Single Gene Tracks Cells In Multiple Ways

Tracking cells in the body is a challenging step in developing gene and cell therapies. Now, researchers have developed a way to make cells visible to many imaging methods, including magnetic resonance imaging (MRI), fluorescence imaging, and single-photon emission computed tomography (J. Am. Chem. Soc., DOI: 10.1021/ja209868g). Bakhos A. Tannous, a neuroscientist at Harvard Medical School, and colleagues designed a reporter gene that creates a target that alone may not be visible on imaging scans such as MRI but that binds a variety of contrast agents. Their reporter’s resulting protein sits on the cell membrane and contains a peptide that an enzyme in cells recognizes and attaches to the vitamin biotin. Once cells are decorated with biotin, they are a target for any molecule attached to the protein streptavidin. To prove that the reporter works, the researchers used it with three imaging techniques in mice. First, they used a virus to add the reporter gene to brain cancer cells, which they then injected into mouse brains. Two weeks later, they injected the mice with imaging labels bound to streptavidin. With all three imaging methods, the researchers detected signals from the tumor.