Researchers at The Ohio State University were able to create a nearly complete human brain that matches the brain maturity of a 5-week-old fetus by using adult human skin cells.

The brain organoid is about the size of a pencil eraser and has an identifiable structure containing 99 percent of the genes present in the human fetal brain, according to a news release. Scientists say it’s the most complete human brain model yet developed.

“It not only looks like the developing brain, its diverse cell types express nearly all genes like a brain,” Rene Anand, a professor of biological chemistry and pharmacology at Ohio State, said in a news release. “We’ve struggled for a long time trying to solve complex brain disease problems that cause tremendous pain and suffering. The power of this brain model bodes very well for human health because it gives us better and more relevant options to test and develop therapeutics other than rodents.

Anand, who began his quest four years ago, studies the association between nicotinic receptors and central nervous system disorders. He’s hopeful that the lab-grown brain will provide ethical and more rapid and accurate testing of experimental drugs before the clinical trial stage.

“In central nervous system diseases, this will enable studies of either underlying genetic susceptibility or purely environmental influences, or a combination,” Anand said in the news release. “Genomic science infers there are up to 600 genes that give rise to autism, but we are stuck there. Mathematical correlations and statistical methods are insufficient to in themselves identify causation. You need an experimental system – you need a human brain.”

Anand and his team built the model system in 15 weeks, using techniques to convert adult skin cells into pluripotent cells, which are immature cells that can be programmed to become any tissue in the body.  They worked to differentiate pluripotent stem cells into cells that are designed to become neural tissue, according to the news release.

While the model lacks a vascular system, it does contain a spinal cord, all major regions of the brain, multiple cell types, signaling circuitry and a retina, according to the news release.  

Anand reported on his research at the 2015 Military Health System Research Symposium.