In vitro liberation of charged gold atoms: autometallographic tracing of gold ions released by macrophages grown on metallic gold surfaces

Abstract

The present study demonstrates that cultured macrophages are able to liberate gold ions from metallic gold surfaces, a process suggested to be called "dissolucytosis", in a way analogous to the release taking place when metallic implants are placed in a body. Using the ultra-sensitive autometallographic (AMG) technique, we demonstrate that murine macrophages grown on a surface of metallic gold liberate gold ions. Ultra-structural AMG reveals that the gold ions are located in an ultra-thin membrane-like structure, "the dissolution membrane", intervened between the macrophages and the metal surface. The presence of AMG silver enhanced gold nanoparticles in the dissolution membrane proves that the release of charged gold atoms takes place extracellularly. The dissolution membrane is most likely secreted and chemically controlled by the "dissolucytes", here macrophages, and the membrane is essential for the dissolution of metal implants and particles, which cannot be phagocytosed. Our findings support the notion that whenever a metallic gold surface is attacked by dissolucytes, gold ions are liberated and taken up by surrounding cells. As gold ions can suppress the inflammatory process, it is reasonable to expect that when dissolucytosis takes place in the living organism the liberated gold ions will cause local immunosuppression.

Inflammatory Response to Therapeutic Gold Bead Implantation in Canine Hip Joint Osteoarthritis

“…7,14,25 In vivo and in vitro studies have shown that metallic gold implants release gold ions in tissues and cell cultures as a result of interaction with oxidative agents most likely provided by macrophages. 4,18 Some believe that the pro-inflammatory properties of gold can be attributed to ionized gold and its metabolites. 4,5 The purpose of the present article is to investigate the tissue inflammatory response surrounding metallic gold beads implanted into dogs as a treatment for spontaneous osteoarthritis.…”

Effects of AS-cast and wrought cobalt-chrome-molybdenum and titanium-aluminium-vanadium alloys on cytokine gene expression and protein secretion in J774A.1 macrophages

“…As opposed to Sethi et al (2002), using both wrought and as-cast CoCrMo, we observed that only as-cast CoCrMo suppressed IL-6 compared to TiAlV, but the increase in TNF-α was seen for both wrought and as-cast CoCrMo alloys. TNF-α increases osteoclast survival rate (Lee et al, 2001), transforms osteoclast precursors to mature osteoclasts (Lam et al, 2000), and activates resident nonactivated osteoclasts even at very low levels (e.g. 100 pg/ ml) (Fuller et al, 2002).…”

“…These ligand-interactions and several others are the primarily interaction between implant surface and macrophages (Ziats et al, 1988) resulting in cytokine release independently of internalization of wear particles (Bi et al, 2002;Fritz et al, 2006;Nakashima et al, 1999). The release of metal ions take place as a result of the dissolucytes (macrophages) controlling the chemical milieu in the membrane (Danscher, 2002;Larsen et al, 2007) in a process called dissolucytosis. Co 2+ and Cr 3+ ions induce necrosis and apoptosis as well as secretion of TNF-α, IL-6, and PGE2 in various cell-types (Catelas et al, 2003;Lee et al, 1997).…”

“…The release of metal ions take place as a result of the dissolucytes (macrophages) controlling the chemical milieu in the membrane (Danscher, 2002;Larsen et al, 2007) in a process called dissolucytosis. Co 2+ and Cr 3+ ions induce necrosis and apoptosis as well as secretion of TNF-α, IL-6, and PGE2 in various cell-types (Catelas et al, 2003;Lee et al, 1997). Few studies have investigated the surface (non-phagocytable foreign body) of implants where macrophages throughout the years interact with both corrosive products and surface properties.…”

Recent progress in histochemistry

“…However, it is recognized that gold ions inXuence the number and function of macrophages. Larsen et al (2007) now demonstrate that cultured macrophages are able to liberate gold ions from metallic gold surfaces in a way analogous to the release taking place when metallic implants are placed in a body. Using the ultra-sensitive autometallographic (AMG) technique, they show that murine macrophages grown on a surface of metallic gold liberate gold ions.…”