Abstract
Photoacoustic imaging is an emerging hybrid imaging technology capable of breaking through resolution limits of pure optical imaging technologies imposed by optical-scattering to provide fine-resolution optical contrast information in deep tissues. We demonstrate the ability of multi-wavelength photoacoustic imaging to estimate relative gene expression distributions using an inducible expression system and co-register images with hemoglobin oxygen saturation estimates and micro-ultrasound data. Tyrosinase, the rate-limiting enzyme in melanin production, is used as a reporter gene owing to its strong optical absorption and enzymatic amplification mechanism. Tetracycline-inducible melanin expression is turned on via doxycycline treatment in vivo. Serial multi-wavelength imaging reveals very low estimated melanin expression in tumors prior to doxycycline treatment or in tumors with no tyrosinase gene present, but strong signals after melanin induction in tumors tagged with the tyrosinase reporter. The combination of new inducible reporters and high-resolution photoacoustic and micro-ultrasound technology is poised to bring a new dimension to the study of gene expression in vivo.
Highlights
Photoacoustic imaging is an emerging hybrid imaging technology capable of breaking through resolution limits of pure optical imaging technologies imposed by optical-scattering to provide fine-resolution optical contrast information in deep tissues
We demonstrate the ability of multi-wavelength photoacoustic imaging to estimate relative gene expression distributions using an inducible expression system and co-register images with hemoglobin oxygen saturation estimates and micro-ultrasound data
Tyrosinase, the rate-limiting enzyme in melanin production, is used as a reporter gene owing to its strong optical absorption and enzymatic amplification mechanism
Summary
Photoacoustic imaging is an emerging hybrid imaging technology capable of breaking through resolution limits of pure optical imaging technologies imposed by optical-scattering to provide fine-resolution optical contrast information in deep tissues. Tyrosinase, the rate-limiting enzyme in melanin production, is used as a reporter gene owing to its strong optical absorption and enzymatic amplification mechanism. Serial multi-wavelength imaging reveals very low estimated melanin expression in tumors prior to doxycycline treatment or in tumors with no tyrosinase gene present, but strong signals after melanin induction in tumors tagged with the tyrosinase reporter. A short-pulsed laser causes localized heating in optically absorbing materials, producing pressure waves. These pressure waves are measured with an ultrasound transducer and provide ultrasonic-resolution imaging of optical absorption, allowing for deep, non-invasive, high optical contrast and high spatial-resolution imaging using non-ionizing radiation. Fluorescent proteins are prone to laser-induced absorption bleaching, complicating photoacoustic imaging
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
