Published online Apr 15, 2022. doi: 10.4251/wjgo.v14.i4.858
Peer-review started: April 28, 2021
First decision: July 14, 2021
Revised: August 31, 2021
Accepted: March 14, 2022
Article in press: March 14, 2022
Published online: April 15, 2022
Processing time: 351 Days and 15.7 Hours
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.
To validate the effectiveness of a bi-specific probe in vivo for enhancing T1-weighted positive contrast to diagnose the early-stage HCC.
The single- and double-antibody-conjugated 5-nm USPIO probes, including anti-AFP-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.
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 non-targeted 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.
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.
Core Tip: Use of single biomarkers might hinder the detection efficiency of existing hepatocellular carcinoma (HCC) molecular probes due to tumor heterogeneity, while negative (T2) contrast agents could result in inaccurate diagnoses. Therefore, we developed double-antigen-targeting magnetic resonance imaging (MRI) probes for hepatic tumors by conjugating alpha-fetoprotein or glypican-3 antibodies simultaneously to a 5-nm ultra-small superparamagnetic iron oxide (USPIO) and investigated its performance in orthotopic HCC mouse model. The bi-specific T1-positive contrast-enhanced MRI probe for HCC demonstrated increased specificity and sensitivity to diagnose early-stage HCC irrespective of tumor size and/or heterogeneity. Moreover, the in vivo enhancement of imaging by the USPIO probes appeared dose-dependent and requires further investigation.