Interleukin-12 is a naturally occurring protein essential for the proper
functioning of the human immune system. Having either too much or too little
interleukin-12 may play a role in the development of many diseases,
including some cancers and auto-immune disorders like Crohn?s, psoriasis,
and rheumatoid arthritis. In turn, modulating interleukin-12 levels could
yield new therapies for those conditions.

In an effort to create a new and cost-effective method for producing
interleukin-12 and make more of the scarce protein available for research
and therapeutic development, a team of scientists at Worcester Polytechnic
Institute?s Life Sciences and Bioengineering Center (WPI) and the Arkansas
Bioscience Institute at Arkansas State University (ABI) reports that hairy
roots from genetically modified tobacco plants can be grown in a contained
novel mist bioreactor system, yielding significant quantities of murine
interleukin-12. A paper detailing the results of the study has been
published early, online, by the journal Biotechnology and Bioengineering and
will appear in the journal?s printed edition early in 2009.

?We are very encouraged by the results of this study,? says Pamela J.
Weathers, PhD, professor of biology and biotechnology at WPI, co-author of
the paper. ?Interluekin-12 is a valuable protein and there just isn?t enough
available for biomedical research, let alone for therapeutic development.
Our study shows that we can use plants to produce interleukin-12, and other
therapeutic proteins, in a cost-effective controlled process.?

The tobacco project is one of several emerging collaborative efforts between
WPI and ABI. In the current study, tobacco plants were modified in the lab
of Carole Cramer, PhD, ABI?s executive director and co-author of the paper.
Cramer?s team successfully inserted into tobacco plants a mouse gene that
directs the production of interleukin 12. Hairy root cultures from those
modified tobacco plants were then grown in a mist reactor developed in the
Weathers lab. As its name implies, the mist reactor uses ultrasonic
technology to spray a fine mist of water and nutrients on the root cultures,
which are suspended in a plastic bag. The nutrient solution is collected at
the bottom of the bag and recycled through the system. In this way, all of
the materials are completely contained and isolated from the environment.
?Some have concerns about growing genetically modified plants in an open
field where they could cross-pollinate with other species. Our mist reactor
overcomes those concerns because the system is completely contained,?
Weathers says. ?There is no interaction with the environment, and once we?ve
collected the therapeutic proteins grown in the roots, all the remaining
material is safely destroyed.?

Traditional pharmaceuticals, like aspirin or statins for lowering
cholesterol, are made by synthesizing and combining chemicals in a
factory-like production setting. Therapeutic proteins are biologic molecules
produced in living cells, which are then isolated, purified and prepared for
use in treating disease. For example, insulin is a therapeutic protein now
produced by inserting a human insulin gene into bacteria, which in turn
prompts the bacteria to make human insulin. Using plants as a production
system for therapeutic proteins can not only be more cost-effective than
animal cell-based production, but can also significantly reduce the risk of
contamination by animal or human viruses or pathogens.

In the current study, Weathers compared the capabilities of the mist reactor
with two other common methods for growing plant cultures?the shake flask
method and the airlift bioreactor. The results showed the mist reactor
produced the highest concentration of interleukin 12. ?Our system is simple
and scalable. We?ll use these data to optimize this kind of process and
scale it up to the next level,? Weathers said.

On the genetics side, the current study used a mouse gene as a model to test
the idea and the process. Now, with positive results in hand, Cramer?s team
can begin to study a human interleukin-12 gene?s ability to direct the
production of the human protein in tobacco plants. "Making large complex
pharmaceutical proteins in a way that is highly reproducible, scalable, and
not cost prohibitive is quite challenging,? Cramer says. ?The mist reactor
seems excellent for producing high-quality proteins for vaccine trials and
therapeutic applications.?

The mist reactor?s capabilities are not restricted to tobacco roots. The
system is being tested on several other plant cultures, including Artemisia
annua, which naturally produces very small quantities of an effective
antimalarial molecule known as artemisinin. ?With our colleagues in
Arkansas, we are making good progress on developing the technology and
understanding the biology that will allow us to use plants to help create
new pharmaceuticals and other chemical building blocks essential for a
healthy society and environment,? Professor Weathers said.
www.checkbiotech.org

About Worcester Polytechnic Institute
Founded in 1865 in Worcester, Mass., WPI was one of the nation's first
engineering and technology universities. WPI's14 academic departments offer
more than 50 undergraduate and graduate degree programs in science,
engineering, technology, management, the social sciences, and the humanities
and arts, leading to bachelor?s, master?s and PhD degrees. WPI's world-class
faculty work with students in a number of cutting-edge research areas,
leading to breakthroughs and innovations in such fields as biotechnology,
fuel cells, and information security, materials processing, and
nanotechnology. Students also have the opportunity to make a difference to
communities and organizations around the world through the university's
innovative Global Perspective Program. There are more than 20 WPI project
centers throughout North America and Central America, Africa, Australia,
Asia, and Europe.

About The Arkansas Biosciences Institute
The Arkansas Biosciences Institute is a five member research consortium
funded by Arkansas? Tobacco Settlement Proceeds Act of 2000. The Consortium
is focused on cutting edge research at the interface of agriculture and
medicine with the long term goal of enhancing the health of Arkansans and
the nation. At Arkansas State University, a new state-of-the-art research
building was constructed to house this new endeavor with a grand opening
held in September 2004. Since 2004, dynamic cross-disciplinary research
clusters have been developed in four target areas: plant-based bioproduction
of proteins for medical and biofuels applications; plant metabolic
engineering; molecular innovations in food sciences; and the interface of
environment, agriculture, and human disease.