A protein chimera self-assembling unit for drug delivery

In the modern view of selective drug delivery of bioactive molecules, the attention is moving onto the setup of the perfect carrier more than in the optimization of the active compound. In this respect, virus-like particles constitute bioinspired nanodevices with the intrinsic ability to transport a large class of molecules, ranging from smart drugs to small interfering RNAs. In this work, we demonstrate the efficacy of a novel construct obtained by fusing a self-assembling protein from the human Rotavirus A, VP6, with the Small Ubiquitin Modifier domain, which maintains the ability to form nanoparticles and nanotubes and is able to be used as a drug carrier, even without specific targeting epitopes. The high expression and purification yield, combined with low toxicity of the empty particles, clearly indicate a good candidate for future studies of selective drug delivery. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2769, 2019.

Biocompatibility of Root Canal Filling Materials: Differences between Vitality and Functionality Tests

Biocompatibility of root canal filling materials is of great interest because they can come into permanent contact with the living periapical tissue, and induce mild or severe inflammatory responses. Usually biocompatibility tests only determine non-cytotoxic effects of dental materials, even if their functional interactions with cells also play a role in the host responses. The purpose of this study is to evaluate peripheral blood monocyte (PBM) vitality and functionality after contact with 5 different root canal filling materials: Thermafil (gutta-percha), Real Seal and Real Seal 1 (methacrylic resins), AureoSeal (MTA) and SuperSeal (EBA). Cellular vitality was determined by MTT test and cellular functionality by Chemiluminescence (CL) technique. Dishes of the materials were covered with cell culture medium (0.5 cm2/mL) and incubated for 24 h. The extracts were added to PBMs and the latter, after 2 h of incubation, were analysed by MTT and by Chemiluminescence (CL). All results are expressed as mean ± SEM. The group means were compared by analysis of variance. Results showed that SuperSeal and AuroSeal exhibited a moderate cytotoxic effect, while the toxicity induced by RealSeal, RealSeal 1 and Thermafil was lower. SuperSeal and AuroSeal induced a significant decrease of both oxidative burst and basal reactive oxygen species (ROS) production. RealSeal 1 caused a doubling of basal ROS production in respect to control. The results demonstrate that a low cytotoxic effect does not guarantee a total integrity of cellular functionality and more differences among biocompatibility of root canal materials can be detected when a functionality test is used.

Cytotoxicity and genotoxicity of glycidyl methacrylate

Methacrylates are used in the polymer form as composite restorative materials in dentistry. However, the polymers can release monomers and co-monomers into the oral cavity and pulp, from where they can migrate into the bloodstream reaching virtually all organs. The local concentration of the released monomers can be in the millimolar range, high enough to induce adverse biological effects. Genotoxicity of methacrylate monomers is of a special significance due to potential serious phenotypic consequences, including cancer, and long latency period. In the present work, we investigated cytotoxicity and genotoxicity of glycidyl methacrylate (GMA) in the human peripheral blood lymphocytes and the CCR-CM human cancer cells. GMA at concentrations up to 5mM evoked a concentration-dependent decrease in the viability of the lymphocytes up to about 80%, as assessed by flow cytometry. This agent did not induce strand breaks in the isolated plasmid DNA, but evoked concentration-dependent DNA damage in the human lymphocytes evaluated by the alkaline and neutral comet assay. This damage included oxidative modifications to the DNA bases, as checked by DNA repair enzymes Endo III and Fpg as well as single and double DNA strand breaks. The lymphocytes exposed to GMA at 2.5 microM were able to remove about 90% of damage to their DNA in 120 min. The ability of GMA to induce DNA double-strand breaks was confirmed by pulsed field gel electrophoresis. The drug evoked apoptosis and induced an increase in the G2/M cell population, accompanied by a decrease in the S cell population and an increase in G0/G1 cell population. Due to broad spectrum of GMA genotoxicity, including DNA double-strand breaks, and a potential long-lasting exposure to this compound, its use should be accompanied by precautions, reducing the chance of its release into blood stream and the possibility to induce adverse biological effects.