TEMPLATE DESIGN © Introduction Methods References Results EFFECT OF MELATONIN ON ODONTOGENIC DIFFERENTIATION OF HUMAN TOOTH GERM STEM CELLS (HTGSCs) 1 Pakize Neslihan Taşlı, 1 Mehmet Emir Yalvaç, 1 Fikrettin Şahin 1.Department of Genetics and BioEngineering, College of Engineering and Architecture, Yeditepe University, 26 Ağustos Campus, Kayisdagi cad., Kayisdagi, TR Istanbul, Turkey Melatonin (N-acetyl-5-methoxytryptamine) has many biological activities in body such as regulate variety of physiological processes, free radical scavenging, control of circadian rhythms and regulation of body temperature. These effects produced through activation of melatonin receptors as MTNR1A, MNTR1B and MNTR1C. It was suggested that melatonin may have an influence on tooth formation and growth. In this study, we tested effect of Melatonin on odontogenic differentiation in HTGSCs. HTGSCs with Mesenchymal stem cell properties were seeded in 6 well and 24 well plates followed by addition of odontogenic differentiation medium with and without Melatonin 50nM for 14 days. Differentiation was evaluated by measuring the level of Alkaline Phosphatase (ALP) activity, von Kossa Staining, immuno-cyto-chemistry with Melatonin Receptor 1A and 1B antibodies and expression levels of MTNR1A, DSPP and COL1A genes with quantitative RT-PCR. The data displayed that hTGSCs express Melatonin Receptors 1A and 1B. Melatonin increases cell viability and odontogenic differentiation of HTGSCs significantly which was confirmed by MTS assay, ALP assay, von Kossa Staining, immuno-cyto-chemistry analysis and quantitative RT-PCR. Discussions Figure1: Immunostaining of Melatonin Receptor 1A and 1B Figure 2 : Cell viability of hTGSCs with and without Melatonin. *p<0.05 Pulpa or dentin regeneration is a challenging task after root canal treatments. Many tooth filling materials show a sort of toxic effects on dental pulp cells reducing the level of regeneration. Our results might suggest that melatonin might have therapeutic potential in pulpa regeneration and recovery of dentin tissue. Figure 3 : Alkalibne Phosphatase activity of differentiated cells with and without Melatonin and hTGSCs. PC : Differentiated cells without Mel NC : hTGSC *p<0.05 Figure 4 : von Kossa staining of differentiated cells with and without Melatonin and hTGSCs as a NC. Figure 5 : Immunostaining of differentiated cells with and without Melatonin and hTGSCs as a NC. Figure 6 : mRNA levels of differentiated cells with and without Melatonin and hTGSCs as a NC, by quantitative Real Time PCR. PC : Differentiated cells without Mel. *p<0,05 Kumasaka, S., M. Shimozuma, et al. "Possible involvement of melatonin in tooth development: expression of melatonin 1a receptor in human and mouse tooth germs." Histochem Cell Biol 133(5): Acknowledgments This study was supported by Yeditepe University. I thank to Burcin KESKIN for preparation of cells for Flow cytometry. I also thank to Muhammet Taşlı, Aysu Yılmaz, Cevriye Pamukçu,Safa Aydın and Aysegul DOGAN for supporting me all the time.