Evaluation of human dental pulp stem cells behavior on a novel nanobiocomposite scaffold prepared for regenerative endodontics

Dental caries is a dental disease affecting public health, which results in many socio-economic consequences. This disease causes loss of tooth hard tissue and subsequent inflammation and loss of the dental pulp. In this study, it was aimed to develop and characterize boron (B) modified bioactive glass nanoparticles (BG-NPs) containing cellulose acetate/oxidized pullulan/gelatin (CA/ox-PULL/GEL) three dimensional scaffolds with tubular morphology for dentin regeneration. 3D nanobiocomposite structures were prepared by thermally induced phase separation and porogen leaching methods and characterized by in vitro degradation analysis, water absorption (WA) capacity measurement, SEM, in vitro biomineralization analysis, porosity measurement and mechanical tests. Scaffolds lost about (30-40)% of their weight during one month and WA capacity decreased with increase in immersion time in phosphate buffer solution (PBS) during one month. According to SEM, aligned and tubular structures were formed with mean diameter of about 11 μm, and BG-NPS were distributed evenly in all parts of the scaffolds. Scaffolds (without BG-NPs) possessed the highest porosity percentage. Addition of 10% BG-NPs improved the mechanical properties of scaffolds. Scaffolds surfaces were fully covered by calcium phosphate (Ca-P) deposits after conditioning in simulated body fluid for 14 days with higher quantity of deposition in groups with inclusion of B-BG-NPs. Human dental pulp stem cells (hDPSCs) were isolated from third molar teeth and used in cell culture studies. In all groups, cells adhered well 1 day after culture. Group B14-10 showed a slight increase of proliferation than group (without BG-NPs) after 7 days of incubation. Alkaline phosphatase activity (ALP) and intracellular calcium amounts increased significantly 14 days after incubation with highest values in B14-10 and B14-20 groups. Confocal laser scanning microscopy (CSLM) analysis, showed that cells on B14-10 and B21-10 scaffold groups, spread more 14 days after culture, and they also possessed extended processes specific to odontoblasts. Alizarin Red quantification showed that the highest calcium deposition was observed on B14-10 scaffolds. Immunohistochemical and Von Kossa stainings showed that scaffolds positively affected the odontoblastic differentiation of the hDPSCs. In this work, results showed that boron modified BG-NPs (B-BG-NPs) incorporated dentin-like constructs bring a new approach for dental tissue engineering applications.