A Dentin-Derived Hydrogel Bioink for 3D Bioprinting of Cell-Laden Scaffolds in Regenerative Dentistry

Objectives: Recent studies in tissue engineering have adopted extracellular matrix (ECM) derived scaffolds as natural and cytocompatible microenvironments for tissue regeneration. The dentin matrix, specifically, has been shown to be associated with a host of soluble and insoluble signaling molecules that can promote odontogenesis. Here, we aim to developed a novel bioink that incorporates these signaling molecules and optimize it for use in 3D printing.
Methods: By blending printable alginate (3% w/v) hydrogels with varying fractions of soluble and insoluble dentin matrix signaling molecules we have created a bioink with favorable printability and odontogenic properties. We then optimized the printing parameters and the concentrations of the individual components of the bioink for print accuracy, cell viability, and odontogenic potential.
Results: We find that, while viscosity, and hence printability of the bioinks, was greater in the formulations containing higher concentrations of alginate, a higher proportion of insoluble dentin matrix proteins significantly improved cell viability; where a 1:1 ratio of alginate and dentin (1:1 Alg-Dent) was most suitable. We further demonstrate high retention of the soluble dentin molecules within the 1:1 Alg-Dent hydrogel blends, evidencing renewed interactions between these molecules and the dentin matrix post crosslinking. Moreover, at concentrations of 100 mg/ml, these soluble dentin molecules significantly enhanced odontogenic differentiation of stem cells from the apical papilla (SCAP) encapsulated in bioprinted hydrogels.
Conclusions: In summary, the proposed bioinks can function as a novel bioprintable and cytocompatible scaffold with natural odontogenic capacity, which can be a useful tool for regenerative dentistry in the future.