Look at the ingredients list on a snack package, and you’ll probably expect to find preservatives, flavorings, and a few words you can’t pronounce — not the ingredients for a brain. Yet one common food additive has recently helped scientists grow tiny clusters of human brain cells in the lab, creating what are essentially “mini-brains.” It sounds like something out of the opening of a horror movie: a mysterious ingredient, a laboratory dish, and a growing brain. Fortunately, these miniature organoids can’t think, feel, or plot world domination. Instead, they offer researchers a powerful window into how the human brain develops and a promising new tool for studying neurological diseases that have long puzzled scientists.
Researchers at Stanford Medicine grew brain tissue called cortical organoids in biologically engineered mice. These mice were bred so that they were missing their cerebral cortex, which is responsible for cognition, language, and decision-making. This resulted in a gap in the mice’s brains, providing an optimal environment for brain cells. The surviving human tissue grew and developed connections to parts of the mouse’s brain and spinal cord. Dr. Sergiu Pasca, the Kenneth T. Norris, Jr. Professor of Psychiatry and Behavioral Sciences, said, “These animal models offer a unique opportunity to study how disease-associated alterations in human brain circuitry manifest in an intact nervous system.” Researchers were shocked by the presence of nerve cells only previously viewed in autopsied human brains.
To grow these “mini brains,” Stanford scientists used xanthan gum to prevent the “mini-brains” from colliding and sticking together. Xanthan gum is a common food thickener in salad dressings, dairy products, and some baked goods made from fermented bacteria from green vegetables like cabbage, Brussels sprouts, and kale. Previously, scientists struggled with the “mini-brains” tendency to gravitate towards one another, making it difficult to create usable organoids that can be safely processed. They used to solve this by painstakingly pulling them apart one by one or growing them one at a time, but this was time-consuming and limited the scale of experimentation. Xanthan gum’s thickening properties increased the viscosity of the culture medium, which, in turn, provided a cushion between the “mini-brains,” keeping them from clumping together and allowing researchers to experiment on larger groups of organoids at the same time. When compared to the organoids grown in the usual method, batches using the xanthan gum had no discernible defects or changes.
Making the organoids easier to grow may help accelerate research into how the brain develops and what can cause development to stall. Bigger, consistent batches can help scientists test treatment methods more efficiently and observe neurological disorders in different ways. While these “mini-brains” might not have any consciousness and can’t replicate the full intricacies of the human brain, they provide a valuable model for scientists to solve the brain’s many mysteries. Despite sounding like a low-budget sci-fi horror flick, these brains aren’t plotting a global uprising or a rebellion against humanity. Instead, they are helping to better understand conditions affecting millions of people worldwide. The real surprise isn’t that scientists grew “mini-brains,” but that the key to doing so came from a Brussels sprout.
