Novel Injectable Borate Bioactive Glass Preparation And In Vivo Osteogenic Capacity Evaluation

OBJECTIVE: To find a new solution for the problems existing in the clinical application of bone cement. In the present study, we fabricated cements composed of borate bioactive glass particles(solid phase) and chitosan(liquid phase) with various solid/liquid ratio, assessed their physicochemical properties and investigated ions release and hydroxyapatite(HA) conversion of cements in simulated body fluid(SBF). This study also explored the response of human bone marrow-derived mesenchymal stem cells(BMSCs) seeded on the surface of cements in vitro and bone regeneration in rabbit femoral condyle defects in vivo.METHODS: The cements composed of BBG particles and chitosan solution with different solid-liquid ratio was prepared, and their injectability, initial setting time, and compressive strength were evaluated. The microstructure of the cements was examined in a scanning electron microscope(SEM). The concentration of ions released from the cements into the SBF was determined using inductively coupled plasma atomic emission spectroscopy(ICP-AES). After seeding the BMSCs onto the cements, we used SEM, CCK-8, ALP activity and qRT-PCR methods to study cell compatibility, cell adhesion, proliferation, and differentiation. In vivo bone regeneration in rabbit femoral condyle defects were evaluated by Micro-CT and histological examination.RESULTS: The cements composed of BBG particles and chitosan solution had controllable injectability, initial setting time, and compressive strength. In SBF, cements released ions and converted to HA. In vitro, the BBG cements supported BMSCs adhesion and proliferation compared to CS cements. Compared to BBG cements, Sr-BBG cements significantly promoted the ALP activity and osteogenic(RUNX2, BMP-2, BSP, COL-Ⅰand OCN) gene expression of BMSCs. Moreover, the bony defects implanted Sr-BBG cements showed more bone regeneration and higher bone and the implant contact(BIC) index.CONCLUTIONS: BBG cement is a potential bone repair material with controllable injectability, initial setting time, and compressive strength. In SBF, cements released ions and converted to HA. In vitro, the BBG cements supported BMSCs adhesion and proliferation compared to CS cements. Sr-BBG cements in vivo effectively promoted bone tissue regeneration, provided a new therapeutic approach for bone defects, especially the critical-sized bone defects.