New technique developed for tracking cells in the body

Mar 20, 2007

Scientists' inability to follow the whereabouts of cells injected into the human body has long been a major drawback in developing effective medical therapies. Now, researchers at Johns Hopkins have developed a promising new technique for noninvasively tracking where living cells go after they are put into the body. The new technique, which uses genetically encoded cells producing a natural contrast that can be viewed using magnetic resonance imaging (MRI), appears much more effective than present methods used to detect injected biomaterials.

Described in the February edition of Nature Biotechnology, the method was developed by a team of researchers from Johns Hopkins' Russell H. Morgan Department of Radiology and Radiological Science, the Hopkins Institute for Cell Engineering, and the F.M. Kirby Research Center for Functional Brain Imaging at the Kennedy Krieger Institute in Baltimore.

In their study, the researchers used a synthetic gene, called a reporter gene, which was engineered to have a high proportion of the amino acid lysine, which is especially rich in accessible hydrogen atoms. Because MRI detects energy-produced shifts in hydrogen atoms, when the "new" gene was introduced into animal cells and then "pelted" with radiofrequency waves from the MRI, it became readily visible. Using the technique as a proof of principle, the researchers were able to detect transplanted tumor cells in animal brains.

"This prototype paves the way for constructing a family of reporter genes, each with proteins tailored to have a specific radiofrequency response," says MRI researcher Assaf Gilad, Ph.D., lead author of the study.

"The specific frequencies can be processed to show up as colors in the MRI image," adds collaborator Mike McMahon, Ph.D., an assistant professor of radiology at the Johns Hopkins School of Medicine "In a way, it's the MRI equivalent of the green and red fluorescent proteins found in nature and used by labs everywhere in the world for multiple labeling of cells."

The problem with using fluorescent proteins, however, is that tissue must be removed from the body for examination under a microscope, which means that the method isn't suitable for use in patients. "In contrast," says Hopkins radiology professor Jeff Bulte, Ph.D., "MRI is noninvasive, allowing serial imaging of cells and cellular therapies with a high resolution unmatched by any other clinical whole-body imaging technique."

Current MRI contrast agents also have several disadvantages. "Their concentration becomes lower every time cells divide," says Peter van Zijl, Ph.D., founding director of the Kirby Research Center for Functional Brain Imaging, "so our ability to see them diminishes.. Also, using magnetic metal allows us to detect only one type of labeled cell at a time." The new approach is not hampered by these limitations.

Source: Johns Hopkins Medical Institutions

Explore further: Team finds key to tuberculosis resistance

add to favorites email to friend print save as pdf

Related Stories

Combination of imaging methods improves diagnostics

Feb 19, 2015

Scientists from the Helmholtz Zentrum München and the Technische Universität München have succeeded in a breakthrough for the further development of contrast agents and consequently improved diagnostics with imaging using ...

Nanovectors combine cancer imaging and therapy

Feb 09, 2015

Researchers at Imperial College London and the Laboratoire de chimie de la matière condensée de Paris (CNRS/Collège de France/UPMC) have designed and developed hybrid gold-silica nanoparticles, which are ...

Scientists build a better eye on our world

Nov 11, 2014

Science begins with observation, and many defining moments in scientific progress followed the introduction of new ways to observe the world, from microscopes and telescopes to X-rays and MRIs.

Recommended for you

Team finds key to tuberculosis resistance

55 minutes ago

The cascade of events leading to bacterial infection and the immune response is mostly understood. However, the molecular mechanisms underlying the immune response to the bacteria that causes tuberculosis ...

Mutation may cause early loss of sperm supply

1 hour ago

Brown University biologists have determined how the loss of a gene in male mice results in the premature exhaustion of their fertility. Their fundamental new insights into the complex process of sperm generation ...

No more bleeding for 'iron overload' patients?

3 hours ago

Hemochromatosis (HH) is the most common genetic disorder in the western world, and yet is barely known. Only in the US 1 in 9 people carry the mutation (although not necessarily the disease).

3-D printing offers innovative method to deliver medication

9 hours ago

3-D printing could become a powerful tool in customizing interventional radiology treatments to individual patient needs, with clinicians having the ability to construct devices to a specific size and shape. That's according ...

Mystery of the reverse-wired eyeball solved

Feb 27, 2015

From a practical standpoint, the wiring of the human eye - a product of our evolutionary baggage - doesn't make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye - resulting ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.