Scientists Grew Mini Human Guts Inside Mice

An anonymous reader quotes a report from Wired: Your gut has an obvious job: It processes the food you eat. But it has another important function: It protects you from the bacteria, viruses, or allergens you ingest along with that food. "The largest part of the immune system in humans is the GI tract, and our biggest exposure to the world is what we put in our mouth," says Michael Helmrath, a pediatric surgeon at Cincinnati Children's Hospital Medical Center who treats patients with intestinal diseases. Sometimes this system malfunctions or doesn't develop properly, which can lead to gastrointestinal conditions like ulcerative colitis, Crohn's disease, and celiac -- all of which are on the rise worldwide. Studying these conditions in animals can only tell us so much, since their diets and immune systems are very different from ours. In search of a better method, last week Helmrath and his colleagues announced in the journal Nature Biotechnology that they had transplanted tiny, three-dimensional balls of human intestinal tissue into mice. After several weeks, these spheres -- known as organoids -- developed key features of the human immune system. The model could be used to mimic the human intestinal system without having to experiment on sick patients. The experiment is a dramatic follow-up from 2010, when researchers at Cincinnati Children's became the first in the world to create a working intestine organoid -- but their initial model was a simpler version in a lab dish. A few years later, Helmrath says, they realized "we needed it to become more like human tissue." [...] Matthew Grisham, a gastroenterologist at Texas Tech University Health Sciences Center who wasn't involved in the new study, says the findings are exciting because these structures have a "human immune cell composition very similar to that of the developing human gut." He says the organoid model will help researchers investigate the mechanisms responsible for intestinal infection, inflammation, and food allergies. The Cincinnati researchers also hope their organoids could one day be used to treat people born with genetic defects that affect their digestive systems, or those who have lost intestinal function to cancer or inflammatory bowel diseases. That these organoids can flourish in a mouse is an encouraging sign that they might be able to grow on their own if transplanted into a person. Using induced pluripotent stem cells taken from patients, scientists could perhaps one day make customized tissue patches to help heal damaged organs. In the near-term, Helmrath says his team plans on making organoids from patients' own cells to test out possible individualized therapies. "This is right around the corner," he says.

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