This
is a neat solution and joins others in the developing field of non
invasive surgery.
It
also sounds like it can be fed in with effectively a needle already
put in place and then recovered in the same way long before it is
necessary to withdraw the needle.
I
do not think that this can quite go much beyond this application but
then we can be surprised. Just doing great biopsies is a great start
and the healing here would be swift.
Johns Hopkins Team
Deploys Hundreds of Tiny Untethered Surgical Tools in First Animal
Biopsies
by Staff Writers
Baltimore MD (SPX) Apr 26, 2013
This image depicts an
mu-gripper near the opening of an endoscopic catheter. Image credit:
Evin Gultepe, Gracias Lab, Johns Hopkins University.
By using swarms of
untethered grippers, each as small as a speck of dust, Johns Hopkins
engineers and physicians say they have devised a new way to perform
biopsies that could provide a more effective way to access narrow
conduits in the body as well as find early signs of cancer or other
diseases.
In two recent
peer-reviewed journal articles, the team reported successful animal
testing of the tiny tools, which require no batteries, wires or
tethers as they seize internal tissue samples. The devices are called
"mu-grippers," incorporating the Greek letter that
represents the term for "micro."
Instead of relying on
electric or pneumatic power, these star-shaped tools are
autonomously activated by the body's heat, which causes their tiny
"fingers" to close on clusters of cells. Because the tools
also contain a magnetic material, they can be retrieved through an
existing body opening via a magnetic catheter.
In the April print
edition of Gastroenterology, the researchers described their use of
the mu-grippers to collect cells from the colon and esophagus of a
pig, which was selected because its intestinal tract is similar to
that of humans. Earlier this year, the team members reported in the
journal Advanced Materials that they had successfully inserted the
mu-grippers through the mouth and stomach of a live animal and
released them in a hard-to-access place, the bile duct, from which
they obtained tissue samples.
"This is the
first time that anyone has used a sub-millimeter-sized device-the
size of a dust particle-to conduct a biopsy in a live animal,"
said David Gracias, an associate professor of chemical and
biomolecular engineering whose lab team developed the microgrippers.
"That's a
significant accomplishment. And because we can send the grippers in
through natural orifices, it is an important advance in minimally
invasive treatment and a step toward the ultimate goal of making
surgical procedures noninvasive."
Another member of the
research team, physician Florin M. Selaru of the Johns Hopkins School
of Medicine, said the mu-grippers could lead to an entirely new
approach to conducting biopsies, which are considered the "gold
standard" test for diagnosing cancer and other diseases.
The advantage of
the mu-grippers, he said, is that they could collect far more samples
from many more locations. He pointed out that the much larger
forceps used during a typical colonoscopy may remove 30 to 40 pieces
of tissue to be studied for signs of cancer. But despite a doctor's
best intentions, the small number of specimens makes it easy to miss
diseased lesions.
"What's the
likelihood of finding the needle in the haystack?" said Selaru,
an assistant professor in the Division of Gastroenterology and
Hepatology.
"Based on a small
sample, you can't always draw accurate inferences. We need to be able
to do a larger statistical sampling of the tissue. That's what would
give us enough statistical power to draw a conclusion, which, in
essence, is what we're trying to do with the microgrippers. We could
deploy hundreds or even thousands of these grippers to get more
samples and a better idea of what kind of or whether a disease is
present."
Although each
mu-gripper can grab a much smaller tissue sample than larger biopsy
tools, the researchers said each gripper can retrieve enough cells
for effective microscopic inspection and genetic analysis. Armed with
this information, they said, the patient's physician could be better
prepared to diagnose and treat the patient.
This approach would be
possible through the latest application of the Gracias lab's
self-assembling tiny surgical tools, which can be activated by heat
or chemicals, without relying on electrical wires, tubes, batteries
or tethers.
The low-cost devices
are fabricated through photolithography, the same process used to
make computer chips. Their fingerlike projections are made of
materials that would normally curl inward, but the team adds a
polymer resin to give the joints rigidity and to keep the digits from
closing.
Prior to a biopsy,
the grippers are kept on ice, so that the fingers remain in this
extended position. An endoscopy tool then is used to insert hundreds
of grippers into the area targeted for a biopsy.
Within about five
minutes, the warmth of the body causes the polymer coating to soften,
and the fingers curl inward to grasp some tissue. A magnetic tool is
then inserted to retrieve them.
Although the animal
testing results are promising, the researchers said the process will
require further refinement before human testing can begin. "The
next step is improving how we deploy the grippers," Selaru said.
"The concept is sound, but we still need to address some of the
details. The other thing we need to do is thorough safety studies."
Further development
can be costly, however. The team has applied for grants to fund
advances in the project, which is protected by provisional patents
obtained through the Johns Hopkins Technology Transfer Office.
Biotechnology investors might also help move the project forward. "It
is more a question of money than time as to how long it will take
before we could use this in human patients," Selaru said
Along with Gracias and
Selaru, the Johns Hopkins researchers who contributed significantly
to the two journal articles were Evin Gultepe, Sumitaka Yamanaka, Eun
Shin and Anthony Kalloo. Additional contributors were Kate E. Laflin,
Sachin Kadam, Yoosun Shim, Alexandru V. Olaru, Berkeley Limketkai,
Mouen A. Khashab and Jatinder S. Randhawa. The researchers are
affiliated with the School of Medicine, the Whiting School of
Engineering and the Johns Hopkins Institute for NanoBioTechnology.
Biopsy with
thermally-responsive untethered microtools, E. Gultepe, J. S.
Randhawa, S. Kadam, S. Yamanaka, F. M. Selaru, E. J. Shin, A. N.
Kalloo, D. H. Gracias, Advanced Materials 25, 4, 514-519
(2013); Biologic tissue sampling with untethered microgrippers,
E. Gultepe, S. Yamanaka, K. E. Laflin, S. Kadam, Y.S. Shim, A. V.
Olaru, B. Limketkai, M. A. Khashab, A. N. Kalloo, D. H. Gracias, F.
M. Selaru, Gastroenterology 144, 4, 691-693
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