lacZ as a Genetic Reporter for Real-Time MRI

Molecular imaging based on MRI is currently hampered by the lack of genetic reporters for in vivo imaging. We determined that the commercially available substrate S-Gal (TM) can be used to detect genetically engineered P-galactosidase expressing cells by MRI. The effect and specificity of the reaction between beta-galactosidase and S-Gal (TM) on MRI contrast were determined both in vitro and in vivo. a-galactosidase activity in the presence of S-Gal (TM) resulted in enhanced T-2 and T-2* MR-contrast, which was amplified with increasing magnetic field strengths (4.7-17.6 T) in phantom studies. Using both lacZ(+) transgenic animals and lacZ(+) tissue transplants, we were able to detect labeled cells in live animals in real time. Similar to phantom studies, detection of the labeled cells/tissues in vivo was enhanced at high magnetic fields. These results demonstrate that the genetic reporter, lacZ, can be used as an in vivo marker gene using high-field-strength MRI. Magn Reson Med 63:745-753, 2010. (C) 2010 Wiley-Liss, Inc.