Bioprinted multifuncional hydrogels as a strategy for Regenerative Dentistry

Abstract

Dentin and pulp regeneration remains as a clinical challenge due to irregular anatomical shape observed among patients, which may interfere with success rate, and lead to low regenerative potential when commonly available treatments are applied. In this way, new treatment options have been investigated to stimulate tissue regeneration within minimally invasive concept, by applying a biomaterial that perfectly shape in defected area and capable of stimulating resident cells from pulp and apical papilla to migrate for material's surface and differentiate to produce a new tissue, what is referred as cell homing therapy. In view of this, the purpose of this study is to develop tri-dimensional injectable or bioprinted scaffolds with porous and interconnected organized structure, containing micro-fluidics channels. These materials will be associated with metal oxides and polyphenols to be released at bioactive and angiogenic concentrations to mediate dentin and pulp regeneration. Firstly, the best concentration of each metal oxide (zinc, strontium, magnesium and silicon oxide) and polyphenol compound (proanthocyanidin, tannic acid, resolvin and resveratrol) will be selected when applied on dental pulp stem cells (DPCs) and endothelial cells (HUVECs) (Phase 1). Thereafter, injectable photoactivated hydrogels will be formulated based on gelatin methacrylate (GelMA) polymer containing the best concentration previously selected for each substance. Materials characterization will be performed to determine the morphology, topography, chemical composition, degradability, porosity, elasticity modulus and compressive strength. Also, the biological potential of these hydrogels will be investigated concerning mineralized matrix deposition and capillary network formation by DPCs and HUVECs, respectively, by direct cell seeding onto material's surface or by encapsulation within hydrogels network (Phase 2). Then, cylindric or tubular hydrogels designed by bioprinting with two surface templates (grid or honeycomb) and distinct porosity and pore distribution will be cultivated in microfluidic in-a-chip models by means of a perfusion bioreactor to evaluate the parameters related with cell viability, proliferation, migration, adhesion/spread, odontogenic and angiogenic differentiation (Phase 3). Finally, obtained injectable hydrogels and bioprinted scaffolds will be adapted in calvaria critical defects (Rattus novergiccus) to analysis in vivo mineralized tissue formation. Also, the biomaterials will be filled inside canal space of root fragments, followed by subcutaneous implantation in nude mouses (nu/nu), in order to evaluate the potential to create a vascularized tissue (Phase 4). At the end, qualitative data will be descriptively analyzed, and quantitative data will be submitted to specific statistical analysis.