Bioengineered Injectable Hydrogel Based on the Dentin Extracellular Matrix and Chitosan

The extracellular matrix of dentin contains macromolecules of biological value that make it a natural source for the prospection of novel smart biomaterials. Here, we described the development of an injectable thermosensitive smart hydrogel resulting from the blending of insoluble macromolecules of the dentin matrix and chitosan. The extrudability and gelation parameters of the prehydrogel were optimized by varying the concentration of individual components. Three-dimensional constructs were fabricated upon injection of the prehydrogel into custom-made molds, followed by incubation at 37 °C. Specimens were characterized for spectral, physical, morphological, mechanical, and biocompatibility features. Fourier-transform infrared (FTIR) analyses confirmed the integration of the dentin organic matrix and chitosan. The degree of porosity of constructs was ∼51%. The water diffusion of constructs reached a plateau after 2 days. Their moduli of elasticity were at a low MPa order, decreasing after storage in simulated body fluid (SBF). The biodegradability of constructs rose following incubation in SBF containing lysozyme or zinc ions. Hydrogel bioactivity was confirmed by FTIR and ultramorphologically suggested by surface precipitates. Hydrogel constructs were shown to be biocompatible with undifferentiated pulp cells (OD-21). Overall, the novel engineered injectable hydrogel based on dentin extracellular macromolecules and chitosan holds promising features for use as a scaffold for the regeneration of damaged load-bearing tissues like dentin and bone.