Inducing substances for chondrogenic differentiation of dental pulp stem cells in the conditioned medium of a novel chordoma cell line.

We successfully established a chordoma cell line, designated TSK-CHO1, derived from the clival chordoma. Currently, there is only one skull base chordoma cell line, UM-chor1, freely available to researchers. The established TSK-CHO1 cells were neoplastic, exhibited pleomorphic features, and secreted brachyury, as revealed by immunocytochemical staining or ELISA of conditioned medium (CM). Cells also secreted SOX9, which enhanced brachyury production. The CM of TSK-CHO1 cells promoted the production of hyaluronic acid and type II collagen during differentiation of human dental pulp stem cells (DPSCs) into fibrocartilage cells. Culture of DPSC pellets in a growth medium supplemented with 10% CM of TSK-CHO1 cells for 2 weeks resulted in the induction of fibrocartilage tissue under normoxic conditions. Brachyury produced by TSK-CHO1 cells promoted the production of collagen type II, peculiar to cartilage, in a dose-dependent manner. The newly established skull base chordoma cell line, TSK-CHO1, is expected to be used for elucidating the pathogenesis of skull base chordoma and for investigating the mechanism underlying the production of fibrocartilage.