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

Objectives: The 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. Methods: Immature 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 cif the mini pig jaw. The resulting constructs were harvested after 6 and 10 weeks and evaluated by histological and immunohistochemical analyses. Results: Six 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. Conclusions: The 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. (J Endod 2012;38:913-919)