Protamine-1 encoded recombinant adeno-associated virus for enhanced brain magnetic resonance imaging

Magnetic resonance imaging (MRI) is a powerful tool for diagnosing and monitoring brain diseases, but its low sensitivity can hinder early detection. To address this challenge, we utilized chemical exchange saturation transfer (CEST) MRI, which greatly enhances sensitivity for detecting low-concentration compounds. In this study, we developed a CEST contrast agent based on a recombinant adeno-associated viruses (rAAVs) encoding the protamine-1 (PRM1) MRI reporter gene. CEST MRI revealed that PRM1 contrast agent effectively highlighted caudate putamen region after injection of the rAAVs into the mouse brain, clearly distinguishing it from the surrounding tissue, with no observable damage. This method provides a sensitive, metal-free CEST contrast agent for <i>in vivo</i> brain cell detection, demonstrating potential for both diagnostic and therapeutic applications in brain diseases.