Nanoceria short-term biodistribution in mice: focus on the brain.

Cerium oxide nanoparticles, also called nanoceria, are widely used for different commercial applications. They could also be of potential therapeutic use due to their antioxidant properties and neuroprotective effects, reported in recent years. Little evidence has been obtained in previous studies regarding the in vivo accumulation of cerium oxide nanoparticles in the central nervous system. However, in view of targeted delivery of nanoceria to the brain across the blood-brain barrier, we here investigated the penetration into the brain of in-house synthesized nanoceria. Brains and peripheral organs of mice, injected once with a suspension at two concentrations (1 or 20 mg/kg) of fluorescein isothiocyanate-conjugated nanoceria, were analyzed 24 h later. The investigation was pursued with confocal microscopy, inductively coupled plasma-mass spectrometry, and electron microscopy. Consistently with previous data, 10 nm nanoceria accumulation was observed in largest amount in the liver and spleen, with deposition also in the kidney and lung. Confocal microscopy revealed penetration of fluorescent nanoceria into the brain parenchyma, albeit in limited amount. Activation of glial cells, both astrocytes and microglia, was observed and is currently being analyzed. The findings indicate that a response of brain cells should be taken into account when nanoceria are administered in vivo.