Your gut has One obvious job: It handles the food you eat. But it has another important function: It protects you from bacteria, viruses, or allergens that you ingest with that food. “The largest part of the immune system in humans is the gastrointestinal tract and the gastrointestinal tract,” says Michael Helmrath, a pediatric surgeon at Cincinnati Children’s Hospital Medical Center who treats patients with intestinal diseases. Our greatest contact with the world is what we put in our mouths. .
Sometimes this system malfunctions or doesn’t develop properly, which can lead to gastrointestinal conditions like ulcerative colitis, Crohn’s disease, and celiac disease—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 colleagues published in the journal magazine Natural Biotechnology that they implanted tiny, three-dimensional balls from human intestinal tissue into mice. After a few weeks, these spheres – called organoids – had developed key features of the human immune system. The model can be used to mimic the human gut system without the need for patient testing.
This experiment is an impressive follow-up from 2010, when researchers at Cincinnati Children’s became the first in the world to create a functioning gut-like organ—but they original model to be a simpler version in the lab dish. A few years later, says Helmrath, they realized “we needed it to become more like human tissue.”
Scientists elsewhere are developing similar miniature replicas of other human organs—including the brain, lungs, and liver—to better understand how they develop normally and how things go bad to cause disease. Organoids are also being used as human avatars for drug testing. Since they contain human cells and display some of the same structures and functions as real organs, some researchers suggest that they are a stand better than laboratory animals.
“It’s extremely important that when we’re trying to create these platforms to test drug efficacy and drug side effects in human tissue models, we’re really making sure we’re close and full. enough as the tissue in which the drug will work. eventually in our human body. So replenishing the immune system is a big part of that,” said Pradipta Ghosh, director of the Center for Research Excellence in Humans at the University of California San Diego, which is developing organics humans for drug screening and testing. Ghosh was not involved in the study.
To develop the organoid, the scientists started with induced pluripotent stem cells, created from adult human cells taken from blood or skin. They have the ability to transform into any type of body tissue. By providing stem cells with a specific mix of molecules, the team lured them into intestinal cells. After 28 days of growing in the plate, the cells formed tissue spheres only a few millimeters in diameter.
The team carefully implanted these spheres into mice that had been genetically engineered to suppress their own immune systems so that organ tissue would not be rejected. (The researchers implanted intestinal organoids next to each mouse’s kidneys, so it didn’t actually connect to the animals’ digestive tracts.) To stimulate the organoids to make human immune cells , they had previously given these mice human umbilical cord blood—a source of stem cells that could be transformed into desired cells.
