NSF PR 98-33 - June 25, 1998
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Feature: Biomaterials Are Transforming Medicine
MIT Scientist and Engineer Describes
a New Field in an NSF Lecture
How can doctors deliver drugs in ways less invasive
and more controlled than an injection? Robert S. Langer
views the question as an engineering design problem.
Langer, Germeshausen Professor of Chemical and Biomedical
Engineering at MIT, described how researchers are
using biomaterials to create engineering solutions
to medical problems in a lecture at the National Science
Foundation's (NSF) headquarters on June 17.
Langer's lecture, "Biomaterials: From Basic Science
and Engineering to Clinical Practice," focused on
advances in biomaterials, a field that Langer pioneered.
"Historically, materials have found their way into
medicine by clinicians," he said. For the first artificial
heart, doctors' search for a strong substance with
flexibility led them to use polyether urethane, found
in girdles. "I thought we could do better," said Langer.
After all, "something designed as a lady's girdle
might not be the best thing to put in a human body."
Since Langer began his work in 1974, genetic engineering
has made possible larger and larger "macromolecule"
drugs, such as growth hormones. With the help of NSF
grants, Langer found that certain hydrophobic polymers
made it possible to deliver macromolecular drugs like
albumin into the body and at a controlled rate over
a period of time.
Since then, biomaterials have enabled the slow release
of ever-larger bioengineered proteins into the body,
with release times ranging from one day to more than
three years. Products like Lupron Depot permit controlled
release of medicines that would normally deteriorate
in minutes to be released slowly over four months.
"I'd like to think these are the tip of the iceberg,"
said Langer. Researchers are also working on ways
to deliver growth hormones and methods to provide
a constant release of insulin for diabetics. Fortune
magazine cited estimates that these new technologies
will cause sales in the drug-delivery sector to almost
triple, reaching $25 billion by 2006.
For medicines like insulin, research is also exploring
methods for administering doses in preprogrammed "pulses,"
or on demand. Using an oscillating magnetic field,
a wristwatch-like device could, for example, release
a dose of insulin just before a diabetic's meal. The
magnetic field would release the drug by squeezing
drug-containing pores at a microscopic level. Trials
using such a device on mice are underway.
With Dr. Henry Brem, an oncologist at Johns Hopkins
University, Langer explored more focused drug delivery
for types of brain cancer. Treatment usually involves
chemotherapy, which can have terrible side effects
for the liver and other organs. For a more targeted
release of the drug BCNU, doctors inserted a dime-sized
polymer wafer containing BCNU in the surgical cavity
at the tumor. As the polymer eroded, it released the
drug over time directly to the tumor without the impediment
of the blood-brain barrier. In this study, physicians
have used the polymer wafers to treat thousands of
brain cancer victims, with significant improvements.
In tissue engineering, cells from a patient can be
cultivated on a polymer mesh or "scaffold", allowing
regeneration of the cartilage for an ear, for example.
Physicians could also apply these techniques to regenerate
damaged tendons, sciatic nerve endings and skin tissue.
"We've raised more questions than we've answered,"
Langer concluded, but biomaterials have already contributed
products "that can relieve suffering and prolong life
for many people."
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