Mesenchymal stem cells acquire characteristics of cells in the periodontal ligament in vitro

Mesenchymal stem cells differentiate into multiple types of cells derived from mesenchyme. Periodontal ligament cells are primarily derived from mesenchyme; thus, we expected mesenchymal stem cells to differentiate into periodontal ligament. Using a combination of immunohistochemistry and in situ hybridization on co-cultures of mesenchymal stem cells and periodontal ligament, we observed a significant increase in mesenchymal stem cells' expression of osteocalcin and osteopontin and a significant decrease in expression of bone sialoprotein, characteristics of periodontal ligament in vivo. Increased osteopontin and osteocalcin and decreased bone sialoprotein expression was detected within 7 days and maintained through 21 days of co-culture. We conclude that contact or factors from periodontal ligament induced mesenchymal stem cells to obtain periodontal-ligament-like characteristics. Importantly, analysis of the data suggests the feasibility of utilizing mesenchymal stem cells in clinical applications for repairing and/or regenerating periodontal tissue.