Ovine periodontal ligament stem cells: Isolation, characterization, and differentiation potential

Periodontal disease leads to destruction of the connective tissues responsible for restraining teeth within the jaw. To date, various conventional therapies for periodontal regeneration have shown limited and variable clinical outcomes. Recent studies have suggested that newly identified human periodontal ligament stem cells (PDLSCs) may offer an alternate and more reliable strategy for the treatment of periodontal disease using a cell-based tissue engineering approach. In the present study, we generated enriched preparations of PDLSCs derived from ovine periodontal ligament using immunomagnetic bead selection, based on expression of the mesenchymal stem cell-associated antigen CD106 ( vascular cell adhesion molecule 1). These CD106(+) ovine PDLSCs demonstrated the capacity to form adherent clonogenic clusters of fibroblast-like cells when plated at low densities in vitro. Ex vivo- expanded ovine PDLSCs exhibited a high proliferation rate in vitro and expressed a phenotype (CD44(+), CD166(+), CBFA-1(+), collagen-I+, bone sialoprotein(+)) consistent with human-derived PDLSCs. Furthermore, cultured ovine PDLSCs expressed high transcript levels of the ligament/tendon-specific early transcription factor scleraxis. Importantly, ex vivo- expanded ovine PDLSCs demonstrated the capacity to regenerate both cementum-like mineral and periodontal ligament when transplanted into NOD/SCID mice. The results from the present study suggest that ovine PDLSCs may potentially be used as a novel cellular therapy to facilitate successful and more predictable regeneration of periodontal tissue using an ovine preclinical model of periodontal disease as a prelude to human clinical studies.