Lab-Grown Human Brain Tissue Works in Rats

There were tiny blobs of lab-grown human brain tissue. Stem cells were cultivated into clumps of tissue. Some of the cells and properties of a real human brain can be found in brain organoids.

They are not as complex as the real thing, so to boost their realism, researchers have tried to transplant human organoids into the brains of rodents. The cells failed to integrate into the brain in previous experiments. The organoids formed connections with the animals' own brain circuits, a sign that they can develop more sophisticated features.

The somatosensory cortices of newborn rats are where the human cells were placed. The organoids grew to occupy a third of the rat brain. Today's research was published in the journal Nature. The assistant professor of neurosurgery at the University of Pennsylvania says that the study pushes forward what organoids can do in terms of their functional integration into the brain.

The transplants of organoids in adult rodents didn't work out. The organoids were placed early in the development of the young rats. The adult brain is not able to form new connections quickly because it is less plastic. Sergiu Pasca, the corresponding author on the study, said in a press briefing that the nervous system shuts down development. The ability for cells to form connections stopped after we transplant.

Pasca and his colleagues found that rat brain tissue was home to nerve fibers that extended into the human body. These connections don't exist in brain organoids grown in a dish, a limitation that has forced scientists to transplant orgaonids into living animals.

According to a professor of stem cell and regenerative biology at Harvard University, sensory stimulation of the tissue is what develops the brain. In a brain, sensory stimulation is needed to form neural pathways.

Not only did the organoids grow and integrate with the tissue, but they also showed characteristics not seen in organoids grown in a dish. The cells taken from patients with Timothy syndrome are used by the researchers to grow organoids. The organoids were able to communicate with other cells by developing abnormal dendrites. Animals were used in earlier organoid experiments.