a lump of tissues in a milky-white broth to distinguish itself as a brain, there must be several different cell varieties present, most importantly nerve cells, which must be able to exchange signals with each other. When the conditions are met, the resulting brain that grows is roughly equivalent to that of a human embryo.

However, this brain cannot grow much larger than a pea because, unlike embryos, brains in a jar don't have a constant supply of blood, and therefore have no source of nutrients.

In addition, these clumps of cells don't have the abilities of a real human brain: Particularly, these brains lack awareness. There is no information coming from the outside into the tissue, and there is no information processing inside the tissue.

Knoblich does not call them mini-brains, but "brain-like organoids."

For research - and pharmaceuticals

These brain organoids can't think. But they can provide a valuable service to both the pharmaceutical industry and to researchers.

In the future, doctors and researchers will be able to remove nerve cells from these organoids to treat neurological disorders.

The cells might also be better for transplant surgeries than cells grown in cell cultures. Unlike cell cultures, cells from organoids have already been shown to function in three-dimensional tissue.

The organoids could also be a testing ground for new drugs, since they simulate the human brain better than lab animals or cells in a culture can, and the effects and side effects of a drug can easily be discerned.

Due to potentially huge marketing opportunities, head researcher Rene Anand withheld publishing his results.

Instead, he created his own company to market his little brains.