Investigating the Toxicological Effect of Titanium Dioxide Nanoparticles on Liver

Transcription

1 Sustainable Nanotechnology Organization (SNO) 2013 Conference Investigating the Toxicological Effect of Titanium Dioxide Nanoparticles on Liver Vaishaali Natarajan, Christina Davis and Srivatsan Kidambi, Ph.D Department of Chemical and Biomolecular Engineering University of Nebraska-Lincoln

2 OUTLINE 1. Introduction 2. Experimental Design 3. Results/Discussion 4. Conclusions 5. Future Studies

3 Number of Products Titanium Dioxide Nanoparticles (TiO 2 NPs) One of the highest manufactured nanoparticles according to National Nanotechnology Initiative of America (Liang, G. et al, 2009) Nanoparticle form: Excellent physicochemical properties Versatile applications: Paints, cosmetics, water/air purification, pharmaceuticals and food products Availability: Predominantly Rutile and Anatase crystal forms Anatase Good fatigue strength Corrosion resistance Machinability Whitening Thermal stability Good electrical properties Photocatalysis Rutile ft/ Liang, G. et al. Influence of Different Sizes of Titanium Dioxide Nanoparticles on Hepatic and Renal Functions in Rats with Correlation to Oxidative Stress. J. Toxicol. Environ. Health, Part A 72, , (2009) Hussain, S.B et al. Crystal structure mediates mode of cell death in TiO 2 nanotoxicity, Journal of Nanoparticle Research 11, (2009)

4 Shi, H., Magaye, R., Castranova, V. & Zhao, J. Titanium dioxide nanoparticles: a review of current toxicological data. Part. Fibre Toxicol , (2013) TiO 2 NPs Exposure to Biological Systems Respiratory Dermal (1-10% of the product content) Oral (0.01 to 2 μg TiO 2 /mg food) Intravenous/ Subcutanous

5 TiO 2 NPs Toxicological Profile Toxicological properties dependent on physicochemical properties; varies drastically from the bulk form International Agency for Research on Cancer: possibly carcinogenic to humans Respiratory system extensively studied; High exposure rate causes serious health concerns in animal models Reference Particle (size nm) Exposure Effect Tang et al., 2011 Anatase TiO 2 (5±1) mg/kg TiO 2 hyperemia, alveolar thickness. Histology: lung gaps expanded, Scuri et al., 2010 P25 Degussa TiO 2 (21) 12 mg/m 3 TiO 2 for 5.6 hr a day, for 3 consecutive days. Neurotrophin expression: NGF, BDNF and their receptors increased in rats. Airway resistance: increased in mice. Li et al., 2010 Anatase TiO 2 (3) 3.3 mg/kg TiO 2 once a wk for 4 wks. Inflammatory action: ACP, ALP increased in BAL. Histology: destroyed alveolar walls. Liu et al., 2010 TiO 2 (5) TiO 2 (200) mg/kg TiO 2 AM phagocytic and chemotactic ability: reduced by TiO 2 NPs. Iavicoli, I. et al Toxicological effects of titanium dioxide nanoparticles: a review of in vitro mammalian studies. Eur Rev Med Pharmacol Sci 15, (2011).

6 Liver and TiO 2 NPs Bio-distribution studies on TiO 2 NPs show retention in the liver Meena, R. & Paulraj, R. Oxidative stress mediated cytotoxicity of TiO2 nano anatase in liver and kidney of Wistar rat. Toxicol. Environ. Chem. 94, 2012 Yamashita, K. et al. Silica and titanium dioxide nanoparticles cause pregnancy complications in mice. Nat. Nanotechnol. 6, , (2011) Fabian, E. et al. Tissue distribution and toxicity of intravenously administered titanium dioxide nanoparticles in rats. Archives of toxicology 82, (2008).

7 Liver and TiO 2 NPs Liver functions: Center for xenobiotic detoxification and clearance Most functions performed by hepatocytes Not many studies carried out to establish the toxicity of TiO 2 NPs on liver cells OBJECTIVE: To investigate the effect of different forms of Titanium Dioxide Nanoparticles on Primary Rat Hepatocyte viability, morphology and liver-specific functions Meena, R. & Paulraj, R. Oxidative stress mediated cytotoxicity of TiO2 nano anatase in liver and kidney of Wistar rat. Toxicol. Environ. Chem. 94,

8 1. Rutile 50nm 2. Anatase 50nm 3. Degussa P25 Isolation of primary hepatocytes by two step collagenase digestion Addition of TiO 2 to the cells Stirring Seeding cells Hepatocytes exposed to 100 ppm TiO 2 everyday

9 Experiments Morphology study: Phase contrast Viability study: Live/Dead fluorescent imaging MTT assay Cell-specific functions study: Urea secretion Albumin secretion Gene expression study: RT-PCR

10 TiO 2 NPs characterization- Dynamic Light Scattering Particle Type Particle Diameter Effective Diameter in Hepatocyte Medium (nm) Zeta Potential (mv) Degussa P25 21nm ± Anatase 50nm ± Rutile 50nm ±

11 Cell Morphology Day 1 Day 4 Untreated P25 Anatase Rutile Scale = 200 microns

12 Cell Viability Control P25 Anatase Rutile Live cells: Calcein AM (Green), Dead cells: Ethidium Bromide (Red) Scale = 200 microns Day 4 of culture with 100 ppm nanoparticle treatment

13 Relative Optical Density at 570 nm Cell Viability Study: MTT Cytotoxicity Assay * 0.8 * * Untreated P25 Anatase Rutile Day 4 of culture with 100 ppm nanoparticle treatment

14 Urea Synthesis (μg/ml/million cells) Introduction Exp. Design Results Conclusion Future Studies Liver-Specific Functions: Urea Synthesis * * * Ctrl P25 Anatase Rutile Day 4 of culture with 100 ppm nanoparticle treatment

15 Albumin secreted (μg/ml/million cells) Liver-Specific Functions: Albumin Synthesis * * * 0 Untreated P25 Anatase Rutile Day 4 of culture with 100 ppm nanoparticle treatment

16 Relative LDH gene expression Gene expression Study: Oxidative Stress * * * Untreated P25 Rutile Anatase Day 4 of culture with 100 ppm nanoparticle treatment

17 The nanoparticles compromise the normal viability and morphology of primary rat hepatocytes at a concentration of 100 ppm Hepatocytes specific functions are compromised when treated with nanoparticles Oxidative stress is induced in the cells by the nanoparticles

18 Investigating the mechanistic aspects of the toxicological effects of TiO 2 on primary hepatocytes Oxidative Stress Investigating the effect of the nanoparticles on in vitro liver model

19 ACKNOWLEDGEMENT Dr. Srivatsan Kidambi Dr. Edward Harris, Department of Biochemistry, UNL Focμs Lab, Department of Chemical and Biomolecular Engineering University of Nebraska-Lincoln