The Bone Regenerative effect of Osteoblasts on Novel Hydroxyapatite Ceramics

Objectives: Nobel interconnected porous calcium hydroxyapatite ceramics (IP-CHA) have a fully opened interconnected porous structure. This unique 3-D structure has the advantage that the biological tissue promptly invades into its pores. However, it is unclear the biological interaction between osteoblasts derived from normal human jaw bone (NHJOB) and IP-CHA. The aim of this study is to examine the utility of this material in the jaw bone tissue regeneration and clinical use of the osteoblasts/IP-CHA composite for the treatment of bone defects.

Methods: NHJOB were isolated from a patient underwent mandibular reconstructive surgery. We cultured NHJOB on IP-CHA with osteogenic medium containing dexamethasone, b-glycerophosphate and ascorbic acid. The expression of osteogenic gene such as alkaline phosphatase (ALP), type I collagen (coll-1), Osteocalcin (OCN) and Osteopontin (OPN) in NHJOB cultured on IP-CHA were analyzed using RT-PCR. Matrix mineralization was also examined by Alizarin Red S staining and ALP staining. IP-CHA was then implanted into the tibia of rats and examined by the histological analysis and micro-focuses X-ray computed tomography (mCT) after 2-8 weeks after implantation.

Results: The osteoblastic marker genes were up-regulated with the incubation period, 1-4 weeks. Extensive staining both of Alizarin Red S and ALP was observed over the entire ceramics area as compared with the control culture. ALP activity continuously increased with the incubation period, 1-4 weeks. In animal experiments, IP-CHA showed superior osteoconduction, with many of the pores filled with newly formed bone tissue. Newly bone formation through interpore connections with osteoblastic rimming and vessels were observed in the pore within 4 weeks after implantation of IP-CHA.

Conclusions: It was strongly suggested that IP-CHA was a useful biomaterial for jaw bone tissue regeneration. The osteoblasts/IP-CHA composite scaffold could be ideal scaffold for bone regeneration and bone tissue engineering due to its excellent osteoconduction and biocompatibility.