Humanity is on the constant search for
improvements in cancer treatments, and the International Space Station has
provided a microgravity platform that has enabled advancements in the cancer
treatment process.
The
oncology community has a recent history of using different microencapsulation
techniques as an approach to cancer treatment. Microencapsulation is a single
step process that forms tiny liquid-filled, biodegradable micro-balloons
containing various drug solutions that can provide better drug delivery and new
medical treatments for solid tumors and resistant infections.
In
other words, by using microcapsules containing antitumor treatments and
visualization markers, the treatment can be directed right to the tumor, which
has several benefits over systemic treatment such as chemotherapy.
Testing
in mouse models has shown that these unique microcapsules can be injected into
human prostate tumors to actually inhibit tumor growth or can be injected
following cryo-surgery (freezing) to improve the destruction of the tumors much
better than freezing or local chemotherapy alone.
The
microcapsules also contain a contrast agent that enables C-T, X-ray or ultrasound imaging to monitor the
distribution within the tissues to ensure that the entire tumor is treated when
the microcapsules release their drug contents.
The
Microencapsulation Electrostatic Processing System-II experiment, or MEPS-II,
led by Dennis Morrison, Ph.D. (retired), at NASA Johnson Space Center, was
performed on the station in 2002 and included innovative encapsulation of
several different anti-cancer drugs, magnetic triggering particles, and
encapsulation of genetically engineered DNA.
The
experiment system improved on existing microencapsulation technology by using
microgravity to modify the fluid mechanics, interfacial
behavior, and biological processing methods as compared to the way the microcapsules
would be formed in gravity.
In
effect, the MEPS-II system on the station combined two immiscible liquids in
such a way that surface tension forces (rather than fluid shear) dominated at
the interface of the fluids. The significant performance of the space-produced
microcapsules as a cancer treatment delivery system
motivated the development of the Pulse Flow Microencapsulation System, or PFMS,
which is an Earth-based system that can replicate the quality of the
microcapsules created in space.
As a
result of this space station research, the results from the MEPS-II experiments
have provided new insight into the best formulations and conditions required to
produce microcapsules of different drugs, particularly special capsules
containing diagnostic imaging materials and triggered release particles.
Co-encapsulation of multiple drugs and Photodynamic Therapy, or PDT, drugs has
enabled new engineering strategies for production of microcapsules on Earth
designed for direct delivery into cancer tissues.
Other
microcapsules have now been made for treatment of deep tissue infections and
clotting disorders and to provide delivery of genetically engineered materials
for potential gene therapy strategies. Microcapsules that were made on the
space station and are targeted at inhibiting the growth of human prostate tumors have been
successfully demonstrated in laboratory settings.
Although
Morrison's team had performed several similar microencapsulation experiments on
space shuttle missions, because of the space station's ability to support
long-term experiments, more progress was made by the eight microencapsulation
experiments conducted on the station in 2002 than from the 60+ prior
experiments conducted on the four space shuttle missions -- STS-77, STS-80,
STS-95 and STS 107.
Benefits
of Space Station Research
The
microgravity environment on the station was an enabling environment that led
the way to better methods of microcapsule development on Earth. The capability
to perform sequential microencapsulation experiments on board the station has
resulted in new, Earth-based technology for making these unique microballoons
that provide sustained release of drugs over a 12–14 day period.
The
station research led directly to five U.S. patents that have been licensed by
NASA and two more that are pending. NuVue Therapeutics, Inc., is one of several
commercial companies that have licensed some of the MEPS technologies and
methods to develop new applications, such as innovative ultrasound enhanced
needles and catheters that will be used to deliver the microcapsules of anti-tumor
drugs directly to tumor sites. More recent research uses a new device for
freezing tumors ("cryo-ablation") followed by ultrasound-guided
deposition of the multi-layered microcapsules containing different chemotherapy
drugs outside the freeze zone within a human prostate or lung tumor.
In a
28-day study, combination therapy resulted in retarding tumor growth 78 percent
and complete tumor regression of up to 30 percent after only three weekly
injections of microencapsulated drug at tiny quantities that should not have
slowed down tumor growth by more than
5–10 percent. NuVue Technologies, Inc., has now obtained two U.S. patents based
on the combination therapy that includes the delivery of the NASA-type
microcapsules.
Upon
securing funding, clinical trials to inject microcapsules of anti-tumor drugs
directly into tumor sites will begin at MD Anderson Cancer Center in Houston
and the Mayo Cancer Center in Scottsdale, Ariz.
Other
potential uses of this microencapsulation technology include microencapsulation
of genetically engineered living cells for injection or transplantation into
damaged tissues, enhancement of human tissue repair, and real-time
microparticle analysis in flowing sample streams that would allow petrochemical
companies to monitor pipeline volume flow.
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