COLUMBUS , Ohio – Nanotechnology may one day help physicians detect the very
earliest stages of serious diseases like cancer, a new study suggests.
It would do so by improving the quality of images
produced by one of the most common diagnostic tools
used in doctors' offices – the ultrasound machine.
In laboratory experiments on mice, scientists found
that nano-sized particles injected into the animals
improved the resulting images. This study is one
of the first reports showing that ultrasound can
detect these tiny particles when they are inside
the body, said Thomas
Rosol , a study co-author and dean of the college
of veterinary medicine at Ohio State University .
“Given their tiny size, nobody thought it would
be possible for ultrasound to detect nanoparticles,” he
said.
It turns out that not only can ultrasound waves
sense nanoparticles, but the particles can brighten
the resulting image. One day, those bright spots
may indicate that a few cells in the area may be
on the verge of mutating and growing out of control.
“The long-term goal is to use this technology to
improve our ability to identify very early cancers
and other diseases,” said Jun
Liu , a study co-author and an assistant professor
of biomedical
engineering at Ohio State University . “We ultimately
want to identify disease at its cellular level, at
its very earliest stage.”
The study is in the current issue of the journal Physics
in Medicine and Biology .
The researchers injected a solution of silica nanoparticles
into the tail vein of each mouse. They then anesthetized
the animals and placed them on their backs on a warm
imaging table.
Rosol said that Liu and her team are working on
creating biodegradable nanoparticles. For the purposes
of this study, however, the researchers wanted to
use a hard substance, silica, to see if their idea
would work. The strongest ultrasound signals are
those produced by sound waves bounce off a hard surface.
While not biodegradable, the nanoparticles used in
the study were biologically inert.
The researchers took ultrasound images of the animals'
livers every five minutes for 90 minutes after the
injection. The nanoparticles had accumulated in the
animals' livers. Another future step for this work
is to label nanoparticles with a molecular road map
of sorts, which would direct the particles to go
to specific locations in the body.
“The liver takes up foreign substances in the body,
so it's not surprising that that's where we saw the
particles,” Rosol said. “But we ultimately want to
be able to make these particles to go to the mammary
glands or other tissues we're interested in.”
The ultrasound images grew brighter over the 90-minute
period. The researchers compared these images to
those from a group of control mice injected with
a saline solution. There was no change in ultrasound
image brightness in the control mice after that injection.
While this research is still in its infancy, Rosol
and his colleagues foresee a day when nanotechnology
can alert a physician to the beginnings of cancer
or heart disease, perhaps in a woman who has a family
history of breast cancer:
“Her doctor could inject the breast with nanoparticles
and the resulting ultrasound image would alert the
doctor to any suspicious areas in the tissue, even
at the cellular level,” Rosol said.
The hope is that combining ultrasound and nanotechnology
may provide a definitive diagnosis in lieu of an
invasive procedure like a biopsy.
“These nanoparticles may make it possible for physicians
to screen for tumors very quickly, and perhaps lessen
the need for a biopsy in many cases,” Liu said.
Nanoparticles are smaller than any cell in the human
body, so they may pass through the walls of the leaky
blood vessels, or capillaries, of tumor tissue and
actually infiltrate the tumor.
“Until now, nobody knew what these particles would
do in the blood,” Rosol said. “But they made it into
the liver.
And despite their miniscule size, nanoparticles
are still big enough to carry a payload of medicine,
Rosol said.
“That the particles made it into the liver suggests
that they could be used to deliver toxic chemotherapeutic
drugs that would act locally on a tissue, at the
site of a tumor, and not have such a pronounced affect
on the rest of the body,” Rosol said. “The problem
with chemotherapy is that the drug affects the whole
body, causing a host of problems such as hair loss,
diarrhea and anemia.”
Rosol and Liu conducted the study with colleagues
from various academic departments at Ohio State :
Andrea Levine and Mamoru Yamaguchi , both with veterinary
biosciences ; John Mattoon , with veterinary
clinical sciences ; Robert Lee , with pharmacy ;
and Xueliang Pan, with statistics .
This work was supported by the Susan
G. Komen Breast Cancer Foundation , the National
Cancer Institute , the National
Center for Research Resources and the National
Science Foundation .
Contact: Thomas Rosol , (614) 688-8749;
Rosol.1@rf.ohio-state.edu
Jun Liu, (614) 247-8904; liu.314@osu.edu
Written by Holly Wagner , (614) 292-8310; Wagner.235@osu.edu
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