Gadolinium-Based MRI Contrast Agents Induce Mitochondrial Toxicity and Cell Death in Human Neurons, and Toxicity Increases With Reduced Kinetic Stability of the Agent

Objectives This preclinical study was devised to investigate potential cellular toxicity in human neurons induced by gadolinium-based contrast agents (GBCAs) used for contrast-enhanced magnetic resonance imaging (MRI). Neurons modeling a subset of those in the basal ganglia were tested, because the basal ganglia region is 1 of 2 brain regions that displays the greatest T1-dependent signal hyperintensity changes. Methods Eight GBCAs were tested. Dopaminergic neurons modeling a subset of those in the basal ganglia were differentiated from an established human neuroblastoma cell line and exposed to increasing concentrations of each agent for 7 days. The tested dosages ranged from clinically relevant concentrations measured in some autopsy patients who had received repeated injections of contrast for MRI, to higher concentrations to reveal dose-dependent toxicity trends. Cell death, mitochondrial membrane potential, mitochondrial oxidative capacity, and mitochondrial function measured by oxygen consumption were quantified in cells treated with each GBCA or the osmolality control mannitol and compared to untreated cells which served as a negative control. Results Mannitol caused no change from negative controls in any of the tests, at any concentration tested. For all GBCAs, cell death increased with exposure dose, with toxicity at clinically relevant doses for agents with lower kinetic stability. Reduction of mitochondrial membrane potential and oxidative respiratory function also generally mirrored the agents' structural kinetic stabilities, with greater impairment at lower concentration for the less stable agents. Conclusions In human neurons modeling a subset of those in the basal ganglia, these results demonstrate a toxic effect of gadolinium-containing MRI contrast agents on mitochondrial respiratory function and cell viability. Toxicity increases as agent concentration increases and as the kinetic stability of the agent decreases.