Delivery of Phenamil Enhances BMP-2-Induced Osteogenic Differentiation of Adipose-Derived Stem Cells and Bone Formation in Calvarial Defects

Bone morphogenetic proteins (BMPs) have been widely used for bone repair in the craniofacial region. However, its high dose requirement in clinical applications revealed adverse effects and inefficient bone formation, along with high cost. Here, we report a novel osteoinductive strategy to effectively complement the osteogenic activity of BMP-2 using phenamil, a small molecule that can induce osteogenic differentiation via stimulation of BMP signaling. Treatment of adipose-derived stem cells (ASCs) with BMP-2 in combination with phenamil significantly promoted the in vitro osteogenic differentiation of ASCs. The efficacy of the combination strategy of phenamil+BMP-2 was further confirmed in a mouse calvarial defect model using scaffolds consisting of poly(lactic-co-glycolic acid) and apatite layer on their surfaces designed to slowly release phenamil and BMP-2. Six weeks after implantation, the scaffolds treated with phenamil+BMP-2 significantly promoted mouse calvarial regeneration as demonstrated by micro-computerized tomography and histology, compared with the groups treated with phenamil or BMP-2 alone. Moreover, the combination treatment reduced the BMP-2 dose without compromising calvarial healing efficacy. These results suggest promising complementary therapeutic strategies for bone repair in more efficient and cost-effective manners.