Co-cultured Bone-marrow Derived and Tendon Stem Cells: Novel Seed Cells for Bone Regeneration.

Tendon-bone healing after injury is an unsolved problem. Several types of stem cells are used as seed cells. However, the optimal co-culture ratio of different types of cells suitable for tissue engineering as well as the stimulator for facilitating the differentiation of stem cells in tendon-bone healing is unclear. In this study, the proliferation of both bone marrow-derived stem cells (BMSCs) and tendon stem cells (TSCs) was increased at a 1:1 co-cultured ratio, and proliferation was suppressed by Tenascin C (TNC). TNC treatment can promote osteogenesis or chondrogenesis of both BMSCs and TSCs under a 1:1 co-cultured ratio. In addition, the expression level of Rho-associated kinase (ROCK) increased in the process of TNC-induced osteogenesis and decreased in the process of TNC-induced chondrogenesis. Furthermore, the level of insulin-like growth factor 1 receptor (IGF-1R) and mitogen-activated protein kinase (MEK) was upregulated during the osteogenesis and chondrogenesis of both BMSCs and TSCs after TNC treatment. Although our study was conducted in rats with no direct evaluation of the resulting cells for tendon-bone healing and regeneration, we show that the proliferation of BMSCs and TSCs was enhanced under a 1:1 co-cultured ratio. TNC has a significant impact on the proliferation and differentiation of co-cultured BMSCs and TSCs. IGF-IR, ROCK, and MEK may become involved in the process after TNC treatment.