Question: How can an organoid be taken as an intestine? And suchlike taken, how does an organoid act in terms of digestion?

Eva Rath answered on 20 Jun 2023:

An organoid cannot be compared to a whole intestine. Intestinal organoids only consist of the cell layer that builds the surface of the intestine (epithelial cells). The intestine has additional features like connective tissue, immune cells, and blood and lymph vessels underneath the epithelial cells of which an organoid consists of. Salivary glands, pancreas and liver produce the digestive fluids needed to break down food into nutrients – of course they are not present in intestinal organoid culture. Therefore, we only study nutrient uptake (which is what intestinal epithelial cells do) and not digestion in organoids. We give only nutrients to organoids, as provided by food after nutrition.

But scientists work to improve organoids as a model:
The major drawback of organoids is that they consist of only few cell types (which is already better than cell lines, which almost exclusively consist of only one cell type). Especially if you want to study complex diseases, this is a limitation. My field of research are inflammatory bowel disease (IBD). Nobody knows exactly why IBD patients suffer from inflammation of their small and/ or large intestines. A hypothesis is that a combination of genetics and a disadvantageous mix of normal gut bacteria cause IBD. In IBD, the body´s immune system fights the harmless bacteria that live in the intestine and actually support your health by producing vitamins and converting dietary fibers. Therefore, if scientists want to explore the mechanisms that cause IBD, they need a model system that includes gut bacteria, IECs and immune cells (that are the actual mediators of inflammation). A lot of scientists work on developing more complex models using organoids: so called “organs on a chip”. These chips are small plastic containers on which organoids derived from different organs (for example gut, kidneys and liver) are linked through a fluid system that mimics the blood flow. Bacteria and immune cells can be added to this system, and the interaction of bacteria and different cells can be studied. With this attempt, scientists hope to get a better insight into the complex processes that result in inflammation (IBD).