Secretion of IL-6 and MCP-1 from MC3T3-E1 Osteoblasts Caused by the Contact with Nano Hydroxyapatite Particles

The levels of inflammatory cytokines, interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) secreted from mouse oriented osteoblast (MC3T3-E1) were measured using sandwich ELISAs as a function of the incubation time and the doses of 20 nm sized hydroxyapatite (HAp) particles. The level of IL-6 was stable with respect to the incubating time and monotonically increased with the dose of HAp. The dose dependent increase of IL-6 by fine HAp suggests the inflammatory responses in accordance with the reports from various metals and polymers. Thus the altering of the function of osteoblast caused by fine HAp particles is not a specific phenomena limited to metal or polymer. On the other hand, the MCP-1 increased with incubation time and was not dose dependent. Considering the gentle increase of MCP-1 at much concentrated dose in case of Ti, the lack of dose dependency in MCP-1 can be normal in case of HAp.