Gold Nanoparticles Inhibit Matrix Metalloproteases without Cytotoxicity

Abstract

Nanoparticles (NPs) are currently the focus of considerable attention for dental applications; however, their biological effects have not been fully elucidated. The long-term, slow release of matrix metalloproteases (MMPs) digests collagen fibrils within resin-dentin bonds. Therefore, MMP inhibitors can prolong the durability of resin-dentin bonds. However, there have been few reports evaluating the combined effect of MMP inhibition and the cytotoxic effects of NPs for dentin bonding. The aim of this study was to evaluate MMP inhibition and cytotoxic responses to gold (AuNPs) and platinum nanoparticles (PtNPs) stabilized by polyvinylpyrrolidone (PVP) in cultured murine macrophages (RAW264) by using MMP inhibition assays, measuring cell viability and inflammatory responses (quantitative reverse transcription polymerase chain reaction [RT-qPCR]), and conducting a micromorphological analysis by fluorescence and transmission electron microscopy. Cultured RAW264 cells were exposed to metal NPs at various concentrations (1, 10, 100, and 400 µg/mL). AuNPs and PtNPs markedly inhibited MMP-8 and MMP-9 activity. Although PtNPs were cytotoxic at high concentrations (100 and 400 µg/mL), no cytotoxic effects were observed for AuNPs at any concentration. Transmission electron microscopy images showed a significant nonrandom intercellular distribution for AuNPs and PtNPs, which were mostly observed to be localized in lysosomes but not in the nucleus. RT-qPCR analysis demonstrated inflammatory responses were not induced in RAW264 cells by AuNPs or PtNPs. The cytotoxicity of nanoparticles might depend on the core metal composition and arise from a "Trojan horse" effect; thus, MMP inhibition could be attributed to the surface charge of PVP, which forms the outer coating of NPs. The negative charge of the surface coating of PVP binds to Zn(2+) from the active center of MMPs by chelate binding and results in MMP inhibition. In summary, AuNPs are attractive NPs that effectively inhibit MMP activity without cytotoxicity or inflammatory responses.

Metallic nanoparticles reduce the migration of human fibroblasts in vitro

“…Also, it was shown that AuNPs can alter cell function without modifications on cell viability, corroborating with our findings. It was observed that macrophages from RAW 264 cell lines exposed to 100–400 μg/ml of AuNPs stabilized with polyvinylpyrrolidone (PVP), with approximately 36 nm of diameter and spherical shape inhibited metalloproteinase (MMP) activity, while they did not alter cell cytotoxicity [47]. The same group showed that these AuNPs did not alter fibroblast viability, while they could inhibit MMP-1 activity [48].…”

Inhibition of matrix metalloproteinases and toxicity of gold and platinum nanoparticles in L929 fibroblast cells

“…The most reliable materials are those that have inhibitory effects on MMPs without being cytotoxic to cells or pulp tissue. We previously reported the effects of AuNPs and PtNPs, stabilized by polyvinylpyrrolidone (PVP) surfactant, on the cellular function of macrophage cells (RAW264 cells), in which those effects were assessed using a combination of MMP‐8 and MMP‐9, and cytotoxicity assays . The objective of the present study was to evaluate the effects of PVP‐stabilized AuNPs and PtNPs on the cellular function of another cell line (L929 fibroblasts), using a combined analysis achieved through assay of another type of MMP (MMP‐1).…”

The Inhibitory Effects of Gold Nanoparticles on VEGF-A-Induced Cell Migration in Choroid-Retina Endothelial Cells

“…Gold nanoparticles downregulate cellular cascades of interleukin-1β-induced pro-inflammatory response [30], and topical application of AuNPs decreases intraocular oxidative damage and inflammation [31]. Besides, AuNPs can effectively inhibit matrix metalloproteinase activity without causing cytotoxicity or inflammation [32]. AuNPs induce oxidative stress in mouse fibroblast, and the cells trigger the autophagic pathways as a survival mechanism to avoid cell death [33].…”