Cell-Based ‘Tracking Devices’ Might Help Monitor Treatments

TUESDAY, July 10 (HealthDay News) — Call it a fantastic voyage.
Scientists have successfully found a way to inject tiny iron filings into
the human body to potentially monitor medical therapies. The particles
work as tracking devices that may help physicians determine if certain
treatments are working.

The development of methods to track cells is critical to stem-cell and
other therapies that rely on the delivery of particular cells to a target
site, such as the heart or other organ, according to the authors of a
small new study.

“Eventually we’ll be able to prove stem cells are going where they are
supposed to be and track cells going into other tissues,” said Dr. David
Newby, study co-author and professor and chair of cardiology at the Centre
for Cardiovascular Science at the University of Edinburgh, in Scotland.

The study, published July 10 in Circulation: Cardiovascular
Imaging
, showed that immune cells tagged with nano-sized iron filings
and injected into the bloodstream can be tracked by magnetic resonance
imaging (MRI) as they move through the human body. The researchers also
demonstrated that the process was safe and did not interfere with normal
cell function.

A type of normal white blood cell known as macrophages ingest
pathogens and cellular debris — including the filings — and take them
along wherever they go. The iron filings are only about 20 nanometers
across. In comparison, the average red blood cell is 8,000 nanometers
wide.

Newby said the critical question the researchers wanted to answer was
whether the tracking cells, once injected into the body, would migrate
where the researchers wanted them to go. “We needed to be able to know if
they wander off,” he said.

The research showed it is possible to track tagged, injected cells for
seven days. Because MRI technology is nonradioactive, the tracking system
would not subject patients to radiation exposure, Newby noted.

The study involved two phases. First, the researchers determined that
blood cells with attached iron filings moved normally, and were indeed
able to survive. Twenty study volunteers participated. Some people were
given injections into their thigh muscles of either unlabeled cells,
iron-filing labeled cells or just the filings. Others received intravenous
injections of the labeled blood cells.

To show that the tracking method could be used to facilitate the
development of cell-based therapies in the future, the researchers
injected one person with labeled immune blood cells, and they tracked the
cells as they migrated to an inflamed area of skin on the thigh. The
inflammation was caused by a Mantoux tuberculosis test, an injection just
under the skin that typically becomes slightly inflamed.

“This is a pretty convincing demonstration that there’s real merit to
this idea of using cells as carriers,” said Matthew Tirrell, a professor
and Pritzker director of the Institute for Molecular Engineering, at the
University of Chicago.

Tirrell said the research opens up new territory for other kinds of
visualization experiments. “There are few examples of any kind of
targeting particles in humans,” he said. “To have the confidence and guts
to do it is impressive, and I think other people will be building on this
work,” he said.

Newby said that the research team hopes to investigate the use of these
techniques to diagnose inflammatory conditions of the heart, such as
transplant rejection, myocarditis or inflammation of the heart, and
sarcoidosis, where there is inflammation in multiple organs. The work may
also be useful in five to 10 years in stem-cell research, he added.

More information

Visit PEW’s Project on Emerging Nanotechnologies to learn more about nanotechnolgy.

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