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By David J. Craig
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Tejal Desai, an ENG biomedical engineering associate professor (left), and Joe Tien, an ENG biomedical engineering assistant professor, draw on the basic principles of physics, chemistry, molecular biology, engineering, and computation to achieve a detailed understanding of the complex machinery that supports life processes at the tiniest scales. Photo by Vernon Doucette |
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When Tejal Desai was a Ph.D. student at the University of California,
Berkeley, she took on a research project so difficult that colleagues
warned her against it, suggesting she might never graduate. But Desai’s
determination paid off.
For her doctoral project, she created a new treatment
for diabetes, consisting of an implantable microscopic device that slowly
releases insulin. The
invention established Desai as a young star in one of the hottest areas
of biomedical engineering — the development of biological microelectromechanical
devices (bioMEMS) for delivering drugs or stem cells. Now an ENG associate
professor of biomedical engineering, she was recently named by Popular
Science one of the 10 U.S. scientists most likely to “redefine
the world.”
Desai is among eight outstanding young scientists hired thus far under
the Whitaker Leadership Development Award, given in recognition of BU’s
pioneering biomedical engineering programs. (See
sidebar for more details.)
Creative drug delivery
Smaller than half the width of
a human hair, the bioMEMS developed by Desai are silicon capsules filled
with insulin-producing pancreatic cells
from healthy animals. The capsules are porous, to let oxygen and other
nutrients flow in, keeping the pancreatic cells alive as well as allowing
the insulin they produce to flow out. The openings are small enough,
however, that the host animals’ antibodies and
white blood cells cannot enter the capsule and destroy the foreign cells.
Having worked successfully in animals, this technology is now being developed
by a private company for human use. With the potential to free people
with diabetes from multiple daily insulin injections and eliminate the
potentially serious consequences of uncontrolled blood-sugar levels,
Desai’s insulin bioMEMS holds the promise of making normal the
lives of millions of individuals worldwide.
Desai also has developed bioMEMS
that can bring medication directly to the site where it can best be used
by the body. These tiny capsules can
be ingested and travel through a patient’s digestive tract, attaching
to the stomach or intestinal wall and releasing medication to treat ailments
such as intestinal or colon cancer. “It is an oral delivery system,” she
says, “that would be intelligent in the sense that it would target
a particular part of the body with the peptides and pharmaceutical agents
it releases.”
Recently Desai has turned her attention to engineering
artificial blood vessels capable of coaxing the body to grow new vessels,
then biodegrading,
leaving behind their natural replacements.
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In Joe Tien’s laboratory, researchers assemble three-dimensional aggregates of cells that they hope one day soon will replace damaged tissue in complex organs such as the lungs and the liver. At left is a model of a tiny dodecahedron gel structure that can be coated on one or more sides to enable it to combine with others and self-assemble into the more complex structure at right that resembles human tissue. Images courtesy of Joe Tien |
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Rebuilding the body
Less sophisticated tissue engineering
already has led to new treatments for serious burns and cartilage damage.
But while relatively simple
tissue such as skin can be biologically engineered using current techniques,
more complicated organs with complex three-dimensional structures and
many cell types pose enormous difficulties. Desai’s colleague
Joe Tien, an ENG assistant professor of biomedical engineering, who
came to BU in 2001, is taking a unique approach toward engineering
complex three-dimensional tissues capable of repairing organs such
as the liver, the pancreas, blood vessels, the lungs, and the brain.
He
coats tiny gel components of various shapes with thin liquid films
and shakes them together. The gel components are attracted and bound
together by capillary action between the coated surfaces, which are carefully
selected so that the resulting three-dimensional structures resemble
the natural structure of the tissue being engineered.
Tien’s goal
is to incorporate several different kinds of cells into branching structures
that will function as a vascular network. The
successful creation of such networks is an essential first step toward
creating complex organs that rely on a vascular system to nourish their
cells and carry away waste products.
Tien and Desai are two of a growing
number of engineers at Boston University who are exploring the enormous
potential of engineering at the nanoscale
for improving human health and vitality. For more information about
Desai’s
work, visit bme.bu.edu/tml; to learn more about Tien’s work, visit bme.bu.edu/micronano.htm.
Sidebar: Biomedical engineering thrives on $14M Whitaker grant
14
November 2003
Boston University
Office of University Relations