Why I Work with Mice in the Research Lab
Several weeks ago, I wrote about what it means to me to be a “responsible researcher.” When I’m designing my experiments, I try to really think about the impact of my work in a global sense — not only about the impact that a certain experiment might have on my research (in other words, is the experiment designed well so that I can get reliable results?), but also the environmental impact of my studies, the impact of my work on the field of cancer research at large, and even my decision to work with mice. That last part is one that I want to talk about today.
Why do I work with mice in the lab?
My research focuses on studying cancer. Our lab looks at how and why cancer develops, how tumors react to therapy — do they respond (shrink)? Do they relapse (shrink at first, but then grow back again)? — and how metastases form. This is inherently difficult work. Cancer is incredibly complex, with huge variability not only between individual patients, but also sometimes you can see large differences in different parts of a single tumor from a single patient. Since we (as researchers) haven’t fully figured out what happens in cancer, it means that treatment of cancer still remains something that’s not so straightforward.
So what are the options that researchers have to study cancer in the laboratory?
One unique property of cancer cells is that, unlike healthy, non-cancer cells in your body, they can grow outside of your body in the laboratory on plastic dishes (these are called “cultured cells” because we culture them in the laboratory).
Under special conditions (like warm temperatures, humidity to prevent drying out, and a special broth that has nutrients necessary for survival), these cultured cells can grow almost indefinitely in the lab. There have been many cells that have been cultured from human tumors. This gives researchers a really nice start for learning a bit about tumors, and cancer cells are easy to maintain and grow in the lab. But there are a few drawbacks to using cultured cancer cells as well. The main disadvantage is the new context of the cells. The plastic dishes where cells are cultured is very different from your body. So the way that the cells are behaving in these conditions are most likely very different from the way that they would behave when they are situated inside of a tumor.
These conditions of being inside a tumor are another disadvantage of using only cancer cells. There are many different types of cells other than cancer cells that make up a tumor (this is called the tumor microenvironment). These different cell types are not present when cancer cells are cultured in the lab, and they can interact with the cancer cells in very significant ways inside of a tumor. There are some researchers that are trying to make models of tumors in the lab that have the different types of cells, but it is not such an easy thing to re-create.
Finally this brings me to using mice for experiments. There are many different ways that mice can be used to study cancer (more on that in a future post!), but ultimately, mice give researchers a way to study cancer cells actually within the context of a tumor.
But wait, you might ask, why can’t you just use samples from human tumors? Do you really need to use mice?
There are several reasons that mice really are necessary. Some reasons are more practical (for example, the life span of a mouse is shorter than the average human life span, so they are easier to study), and some reasons are more ethical.
One of the ways that researchers gain insight into tumor development and also potential therapies is by looking at particular genes inside of a tumor. This means that we need to manipulate a gene and then see what happens inside the tumor. In a mouse, we are able to directly modify genes and then see what happens, all in a relatively short period of time. This would not be possible in humans for many reasons, including the fact that since we don’t know what role the gene has, it would be unethical to perform these experiments in humans since it could be possible that altering a particular gene could have a fatal effect in humans. With mice we are also able to study some rare types of cancer, where getting human samples would take a long time.
In the end, it was a difficult decision for me to work with mice. I mentioned before that I say “thank you” to every mouse that I work with in my experiments because I want to acknowledge the impact that the mouse has on my research. I also have a clear impact on the mouse that I’m using, but it’s important for me not to lose sight of the fact that this works both ways.
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