Comparison of osteoblast responses to hydroxyapatite and hydroxyapatite/soluble calcium phosphate composites

Abstract

Hydroxyapatite/soluble calcium phosphate composites (HAp/SCaP) are novel HAp‐based materials with enhanced solubility that have been developed by annealing HAp in a vacuum. This study compared the effects of HAp and HAp/SCaP on osteoblast proliferation, differentiation, and mineralization using an MC3T3‐E1 cell culture system. MC3T3‐E1 cells were cultured on HAp or HAp/SCaP, and the number of attached cells and their morphology were examined. The influence of the extract from HAp/SCaP on osteoblast differentiation was determined by the measurement of alkaline phosphatase activity and reverse transcriptase‐polymerase chain reaction analysis of the expression of osteoblastic markers. In addition, mineralization was evaluated by the staining of calcium deposits with Alizarin red. Attachment of a greater number of cells exhibiting no degeneration in their morphology was observed on HAp/SCaP compared with HAp after incubation for 7 days or more. Culturing cells with the extract from HAp/SCaP resulted in promotion of alkaline phosphatase activity, the expression of type I collagen, and bone‐like tissue formation. The results of the present study indicate that HAp/SCaP shows greater ability in osteogenesis than HAp by increasing collagen synthesis and calcification of the extracellular matrix. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 127–135, 2005