Are
you leery about getting shots from your doctor? Do you feel woozy at
the mere thought of a needle entering your skin? Well, the days of
anguish and pain could be long behind. Researchers at MIT have come
up with a device that could completely remove the need to draw
blood.
The
research is of special interest to diabetics, who currently need to
draw blood at least four times a day to test their glucose levels.
The clinical trial described in Nature Medicine used the new
technique to successfully monitor glucose levels in seven volunteers
with type 1 diabetes.
"We're hopeful that this could eventually
be a universal way of noninvasively sampling a variety of substances
from humans," said Robert Langer, the Kenneth J. Germeshausen
Professor of Chemical and Biomedical Engineering at MIT and an
author of the paper. "Blood tests for any number of things, such as
cholesterol and bilirubin, could someday be replaced with this
technique."
The
researchers expect that the first application will be a portable
device for noninvasively monitoring glucose. The device could be
available in three to five years, and should be comparable in price
to other glucometers that are currently on the
market.
Earlier work showed that the technique
could also be used in reverse: drugs such as insulin can be
delivered through the skin via ultrasound (the work in the Science
paper focused on animal models and skin from human
cadavers).
As a
result, "this approach could be further developed to combine the
sensing and delivery parts into one design," the researchers write
in Nature Medicine.
Breakdown With The
Ultrasound
The
new technique relies on ultrasound. Professor Langer explained that
the outer layer of skin is composed of dead cells and fatty layers
arranged like bricks and mortar, respectively. Ordinarily that
barrier is almost impervious. Ultrasound, however, disorganizes the
fatty layers, creating pathways for molecules to travel through.
Basically, the device increases the permeability of
skin.
In
the clinical trial and in tests on rats and skin from human
cadavers, the researchers applied ultrasound to the skin for two
minutes. After the ultrasound treatment, they put saline solution
into the cylinder and applied a vacuum to it for five minutes to
extract a very small amount of fluid from the interstitial spaces
surrounding the cells. This fluid is not blood, but is known to have
the same concentrations of glucose and other substances as in
blood.
Professor Kost notes that skin
permeability remained high for about 15 hours after an ultrasound
treatment. As a result, he envisions that diabetics, for example,
could apply ultrasound in the morning, then put a patch on the
pretreated site. "The patch would have sensing capabilities and a
display showing the glucose levels, and alarms if those levels go
out of a safe range."
No Pain, Much
Gain?
Volunteers reported no pain during the
procedure. The experiments also indicated that ultrasound does not
damage the skin, although the researchers note, "further studies
assessing safety will be required."
With
further work, the researchers expect significant improvements. For
example, the ultrasound sonicator is already getting much smaller
than the laboratory sonicator used in the initial clinical studies.
"We expect a battery-powered device about the size of a cigarette
pack," Professor Kost said.
Professor Langer said that eventually the
technique could make drawing blood obsolete. However, he noted that
the detection of some substances requires a larger sample than the
ultrasound extraction can currently provide. The researchers believe
that as analysis techniques for these substances get better, that
should change. In addition, the technique currently requires one
blood sample before the ultrasound treatment for calibration.
Professors Langer and Kost say that eventually this, too, will be
unnecessary.
The
ultrasound technique could make life easier for many. Professor
Langer remembers when his son, then four, had to get blood taken.
"He ran around the MIT infirmary for over an hour because he was so
scared," he said. Let’s hope that the entire trauma from getting
blood taken is behind us. Perhaps now, those of us who are
intimidated by the thought of getting stuck with a needle can take
in a deep breath and relax a little easier.
