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Genetically Engineered Magnetic Genes

Genetically Engineered Magnetic Genes

Researchers have developed a technique to make genes produce their own magnetic nanoparticles.

Using genes from a magnetically sensitive bacterium, scientists have genetically engineered mammalian cells that can produce magnetic nanoparticles.

The technique, developed by a team of researchers from the Emory University could give medical researchers a new way to track cells in the body with more precision.

mri scan magnetic gene Genetically Engineered Magnetic Genes

The magnetic genes come from a pond dwelling bacteria that uses it to function as a kind of biological compass needle. Scientists found that when inserted into the DNA of mice, the gene caused the cells to produce their own magnetic nanoparticles.

When injected into the brains of live mice, researchers found that the cells could be seen clearly with an MRI scan.

Previous methods of tracking cells withing the body called for the injection of genetically engineered proteins, a technique known as fluorescent microscopy. This enables scientist to “tag” particular proteins that they’re interested in, track the patterns of gene expression as well as the particular types of cells.

The problem is that fluorescent microscopy is limited to areas nearer the surface of the skin, this makes it difficult to get images from inside living animals. MRI scans however, are able to produce images of deep inside the body.

Xiaoping Hu, a professor of biomedical engineering at Emory and an author of the study says,

“The idea of using gene-directed production of MRI contrast is highly desirable…Optical markers cannot be used to look very deep.”

Hu hopes that his genetically engineering cells will prove to be successful, opening a new window from which to view many biological processes, from the formation of tumors to the migration of stem cells injected to treat disease.

“It’s just amazing that they can get a mammalian cell to actually make the material,” says Lee Josephson, an associate professor at the Harvard Medical School’s Center for Molecular Imaging Research. “I think it’s a really meaningful piece of work.”

Finding a efficient way of getting good MRI images at a high enough resolution to track cellular process has proved to be quite a task.

One approach is to incubate cells with magnetic nanoparticles before injecting them into the body. This techniques does work but over time, the magnetic markers begin to divide and the signal becomes weaker and is eventually lost.

florecent microscopy.thumbnail Genetically Engineered Magnetic Genes

Another method is to use genes that produce ferritin, the molecules that store iron. Again this method has shown promise but the form of iron in ferritin is not easily detectable.

However neither of these techniques has proven to be quite as efficient as the method described in the Emory study

Despite the obvious potential in the new technique, some researchers are quick to outline its drawbacks. According to Michal Neeman, a professor at the Weizmann Institute of Science, in Israel, who studies molecular imaging using ferritin, the underlying physics of an MRI scan mean that the images will never have the fine resolution of surface-level optical microscopy. And although the study is exciting, she says,

“the magnetic properties of the particles need to be studied with more detail.”

Still, the fact that a single bacterial gene could could enable a variety of cells to produce their own magnetic properties opens up a whole new world of possibilities, from new cell imaging techniques to using bacteria as bacteria as biological factories for producing nanoparticles.

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