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Every second there are about 1 million cells dying in our body and this is normal!  It sounds like a huge number but if this didn’t happen we’d get some pretty nasty diseases.  My work is all about how our immune system cells recognise and eat the constant stream of dying cells.  If the dying cells aren’t eaten quickly, they fall apart and spew their contents into our bodies and this causes inflammation and disease.  So spotting death and dealing with it quickly are essential.  No one wants to be full of rotting cell corpses!

The immune system cells that do the eating are called macrophages (this means big eater) and they are the prettiest and best cells in our body (in my entirely ‘unbiased’ opinion).

Here’s a picture of a big macrophage eating dying cells.  The three circular structures in the middle are nuclei (macrophages can have more than 1 as these cells can fuse).  The intense purple bits (see the arrows) are dying cells that have been eaten.

They walk around all day and right through all our tissues to keep checking for death and infection.  If they find death, they eat it and keep things calm.  If they find infection, they eat it and ring alarm bells so the whole of the immune system power can be thrown at the invasion.

Here’s a snap of cells I’ve made fluorescent.  The red cell is a macrophage and the green are the dying cells!  This microscopy is called fluorescence microscopy and it lets us see cells (and molecules) if we make them fluorescent.

I am really interested in working out how macrophages ‘sense’ the death in their environment.  They seem to do this by detecting little bits of dying cells that are released.  In fact this cell death is pretty cool to look at too.

When you see a cell dying (by a process known as apoptosis – pronounced ‘ap-oh-toe-sis’) its surface looks like it is boiling as its membrane bubbles.  Check out this image which shows the cell membrane green and you can see surface ‘bubbles’.  Some of these bubbles are released and are a sure sign that death is around.  The macrophages eat these tasty little starters and follow the trail until they find the main cell corpse – the main course!

Why is this all interesting?  Well, quite simply, when cell death happens in a poorly controlled manner you get diseases including cancer, heart disease, neurodegeneration (brain getting ‘old and weak’ – ask your teacher!), autoimmunity (where your immune system attacks you).  So if we can understand death and removal of dead cells, we ought to be able to make a real difference!

But I am also a University lecturer and so communicating my passion for research into death is a key part of my job.

Coffee, coffee, coffee.  But in between I can spend a huge amount of time planning work and thinking up experiments.  I don’t often get chance to be in the lab myself now but the best days are those when I am in the lab.  On with the white coat and gloves and heading in to culture some cells.  Here’s a snap of me and my team from a couple of years ago.  OK so it’s a blue coat but you get the idea right?

Often my research will include taking blood out of willing donors and splitting the blood down to its individual parts.  If we centrifuge our blood (with a dense liquid added) we can split it into layers.  On this photo we see the liquid part of our blood at the top.  This is the straw coloured plasma.  At the bottom we can see the red cells (very very very deep red from all the red blood cells) and in the middle will be the white blood cells and the dense liquid.  We normally isolate monocytes (a type of white blood cell – also known as a leukocyte – that, when mature, is a macrophage).  By growing these monocytes in culture we can make them grow up into macrophages and we can watch what they do.

Here’s a video of a monocyte that matures into a macrophage before recognising a nearby cell that dies…..and then gets eaten.

To keep our cells in culture free from infections, we use special cabinets that filter the air to keep it clean.  So this protects our cells from the outside world.  But these cabinets can also protect the scientist from the work (some stuff we do in labs can be really dangerous).

But I’m also a University lecturer so on teaching days things can be very different – fun but in a different sort of way.  It can take some real preparation to be able to stand up and talk to 400 students and explain new and complicated material.  But if students see that I enjoy it, they seem to enjoy it too.  I always start with a song (but thankfully for the students, it isn’t me singing).