Ana L. Di Virgilio

Response of UMR 106 cells exposed to titanium oxide and aluminum oxide nanoparticles

The cytotoxicity potential of TiO(2) and Al(2)O(3) nanoparticles (NP) in UMR 106 cells was studied by evaluating the lysosomal activity with neutral red uptake assay (NR), and the mitochondrial activity with tetrazolium MTT test. Different NP concentrations (10-300 microg/mL range) were used. A significant (p < 0.001) increase in the absorbance (stronger for TiO(2) NP) was detected in both NR and MTT assays after 24-h exposure to the NP. However, the total cell proteins and the cell proliferation rate demonstrated (p < 0.05) that the cell viability decreased after 96 h exposure to NP. The formation of NP-containing vesicles within the cells was observed by transmission electronic microscopy. Such event could explain the high cellular activity detected during the early stages of exposure not related to the increase in cell viability. Results showed that the effects of NP on cell lines are dependent on the chemical composition of the particles, their concentration, exposure time, and the type of treated cell. It can be concluded that the presence of TiO(2) and Al(2)O(3) NP in the cell surroundings can lead to cytotoxic effects. In the case of osteoblast cells, such events may induce osseointegration failures in orthopedic and dental implants that release NP.

Vanadium, Ruthenium and Copper Compounds: A New Class of Nonplatinum Metallodrugs with Anticancer Activity

Cancer is a group of diseases involving abnormal cell growth. The cells grow uncontrollably with the potential to invade and spread to other parts of the body. This disease is one of the principal death causes in the world, thus becoming a significant topic of scientific research. On the other hand, transition metals play a fundamental role in different living systems. In particular, Metallodrugs represent new and powerful tools for diverse therapeutic applications. To date, various metallodrugs display interesting biological activities for chemotherapy. In this field, cisplatin was the first inorganic compound with high relevance in cancer treatment. This compound was a leader agent in clinical use. Toxicity and resistance problems trigger the development of other platinum drugs with better clinical perspective and also raise the scientific interest for the putative antitumor properties of V, Ru and Cu compounds. Several scientific articles show that complexes of these metals are the new metal-based drugs used in the treatment of several cancers, such us, lung, colon, breast, bladder, etc. In this review we recapitulate current information and new advances on antitumor in vitro effects of several organic and inorganic compounds derived from copper, ruthenium and vanadium. These metal derived compounds targeting DNA or cell proteins involved in cell signaling pathways related to cancer. The mechanisms of cell death of these metallodrugs have also been comprehensibly reviewed. The knowledge of these mechanisms of death and the relationship between chemical structure and biological activity may be useful for the design of new metal-based drugs with promising pharmacologic applications as anticancer agents.

Biocompatibility of magnesium particles evaluated by in vitro cytotoxicity and genotoxicity assays

Mg is a biodegradable biomaterial which may release particles (MP) to the environment. The possible cyto- and genotoxic effects of MP derived from magnesium powder (mesh 325) were analyzed on rat osteosarcoma UMR106 cells in order simulate the effect of Mg debris. Neutral red (NR) incorporation and acridine orange/ethidium bromide (AO/EB) staining techniques were used as endpoints to analyze the cytotoxic effects at 25-1000 μg/mL concentration range. Genotoxicity was estimated according to micronucleus (MN) formation and the Comet assay (CA). Results showed that MP size changes with time due to corrosion. Changes in lysosomal activity were observed after 24 h only at 1000 μg/mL. Accordingly, AO/EB staining showed a significant decrease in the number of living cells at 500 μg/mL. Transmission electronic microscopy showed MP internalization (60 and 200 nm diameter) in cells after 2-h treatment, whereas no MP was detected after 24 h. A significant dose-dependent increase in MN frequencies was observed at 25-100 μg/mL range (nontoxic range). DNA damage induction was assessed by CA only at 500 μg/mL. Results showed dose-dependent cytotoxic and genotoxic effects of MP on UMR106 cells with different threshold values of MP concentration.

Hydroxylamido–amino acid complexes of oxovanadium(V). Toxicological study in cell culture and in a zebrafish model

Oxovanadium(V) complexes [VO(NH(2)O)(2)(val)] and [VO(NH(2)O)(2)(met)] caused inhibition of cell proliferation in two osteoblast cell lines, MC3T3-E1 and UMR106, as well as the viability of zebrafish eggs. In MC3T3-E1, both compounds inhibited cell proliferation (up to ca. 40% at 25 μM [VO(NH(2)O)(2)(val)] and 25% at 25 μM [VO(NH(2)O)(2)(met)]). This effect occurs in a dose response manner from 2.5 μM (p < 0.01) with a more deleterious action of [VO(NH(2)O)(2)(met)]. In UMR106 tumoral cells, [VO(NH(2)O)(2)(val)] inhibited cell proliferation up to 75% from 25 μM while [VO(NH(2)O)(2)(met)] behaved as an inhibitory agent in the whole range of concentrations (p < 0.01). Similar toxic effects were obtained from morphological studies in cell cultures. Moreover, the IC(50) values for both complexes in culture studies correlated with the IC(50) values obtained with an in vivo model of toxicity (FET test). Besides, the cytotoxicity evaluation in cell culture showed a decrease in mitochondrial activity which was stronger for [VO(NH(2)O)(2)(met)] than for [VO(NH(2)O)(2)(val)] (44% vs. 58% at 25 μM) in both cell lines (p < 0.001). Genotoxicity assessed by micronuclei induction also showed a stronger effect of [VO(NH(2)O)(2)(met)] in both cell lines. Besides, [VO(NH(2)O)(2)(val)] caused DNA damage determined by comet formation in MC3T3-E1 cells in the range of 2.5-25 μM, while this effect could not be observed in the osteosarcoma cells. On the other hand, [VO(NH(2)O)(2)(val)] enhanced ROS levels over basal up to 225% and 170% at 100 μM in MC3T3-E1 and UMR106 cells, respectively (p < 0.01). For [VO(NH(2)O)(2)(met)] a similar situation was observed, suggesting an important role for oxidative stress in the toxicity mechanism of action. Although both complexes showed interesting results that would deserve further drug development [VO(NH(2)O)(2)(val)] was more stable than [VO(NH(2)O)(2)(met)] in the solid state. Therefore, we consider that [VO(NH(2)O)(2)(val)] is a good candidate to be tested in in vivo models as a potential antitumoral agent.

Dinuclear copper(II) complexes with valsartan. Synthesis, characterization and cytotoxicity

Two novel dinuclear complexes involving the antihypertensive drug valsartan and copper(II) ion have been prepared in water and DMSO. The complex compositions were determined as: [Cu(vals)(H(2)O)(3)](2).6H(2)O and [Cu(vals)(H(2)O)(2)DMSO](2).2H(2)O. They were thoroughly characterized by elemental and thermal analysis, spectrophotometric titrations and UV-visible, diffuse reflectance, FTIR, Raman and EPR spectroscopies. No effect of the ligand on two tested osteoblastic cell lines in culture (one normal MC3T3E1 and one tumoral UMR106) was observed in concentrations up to 100 μM. Higher concentrations of Valsartan are required to induce cytotoxicity in both cell lines. The antiproliferative effect of the tested complex ([Cu(vals)(H(2)O)(3)](2).6H(2)O) in a dose-response manner, was higher in the UMR106 osteoblastic cell line than that of the MC3T3E1 normal line at concentrations ≥100 μM. Morphological alterations are in accordance with proliferative observations.

Evaluation of the antibacterial effects of vancomycin hydrochloride released from agar-gelatin-bioactive glass composites

The aim of this work was to evaluate the perfomance of agar-gelatin (AG) composites and AG-containing 45S5 bioactive glass (BG) microparticles (AGBG) in relation to their water uptake capacity, sustained release of a drug over time, and antibacterial effects. The composites were fabricated by the gel-casting method. To impart the local drug release capacity, vancomycin hydrochloride (VC) was loaded in the composites in concentrations of 0.5 and 1 mg ml(-1). VC release was assessed in distilled water at 37 °C up to 72 h and quantified spectrophotometrically. The antibacterial activity of composites was evaluated by the inhibition zone test and the plate count method. The experiments were performed in vitro up to 48 h on three staphylococcus strains: Staphylococcus aureus ATCC29213, S. aureus ATCC6538 and Staphylococcus epidermidis ATCC12228. The results showed that the addition of BG to AG composites did not affect the degree of water uptake. The release of VC was significantly affected by the presence of BG. VC release was higher from AGBGVC films than from AGVC ones over prolonged incubation times. Bacterial inhibition zones were found around the composites. The halos were larger when the cells were put in contact with AGVC composites than when they were put in contact with AGBGVC ones. Nevertheless, the viable count method demonstrated that the composites inhibited Staphylococcus cell growth with no statistical differences. In conclusion, the addition of BG did not reflect an improvement in the parameters studied. On the other hand, composites loaded with VC would have a role in prophylaxis against bacterial infection.

Vanadium Effects on Bone Metabolism

Vanadium compounds are present in trace amounts in living organisms. In mammals, once absorbed from the gastrointestinal tract, they distribute among tissues and storage mainly in liver, kidney and bone. Vanadium compounds in pharmacological doses exert interesting effects as insulin enhancers, antitumoral and osteogenic agents. This review deals with the more relevant information about the osteogenic effects of vanadium compounds. Their actions on the different components of hard tissue and bone related cells in culture are summarized. Besides, the putative mechanism of action and the effects on in vivo models are also discussed.

Copper complex with sulfamethazine and 2,2′-bipyridine supported on mesoporous silica microspheres improves its antitumor action toward human osteosarcoma cells: cyto- and genotoxic effects

Ideal drugs to cure cancer leave normal cells unharmed while selectively turning tumor cells unviable. Several copper complexes have been able to selectively slow down tumor proliferation. We hypothesized that Cu(smz)2(bipy)·H2O (1)—a copper-complex that has two ligands capable of interacting with DNA—would outperform Cu(smz)2(OH2)·2H2O (2), and also that supporting 1 on mesoporous silica spheres would decrease even further tumor cell viability in vitro. After exposing osteosarcoma cells (MG-63) and normal phenotype cells of bone origin (MC3T3-E1) to either complex, we studied their toxic effect and mechanisms of action. We determined cell viability (MTT assay) and quantified formation of reactive oxygen species (oxidation of DHR-123 to rhodamine). Moreover, we assessed genotoxicity from (i) formation of micronucleus (MN assay) and (ii) damage of DNA (Comet assay). After the exposure of 1 supported on silica spheres, we tested cell viability. Our results confirm our hypotheses: inhibition of tumor cells follows: supported 1 > dissolved 1 > 2. Future work that enhances the load of the complex exclusively in mesopores may improve the ability of 1 to further inhibit tumor cell viability.