Chitosan in association with osteogenic factors as a cell-homing platform for dentin regeneration: Analysis in a pulp-in-a-chip model

Objective: In this paper we propose the association of beta-glycerophosphate (beta GP) and calocium-hydroxide with chitosan (CH) to formulate a porous bioactive scaffold suitable as a cell-homing platform for dentin regeneration. Methods: Calcium hydroxide and beta GP solutions were incorporated into chitosan to modulate scaffold architecture and composition by a phase separation technique. Architecture, chemical composition, and degradability were evaluated, and biological characterizations were performed by the seeding of dental pulp cells (DPCs) onto scaffolds, or by cultivating them in contact with leachable components (extracts), to determine cytocompatibility and odontoblastic differentiation. Cell-free scaffolds were then positioned in intimate contact with a 3D culture of DPCs in a pulp-in-a-chip platform under simulated pulp pressure. Cell mobilization and odontoblastic marker expression were evaluated. Deposition of mineralized matrix was assessed in direct contact with dentin, in the absence of osteogenic factors. Results: Incorporation of calcium hydroxide and beta GP generated a stable porous chitosan scaffold containing Ca-P nanoglobule topography (CH-Ca-beta GP), which favored cell viability, alkaline phosphatase activity, and mineralized matrix deposition by cells seeded onto the scaffold structure and at a distance. The pulp-in-a-chip assay denoted its chemotactic and bioactive potential, since dentin sialoprotein-positive DPCs from 3D culture adhered to CH-Ca-beta GP more than to plain chitosan. The higher deposition of mineralized matrix onto the scaffold and surrounding dentin was also observed. Significance: A CH-Ca-beta GP scaffold creates a microenvironment capable of mobilizing DPC migration toward its structure, harnessing the odontogenic potential and culminating in the expression of a highly mineralizing phenotype, key factors for a cell-homing strategy. (c) 2022 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.