Cilomilast enhances osteoblast differentiation of mesenchymal stem cells and bone formation induced by bone morphogenetic protein 2

► The increase in BMP-2 induced bone formation in the presence of PDE4 inhibitor was studied. ► ALP, Runx2, Osx, and OCN were analyzed in the osteoblast differentiation. ► BMP-2 induced bone formation acts via Smad pathways. ► Osteogenesis enhancement due to BMP-2 and PDE4 inhibitor is correlated with the activation of 2 pathways: Smad and cAMP. MSCs treated with BMP-2 and cilomilast showed more rapid mineralisation.