Self-Assembling Peptide Nanofiber Hydrogels Targeted for Dental Tissue Regeneration

Recent isolation of postnatal stem cells from tooth-derived tissues opens new avenues in regenerative dentistry. These cells are capable of differentiating into various cell types including odontoblasts, and they produce a dentin matrix after transplantation in vivo. Combining them with a suitable scaffold might enable us to engineer dental tissues in the near future. Peptide-based hydrogels are particularly interesting as they self-assemble into networks of nanofibers, form macroscopic gels and serve as a matrix for cell encapsulation. Cell-matrix interactions can be tailored, and high control at the molecular level allows us to target these scaffolds for soft or mineralized tissue regeneration using tooth-derived stem cells. Objective: The aim of this study was to optimize peptide-based hydrogels for adhesion, proliferation and differentiation of dental stem cells. Methods: SHED (stem cells from human exfoliated deciduous teeth) and DPSC (dental pulp stem cells) were seeded in different peptide hydrogels and cultured for four weeks with different osteogenic supplements. The influence of cell adhesion motifs, gel density and enzyme-cleavable sites on cell viability and proliferation was investigated by MTT- and DNA-assay. Gene expression profiles after osteogenic induction were analyzed by real-time PCR using odontoblast-specific markers. Histologic analysis was performed to assess degradation and remodeling of the gel, extracellular matrix formation and mineral deposition. Results: Cells proliferate and differentiate within the gels, degrade the peptide matrix and produce collagen. The behavior depends on the type of cells and supplements. SHED show a spindle-shaped morphology, high proliferation rates and collagen production, resulting in soft tissue formation. DPSC differentiate into osteoblast-like cells and deposit mineral. Conclusion: Peptide hydrogels might be suitable to engineer soft or mineralized dental tissues using SHED or DPSC, respectively, in combination with appropriate differentiation factors. This research was supported by the Alliance for Nanohealth to JDH and NIH grant RO1-DE013368 to RDS.