Experimental study of prostate stem cell antigen specific MR molecular probe and in vivo MRI in nude mice model grafted with human prostatic cancer

Objective To construct the prostate stem cell antigen(PSCA) specific MR molecular probe 7F5@GoldMag,and to examine its biochemical characteristics,in order to investigate the feasibility of MRI of 7F5@GoldMag in prostatic cancer using a clinical 3.0T MR system in vitro and in vivo.Methods PSCA specific MR molecular probe 7F5@GoldMag was constructed using conjugating anti-human PSCA mAb 7F5 with GoldMagTM-CS nanoparticles,and the coupling efficiency was calculated.The specific binding capability for 7F5@GoldMag to prostatic cancer cells was detected using laser confocal microscopy,transmission electron microscope and flow cytometry.GoldMagTM-CS nanoparticles solution in different concentration was scanned to ascertain the lowest concentration that can be detected with MR system.Prostatic cancer cell line PC-3 and hepatic cell line SMMC-7721 were cultured(the later was control group) and nude mice models were established.The two cell lines were cross-matched with 7F5@GoldMag and non-related IgG@GoldMag.T2 weighted images were obtained and the signal intensity was measured in each group.After conventional scan,T2 weighted images were obtained after the probe was injected into nude mice model through caudal vein 6,12 and 24 h later,respectively.Statistical analysis were performed to assess the statistical differences of tumor signal intensity.Results PSCA specific MR molecular probe(7F5@GoldMag) was successfully constructed.The results of laser confocal microscopy,transmission electron microscope and flow cytometry proved that 7F5@GoldMag could specific bind with PC-3 cells.T2WI signal intensity of GoldMagTM-CS was significantly lower than that of agarose gel even if the former was diluted by 640 times.7F5@GoldMag could specifically decrease T2WI signal intensity of PC-3 cells in vitro.After 7F5@GoldMag was injected into nude mice model through caudal vein 6,12 and 24 h later,T2WI signal intensity of PC-3 tumor was significantly lower than that of conventional scan(F=43.675,P0.05).The signal intensity of control groups did not show significant difference.Conclusion PSCA specific MR molecular probe is successfully constructed by conjugating anti-human PSCA mAb 7F5 with GoldMagTM-CS nanoparticles,which can specifically bind with PC-3 cell and has target-directed enhancement effect in PC-3 cell line in vitro and in nude mice model grafted with PC-3 in vivo using a clinical 3.0T MR scanner.