Toxicological Risk Assessments of Iron Oxide Nanocluster- and Gadolinium-Based T1MRI Contrast Agents in Renal Failure Rats.

Gadolinium-based contrast agents (GBCAs) are widely used for T1-weighted magnetic resonance imaging (MRI) in clinic diagnosis. However, a major drawback of GBCAs is that they can increase the toxicological risk of nephrogenic systemic fibrosis (NSF) in patients with advanced renal dysfunction. Hence, safer alternatives to GBCAs are currently in demand, especially for patients with renal diseases. Here we investigated the potential of polyethylene glycol (PEG)-stabilized iron oxide nanoclusters (IONCs) as biocompatible T1MRI contrast agents and systematically evaluated their NSF-related risk in rats with renal failure. We profiled the distribution, excretion, histopathological alterations, and fibrotic gene expressions after administration of IONCs and GBCAs. Our results showed that, compared with GBCAs, IONCs exhibited dramatically improved biosafety and a much lower risk of causing NSF, suggesting the feasibility of substituting GBCAs with IONCs in clinical MRI diagnosis of patients with renal diseases.