Controlled dual delivery of BMP-2 and dexamethasone by nanoparticle-embedded electrospun nanofibers for the efficient repair of critical-sized rat calvarial defect

There is an urgent need to develop biomimetic bone tissue engineering scaffolds for the repair of critical-sized calvarial defect. In this study, we developed a new nanoparticle-embedded electrospun nanofiber scaffold for the controlled dual delivery of BMP-2 and dexamethasone (DEX). The scaffold was achieved by (1) the encapsulation of BMP-2 into bovine serum albumin (BSA) nanoparticles to maintain the bioactivity of BMP-2 and (2) the co-electrospinning of the blending solution composed of the BSA nanoparticles, DEX and the poly(ε-caprolactone)-co-poly(ethylene glycol) (PCE) copolymer. The in vitro studies showed that the bioactivity of DEX and BMP-2 was preserved in the dual-drug-loaded nanofiber scaffold, and a sequential release pattern in which most of the DEX was released in the original eight days and the BMP-2 release lasted up to 35 days was achieved. The in vitro osteogenesis study demonstrated that the drug-loaded groups exhibited a strong ability to induce differentiation toward osteoblasts. In vivo osteogenesis studies also revealed that the degrees of repair of rat calvarial defect achieved with the drug-loaded nanofiber scaffolds were significantly better than those obtained with the blank materials; in particular, the dual-drug-loaded nanofiber scaffold manifested the best repair efficacy due to a synergistic effect of BMP-2 and DEX. Therefore, the dual-drug-loaded nanofiber scaffold is deemed a strong potential candidate for the repair of bone defects in bone tissue engineering.