Cell specialisation

Lina is sick. Poor thing. Uuu... I need to go to a repair shop. A repair shop?

Lina probably has a fever. She is delirious. Everybody knows that if you're ill, you see a doctor. If the car breaks down, you go to a repair shop. But why, really?

Yes, it's obvious. Because we humans are good at different things. We are -- specialised. And the same goes for cells. They are also specialised.

In a human body, there are hundreds of different kinds of cell. Nerve cells, bone cells, eye cells, and lots of other cells with their unique properties and tasks. When a sperm and an egg fuse at conception, the very first cell of a new human is created. That cell is not specialised. However, it does have a special ability.

From this first cell, it must be possible for all other cell types to develop. That ability makes it a stem cell. The first cell starts to divide. It becomes an embryo, a tiny cell clump, that will grow and become a small human being. The cells continue to divide.

The embryo grows, and eventually the cells become more specialised. They change, in form and function, and develop into blood cells, nerve cells, and the special cell types for various organs. This process is called cell differentiation. When the cells are differentiated - and specialised - they can no longer develop into any other kind of cell. They are no longer stem cells.

There are different kinds of stem cell. We saw that stem cells in the embryo have a maximal ability to develop into any cell type. But stem cells exist also in adults. In this case, stem cells form a repair system for replacing damaged cells, and damaged tissue. This makes stem cells very interesting to scientists.

Can stem cells be used to produce organs that exactly match your body? If your kidney is damaged and has to be removed, can it be replaced with a new one, grown in a laboratory? Yes, maybe. Already, there are examples of knees being repaired with artificial tissue, created with the help of stem cells. Many scientists are working hard to produce other organs this way.

Perhaps this is the future in our hospitals. You could say that the researchers are trying to design replacement parts for the human body... a bit like when you produce parts for a car. Perhaps, there are some similarities between mechanics and doctors. But Lina doesn't need any replacement parts.

She just needs some extra sleep and maybe a little medicine. Get well, Lina!