Bioengineering of Dental Stem Cells in a 3-Dimensional Fibrin Hydrogel

Adult stem cells have been isolated from various tooth-derived tissues. These are capable of differentiating into different cell types including odontoblasts, and they form dentin-pulp-like complexes after transplantation in vivo. Combining these cells with a compatible scaffold might provide an applicable system to regenerate dental soft or mineralized tissues. Objectives: The aim of this study was to assess proliferation and differentiation of tooth-derived stem cells in a PEGylated fibrin hydrogel and to explore the potential of this delivery system for regenerative dentistry. Methods: Three tooth-derived stem cell lines were seeded in PEGylated fibrin hydrogels: SHED (stem cells from human exfoliated deciduous teeth), PDLSC (periodontal ligament stem cells), and DPSC (dental pulp stem cells). Cells were cultured with different osteogenic supplements. Viability, proliferation and alkaline phosphatase activity were monitored at various time points. After four weeks, RNA was extracted and quantitative real-time PCR was performed for marker genes of odontoblast differentiation. Histologic analysis included H&E, Masson's trichrome and von Kossa stain. Results: Cells in the fibrin gels proliferated continuously over a period of 28 days. After osteogenic induction, alkaline phosphatase activity increased about 20fold in SHED and DPSC, but 50fold in PDLSC, and odontoblast-specific genes were upregulated in all cell lines. Histologic analysis revealed degradation of fibrin and production of a collagenous matrix. Mineral deposition was observed for cells treated with osteogenic supplements. Conclusion: Fibrin hydrogels allow for growth and differentiation of all three stem cell lines. The tendency to form mineralized tissue is highest in PDLSC, followed by DPSC, whereas SHED might be more suitable for soft tissue regeneration. The mechanical properties of fibrin make it a suitable carrier system to insert cells into small defects. This research was supported by NIH grant RO1-DE013368 to RDS and a Seed Grant from The Whitaker Foundation, UTMDACC to RDS and LS.