Effect of bead size for scaffold on mouse osteoblasts

Introduction: The objective of this study was to evaluate the effect of bead size for injectable 3D composite scaffold (3D) on the behavior of KUSA/A1 mouse osteoblasts. Materials and Methods: b-TCP porous beads 300 to 500 (SB), 500 to 700 (MB) and 700 to 850 mm (LB) in diameter were fabricated. A 3D of b-TCP porous beads and alginate was obtained. KUSA/A1 was loaded onto the 3D and was cultured for 3, 7, and 14 days. The 3D with beads of various diameters was visualized by SEM. The total amount of DNA, alkaline phosphatase (ALP) activity and osteocalcin (OCN) expression were assessed using ELISA. KUSA/A1 loaded into the 3D was subcutaneously implanted into the back of 6-week-old KSN nude mice. The mice were killed and the tissue blocks were subjected to hematoxylin and eosin staining for histological examination after 4, 8 and 12 weeks implantation. Results: SEM observations showed that bone-like nodule formation appeared on the surface after 7 days for the various sizes of 3D. After 3 days in culture, LB showed significantly the highest DNA levels and the lowest OCN expression in the three 3D. By 3 days, cells in the 3D with MB showed significantly higher ALP activity than the other bead sizes. However, by 7 and 14 days in culture there was no significant difference in DNA levels, ALP activity or OCN expression. The interconnected alginate was completely degraded, and newly formed bone was observed in the connective tissue for all sizes of 3D after 8 weeks implantation. Statistical analysis was performed by one way ANOVA. Conclusion: The results suggest that the MB size structure is more favorable to osteogenic differentiation than the other bead size structures in the early stage. In vivo findings indicate that b-TCP bead and alginate composites support bone regeneration.