A human photoacoustic imaging reporter gene using the clinical dye indocyanine green.

Photoacoustic imaging (PAI) combines optical contrast with the resolution and depth-detection of ultrasound and is increasingly being utilized for medical imaging in patients. PAI reporter genes would allow for monitoring of cell and gene therapies, but current reporters have immunogenicity and/or toxicity concerns that may limit clinical translation. Here we report a PAI reporter system employing the ability of human organic anion transporting polypeptide 1b3 (Oatp1b3) to take up the clinical dye indocyanine green (ICG) into cells. Following ICG administration, cells synthetically expressing Oatp1b3 exhibited significantly increased PAI signals compared to control cells both in vitro and in mice. Several benefits of this technology are the human derivation of Oatp1b3, and the high extinction coefficient, low quantum yield and pre-existing clinical approval of ICG. We posit that the Oatp1b3-ICG reporter system could be useful for in vivo gene and cell tracking in preclinical and clinical applications.