Human Cementoblastoma- Derived Cells Express Cartilage- LikePhenotype In vitro and In vivo and Induce Bone Formation

The molecular mechanisms that regulate proliferation and differentiation of cementoblasts, have not been elucidated to date. In this paper, it is shown that human cementoblastoma-derived cells (HCDC) express greater levels of cartilage markers such as type II and X collagens, aggrecan (ACAN) and SRY-box 9 (SOX9) stem cell markers; MCAM (melanoma cell adhesion molecule; synonym: CD146) and STRO-1 than human gingival fibroblasts (HGF). Our in vivo studies demonstrate that HCDC induce bone formation through endochondral ossification as observed 14 days after HCDC were implanted in rat critical-size calvarial defects. At 30 and 60 days post-implantation, the defects treated with HCDC were filled with 70 ± 1.6 and 91 ± 1.3% of newly formed bone. To confirm the identity of this tissue, we analyzed the newly formed bone using histomorphology and immunostaining. The results showed the expression of bone sialoprotein (BSP) and osteocalcin (OCN). Immmunostaining of human periodontal structures showed that cementoblasts and periodontal ligament cells express cementum protein 1 (CEMP1), cartilage markers, type II and X collagens and CD146 which has been identified as a marker for chondroprogenitor cells. Altogether these results indicate that HCDC has the capacity of multilineage differentiation and induces regeneration of mineralized tissues other than cementum.