Dental Pulp Stem Cells (DPSCs) have demonstrated immense potential for therapeutic purposes due to their easy accessibility as well as their capacity for self-renewal. Nonetheless, despite the increasing body of knowledge of stem cell transplantation, achieving specificity in cell responses remains challenging. In our previous study, we have shown that monodispersed Polybutadiene (PB) forms a convenient biocompatible scaffold to which cells can adhere without additional coatings. DPSCs plated on these PB substrates were able to adjust their moduli in response to the film thickness. However, a threshold at 2.3 MPa was observed after 28 days such that large amounts of biomineralized deposits would be produced if the substrate moduli were higher than this value. In this work we investigated how direct cell-cell contact of DPSCs cultured on PB substrates with different thicknesses(20nm and 200nm), representing hard and soft substrate mechanics effects, respectively, impacts differentiation pathways. The substrates were designated into 3 groups: contact group, non-contact group, and control group. Cell moduli and morphology were investigated by Atomic Force Microscopy and Confocal Laser Scanning Microscopy, respectively, after the first week of culture. Reverse Transcriptase Polymerase Chain Reaction was performed for selected gene markers: Alkaline Phosphatase(ALP), Runt-related transcription factor(Runx), and late markers, Dentin Sialophosphoprotein(DSPP) and Osteocalcin(OCN). The latter served as indicators of odontogenic and osteogenic differentiation. In addition, microarray was conducted to explore whether genetic expressions were affected by cell contacts. Finally, biomineralization images were captured on day 28 using Scanning Electron Microscopy. Our experimental results signify that DPSCs on substrates with different mechanics can alter their behaviors through direct cell-cell contact. No biomineralization was found on either hard or soft substrates when cells physically contact; however, differentiated and non-differentiated cells were capable of coexisting within a single culture when they did not contact across different substrates, where the phenotype was governed by the substrate mechanics. This study explored the influence of purely mechanical heterogeneity and the significance of cell communication, which are important for applying printed scaffolds as dentin/tooth regenerative biomaterials and promoting stem cell-based treatments.

Elucidating the effects of direct physical contact between dental pulp stem cells cultivated on polybutadiene with different stiffness on proliferation and differentiation behaviors

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.