Getting seven experiments on the International Space Station requires a really good idea. Like a brand new way to attack tumors\u2014one that you can only make in space.<\/p>\n
Space has unique advantages for making medicines. Its very low gravity makes it possible to grow molecules in shapes and uniformity that are difficult to create on Earth. If they can be reliably and affordably produced, such molecules could have all kinds of novel uses in industry and medicine.<\/p>\n
University of Connecticut engineer Yupeng Chen has been growing one such unusually rod-shaped nanoparticle, called a Janus base nanotube, on the International Space Station (ISS). The success of Chen\u2019s last five experiments has led to this latest $1.9 million award from the Center for Advancement of Science in Space and NASA’s Division of Biological and Physical Sciences. With it, Chen and his colleagues will use the space station\u2019s unique environment to grow pharmaceuticals whose shape is their secret weapon.<\/p>\n
During this mission, the team will grow Janus base nanotubes that carry interleukin-12. Interleukin-12 is a protein already produced naturally by the human body, but only in small quantities. It stimulates the development of helper T-cells, which recruit other parts of the immune system to kill invaders and cancer cells. Many tiny, incipient cancers are killed off by our body\u2019s interleukin-12 response all the time.<\/p>\n
But cancerous tumors that become big enough to be noticed are clever. They often have ways to dampen the body\u2019s interleukin-12 response. However, delivering enough interleukin-12 could overwhelm the tumor\u2019s responses. The technique has worked well in the lab – so well that it has already been tried in humans. But there were some problems.<\/p>\n
\u201cGood tumor control, but the side effects in humans are very severe,\u201d says UConn School of Medicine immunologist Kepeng Wang, who is working with Chen on the project. During a past clinical trial, there was a tendency for interleukin-12 therapy to provoke fevers, flu-like symptoms, and other problems. Two people in the trial died. The results were clear. \u201cYou cannot inject the naked protein\u201d into people, Wang says.<\/p>\n
But perhaps you could inject it clothed.<\/p>\n
Others have attempted to wrap toxic drugs inside of benign exteriors. Many of these efforts have involved nanoparticles: tiny roundish shells only a few hundred atoms or so across that can safely pass through the bloodstream until they get to their target. But round nanoparticles are too wide to get inside most solid tumors.<\/p>\n
Solid, though, is something of a misnomer; tumors do tend to be less dense than healthy tissue. They have cracks and openings that a sufficiently small drug could sneak through. Most anti-cancer medications aren\u2019t small enough. Nanoparticles aren\u2019t generally small enough, either.<\/p>\n
The super-skinny Janus base nanoparticles Chen\u2019s lab is working on are different. They can slip into the cracks and attack tumors from the inside. With cross sections of just 20 nanometers, they can also pass through the tiny windows between cells in the working area of the kidneys, and the openings in cartilage in the joints. Such skinny molecules could treat all sorts of disorders simply by getting to places other drugs can\u2019t.<\/p>\n
They can also contain small molecules such as interleukin-12 within themselves, and then release them inside of a tumor. That would hopefully spare patients the severe side effects that occurred with naked interleukin-12.<\/p>\n
Such specially shaped molecules would be game-changing, and manufacturing them in space has many advantages. For example, it\u2019s well known that crystals grow better in microgravity.<\/p>\n
\u201cThey have more time to fill cavities and assemble, because there are no gravitational pressures. Since our nanotubes are self-assembled, there is a lot of similarity to crystallization. Without gravity, there\u2019s no sedimentation, the molecules can rotate and assemble freely, and make better structures,\u201d Chen says.<\/p>\n