Papers by Keyword: Carbonate Substituted Hydroxyapatite

Abstract: The mechanism by which carbonate substitution within the hydroxyapatite (HA) lattice improves osteoconduction is unclear. Discs of dense, sintered, phase-pure HA and carbonate substituted hydroxyapatite (CHA) were cultured with human CD14+ cells in the presence of macrophage-colony stimulating factor (M-CSF) and soluble receptor activator of nuclear factor (NF)-κB (sRANKL), during which time osteoclasts developed and resorbed the ceramic surface. Discs were then seeded with human osteoblasts (HOBs), and proliferation and collagen synthesis measured. Proliferation was increased on resorbed compared to control (unresorbed) surfaces on both materials. Collagen synthesis was increased on CHA compared to HA, an increase accelerated on a previously resorbed surface. The results suggest that osteoclasts can condition synthetic bioceramic surfaces and alter the responses of osteoblasts which subsequently populate them. Carbonate substitution may enhance osteoconduction via effects on enhanced bioresorption.

Abstract: Human osteoclasts derived from CD14+ precursors were cultured on discs of stoichiometric hydroxyapatite (HA) and carbonate substituted hydroxyapatite (CHA) of varying carbonate contents. Resorption of the ceramic increased with increasing carbonate content up to 2.35 wt. %. Development of osteoclasts is qualitatively different on ceramics compared to dentine, occurring in discrete, confluent subpopulations, which suggests local cell signalling may be important in the process. Resorption appears to drive further development of osteoclasts. Controlling carbonate content may be one way of controlling the rate of resorption of synthetic HA ceramics.