Human Mini-Brains Help Scientists Take a Step into the Future

Have you ever wondered how humans could be developed without sexual reproduction? While cheesy sci-fi and dystopia movies have explored this topic for decades, the first real scientific breakthrough has been made in the direction of human organoid development. We are still a long, long way off from ever being able to clone a functioning human being, but scientists have discovered a good way to grow mini-brain organoids from human pluripotent stem cells. These tiny brains have similar structure to functioning human brains and the neurons have displayed the ability to communicate with each other.

Mini-brain organoids are not a new idea. In fact, scientists have been producing mini-brains for five years, but these tiny brains varied dramatically in structure, were extremely small (about the size of a pin head), and did not possess many of the characteristics of a functioning human brain. However, Ben Novitch, UCLA’s Professor of Neurobiology and member of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, led a team that developed organoids that were more accurate to functioning human brains in structure, shape, and size. The team remarkably developed organoids that resembled many different parts of the human brain (like the basal ganglia and the cortex) by altering their growth method from previous researchers like the number of stem cells and the type of petri dish used. Even more remarkable than the mini-brain’s structure is their ability to communicate with one another like the neural cells of a typical human brain.

On November 11, 2017, researchers presented their exceptional findings at the 2017 Society for Neuroscience annual meeting. These findings included the transplant of human mini-brain organoids into mouse brains. Researchers found that the neurons from the mini-brain incorporated with the mouse neurons and underwent angiogenesis, the recruitment of blood vessels to certain cells in order to gain nutrients and dispose of waste. The organoid neurons developed astrocytes and axons to connect the organoid and the mouse brain. Researchers report that the axons communicate with the mouse brains and the organoid neurons fire at the same time as the mouse brain neurons. This research encouraged the researchers to think of a new project in which they use the organoid brains and find a way to supply them with human blood so they can study how the organoids react to certain drugs.

These mini-brains are not just for looks; they actually have valuable uses in the neurobiological, medical, and pharmaceutical fields. Since the mini-brains mimic the structure and cell-types of a functioning brain, researchers can use the organoids to test the effect of diseases, drugs, and treatments on the neural cells in great numbers: thousands of organoids can be tested simultaneously in a lab. Scientists can study the effect of a drug on the organoids to see which parts of the cells the drug affects and to determine if it would be safe to use on humans. Additionally, the organoids can be used to discover the effects of certain diseases on the neurons. One prominent research study has been conducted using the organoids to determine how the Zika virus affects the brains of fetuses. From this research, scientists discovered that the Zika virus infects a cell by binding to four cell receptors on the surface of the cell membrane. From this discovery, the researchers were able to develop treatments for the Zika virus that could potentially protect a fetus from brain damage. There are other studies in progress for similarly debilitating diseases like schizophrenia, Huntington’s disease, autism, epilepsy, and even more.

Clearly the development of these structurally significant mini-brains is a major milestone in research medicine. The mini-brains are similar enough to human brains that they are able to be used to develop treatments, discover causes of diseases, and test drug effects before they are ever tested on humans.

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