Preparation of dexamethasone-loaded calcium phosphate nanoparticles for the osteogenic differentiation of human mesenchymal stem cells.

As an earliest known and readily available osteogenic inducer for stem cells, dexamethasone (DEX) plays a key role in affecting cell functions and cellular processes, especially for cell proliferation and differentiation. However, the clinical application of DEX has been limited because of its uncontrolled release. An ideal carrier is desired to control the DEX release for the osteogenic differentiation of stem cells and bone tissue engineering. Biphasic calcium phosphate nanoparticles (BCP-NPs) should be potential carriers for DEX due to their osteoconductive properties and good biocompatibility as a bone graft biomaterial. In this study, DEX-loaded BCP-NPs were prepared by two methods: (1) immersion of BCP-NPs in a DEX solution (denoted DEX/BCP-NPs), (2) DEX incorporation during BCP-NP formation in a calcifying solution (denoted DEX@BCP-NPs). The DEX@BCP-NPs showed a higher DEX loading amount and more sustainable DEX release than did the DEX/BCP-NPs. The DEX@BCP-NPs were used for the culture of human bone marrow-derived mesenchymal stem cells (hMSCs) and showed a promotive effect on the proliferation of hMSCs. Furthermore, the DEX@BCP-NPs significantly increased the alkaline phosphatase (ALP) activity, calcium deposition and gene expressions of the osteogenic markers of hMSCs when compared to BCP-NPs without DEX loading. The results demonstrated BCP-NPs were good carriers for DEX loading and the DEX@BCP-NPs should be useful for bone tissue engineering.