Preparation of 68Ga-PSMA-617 and its microPET imaging in BGC-823 cell bearing mice

Abstract

Objective To prepare 68Ga-PSMA-617 and perform its microPET imaging on both normal BALB/c mice and BGC-823 (PSMA expression) tumor bearing mice. Methods 68GaCl3 was eluted from 68Ge-68Ga generator by 0.05 mol/L HCl, then added to the DKFZ-PSMA-617 and heated at 85 ℃ for 5 min. The labeling efficiency and in vitro stability of 68Ga-PSMA-617 in sodium chloride solution and HSA were analyzed by radio-HPLC. Water partition coefficient and plasma protein binding rate were also evaluated. MicroPET imaging was performed in normal female BALB/c mice and human gastric tumor (BGC-823) bearing mice at 60 min post-injection of 68Ga-PSMA-617. 18F-FDG was also injected to BGC-823 tumor bearing mice to acquire microPET imaging for contrast. Results The labeling yield of 68Ga-PSMA-617 was 97.9%, and it could be used directly without purification. 68Ga-PSMA-617 showed good in vitro stability in sodium chloride solution and 5% HSA, the radiochemical purities were 94.9% and 81.0% respectively at 80 min post-incubation. 68Ga-PSMA-617 was water-solubility substance, and it cleared mainly through the kidneys. MicroPET imaging showed that 68Ga-PSMA-617 could be accumulated in tumor (T/NT=2.28), which was better than 18F-FDG. Conclusions Preparation of 68Ga-PSMA-617 is convenient and has a high labeling yield. It can specifically target to PSMA expression tumors and has a promising prospect in clinical application. Key words: Prostate-specific membrane antigen; Isotope labeling; Gallium radioisotopes; Positron-emission tomography; Neoplasms; Mice; Mice, nude