Dexamethasone-loaded hollow hydroxyapatite microsphere promotes odontogenic differentiation of human dental pulp cells in vitro

A sustained-release system was established by synthesis of dexamethasone-loaded hollow hydroxyapatite microspheres (DHHAM). The in vitro effect of DHHAM on odontogenic differentiation of human dental pulp cells (hDPCs) was evaluated. Hollow hydroxyapatite microspheres (HHAM) are successfully manufactured using simple biomimetic one-step strategy in the presence of glycine and sodium dodecyl sulfonate. Dexamethasone (DEX) was loaded to the system after the formation of HHAM. The drug encapsulation capacity of DEX in HHAM is 40.3% and its loading efficiency is 16.7%. The cumulative release of DEX in vitro is 55% up to 35 days. Results of Real-time Polymerase Chain Reaction (Real-time PCR), alkaline phosphatase (ALP) activity and Alizarin Red S staining revealed that DHHAM can obviously promote bio-mineralization of hDPCs in the absence of osteogenic medium and enhance the gene expression of ALP, Runt-related transcription factor 2 (RUNX2), osteocalcin, dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP1). The data suggest that sustained release of DEX from DHHAM could efficiently enhance odontogenic differentiation of hDPCs.