Health hazards of nanoparticles: understanding the toxicity mechanism of nanosized ZnO in cosmetic products.

In recent years, nanoparticles are being used extensively in personal healthcare products such as cosmetics, sunscreens, soaps, and shampoos. Particularly, metal oxide nanoparticles are gaining competence as key industrial constituents, progressing toward a remarkable rise in their applications. Zinc oxide and titanium oxide nanoparticles are the most commonly employed metal oxide nanoparticles in sunscreens, ointments, foot care, and over the counter topical products. Dermal exposure to these metal oxides predominantly occurs through explicit use of cosmetic products and airway exposure to nanoparticle dusts is primarily mediated via occupational exposure. There is a compelling need to understand the toxicity effects of nanoparticles which can easily enter the cells and induce oxidative stress. Consequently, these products have become a direct source of pollution in the environment and thereby greatly impact our ecosystem. A complete understanding of the toxicity mechanism of nano-ZnO is intended to resolve whether and to what extent such nanoparticles may pose a threat to the environment and to human beings. In this review article, we have discussed the characteristics of metal oxide nanoparticles and its applications in the cosmetic industry. We have also highlighted about their toxicity effects and their impact on human health.

Targeting Wnt Signaling through Small molecules in Governing Stem Cell Fate and Diseases.

BACKGROUND: The conserved Wnt/ß-catenin signaling pathway is responsible for multiple functions including regulation of stem cell pluripotency, cell migration, self-renewability and cell fate determination. This signaling pathway is of utmost importance, owing to its ability to fuel tissue repair and regeneration of stem cell activity in diverse organs. The human adult stem cells including hematopoietic cells, intestinal cells, mammary and mesenchymal cells rely on the manifold effects of Wnt pathway. The consequences of any dysfunction or manipulation in the Wnt genes or Wnt pathway components result in specific developmental defects and may even lead to cancer, as it is often implicated in stem cell control. It is absolutely essential to possess a comprehensive understanding of the inhibition and/ or stimulation of the Wnt signaling pathway which in turn is implicated in determining the fate of the stem cells. RESULTS: In recent years, there has been considerable interest in the studies associated with the implementation of small molecule compounds in key areas of stem cell biology including regeneration differentiation, proliferation. In support of this statement, small molecules have unfolded as imperative tools to selectively activate and inhibit specific developmental signaling pathways involving the less complex mechanism of action. These compounds have been reported to modulate the core molecular mechanisms by which the stem cells regenerate and differentiate. CONCLUSION: This review aims to provide an overview of the prevalent trends in the small molecules based regulation of stem cell fate via targeting the Wnt signaling pathway.