Primary human osteoblast-like cells from four donors (2 males and 2 females, aged 60–85 years, cells isolated from the femoral head, IRB approval: EA4/035/14) in passage 2 were pooled. The patients gave written informed consent. Cells were cultured in DMEM/Ham's F-12 medium (Biochrom, Berlin, Germany) with 10% fetal bovine serum (FBS; Biochrom, Berlin, Germany), 1% penicillin/streptomycin (P/S; Biochrom, Berlin, Germany) and freshly supplemented 0.05 mM l -ascorbic acid (L-Asc) and 0.05 mM β-glycerol phosphate (β-Gly) (both Sigma-Aldrich/Merck, Darmstadt, Germany), henceforth called growth medium (GM).
The following groups were analyzed: 1) cells only (Medium), 2) titanium K-wire (CTRL), 3) porous K-wire (Porous), and 4) porous K-wire loaded with gentamicin (Genta). The porous K-wires of group 3 and 4 were coated with silver nanoparticles. For the cytocompatibility test, a toxic control was used: 5) 10% 2-hydroxyethyl methacrylate (HEMA; Positive). The experiments were done in triplicate and repeated once, resulting in n = 6 per group. For the experiments, 1.4 mm K-wire pieces (7 mm length) were transferred to inserts (10 mm diameter and polycarbonate membrane with 8 μm pores; Thermo Scientific/Nunc, Schwerte, Germany) and placed in the culture wells.
The following groups were analyzed: 1) cells only (Medium), 2) titanium K-wire (CTRL), 3) porous K-wire (Porous), and 4) porous K-wire loaded with gentamicin (Genta). The porous K-wires of group 3 and 4 were coated with silver nanoparticles. For the cytocompatibility test, a toxic control was used: 5) 10% 2-hydroxyethyl methacrylate (HEMA; Positive). The experiments were done in triplicate and repeated once, resulting in n = 6 per group. For the experiments, 1.4 mm K-wire pieces (7 mm length) were transferred to inserts (10 mm diameter and polycarbonate membrane with 8 μm pores; Thermo Scientific/Nunc, Schwerte, Germany) and placed in the culture wells.