Brain Blobs and the Power of Hormones

Monday - June 19 2023, 00:54 UTC - 1 year ago

This article discusses the progress made in growing mini-brains and the discovery of their unique ability to produce hormones. Scientists from Japan have developed mini-brains that mimic the pituitary gland, the hormone center of the brain, and implanted them into mice. The mini-pituitary was able to pump out hormones for over 24 weeks without any side effects or immune rejection, paving the way for research into potential pituitary regenerative medicine. Additionally, scientists were able to make the mini-pituitary produce a hormone to launch a counterattack to battle immune stress.

Brain organoids have come a long way. These mini-brains, at most the size of a pea, are made from stem cells or reprogrammed skin cells and churned inside a bioreactor full of nutrients. With different molecular ingredients, scientists can nudge mini-brains to gradually develop striations and structures similar to a growing fetal brain, with the hope of one day replacing faulty brain regions with lab-grown brain blobs. This week, a team from Japan added a long-overdue superpower to mini-brains: pumping out hormones that control life.

Starting with human stem cells, they grew an unconventional batch of mini-brains that mimic the pituitary gland, the hormone center of the brain. A tiny nugget tucked at the base of the skull, the pituitary is a central highway that links the brain to other parts of the body, controlling stress, metabolism, heart and blood vessel responses, and reproduction. When transplanted into mice with a damaged pituitary gland, the human cells pumped out a crucial hormone that’s normally secreted by the gland at a steady pace. The transplant lasted for over 24 weeks without any side effects or immune rejection. The craziest part was that the mini-pituitary was tucked near the kidneys—instead of the brain—underneath a protective fiber-like sheath that enveloped it. Although still requiring surgery, the method shows that when it comes to brain-made hormones that flow into the bloodstream, it’s not always necessary to transplant healthy replacements into the host’s brain itself. Injecting the mice with a chemical that mimics bacterial infection made the transplanted nugget pump out a hormone from its new kidney habitat to launch a counterattack to battle immune stress. While far from ready for use in humans with pituitary problems, these "soggy" organoids help bridge the gap between brain and body using their unique form of hormonal ambassadors. "This method of generating purified pituitary tissue opens new avenues of research for pituitary regenerative medicine," said study author Dr. Hidetaka Suga of Nagoya University.

The Hormonal Brain .

Mini-brains are a breakthrough for neuroscience. They give unprecedented insight into the early stages of human development. They spark with electrical activity. And, perhaps a bit Frankenstein-y, mini-brain chunks can physically hook up to dissected muscle in a lab dish and control their contractions on demand, and restore eyesight to injured rats. Their increasing sophistication even prompted a heated debate on whether these disembodied brainy chunks may become conscious.

Yet they’ve been lacking one major ability: showering the rest of the body with a deluge of hormones. When thinking of brain cells, neurons immediately come to mind. I picture their computational prowess, using electrical signals to weave into dynamic networks that underlie our cognition, learning, reasoning, and memories. But neurons aren’t the only cells in the brain.

There’s a tiny nugget tucked deep inside the back of the head that wields tremendous powers. As a kid, it helps you grow. In adults, it pumps out doses of stress hormones—when needed to keep you on your feet—and maintains basal metabolic rates. Called the pituitary gland, it links the brain to the body using a network of hormones, coordinating communication between delicate tissue layers, and controlling activity throughout the body.