Glucose metabolism and stem cells

Author: Vanessa da Gama Oliveira (IG: @vgama)

SCG ID: 2206201908

Do you know what is glucose? What about stem cells?

Stem cells

Stem cells are cells that are self-renewable and can become (differentiate) into another cells types. They are like the Mystique from X-Men or the Pokémon Ditto. But, different from these characters, the stem cells can transform only once and then cannot be stem cells again.

They can be embryonic cells, these one which are in the embryo and are going to become (differentiate) in all types of different cells of the fetus, that is going to be a new baby. They also can be adults, that are the stem cells in the baby’s umbilical cord and the bone marrow from everyone. The embryonic stem cells can become any kind of cells (they are pluripotent). This means that they can become more than 200 of different cells types!!! The adult stem cells can become other cells too, but with some “limits” (they are multipotent).

For example, an adult stem cell from de blood (hematopoietic) can become any blood cell like red blood cells and lymphocytes, but they can become a skin cell or a brain cell.

Glucose

Glucose is the sugar that is in our blood and it’s our main energy source. It’s also part of sucrose, another kind of sugar (but bigger), that is the sugar we use to sweeten the cakes and the coffee. We need to use glucose because, besides being our main energy’ source, our brain only works well using it.

But in excess, the glucose we eat and don’t use becomes fat. Moreover, if our cells aren’t able to absorb glucose, it’s excess will remain in the blood. This is what we call diabetes and can provoke several problems in the body.

Puting the things together

Ok so we know that glucose is part of the sugar that sweeten our food, coffee and juices. We also know that glucose circulates in our blood and gives us energy to make everything we do daily. And we know that when it’s in excess, it makes us to be fat and diabetics. But you can be thinking “so what?”. What else do I need to know about it? And what does sugar have to do with stem cells? Three scientists from England investigated and saw why these two things are related (see the original paper here).

When glucose leaves the blood and enters the cell, it’s used to generate energy. This happens when glucose is broken (metabolized) in a process called glycolysis, that means “glucose breakdown”. These scientists study that (and how) this glucose breakdown process regulates the ability of embryonic stem cell (those super-cells that can become any other cell kind) to self-renew. This self-renew ability makes it possible for stem cells to multiply all their lives without becoming other cell kinds.

For stem cells do not differentiate, they need to be in an environment with low levels of oxygen and high glucose levels. Yes! If the stem cells continue to be stem cells, they have to have a lot of sugar inside them. They need a lot of energy to be supercells!

And how does the cell know that there is too much sugar inside it? Through the metabolism of this glucose. When glucose is metabolized, other substances as lactate and NADH are generated. The stem cells have sensors that attach to the NADH and think: okay. There's glucose here. That is also why it needs to have little oxygen. Because little oxygen favors the glucose to enter the cell. In addition, if you have too much oxygen, glucose can be metabolized by other routes.

If you have little glucose, the stem cell will lose pluripotency and will eventually turn into another cell type. Likewise, if the glycolysis sensors (those that bind to NADH) are changed or removed from the cell, it’ll also lose pluripotency.

And so what?

How much important is knowing this relationship between stem cells and glucose? The stem cells will continue to be stem cells, even if we don’t know nothing about them, won’t they? In our body they will, but outside the body maybe they won’t.

It is very important that we can keep stem cells out of the body without being differentiated. This is called cell culture: when you keep a lot of living cells on glass plates, giving the nutrients and other conditions they need to not die. And in the case of stem cells, to not differentiate. And it is very difficult to keep them in culture.

Now we know that in addition to low levels of oxygen, it takes a lot of glucose and why. In this way, it is possible to have a lot of pluripotent stem cells in the culture and they can be used, for example, for regenerative medicine. They can be used to repair damaged organs in the body, without the need for a transplant (since they can be transformed into the cells of that organ).

What did you think of all this? Did you ever imagine that sugar (glucose) could have some connection with stem cells? Would you like to know more about the roles and little-known sugar roles? PS: Post originally post on the blog: oqueacientistadisse.wordpress.com/ (with Portuguese versions) Reference (the link is already included in the text): https://doi.org/10.1016/j.stemcr.2019.02.005