Zinc oxide nanoparticles promote the aging process in a size-dependent manner

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Toxicology

Background:

• Zinc oxide nanoparticles (ZnO NPs) are widely used in cosmetics, sunscreens, biosensors, and drug delivery.
• Mesenchymal stem cells (MSCs) serve as in vitro models for assessing acute toxicity.

Purpose of the Study:

• To evaluate the size-dependent cytotoxicity and aging effects of ZnO NPs on bone marrow and adipose MSCs.
• To determine safe concentration thresholds for different ZnO NP sizes.

Main Methods:

• Treatment of MSCs with ZnO NPs of average sizes 10-30 nm and 35-45 nm.
• Assessment of cytotoxicity using cell-cycle analysis and β-galactosidase assays.
• Analysis of aging-related gene expression (NF-kB, p53, Nanog).

Main Results:

• Safe concentrations were identified as 5 µg/ml for 10-30 nm ZnO NPs and 10 µg/ml for 35-45 nm ZnO NPs.
• Smaller ZnO NPs exhibited more detrimental effects on DNA synthesis entry.
• Smaller ZnO NPs promoted cellular senescence, upregulated aging genes (NF-kB, p53), and downregulated Nanog.

Conclusions:

• The size of ZnO NPs significantly influences their cytotoxicity and aging effects on MSCs.
• Smaller ZnO NPs are more potent inducers of cellular aging compared to larger ones.
• Findings underscore the importance of considering nanoparticle size in safety assessments for biomedical and cosmetic applications.