Objectives: The aim of this study was to investigate the effects of HEMA (2-hydroxy-ethyl-methacrylate) and TEGDMA (triethylene-glycol-dimethacrylate) on the odontogenic differentiation potential of Stem Cells derived from the Apical Papilla (SCAP) of human developing teeth. Methods: SCAP cultures were established form the apical papilla of third molars at the stage of root development after enzymatic dissociation with collagenase I/dispase. All donors signed an informed consent. Cell cultures were screened for stem cell markers, including STRO-1, CD146, CD34 and CD45 using flow cytometry. Cytotoxicity was evaluated with the MTT assay. DTSCs were then induced for osteo/odontogenic differentiation by media containing dexamethasone, KH2PO4, b-glycerophosphate and L-ascorbic acid in the presence of nontoxic concentrations of HEMA (0.05-0.5mM) and TEGDMA (0.05-0.25mM) for 3 weeks. Additionally, the effects of a single exposure (72h) to higher concentrations of HEMA (2mM) and TEGDMA (1mM) were evaluated. Results: SCAP cultures were positive for STRO-1 (1.70 ± 0.37 %), CD146 (63.54 ± 3.72%), CD34 (10.55 ± 1.74%) and negative for CD45. In the absence of monomers cell migration, differentiation and production of mineralized dentin-like structures could be observed. Cells also progressively expressed differentiation markers, including dentin sialophosphoprotein-DSPP, bone sialoprotein-BSP, osteocalcin-OCN and alkaline phosphatase-ALP. On the contrary, long-term exposure to nontoxic concentrations of HEMA and TEGDMA delayed the differentiation and mineralization processes of SCAP cells, whereas, one time exposure to higher concentrations of these monomers delayed to a higher extend the amount of mineralized matrix produced (p<0.01). BSP, OCN, ALP and especially DSPP expression were also down-regulated. Conclusion: These findings suggest that HEMA and TEGDMA are able to disturb the odontogenic differentiation potential of stem/progenitor cells derived from the apical papilla, which might have significant consequences for pulp tissue homeostasis and repair when resin-based materials are applied on developing teeth.
Supported by a grant of DAAD (German Academic Exchange Service)