Above: Protein crystals grown on Earth are deformed by gravity.
Above: Researchers and public health agencies can use satellite images
to track areas of high risk for disease outbreak.
Above: Scientists use x-ray crystallography in drug design to determine
the molecular structure of target proteins.
Above:Crystals grown in space can form flawlessly.
Attacking from Above & Below - Space-Based Fight Against Disease
Penicillin, one of the most important discoveries in medical history, was found
purely by accident. Today, with the furious scramble to treat and cure diseases
ranging from malaria to AIDS, drugs are engineered rather than stumbled upon.
As important as treatment is to the victims of disease, the ability to track and
predict outbreaks can help prevent entire populations from ever succumbing to
a given illness. Surprisingly enough, space exploration has resulted in new ways
to fight disease at both the drug development and epidemiological levels.
A Green Thumb for Space Crystals
For the most part, drugs are not so much "discovered" anymore. They
are designed. Scientists can now target a specific protein of a pathogenbe
it bacterial or viral to maximize a drugs effectiveness while at the
same time minimizing possible side effects. This method, known as rational drug
design, has one major downside. The exact structure of the target protein must
be determined, down to the last molecule.
To uncover this molecular structure, scientists use x-ray crystallography.
A crystal of the protein is bombarded with x-rays to produce a pattern which,
much like a fingerprint, reveals the identity of the proteins atomic structure.
But to get an accurate pattern, the crystal must be as free of imperfections as
possible. Growing such crystals can be extremely difficult, even impossible, on
Earth because gravity causes the crystals to settle on top of one another resulting
in structural flaws.
So, how do you grow crystals without gravity getting in the way? This is where
NASA has been able to help out. In the microgravity of space, the 3-dimensional
structures of crystals can form flawlessly and achieve larger sizes. Protein crystals
grown on Space Shuttle missions provide scientists with up to 40% more information
than crystals grown on Earth.
In fact, NASA missions have led to the discovery of 30 protein structures and
several novel drugs that are in various stages of clinical trials. Close to completion
is a treatment for T-cell lymphoma, an aggressive form of cancer. Drugs to treat
psoriasis and rheumatoid arthritis are also on the way.
Potential treatments or cures for diseases ranging from influenza to diabetes
are being developed based on protein structures. Many of these target protein
structures could not have been determined without the help of crystals grown in
Stalking a Tropical Killer
Chagas disease is an increasingly widespread, yet largely ignored, parasitic
infection that affects an estimated 1820 million people in Central and South
America. The parasite can remain dormant for years, but once active, it usually
attacks the heart muscle of its host. Eventually, the muscle becomes so thin that
it bursts from regular blood pressure levels. Chagas deaths are often mistaken
as heart attack fatalities. Currently, there is no cure.
By the early 1990s, Costa Rican researchers and their Latin American
collaborators had isolated extracts from the native rain forest plants that block
key enzymes in the parasite. Still, they needed to know the structure of the target
enzyme in order to determine exactly what substance in the plants was interacting
All previous attempts to grow crystals of the target enzyme had failed, until
a Costa Rican astronaut suggested asking NASA for help. Since 1996, Chagas crystals
have been flown on three Shuttle missions, and efforts at finding a cure for Chagas
have doubled. Project ChagaSpace is an international cooperative effort with seven
countries working full-time to find a much-needed cure.
Tracking Disease From Space
Many diseases, such as lung cancer or heart disease, can develop as the result
of genetic predisposition or personal lifestyle choices. Others tend to be spread
by external agents, or vectors, such as insects or rodents. Malaria, cholera,
hantavirus, and Chagas disease are all examples of vector-borne diseases.
The ability to track these vectors and other risk indicators helps public health
officials prevent or reduce the impact of potentially devastating disease outbreaks.
The remote sensing technologies NASA uses to study other planets and monitor the
Earths environment are very good at tracking these indicators that are associated
with disease outbreaks.
Populations of disease-carrying mosquitoes increase as the result of certain
weather patterns. Deer ticksthe carriers of Lyme diseaseare more prevalent
in areas with certain types of vegetation. The insect that carries the Chagas
parasite is linked to high levels of deforestation, as well as seasonal warm weather.
Satellite imagery can be used to track these indicators in the air, on land, or
in the sea. Maps indicating areas of high risk can then be developed. Shifts in
high risk areas can easily be tracked with remote sensing data, and preventative
measures such as pesticide application can be taken as needed.
In an effort to facilitate the use of remote sensing in public health efforts,
NASA sponsors the Third World Foundation. The organization trains scientists from
developing nations to use the technology in tracking diseases specific to their
countries. The space agency makes the technology and data sets available for use
by these researchers worldwide.
In the future, NASAs role in disease-related research will continue to
grow. The International Space Station will offer a platform for microgravity crystal
growth experiments. The agencys arsenal of Earth-observing technologies
is expanding as well. More and higher resolution data will be available to public
health organizations and epidemiologists. By putting on the squeeze from above
and below, NASA is making a contribution in the fight against disease planet-wide.