# Detrimental Synergistic Effects of Atmospheric Ozone and Polystyrene Nanoparticle Exposure on Human Adult Myogenic Progenitor Cells

## TL;DR

This study shows that ozone and polystyrene nanoparticles together harm muscle cells more than either alone, affecting their viability and function.

## Contribution

The novel finding is the synergistic toxicity of ozone and polystyrene nanoparticles on human muscle progenitor cells.

## Key findings

- Combined exposure to ozone and polystyrene nanoparticles significantly reduces cell viability in human myogenic progenitor cells.
- Differentiation capability of treated cells is notably impaired, especially with combined pollutant exposure.
- Pollutant exposure alters microRNA expression and increases superoxide anion levels in these cells.

## Abstract

Ozone (O3) and polystyrene nanoparticles (PNPs) display diffusive behavior that leads to toxicity in many tissues of the adult organism. In this study, we evaluated the interactions between atmospheric pollutants and human muscle, using human myogenic progenitor cells (huMPCs) derived from vastus lateralis skeletal muscle. To achieve this goal, O3 and PNPs were first tested individually to understand the impact of the single pollutant on huMPCs. Subsequently, pollutants were tested in combination to examine their potential synergistic effects, given the simultaneous presence of multiple pollutants in the atmosphere. Cell viability was assessed after treatment with O3 and PNPs, and it seems to be significantly affected in huMPCs exposed to the pollutants, tested both alone and in combination. Similarly, the differentiation capability of treated huMPCs was evaluated, and it was found to be significantly reduced compared to controls, especially when O3 and PNPs are tested in combination. Furthermore, an alteration in the expression of microRNAs involved in myogenic cells' proliferation and differentiation pathways was found. In light of the correlation between pollutants and increased oxidant levels, and O3's ability to produce the superoxide anion, superoxide anion levels in huMPCs exposed to pollutants were also assessed, and an increase in this oxidant was recorded. Thus, this preliminary study suggests that exposure to O3 and PNPs affects human muscle, as it alters all the analyzed parameters in huMPCs, filling a gap in the current literature.