Inhibition of connexin 43 prevents trauma-induced heterotopic ossification

Heterotopic ossification (HO) can result from traumatic injury, surgery or genetic diseases. Here, we demonstrate that overexpression of connexin 43 (Cx43) is critical for the development and recurrence of traumatic HO in patients. Inhibition of Cx43 by shRNA substantially suppressed the osteogenic differentiation of MC-3T3 cells and the expression of osteogenic genes. We employed a tenotomy mouse model to explore the hypothesis that Cx43 is vital to the development of HO. Inhibition of Cx43 by a specific shRNA decreased extraskeletal bone formation in vivo. In addition, we demonstrated that ERK signaling activated by Cx43 plays an important role in promoting HO. ERK signaling was highly activated in HO tissue collected from patient and mouse models. Importantly, de novo soft tissue HO was significantly attenuated in mice treated with U0126. Inhibition of Cx43 and ERK led to decreased expressions of Runx2, BSP and Col-1 in vivo and in vitro. Moreover, HO patients with low Cx43 expression or ERK activation had a lower risk of recurrence after the lesions were surgically removed. Our findings indicate that Cx43 promotes trauma-induced HO formation by activating the ERK pathway and enhances the expression of osteogenic markers.