Partial Rescue of Enamel Defects in Runx2 Conditional Knockout Mice

This study aimed to explore the rescue effect of exogenous Runx2 overexpression on enamel defects caused by Runx2 knockout in mouse ameloblasts. Immunohistochemistry was used to detect the expression of Runx2 in ameloblasts of Tg;cKO mice. HE staining was used to observe the morphology of mature ameloblasts and the residual enamel matrix protein. A stereoscopic microscope and scanning electron microscope were used to observe the tooth surface morphology and enamel rod structure. The results showed that RUNX2 protein was successfully expressed in early maturation stage ameloblasts in Tg;cKO mice on postnatal day 10. Compared with cKO mice, Tg;cKO mice showed no significant improvement in the morphology and arrangement of late maturation stage ameloblasts on postnatal day 15, but the residual amount of enamel matrix protein was significantly reduced. Compared with cKO mice, the 3-month-old Tg;cKO mice had less enamel abrasion, reduced pores between enamel rods, and more regular enamel rods. This study demonstrated that human-derived Runx2 overexpression could partially rescue the enamel defect caused by Runx2 knockout in mouse ameloblasts.