Papers by Keyword: Macrophage

Abstract: The effect of manufactured nanoparticles on the expression of proinflammatory cytokine genes was examined. THP-1 cells differentiated into macrophage cells were exposed to TiO₂ and NiO medium dispersions. After 2, 6, 12, or 24 hours exposure, the expression of IL-1β, IL-6, IL-8, TNF-α and HO-1 genes was determined by real-time PCR. TiO₂ nanoparticles did not affect cytokine production. In addition, TiO₂ nanoparticles did not dissolve in the dispersion. On the other hand, NiO nanoparticles enhanced the expression of all the genes tested. NiO dispersions were composed of 58.3 μg/mL of NiO nanoparticles and 45.8 μg/mL of Ni²⁺. The release of metal ions from the nanoparticles is associated with their cytotoxicity. Therefore, the effect of an NiCl₂ solution containing 45.8 μg/mL of Ni²⁺ on the expression of cytokine genes was also examined. The effects of NiCl₂ were similar to those of the NiO nanoparticles. Furthermore, the effect of ZnO, SiO₂-coated ZnO, Sb₂O₃, and Cr₂O₃ nanoparticles on the expression of IL-1β, IL-8 and TNF-α genes was examined. Soluble nanoparticles, such as ZnO, SiO₂-coated ZnO, and Cr₂O₃ enhanced the gene expression of cytokines. Sb₂O₃ nanoparticles showed poor solubility and did not affect the expression of cytokine genes. In conclusion, these results suggest that nanoparticle solubility plays an important role in regulating the expression of proinflammatory cytokines.

Abstract: The reports on cytotoxic studies of carbon nanotubes (CNTs) increased exponentially. In the present study, we investigate murine macrophage RAW264.7 cell response for the CNTs immobilized on a polystyrene substrate. We prepared CNT-coated dishes, and estimate the interaction of RAW264.7 cells with CNTs by cell adhesion, proliferation assay, and measurement of TNF-α production. As a result, the highest cell adhesion and proliferation was observed on a commercially cell culture polystyrene dish, while CNT-coated dish indicate slightly lower activity of them. Moreover, amount of production of TNF-α on the CNT-coated dishes was considerable lower than that in the case of lipopolysaccharide (LPS) addition as a control. These results indicated that CNT-coated dishes could not show strong cytotoxicity for RAW264.7 cells in vitro.

Abstract: A series of linear poly(2-hydroxyethyl methacrylate) (PHEMA) with defined molecular weights (MW) and narrow molecular distributions were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using cumyl dithiobenzoate (CDB) as a chain transfer agent. Murine fibroblasts (3T3) were exposed to eluates from various PHEMA samples, washed or unwashed, and with or without dithioester end groups. After 72 hrs in cell culture, no cytotoxic response was elicited by the polymer samples devoid of dithioester end groups, and which also underwent a thorough washing regime. Specimens throughout the entire MW range were internalized by a macrophage (cell line Raw 264), suggesting that such polymers can be used as models for studying the biodegradation of PHEMA.

Abstract: The role of silica and macrophages in fibrosis is well documented, but in bone formation it is relatively unknown despite decades of research with bioactive glasses. In this study macrophages were isolated from rat peritoneal and then cultured for five days in the presence of two types of silica microparticles with different solubilities. After the fifth day the culture medium was collected, purified and used as an additive in bone marrow derived rat stem cell cultures. The stem cells were cultured for five days in α-mem containing only 0,5% of FCS, enabling cell survival but disrupting their proliferation. As controls, stem cells were also cultured in α-mem containing silica microparticles. At days one and five the amount of soluble collagen was assayed from the culture medium and the cells were counted. All stem cell cultures with macrophage medium additives were found to be proliferative, with statistically significant difference to controls. However, collagen was only produced in cultures containing medium from macrophages cultured with fast-dissolving silica microparticles. This suggests that silica can induce cell proliferation and extra cellular matrix protein secretion which is mediated by macrophages, and that the solubility of silica is also a major factor in this reaction.

Abstract: Both biochemical cell functional test and animal implantation test were done to investigate the reaction to fine particles. Particles cause nonspecifically phagocytosis to cells and inflammation to tissue for the size below 10m. With the size below 50nm particles may invade into the internal body through the respiratory or digestive system and diffuse inside body. Ti mapping by XSAM after the compulsory exposure test to the respiratory system showed the internal diffusion of 30nm TiO2 particles. They diffused with time course to lung, liver and spleen after injection from caudal vein. Nanoparticles might be the objects whose existence has not been assumed by the biophylactic system.

Abstract: Macrophages play a critical role in inflammatory response to implanted biomaterials and formation of restenosis. Macrophage adhesion may lead to macrophage activation and smooth muscle cell proliferation. Titanium oxide films on stainless steel are potential biomaterials for application to vascular stents. They have different influences on smooth muscle cell proliferation in in vivo tests, which could be the main reason for restenosis, but the mechanism is not clear. In this study we show that titanium oxide films can reduce inflammatory reaction with macrophages. Unstimulated macrophages release small amounts of chemical substance such as NO and give slight effect on smooth muscle cell proliferation.

Abstract: Ti-O film is a kind of potential biomaterial may be applied in medical devices. But the mechanism of its good biocompatility is not so clear. This study revealed that when Titanium oxide contact with macrophage and plasma, the activation, adhesion and secretion of inflammatory molecule MCP-1 of macrophage is lower than reference material. Ti-O film also show minor contact activation to plasma. So reducing the host reaction including contact activation and inflammation may be the important reason for the good biocompatibility of Ti-O film.

Abstract: Mice macrophages which were mixed with β-tricalcium phosphate (β-TCP) ceramics powder were cultured, both calcium and phosphorus concentrations in the culture medium were evidently higher than that of β-TCP ceramics powder without cells. The microscope and SEM observation showed that macrophages wrapped β-TCP particles, and then phagocytized them into cytoplasm. The pH values inside and outside macrophage in β-TCP-bearing were tested. The histochemistry observation showed that there were many carbonic anhydrase positive grains in the cytochylema of macroghage after β-TCP ceramics powder being implanted. TEM investigation indicated that many β-TCP particles were phagocytized into the cytochylema of macroghage, and then vacuole was found after particles had degraded. The results showed that macrophages could take part in the degradation of calcium phosphate ceramics in two different ways.