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I work with human embryonic stem cells, but unlike a lot of scientists who might want to find ways to produce hearts, livers, kidneys or brains from their stem cells, I’m trying to find out how we can make a stem cell stay as a stem cell. A lot of the time stem cells decide (without us telling them what to do) to become a different cell type, such as a muscle cell or a heart cell. Sometimes different stem cells that are next to each other might become different types of cells. This can be a problem if you have stem cells that you want to make into a liver, but some of them are already becoming heart and kidney, because a mix of different types of cells would be useless for treating your patient with liver disease. Because of this, some scientists, including me, are trying to find what makes stem cells happy to stay as stem cells.

One thing we know about stem cells is that they consume a lot of glucose sugar. When the stem cells become other types of cells they start to consume a lot less sugar. We are trying to find out how this is controlled and how we can affect how much sugar the stem cells consume. One thing that we know affects how much sugar the stem cells need is how much oxygen is available to the stem cells. All cells in our bodies need oxygen to live and get oxygen from the blood, but some cells need and get more oxygen than others. It seems that stem cells need less oxygen than other cells and giving them more oxygen than they need changes the way they behave and makes them less happy to stay as stem cells. At the same time, giving them more oxygen than they need makes stem cells consume less sugar. I’m interested in how and why having more oxygen makes stem cells consume less sugar and makes them less happy to be stem cells.

One great thing about my work in a lab is that I can start work whenever I want in the morning! Generally I start work at 9 and go home at 5, but some days I get in later and some days I leave early – on the best days I get to work late and leave early!

To keep the stem cells happy, I need to feed them every day and move them onto new plates every few days so that they don’t grow on top of each other. This means that I have to look at them every day to see whether I think they just need to be fed or whether there are too many of them on that plate and I need to take some of them to go onto a new plate where they will have more space. Because the stem cells are so needy I have to go into the lab to do some work on weekends quite often, which is really annoying!

Although feeding the stem cells is something I do every day, it isn’t actually the work I do to try to learn new things about the stem cells. To learn more about the how stem cells consume sugar and how they are affected by the amount of oxygen available, I have to do various experiments to compare stem cells that I have grown separately and differently. For example, I always have stem cells that are being grown with a lot of oxygen and also stem cells that have very little oxygen. These stem cells are grown in a liquid with sugar and other nutrients in it that the stem cells need to grow. If I know how much glucose sugar there is in this liquid before I put the stem cells into it and then I can measure how much sugar is left in it a bit later, then I can work out how much sugar the stem cells have eaten from that liquid. As I do this experiment with stem cells that are grown in lots of oxygen and stem cells that are grown with very little oxygen, I can see whether the cells grown in less oxygen eat more or less sugar. Recently I found out that stem cells grown in less oxygen do eat more glucose sugar.