Porphyrin-Containing Gadolinium Complex as a Tumor-Targeting Magnetic Resonance Imaging (MRI) Contrast Agent

Objective: Gadolinium diethylenetriaminepentaacetic di[5-(4'-amidophenyl)-10,15,20- tris(4'-sulfonatophenyl) porphyrin trisodium salt] (Gd-DTPA-2APTSPP) was synthesized by the reaction of diethylenetriaminepentaacetic dianhydride with 5-(4'-aminophenyl)-10,15,20-tris(4'-sulfonatophenyl) porphyrin and subsequently chelation with gadolium chloride. Methods: This gadolinium complex was characterized and its properties in vitro and in vivo were also evaluated. Compared with Gd-DTPA, Gd-DTPA-2APTSPP possessed high relaxivity r1, low cytotoxicity to HeLa cells and high enhanced signal intensities of the VX2 carcinoma in rabbits for a prolonged time. Conclusion: Moreover, Gd-DTPA-2APTSPP can distinguish the VX2 carcinoma from the reactive hyperplasia incited by inflammation and normal tissues in rabbits. Therefore, Gd-DTPA-2APTSPP can be taken up selectively by tumors and show the potential as a tumor-targeting MRI contrast agent.