The In Vitro and In Vivo Osteogenic Capability of the Extraction Socket-Derived Early Healing Tissue

Healed extraction socket is one autologous bone source. Extraction socket-derived early healing tissue (ESEHT) contains stem cells, osteoblasts, and growth factors, suggesting that it should have an osteogenic potential. The objective of this preliminary study is to explore the in vitro and in vivo osteogenic ability of ESEHT.

ESEHT from 2-week healing extraction sockets and proper alveolar bone (PAB) from interdental septa or surrounding socket walls were acquired from beagle dogs. For in vitro experiments, ESEHT and PAB were separately cocultured with mouse bone marrow-derived stromal cell lines (st2 cells) using a transwell system. The effect of ESEHT or PAB on migration, proliferation, and osteogenic differentiation of st2 cells was investigated. For in vivo study, 36 inflammatory Class II furcation defects in the bilateral mandibles of dogs were surgically created, and then ESEHT and PAB from the maxilla of the same dogs were implanted into defects. Histologic observation and histometric analysis were performed after an 8-week healing period.

The in vitro results indicated that ESEHT and PAB significantly promoted cellular migration, proliferation, alkaline phosphatase activity, expressions of bone sialoprotein, and Runt-related transcription factor 2 in messenger RNA and protein levels and, moreover, that ESEHT showed stronger activities than PAB except in chemotactic activity. The in vivo tests showed that ESEHT and PAB had a similar function in enhancing percentages of regenerated cementum and regenerated bone, which were significantly higher than those in blank control groups.

Results showed that ESEHT possesses better effects on migration, proliferation, and osteogenic differentiation of mesenchymal stem cells in vitro but similar promotion effect on periodontal regeneration in vivo compared with PAB, suggesting that ESEHT may be one of the most effective graft materials for periodontal regeneration.