Bi-specific T1 positive-contrast-enhanced magnetic resonance imaging molecular probe for hepatocellular carcinoma in an orthotopic mouse model

BACKGROUND Hepatocellular carcinoma(HCC)is the second leading cause of cancer-related mortality.HCC-targeted magnetic resonance imaging(MRI)is an effective noninvasive diagnostic method that involves targeting clinically-related HCC biomarkers,such as alpha-fetoprotein(AFP)or glypican-3(GPC3),with iron oxide nanoparticles.However,in vivo studies of HCC-targeted MRI utilize single-target iron oxide nanoprobes as negative(T2)contrast agents,which might weaken their future clinical applications due to tumor heterogeneity and negative MRI contrast.Ultra-small superparamagnetic iron oxide(USPIO)nanoparticles(approximately 5 nm)are potential optimal positive(T1)contrast agents.We previously verified the efficiency of AFP/GPC3-double-antibody-labeled iron oxide MR molecular probe in vitro.AIM To validate the effectiveness of a bi-specific probe in vivo for enhancing T1-weighted positive contrast to diagnose the early-stage HCC.METHODS The single-and double-antibody-conjugated 5-nm USPIO probes,including antiAFP-USPIO(UA),anti-GPC3-USPIO(UG),and anti-AFP-USPIO-anti-GPC3(UAG),were synthesized.T1-and T2-weighted MRI were performed on day 10 after establishment of the orthotopic HCC mouse model.Following intravenous injection of U,UA,UG,and UAG probes,T1-and T2-weighted images were obtained at 12,12,and 32 h post-injection.At the end of scanning,mice were euthanized,and a histologic analysis was performed on tumor samples.RESULTS T1-and T2-weighted MRI showed that absolute tumor-to-background ratios in UAG-treated HCC mice peaked at 24 h post-injection,with the T1-and T2-weighted signals increasing by 46.7%and decreasing by 11.1%,respectively,relative to pre-injection levels.Additionally,T1-weighted contrast in the UAG-treated group at 24 h post-injection was enhanced 1.52-,2.64-,and 4.38-fold compared to those observed for single-targeted anti-GPC3-USPIO,anti-AFP-USPIO,and nontargeted USPIO probes,respectively.Comparison of U-,UA-,UG-,and UAG-treated tumor sections revealed that UAG-treated mice exhibited increased stained regions compared to those observed in UG-or UA-treated mice.CONCLUSION The bi-specific T1-positive contrast-enhanced MRI probe(UAG)for HCC demonstrated increased specificity and sensitivity to diagnose early-stage HCC irrespective of tumor size and/or heterogeneity.