one of the biggest causes of loss of sight in
older people, where blood vessels grow
over the back of the eye. It can also be
used in interventional cardiology — a
polymer coating with anti-cancer drugs
stops blood vessels and clots.
Another cancer treatment known as
BCNU that is used to treat fibroblastoma
only lasts 12 minutes outside the body.
But by being distributed through a
biodegradable non-toxic polymer, it can
be used in localised chemotherapy by
implanting wafers of the substance in the
brain after surgery. Slow release
polymers developed by Langer have also
been used to treat prostrate cancer,
schizophrenia and alcoholism.
‘In the past, scientists would take the
materials used in household objects as
inspiration for medical polymers,’ said
Langer. ‘The strength and flexibility of a
ladies’ girdle inspired clinicians to use
polyether urethane in artificial hearts,
Dacron fabric from clothing was used in
vascular grafts and lubricating silicone
inspired breast implants for example.
Our approach was to create the polymers
from scratch to exactly fit the purpose.’
Langer’s laboratory has also worked
on memory metal for minimally invasive
surgery. Wires, which are straight and
easy to insert at room temperature, can
form stents for gall bladder or cardiac
operations at body temperature, or even
form a self-tying knot.
He has also applied his unique skills
to inhaled drugs, which are often ineffi-
cient as the powdered drugs tend to
aggregate in the inhaler and on delivery,
especially in granules two microns or less
Langer graduated
from MIT in 1974
determined to do
‘some good’. Now
his innovations
have been
recognised with
technology’s
equivalent of the
Nobel prize
‘Once, materials used in household objects
inspired medical polymers. Our approach was
to create them from scratch to fit the purpose’
in size. ‘We decided to make the
aerosols big but light and porous,’ he
said. ‘This way it floats into the deep
part of the lung, the bigger particle
doesn’t aggregate, and the phagocytes
which destroy drugs in the lung don’t
eat it as fast.’
Langer’s polymers are also used as a
scaffold on which to grow body tissues
in a culture then transplant. ‘There is a
donor shortage,’ said Langer. ‘Our
method can be used to deliver liver,
bone, cartilage, liver, intestine, heart
muscle and urethra tissue. In the
future we could rebuild an entire nose
using cartilage cells from the ear.
Initially, it could only be used for
cosmetic purposes, as grown cartilage
is not strong enough for knee injury.
But we can grow a replacement outer
ear for soldiers who have lost one in
battle, for instance.’
Elsewhere, Langer’s technology has
already helped a child with severe
burns on his chest heal without
scarring by putting on a skin cell
polymer scaffold at the time of injury.
Other work that is in an early stage
is using a polymer scaffold to build a
new spinal column in people disabled
through spinal damage. ‘We’re
carrying out animal trials, but there
the EnGIneeR 14–27 JULY 2008 31
are great steps ahead of us before we
can treat humans,’ said Langer.
‘Our technologies raise principles in
engineering and biotechnology that can
relieve suffering and prolong life,’ he
said, but admits there are limits. ‘Skin
is an easy tissue to grow — it is thin
and sloughs off. A liver, however, is
made of five different cell types and is
vascularised, so we can’t yet grow a
whole one.’
Langer is co-director of a major
nanotechnology grant, and his
laboratory is to use the new technology
to deliver drugs and genetic material
such as SRNA and DNA right to the
cells that need them.
And the next big thing in bio-
engineering? Langer said: ‘The three
areas we’ve done a lot of work in are
new materials, growing new tissues
and organs and drug delivery. I think
nanotechnology is a cutting-edge area,
which could be combined with other
areas such as stem cell biology.
‘We also want to get a better
understanding of the immune system
and the brain from the perspective of
engineering — immuno-engineering or
neuro-engineering, if you like. I think
those areas could be new frontiers, and
very little has been done to date.’
INTERVIEW
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