Scientists’ inability to follow the whereabouts of cells injected into the human body has long been a major drawback in developing effective medical therapies. 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.

In their study, the researchers from Johns Hopkins’ Russell H. Morgan Department of Radiology 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 tumour 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 colours in the MRI image

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 labelled cell at a time.” The new approach is not hampered by these limitations.; Source: Johns Hopkins Medical Institutions