In vivo investigation of PCL/PHBV/Hydroxyapatite Nanocomposite Scaffold in Regeneration of Critical-sized Bone Defects

Several synthetic and natural scaffolds have been developed for bone tissue engineering (BTE). This study was designed to fabricate and characterize a composite scaffold based on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/polycaprolactone (PCL) polymers containing 5 % Hydroxyapatite (HA) nano-particles (HA5) for regeneration of bone critical size defect in a rat animal model. In the first step of this study, the PHBV/PCL (30 and 70 wt.%, respectively) with and without HA nanoparticle scaffolds were fabricated by Dual-Leaching Technique and then evaluated for FTIR spectroscopy, SEM, degradation rate, cell binding and proliferation. In the second step, the scaffolds were applied for cell differentiation and animal study. Human osteoblast-like Saos-2 cell line was seeded onto the scaffolds and Alkaline Phosphatase (ALP) activity was assayed on 7 days and 14 post-culture. The capacity of scaffolds to promote the bone regeneration genes was also investigated using quantitative RT-PCR. The critical size defects were made on the dorsal part of the rat's calvarium and were filled with PCL70PHBV30 and PCL70PHBV30HA5 scaffolds and were then evaluated histologically and histomorphometrically. The higher mean percentage of new bone formation, bone cells and osteon, as well as lower fibrous connective tissue, was detected in the PCL70PHBV30HA5 group than that of the other groups. In conclusion, the HA nanoparticles at 5 % concentration have been well distributed in the PCL70PHBV30 scaffold that could accelerate bone regeneration.