Fig. 3.

In MG-63 / THP-1 co-cultures OPG, in contrast to OPN, is secreted by osteoblastic cells. THP-1 macrophage-like cells co-cultured with MG-63 osteoblasts were stimulated with LPS (100 ng/ml) or UHMWPE particles (cell-to-particle ratio of 1:500). The secretion of the osteoblastic marker OPG and the multifunctional protein OPN were quantified in cell culture supernatants. OPG secretion [pg/ml] by both co-cultures and controls as per 10 μg of total MG-63 osteoblast-derived protein at 6 h (a) and b 24 h of incubation is shown. c OPN secretion [pg/ml] by both co-cultures and controls as per 100.000 cells at 6 h of incubation is exemplarily shown. d OPN secretion, as normalized to the unstimulated control, of MG-63 cells, THP-1 cells and the respective co-cultures activated by LPS (100 ng/ml) or UHMWPE (cell-to-particle ratio of 1:500) is exemplarily shown for 6 h of incubation. THP-1 cells are the source of the protein in the current setup. *p < 0.05; **p < 0.01