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Tiny Particles, Big Impact: Titanium Dioxide (TiO2) Nanoparticles and Skin Barrier Disruption
Shi Fu
1, Divleen K. Singh
*1, Huiting Luo
1, Linda Liu
1, Diya Rai-Gersappe
2, Shiffoni Sukhlal
1, Gurtej Singh
1, Duc T. Bui
1, Sami Khan
1, Marcia Simon
1, Miriam Rafailovich
1, Alexander B. Dagum
11Stony Brook University, Stony Brook, NY; 2Vassar College, Poughkeepsie, NY
Background: The effects of different substances on cell functionality can be tested on bioprinted tissue engineered skin constructs. TiO
2 nanoparticles are a part of environmental pollution. When exposed to multiple cell types, adverse effects were reported. We explored rutile TiO
2's impact on keratinocytes and fibroblasts.
Methods: Skin equivalents were made from human keratinocytes and dermal fibroblasts treated with 0.4 and 0.8 mg/mL TiO
2 nanoparticles. Both or one cell type contained nanoparticles and were compared to the no particle control. The effect on functionality was determined from collagen contraction and colony formation efficiency (CFE) assays. The impact on cell differentiation was found from qRT-PCR.
Results: There was no change in collagen contraction. CFE decreased by 63% relative to the control. Histology showed constructs using keratinocytes containing 0.4 mg/mL TiO
2 exhibited 50% reduction in stratum corneum and epidermal thickness relative to the control and held large TiO
2 nanoparticle aggregates. qRT-PCR showed significant mRNA upregulation of differentiation markers filaggrin, involucrin, corneodesmosin, keratin 10, and mucin 15. Keratinocyte differentiation's early onset is a factor in their reduced proliferation. Differentiation was thought to trigger nanoparticle secretion from keratinocytes and encapsulation in a mucin-like substance, resulting in large aggregates. As skin equivalents developed, aggregates moved to the stratum corneum, from which we observed elimination. Increasing TiO
2 concentration to 0.8 mg/mL for keratinocytes resulted in larger aggregates, epidermal damage, and no stratum corneum formation.
Conclusion: TiO
2 affects keratinocytes in skin equivalents, inhibits proliferation, causes early differentiation, and results in a thinner epidermis and stratum corneum. After particle agglomeration, encapsulation and secretion occurred, showing the epidermal layer's ability to protect skin from pollutants. We need to understand TiO
2 nanoparticle interactions in biological systems and applications in dermatological contexts.
Histological and qRT-PCR results after treatment of human keratinocytes and dermal fibroblasts with different concentrations of titanium dioxide nanoparticles.
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