HUMAN intestinal tissue has been made in the lab for the first time from stem cells. The achievement is a big step towards replacing diseased gut tissue with fresh material in people with intestinal conditions such as inflammatory bowel disease and Crohn’s disease.
Measuring a few millimetres across, the pieces of intestinal tissue made by the month-long process contain all the cells and features found in normal gut tissue, and grow by the same route as in embryos. “Our organoids are not quite the shape of the intestine, but like segments of it,” says team leader James Wells of the Cincinnati Children’s Hospital Medical Center in Ohio.
Wells’s team first turned human skin cells into pluripotent stem cells, which can grow into any type of tissue. They then made flat sheets of a specific layer of gut tissue by exposing the stem cells for three days to a growth factor called activin A. Next, they made the sheets roll up into spheres and tubes by exposing them to a further pair of growth factors.
Finally, the team grew the tissue in a three-dimensional system, which coaxed it into forming all the structures found in gut tissue, including the finger-like villi that protrude inwards to increase surface area, and recesses called crypts containing the intestinal stem cells that renew the gut lining weekly (Nature, DOI: 10.1038/nature09691).
The organoids also developed layers of muscle vital for squeezing food through the gut. The next step is to add nerve cells to make the muscles contract, then test these in animals.