Cytotoxicity tests on eye drop preparations by LDH release assay in human cultured cell lines

Comparison of cell viability between mouse-derived ES-D3 cells and Balb/c 3T3 cells using denture-base lining materials

The study was done to compare cell viability between ES-D3 and Balb/c 3T3 cells, and evaluate the difference in cell viability between these cell lines using denture-base lining materials for prosthetic dentistry. To compare the cytotoxicity, three acrylic and three silicone dental materials were used. The cell viability was examined by MTT and lactate dehydrogenase (LDH) methods. The cell viability immediately after malaxation or light irradiation was lower only for the acrylic materials in 3T3 cells, and for both silicone and acrylic materials in ES-D3 cells. However, the cell viability determined 24 h after malaxation or light irradiation by the MTT and LDH methods did not significantly differ between samples. It was observed that ES-D3 cells are more sensitive depending on the type of material. The results suggest that ES-D3 cells can be used as in vitro systems for conducting biosafety assessment to predict embryotoxicity.

Mmp-9 responsive PEG cleavable nanovesicles for efficient delivery of chemotherapeutics to pancreatic cancer

Significant differences in biochemical parameters between normal and tumor tissues offer an opportunity to chemically design drug carriers which respond to these changes and deliver the drugs at the desired site. For example, overexpression of the matrix metalloproteinase-9 (MMP-9) enzyme in the extracellular matrix of tumor tissues can act as a trigger to chemically modulate the drug delivery from the carriers. In this study, we have synthesized an MMP-9-cleavable, collagen mimetic lipopeptide which forms nanosized vesicles with the POPC, POPE-SS-PEG, and cholesteryl-hemisuccinate lipids. The lipopeptide retains the triple-helical conformation when incorporated into these nanovesicles. The PEG groups shield the substrate lipopeptides from hydrolysis by MMP-9. However, in the presence of elevated glutathione levels, the PEG groups are reductively removed, exposing the lipopeptides to MMP-9. The resultant peptide-bond cleavage disturbs the vesicles’ lipid bilayer, leading to the release of encapsulated contents. These PEGylated nanovesicles are capable of encapsulating the anticancer drug gemcitabine with 50% efficiency. They were stable in physiological conditions and in human serum. Effective drug release was demonstrated using the pancreatic ductal carcinoma cells (PANC-1 and MIAPaCa-2) in two-dimensional and three-dimensional “tumor-like” spheroid cultures. A reduction in tumor growth was observed after intravenous administration of the gemcitabine-encapsulated nanovesicles in the xenograft model of athymic, female nude mice.

Enhancement of systemic tumor immunity for squamous cell carcinoma cells by an oncolytic herpes simplex virus

RH2 is a neurovirulent γ134.5 gene-deficient herpes simplex virus type 1 (HSV-1) with a lytic ability in human squamous cell carcinoma (SCC) cells; it is related to spontaneously occurring HSV-1 mutant HF10. The effect of RH2 on SCC was examined using a syngeneic C3H mouse model. After infection of mouse SCCVII cells with RH2, cell viability was decreased at first, but recovered by prolonged culture, indicating the limited replication of RH2. The antitumor ability of RH2 was examined using a bilateral SCCVII tumor model. The growth of the RH2-injected tumors was suppressed compared with that of phosphate-buffered saline-injected tumors. Moreover, the growth of contralateral tumor of RH2-treated mice was also suppressed significantly. The splenocytes of C3H mice treated with RH2 lysed more SCCVII cells than NFSaY83 cells and YAC-1 cells. The cytotoxicity of the splenocytes on SCCVII cells was significantly greater than that of splenocytes from tumor-bearing mice. Removal of CD8(+) T cells from splenocytes decreased their cell killing activity remarkably. The antitumor effect of RH2 on SCCVII xenografts in nude mice was not demonstrated. These results indicate that RH2 exhibited a suppressive effect on mouse SCC, even if the replication of RH2 was limited. This is ascribed to the ability of RH2 to enhance existing tumor-specific cytotoxic T lymphocyte activity.

A physiological perspective on the swelling properties of the mammalian corneal stroma

PURPOSE

The present studies were designed to assess whether measurement of corneal stroma swelling in the laboratory, especially in non-physiological solutions, was associated with a measurable effect on the keratocytes.

METHODS

Complete corneal stroma preparations were made from quality- and age-selected recent post-mortem cattle eyes. These were either assessed immediately or incubated in three different solutions, namely a balanced salts solution with glucose (BSSG), isotonic phosphate buffered saline (PBS) or pure water. Incubations were carried out at 37 degrees C for 9h, and repeated measures of wet mass made so that the rates and extent of swelling could be determined. After incubation, an aqueous extract was made of the stroma for measurements of the levels the enzymes lactate dehydrogenase (LDH), aldehyde dehydrogenase (ALDH) and N-acetyl-beta-glucosaminidase.

RESULTS

The initial rates of swelling were lowest in BSSG, marginally faster in PBS and much faster in water. The secondary rates of swelling showed the same sequence being 10.0%/h in BSSG, 14.8%/h in PBS and 34.2%/h in water. Compared to non-incubated preparations, reductions in all three enzyme activities occurred. For LDH, these were 15% with BSSG, 40% in PBS and 80% with water. Similar results were seen with ALDH activity when comparing the three incubation solutions, while incubation in BSSG also resulted in a substantial (40%) reduction in N-acetyl-glucosaminidase activity.

CONCLUSIONS

When immersed in an isotonic BSSG with added glucose at 37 degrees C, the swelling of a complete bovine corneal stroma is much less than smaller pieces of stroma, and also slightly less than if isotonic PBS was used. With the use of BSSG, little or no change in cytoplasmic enzyme activities occurred, but measurable decreases were noted with PBS and very substantial decreases when water was used, indicating a toxic effect on the keratocytes. The observation that substantial decreases in a lysosomal enzyme activity could occur even with the use of BSSG indicate substantial stress is imposed on the stroma during these types of experiments. Notwithstanding, the data collectively indicate that the keratocyte cells within the collagen matrix of the stroma can be substantially damaged and this needs to be taken into account in future experiments on the true physiology of the corneal stroma.

Phagocytosis of titanium particles and necrosis in TNF-alpha-resistant mouse sarcoma L929 cells

In the oral cavity, titanium is an excellent biocompatible material. However, it is reported that high ratios of intracellular titanium particles can cause cell apoptosis or necrosis by as-yet unknown mechanisms. The purpose of this study was to investigate the response of tumor necrosis factor alpha (TNF-alpha)-resistant L929 fibroblasts to titanium particles. Cells were cultured in Eagle's medium supplemented with fetal bovine serum and L-glutamine. Titanium particle sizes were less than 9 micro. Cytotoxicity was assayed by a cell counting kit, trypan blue dye exclusion test and lactate dehydrogenase (LDH) leakage. The production of reactive oxygen species (ROS) was detected by a confocal laser scanning microscope (CLSM) using dichlorofluorescein diacetate as a fluorescent probe. Morphology was viewed by a CLSM and with an X-ray microanalyser (XMA). When titanium particles were added to cells, the viability decreased to around 50% at a particle concentration of 2.0%. The number of dead cells and LDH activity in the culture media increased significantly between 1 and 2 days. However, formation of active oxygen species did not occur, since no dichlorofluorescein fluorescence was observed. A scanning electron photomicrograph (SEM) revealed a large number of particles covering or adhering to cellular components in lysed cells compared with flattened control cells attached to the substrate. The XMA showed that the titanium accumulation was coincident with the deformed cell shape. The CLSM also confirmed that particles were within the cells. From these results it was concluded that titanium particles ingested in large quantities into the cell induced necrosis by a pathway other than by producing ROS.

Silver nitrate: antimicrobial activity related to cytotoxicity in cultured human fibroblasts

The aims of this study were to ascertain whether silver nitrate (AgNO3) concentrations below those used in clinical practice inhibit bacterial growth, and in parallel study the cytotoxic effects on human fibroblasts. The cytoprotective effects of fetal calf serum (FCS) were also evaluated. The cytotoxic effects of eight different silver nitrate concentrations were determined by assessing mitochondrial activity of viable cells capable of cleaving tetrazolium salts. Antimicrobial activity of AgNO3, range: 7-550 x 10(-5)%, was tested against Staphylococcus aureus, Citrobacter freundii, and Pseudomonas aeruginosa. Silver nitrate concentrations exerting antimicrobial effects were: S. aureus, >70 x 10(-5)%; P. aeruginosa, >/=270 x 10(-5)%, and C. freundii, >/=550 x 10(-5)%. With 2% FCS, the lowest AgNO3 concentration studied (7 x 10(-5)%) showed cytotoxic effects (cell survival 71 +/- 19%) at only 2 h of incubation. Under these conditions AgNO3 cytotoxicity was time- and concentration-dependent in all exposure periods. Cytotoxicity was greatly enhanced causing 76% fibroblast growth inhibition at concentrations of 14 x 10(-5)% and contact time of 2 h. The AgNO3 concentration of 7 x 10(-5)% was also cytotoxic with 5% FCS in the media compared with controls, although cell survival was higher than with 2% FCS. The cytoprotective action of FCS was clearly shown at the concentration of 10% at which AgNO3 cytotoxicity of 7 x 10(-5)% to 28 x 10(-5)% was partially or completely inhibited. Our results show that AgNO3 at concentrations 100-700 times more diluted than that normally used in clinical practice retained effective inhibitory activity against some of the above-mentioned microorganisms. However, even these concentrations are cytotoxic for cultured fibroblasts. Thus, silver nitrate concentrations up to 100 times more diluted can be used, since they possess bacterial growth-inhibiting power, are less cytotoxic and therefore favour wound healing.