Study on the composite with sequential and sustained release of multiple growth factors for bone repair

Previous studies on the drug carrier of single growth factor for bone repair have encountered a challenge that the regeneration of the new bone was not completely restored [1], Thus, the drug carrier systems with multiple growth factors have emerged [2]. The current studies of drug carrier with multiple growth factors still face the difficulties that the growth factors needed to be sequential and sustained released. To achieve the goal of sequential and sustained release of multiple growth factors, here we propose an injectable drug-loaded implant including poly(lactide-co-glycolide) (PLGA)/poly(vinyl alcohol) (PVA) microspheres and chitosan-based hydrogel. A fluorescent dye, fluorescein isothiocyanate (FITC), was employed as a model drug which was encapsulated in the PLGA/PVA microspheres and hydrogel. Optical microscope, scanning electron microscope, and laser confocal microscope were applied to analyze the material structure and morphology of microspheres. Fourier transform infrared spectroscopy was applied to characterize the bonding of chitosan-based hydrogel. The release profile of FITC released from the PLGA/PVA microspheres and hydrogel were studied. The cell viability of the proposed implant was also examined. It was found that the PLGA/PVA microsphere-embedded hydrogel demonstrated a sequential and sustained release profile, and the composite achieved a high cell viability. Most importantly, the composite could be applied through an injectable style, which accommodates to clinical use. This composite can then be applied to encapsulate and release multiple growth factors for bone repair and bone tissue engineering.