Scientists from the California Institute of Technology (Caltech) have developed a method to visualize gene expression in cells using magnetic resonance imaging (MRI).

Their study, published Dec. 23 online in the journal Nature Communications, was led by Mikhail Shapiro, an assistant professor of chemical engineering at Caltech.

Shapiro and his team developed a method to link MRI signals to cells, including tumor cells. The technique could eventually be used in humans, and would be a non-invasive procedure.

"We thought that if we could link signals from water molecules to the expression of genes of interest, we could change the way the cell looks under MRI," said Arnab Mukherjee, a postdoctoral scholar in chemical engineering at Caltech and co-lead author on the study, in a statement.

The investigators tested their technique on aquaporin cells, a protein that naturally occurs in humans and sits within the membrane that envelops cells and acts as a gatekeeper for water molecules. Results showed that increasing the number of aquaporins on a cell made it appear clearer in MRI images when using a specific imaging strategy sensitive to the movement of water molecules. Using this imaging technique, the researchers found it was successful in monitoring gene expression in a brain tumor in mice.

"Overexpression of aquaporin has no negative impact on cells because it is exclusive to water and simply allows the molecules to go back and forth across the cell membrane," Shapiro said. “Aquaporin is a very convenient way to genetically change the way that cells look under MRI."

And because aquaporin is safe for humans, it could be used to examine gene expression.

"An effective reporter gene for MRI is a 'holy grail' in biomedical imaging because it would allow cellular function to be observed non-invasively," Shapiro said "Aquaporins are a new way to think about this problem. It is remarkable that simply allowing water molecules to more easily get into and out of cells in a tissue gives us the ability to remotely see those cells in the middle of the body."