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Shawshank Redemption in the lab

On the one that got away

Johanna Lee 29 December 2014

Life sentence: a world of racks

We could fool ourselves by comparing the cage to a nice hotel room. But let’s be honest: this is a prison

When I was a graduate student in biomedical science, I worked in a mouse lab. We used mice as an animal model to study a rare disease – to understand the mechanism and hopefully find a cure.

You have to be fast with mice. Picking them up is the first challenge. You use one hand to grab the tail, and when it tries to escape forward, your other hand should gently and firmly pinch the skin on the back of its neck and lift it up. If you’re not fast enough, it could turn around and bite you.

I was lucky to have been bitten the first day handling mice. It hurt! I’ll never forget that. It also made me aware from day one that mice are living beings that feel stress and fear. They will do whatever it takes to survive – just like us.

The mice at our institute are housed in an elaborate facility in the basement. You need to swipe your badge to access the lower level and swipe again at the entrance. The entrance opens into a long hallway with doors to individual mouse rooms lined along the walls. Inside each room are tall metal racks up to the ceiling, with clear plastic cages placed neatly on top. These cages – each about the size of a shoebox – are where lab mice stay from birth to death.

We are required to follow numerous guidelines to treat the mice in the most humane way possible. No more than five mice can be housed in each cage and they are given unlimited food and water. The mouse technicians check the mice every day and report anything unusual, or if any of them seem ill or in pain. Their cages are changed and cleaned regularly, probably more often than I clean my house. We could fool ourselves by comparing the cage to a nice hotel room – with cleaning maids and the whole all-you-can-eat package. But let’s be honest: this is a prison.

It all happened one day when I got a notification from the mouse facility technician that there was a mouse running freely along the racks in my mouse room. This had never happened before. I hurried down to investigate. By thoroughly checking all of my cages, I finally found the answer: there was a hole in one of the cages! The hole was at a top corner of the cage, about the size of a quarter. I could clearly see tiny bite marks surrounding the small opening. It seems that the mouse managed to find a small crack on the side of the cage and started nibbling its way to freedom.

It’s the Shawshank Redemption of the lab mouse!

By the time I found the damaged cage, another mouse in the cage had also gone missing. But to my surprise, three mice remained in the cage. They saw the hole that led to the outside world and watched their friends escape to freedom. But they chose to stay anyway. They might have watched their cage-mate bite at the plastic all day and thought: “That dude is crazy!”

(Another possibility, however, is that they were too big to fit through the hole. Sadly, most lab mice are obese due to overeating and lack of exercise.)

I guess it shouldn’t be so surprising if the mice stayed in the cage of their own will. It’s all they have seen their entire lives. There’s plenty of food and water. It’s familiar and safe. Why would they give that up to enter the dangerous and terrifying unknown? The cage seems like a prison to me because I know what it could be like outside the cage. But to them, the cage has always been their home – their whole world. They probably never imagined another option.

Perhaps we’re all like lab mice living in a plastic cage. We may not be locked up physically, but our fears and limitations form an invisible boundary that prevents us from being truly free. If there was a crack in this cage we live in, I wonder how many people would be willing to bite their way out?

I never found that missing mouse. There’s no doubt that he could not have survived for long. The mouse facility is pretty much sealed off from the outside world, no cracks or openings whatsoever. Of course, this was designed purposely to make sure no animal escapes. The last thing we want is genetically modified or disease-infected mice running around in the wild. (Although even if they did manage to escape, they are so accustomed to laboratory settings there is no way they could survive for long on their own – let alone find a mate.)

I know how the story ended. After the little fugitive squeezed itself through the hole, he ran along the metal rack, sniffing and searching along the way, eventually finding his way to the floor. He probably ran along the side of the walls, as all mice do. Eventually, he found food in the only place possible – the mousetrap on the floor.

Yes, he died a horrific death. But it’s also a heroic death. There won’t be a movie about him, and I know none of the other mice will be telling this story to their kids. But he’ll always inspire me. He gnawed his way through the boundaries that restricted and defined him, with the urge to be free surpassing all fear. He accomplished something that no lab mouse has ever dreamed of. In those few moments of freedom, he must have been the happiest lab mouse in history.

I hope it was worth it, I really do.