Eco-, geno- and human toxicology of bio-active nanoparticles for biomedical applications.

Gene delivery has become an increasingly important strategy for treating a variety of human diseases, including infections, genetic disorders and tumours. To avoid the difficulties of using viral carriers, more and more non-viral gene delivery nanoparticles are developed. Among these new approaches polyethylene imine (PEI) is currently considered as one of the most effective polymer based method solution and considered as the gold standard. The toxicity of nanoparticles is a major concern when used for medical application. In this study we chose two nanoparticles for an in depth toxicological and ecotoxicological evaluation, one well characterized, PEI, and another novel polymer, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). In the present study we have assessed the toxicity of these cation nanoparticles as such and of the polyplexes - nanoparticles covered with DNA. As these nanoparticles are also frequently used in high volumes in various industries and as such may enter in the environment, we also made an initial assessment of ecotoxicological effects assessment. The following nanoparticles related aspects have been studied during the project: development and characterization, ecotoxicity, general toxicity and specific toxicity. To this end a battery of different tests was used. The conclusion of these tests is that toxicity is varying between different nanoparticles and between different DNA covering ratios. In general, in the different systems tested, the PEI polymer is more toxic than the PDMAEMA polymer. The same difference is seen for the polyplexes and the higher the charge ratio, the more toxic are the polyplexes. Our study also clearly shows the need for a broad spectrum of toxicity assays for a comprehensive risk assessment. Our study has performed such a comprehensive analysis of two biomedical nanoparticles.

Ultrastructural features of hepatocytes in cultured Eurasian perch ( Perca fluviatilis L.) as affected by nutritional and husbandry conditions.

A wide range of factors can be attributed to the syndrome of fatty liver observed in some cultured fish species. The objective of the study was therefore to quantify different hepatocyte ultrastructural features as potentially influenced by twelve nutritional and husbandry factors, in order to discriminate the most influent factors in Eurasian perch (Perca fluviatilis), a typical carnivorous temperate fish species. Twenty-four groups of juveniles (initial weight 57.6 (SD 14.4) g) were intensively reared for 116 d and fed sixteen different isoproteic diets. The distribution of the experimental treatments was based on a multivariate fractional factorial design (L(24) 2(12)) with either high (+1) or low (-1) level of each of the following factors: diet (lipid and protein sources, lipid content, astaxanthin enrichment), feeding level, daily and weekly distribution frequency, fish density, initial weight heterogeneity, temperature, photoperiod, and light spectrum. Liver lipid droplets, glycogen, mitochondria and rough endoplasmic reticulum (RER) were semi-quantified and analysed by a soft imaging system using transmission electronic microscopy photographs. Important variability of hepatocyte ultrastructural features was observed. The present study confirms that the rearing temperature, through its influences in the general metabolic activity, seems to be the main factor modifying mainly lipid droplet accumulation and RER development. However, factors that could be pooled under the designation of factors leading to food accessibility and lipid and protein quality intensify or compensate the effect of temperature.