The Effect of Collagen Coating in Crystallized Hydroxyapatite Scaffold

ABSTRACT

PURPOSE: Hydroxyapatite (HA) has been widely used due to its chemical similarity to bone and good biocompatibility. HA is composed of macropores and micropores. Too much irregularities of the micropores are ineffective against the adhesion and proliferation of osteoblast. Many efforts have been tried to overcome these drawbacks. HA crystal coating on the irregular surface of HA scaffold, crystallized HA, is one of the method to improve cell adhesion. Meanwhile, the collagen has been incorporated with HA to create composite scaffold that chemically resembles the natural extracellular matrix components of bone. The authors proposed to examine the effect of collagen-coated crystallized HA on the adhesion and proliferation of osteoblast. METHODS: HA powder containing 10 microM pore size was manufactured as 1 cm pellet size. In order to make crystallized HA, 0.1 M EDTA solution was used to dissolve HA powder and heated 100degreesC for 48 hours. Next, the crystallized HA pellets were coated with collagen (0.1, 0.5, and 1%). The osteoblasts were seeded into HA pellets and incubated for the various times (1, 5, and 9 days). After the indicating days, methylthiazol tetrazolium (MTT) assay was performed for cell proliferation and alkaline phosphatase (ALP) activity was measured for bone formation. RESULTS: In SEM study, the surface of crystallized HA pellet was more regular than HA pellet. MTT assay showed that the proliferation of osteoblasts increased in a collagen dose-dependent and time-dependent manner and had a maximum effect at 1% collagen concentration. ALP activity also increased in a collagen dose-dependent manner and had a highest effect at 1% collagen concentration. CONCLUSION: These data showed that crystallization and collagen coating of HA was effective for osteoblast proliferation and ALP activity. Therefore, our results suggest that crystallized-HA scaffold with collagen coating is may be a good strategy for tissue engineering application for bone formation