James Cameron’s 2009 epic alien adventure, Avatar, transports us to Pandora, a moon orbiting an exoplanet in the nearby star system (Alpha Centauri A) approximately 4.37 light-years from Earth. We learn about its history, biodiversity, and picturesque scenery through the Na’vi—a race of giant, blue-skinned humanoid aliens who inhabit it. 

The premise of the film is that humans can enter the world of these 10-foot aliens, by way of an Avatar—a genetically engineered half-human, half-Na'vi hybrid. A human driver controls their specific Avatar with their mind, thanks to a high-tech linking mechanism. 

Although that sort of technology doesn’t exist off-screen, NASA does have its own version of an Avatar program on the International Space Station in the form of its rodent research program. To better understand how microgravity affects various organ systems, the space agency relies on data collected from its astronauts but also from various groups of rodents (affectionately dubbed moustronauts). 

Se-Jin Lee, a professor at the Jackson Laboratory and University of Connecticut School of Medicine is the lead researcher on a new experiment headed to the space station this week. Lee and his team are sent a crew of 40 mice to the space station aboard SpaceX's Dragon spacecraft to study muscle degradation in space.

“Mice are avatars for human disease,” Lee told Supercluster. “We use mice because their physiology and biology is very close to that of humans.” 

Mice are what scientists refer to as model organisms: An organism whose biological processes are similar to humans and have been widely studied. Rodents are just one example; other types include fruit flies, and certain types of yeast. 

These types of organisms not only share commonality among biological processes but also have shorter lifespans, making it easier to study long-term and multi-generational effects in a condensed period of time. The average life expectancy of a mouse is approximately two years. When we examine what happens with rodents as they age, we notice similarities to the degenerative processes that affect humans later in life—but these processes occur much more rapidly in animals.

Rats and mice have been used extensively in spaceflight studies, dating back to the dawn of the space age in the 1950s. But as many of those early missions were brief, lasting no more than two weeks, researchers were limited in the data they could collect. That all changed with the advent of the commercial cargo program.

Lee says that the focus of his team’s research has been on a molecule called myostatin—a protein that limits muscle growth in both mice and humans. Without myostatin, their muscles grew to twice the normal size, earning them the moniker “mighty mice”. (A nod to the famed cartoon character Mighty Mouse.) Though, visually the mighty mice are only slightly more buff.

“With twice the amount of muscle mass, you would think it would be like Arnold Schwarzeneggar standing next to me,” Lee joked when asked if observers could easily distinguish between the normal mice and their beefy counterparts. “The visual differences are more subtle, but you can tell them apart.”

Based on their initial results, the team is hopeful that Myostatin could be used to treat a variety of muscle-wasting disorders. By sending these enhanced mice into space, the team can see how they adapt to microgravity and how their muscles respond.

Because microgravity mimics the same type of muscle loss associated with common muscle-wasting disorders we see on Earth, the team wants to test blocking myostatin on orbit to determine if it can prevent muscle loss in space.

To that end, Lee and his team are sending a two-part experiment into space. The first part will look at how the mighty mice respond to microgravity. Will they lose muscle mass? Will it more than their not-so-mighty counterparts? Only time will tell. The second part looks at the effectiveness of an experimental drug that not blocks myostatin but also another protein called actavin, which plays a crucial role in regulating bone density.

A total of 40 female mice flew on the CRS-19 Dragon when it launched on Thursday December 5th atop a Falcon 9 rocket. The lot is divided into five groups, each with a different goal. One group will be comprised of the mighty mice, one will be a control group composed of normal mice, a third set will be normal mice that are given the myostatin blocker, while the last two groups are just along for the ride. Their jobs begin when they return to Earth. At that point, each of the remaining mice will be given a dose of the myostatin-blocking drug to see if it will help them recover muscle mass lost while in space.

This research could help lead to improved therapeutics for patients on Earth, like the elderly or those affected by muscular dystrophy, but could also improve astronaut health on long-duration missions.

“One of the biggest problems in spaceflight is that astronauts are not subjected to the same gravity that we experience on Earth,” explained Lee, “and as a result they lose a tremendous amount of muscle mass.”

With plans to return to the moon and eventually set foot on Mars, this is one side effect of spaceflight that researchers are eager to mitigate.

As part of that fourth resupply mission, this same Dragon carried the first crew of moustronauts to ever fly on a commercial vehicle. Additionally, it ferried the rodent habitat the new crew will inhabit for the next month. All 40 mice are expected to return to Earth alive with Dragon on January 6th so that any potential muscle loss during their stay can be evaluated.

The International Space Station is close to celebrating a major milestone: 20 years of continuous human presence. All of the research on board this Dragon as well as the others that came before it, has played a crucial part in not only understanding the effects of living and working in space but is also preparing us for the future where we could one day live on Mars.

There are still many more spaceflight-related health issues to address before we set foot on the red planet, but thanks to these mighty mice, we may be one step closer.