CeO2 nanoparticles improve prooxidant/antioxidant balance, life quality and survival of old male rats.

Due to its unique redox chemistry, nanoceria is considered as potent free radical scavenger and antioxidant. However, their protective capacity in aging organisms remains controversial. To detect the anti-aging effects associated with the redox activity of 2 and 10 nm nano-CeO2, different test systems were used, including in vitro analysis, in situ assay of mitochondria function and in vivo studies of suitable nano-CeO2 on aging of male Wistar rats from 22 months-old to the end of life. The 2 nm nanoparticles exhibited not only antioxidant (·OH scavenging; chemiluminescence assay; decomposition of H2O2, phosphatidylcholine autooxidation) but also prooxidant properties (reduced glutathione and reduced nicotinamide adenine dinucleotide phosphate oxidation) as well as affected mitochondria whereas in most test systems 10 nm nano-CeO2 showed less activity or was inert. Prolonged use of the more redox active 2 nm nano-CeO2 (0.25-0.3 mg/kg/day) in vivo with drinking water resulted in improvement in physiological parameters and normalization of the prooxidant/antioxidant balance in liver and blood of aging animals. Survival analysis using Kaplan-Meier curve and Gehan tests with Yates' correction showed that by the time the prooxidant-antioxidant balance was assessed (32 months), survival rates exceeded the control values most considerably. The apparent median survival for the control rats was 900 days, and for the experimental rats-960 days. In general, the data obtained indicate the ability of extra-small 2 nm nano-CeO2 to improve quality of life and increase the survival rate of an aging organism.