How Tiny Lab-Grown Organs Helped Us Study COVID-19

Story by CuriosiTEA JC Team

Original Research Article: Han et al., Nature Methods, 2022.

Journal link: https://www.nature.com/articles/s41592-022-01453-y

When COVID-19 spread around the world, scientists needed a safe way to study it. So they grew organoids (i.e. tiny models of human organs) in the lab from human cells. With these little models, they could watch how the virus affect different organs and test medicines and vaccines. Organoids are also animal free, because they are grown from human cells instead of using animals.

COVID-19 was one of the worst sicknesses in recent history. A lot of people think it only hurts the lungs. But the virus, called SARS-CoV-2, can also hurt the heart, kidneys, brain, gut, and more. Before scientists could make treatments, they had to figure out how the virus gets into cells and what it does once it is inside. Organoids gave them a safe way to do that.

Studying a dangerous virus in real people isn’t safe. So scientists asked one big question: could tiny lab-grown organs act enough like real organs that we can learn which cells the virus infects and find treatments?

Organoids are grown from stem cells, which are special cells that can turn into many other kinds of cells. Different teams grew organoids for lots of body parts — lungs, intestines, kidneys, liver, brain, tonsils, retinas, heart, and capillaries (tiny blood vessels). Then they added the virus and watched. It turned out the virus didn’t attack every cell. To get inside, SARS-CoV-2 uses its spike protein to grab onto a spot on the cell called ACE2. Cells that had ACE2 could get infected. Cells without it were mostly safe.

Some organoids were grown from stem cells and some from adult tissue, and both kinds mattered. Stem cells grow fast, but the organoids they make can act like the cells of a baby. Since COVID-19 mostly affects adults, scientists also needed organoids made from adult tissue to see how the virus acts in grown-up cells. Scientists used them to test medicines and to study how the body fights back after a vaccine.

Organoids are helpful, but they’re not perfect. Most are just one kind of organ, and they’re missing immune cells. They also don’t connect to each other the way re

al organs do, even though in a real body the organs all work together. So scientists want to build better organoids — adding immune cells, linking organoids together.

Student Reflection: What surprised me most was that this virus can hurt so many organs. I always thought COVID-19 was just affecting lung. A question I still have is how scientists will add immune cells and connect organoids together, because that seems like a big missing piece. This connects to the real world because a lot of medicine gets tested in tiny lab models first. It made me realize how much work happens before a single pill or shot ever reaches a person.