Experimental Formation of Dentin-like Structure in the Root Canal Implant Model Using Cryopreserved Swine Dental Pulp Progenitor Cells

ObjectivesThe purpose of the present study was to present histological and immunohistochemical evidence showing the regenerative capacity of swine dental pulp stem cells (S-DPSCs) seeded on organic or synthetic scaffolds and implanted as hybrid root implants in the jaw bone of minipigs.MethodsImmature permanent incisor teeth and unerupted premolars at the early root-forming stage were extracted from three 7-month-old minipigs, and mesenchymal stem/progenitor cells were isolated from dental pulp. Cells were cryopreserved in liquid nitrogen. A year later, new permanent incisor and premolar teeth were extracted; pulp tissue was removed; and pieces of root canals of the extracted teeth, containing collagen or Poly(lactic-co-glycolic acid) scaffolds seeded with the autologous cryopreserved DPSCs, were implanted into the fresh post-extraction socket of the mini pig jaw. The resulting constructs were harvested after 6 and 10 weeks and evaluated by histological and immunohistochemical analyses.ResultsSix weeks postoperatively, the central canal space of the root implants showed degrading scaffold material. New extracellular matrix had been deposited in a polar predentin-like pattern on the canal dentinal walls by cuboidal nonpolarized cells. Ten weeks postoperatively, newly formed organic matrix had been consistently deposited on the canal walls. The presence of a continuous layer of polarized cells showing typical columnar morphology adjacent to the newly deposited organic matrix was evident.ConclusionsThe interactions of S-DPSCs with the dentin matrix of roots implanted in the jawbone of minipigs constitute a model to study in vivo organization and differentiation potential of DPSCs.