Rocket Bio 101: Why Send Cells to Space?

T-Cell (Lawrence Berkeley National Laboratory)

To say the immune system is complex is like saying that Mt. Everest is tall.  It may be true but it is also a mammoth understatement.

The immune system is an immense network of millions of cells that roam your body like a tiny army.  Some seek out invading pathogens and alert other cells to their presence, some attack and destroy those pathogens, and still others help your body remember those pathogens so that you can get rid of them faster if they return. A healthy immune system is extremely efficient at protecting you from the bacteria and other foreign agents you encounter numerous times in a normal day.  However, as we get older - or, as it turns out, go into space - the immune system begins to fail.   Our lab is trying to figure out why.

We study a type of immune cell, known as a T-cell or T-lymphocyte, that is critical for a healthy immune system.  When a pathogen invades your body, specialized cells will carry and present pieces of the pathogen to T-cells.  This activates the T-cells through a series of internal signals.  Activated T-cells make and secrete protein factors that stimulate other T-cells to grow, an important step in clearing an infection.  But when our bodies go into space, our T-cells don't act like they normally do.  From past experiments on various space flights we know that microgravity is the main culprit. Though we don't know exactly what goes wrong, microgravity interrupts some step in the normal activation pathway.  So even though the cell presenting the pathogen is telling the T-cell to 'turn on' the T-cell doesn't get the message.

We are trying to understand more about how microgravity interrupts those signals in our upcoming experiment on the ISS.  We will be comparing T-cells in normal earth gravity to T-cells in microgravity after an activation event -- like a simulated infection for the cells -- and looking for differences in the genes each express at three different points in time after the 'infection'. These differences will help us understand why T-cells in space don't 'turn on'. 

T-Cells (plus a few trillion other cells) in space! (NASA)

This brings us to a big question - why?  Why do we care about what T-cells do when they are in space?  Well, beyond how exciting it is to understand how our bodies function (and we think it's very exciting!), there are many practical reasons to look at why T-cells don't work as well in space as they do here on earth.  For one, if we plan to send people to Mars or asteroids or the frontiers beyond, it is critical to know how spending a long time in microgravity affects our immune system, and what we can do to protect ourselves from those effects.  By understanding exactly what goes wrong in our experimental cells, we can also learn how to mitigate those errors.

This doesn't just apply to astronauts -- as we get older, our immune system also becomes less effective.  It is hard for scientist to directly investigate how aging weakens the immune system because the changes occur over many decades.  However, a trip to space is comparatively quick, and the changes caused by microgravity are very similar to the changes that occur as we age.  So learning about what happens to T-cells in space can also help us learn about what happens to us back here on earth. 

Our big test day is coming up soon, so you'll get to see exactly what it takes to get a T-cell into orbit (hint: a lot of hard work and an excellent team) as well as how we put our experiment together.  Stay tuned!