gms | German Medical Science

81st Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

12.05. - 16.05.2010, Wiesbaden

TiO2 particles increase the mutagenic risk as detected in primary human oropharyngeal epithelial cells

Meeting Abstract

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 81st Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Wiesbaden, 12.-16.05.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. Doc10hno026

DOI: 10.3205/10hno026, URN: urn:nbn:de:0183-10hno0265

Published: July 6, 2010

© 2010 Brus et al.
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Outline

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Introduction: TiO2 is thought to be nonmutagenic but is discussed to increase inflammatory responses triggering mutagenesis. Thus TiO2 was analyzed regarding effects on micronucleus (MN) formation in our OECD-conform MN assay using primary human oropharyngeal epithelial cells (EC).

Methods: After receiving patients’ informed consent, mucosal biopsies were taken and EC isolated by tryptic digestion. Thereafter, EC were grown using KSFM (keratinocyte serum-free medium with 20 ng/ml of epidermal growth factor) in petri-dishes coated with extracellular matrix proteins (EMP). After two passages, EC of 48 donors were seeded into EMP-coated 24-well plates. Following 3 days at 3.5% CO2, 36.5°C, 95% relative humidity, supernatants were aspirated and pure KSFM (negative control; NC), 100 pM mitomycin C (positive control; PC), or 100 µg/cm2 TiO2 were administered in a total volume of 1.00 ml KSFM to duplicate wells. After 24-h, cytokinesis was blocked by cytochalasin B. 24 hours later, supernatants were withdrawn, EC ethanol-fixed, and DNA DAPI-stained. In each well MN were counted in 1000 bi-nucleated EC (BN).

Results: 43/48 EC (89.6%) responded with significant MN induction in PC (>130% NC). Neither significant difference in MN formation in NC in comparison of males vs. females nor between donors with differing nicotine consumption (below or above 30 pack years) was found; the medians were the same (20 MN in 1000 BN). Differences of these groups regarding medians and interquartile ranges of MN-formation in PC or TiO2-treated EC were only insignificant. In the t test for paired samples a significant induction of MN formation by TiO2 (p<0.01) was found.

Conclusions: TiO2 is able to increase MN formation in pEC. This outcome is only slightly influenced by sex and smoking behavior.