During the last decades, the rheology of cells has been studied almost entirely in single cells. While cell-to-cell variation is typically very large and most studies were carried out in the nonlinear viscoelastic regime, we quantify average linear viscoelastic cell properties like storage and loss moduli and normal stress in monolayers of different cell types showing that murine 3T6 fibroblasts, human fibroblasts, and HeLa cells differ considerably in their storage modulus. To this end, we modified a commercial rheometer to set up a parallel-disk configuration at gap widths of a few micrometers and optically detected the cell concentration in the gap. This enables studying the linear viscoelastic behavior of the cells and permits quantifying the impact of drugs affecting the cytoskeleton or the extracellular matrix connection. Thus, due to its high-content approach, without the need of treating the samples in the rheometer, this envisions the use of this method as a fast diagnostic tool. The method also allows for quantitatively studying of the impact of pre-stress on the storage and loss moduli of the cells

Bioglass(®)-based scaffolds for bone tissue engineering have been developed, which can also serve as carriers for drug delivery. For this, P(3HB) microspheres (PMSs) loaded with tetracycline were fabricated and immobilised on the scaffold surfaces by a modified slurry dipping technique. The sustained drug delivery ability in simulated body fluid was confirmed by using UV-Vis absorption spectroscopy measurements. The MTT assay using mouse fibroblast cells provided evidence that the tetracycline loaded microspheres produced in this study show limited cytotoxicity. The scaffolds developed in this work provide mechanical support, adequate 3D surface roughness, bioactivity and controlled drug delivery function, and are thus interesting candidates for bone tissue engineering applications.

In a search for alternative, environmentally friendly and effective disinfecting agents, a commercially available protease—Neutrase®—was tested in this work for inactivation of koi herpesvirus (KHV) and of viral haemorrhagic septicaemia virus (VHSV). For comparison, the stability of these viral pathogens in similar configurations at various pH values and concentrations of peracetic acid or quicklime, typically used for disinfection, was tested. Therefore, virus suspensions were incubated with various concentrations of different agents for 24 hr and the titre of the remaining infectious particles was determined by virus titration. Furthermore, the treatment of both viruses, with the agents at concentrations that were previously appointed as effective, was also examined in the presence of solid material (quartz sand). All procedures investigated in this study, including the protease treatment, were able to reduce the titre of KHV and VHSV below the detection limit of the titration. Although further studies are necessary, this is the first report of the application of a protease for the inactivation of the selected fish pathogens, demonstrating the great potential of the latter for disinfection.

Research of cyprinid herpesvirus 3 (CyHV-3) is focused on the infection mechanism and disease development in animals using genetic and immunological approaches to improve treatments and diagnostics. In contrast, only few tried to investigate the CyHV-3 replication behaviour in available cell cultures. Whereas, obtaining high virus yields by in vitro replication enables achieving of the mentioned above goals easier and more reliable. The following work presents an attempt to illuminate the KHV replication in common carp brain (CCB) cell cultures from the engineering point of view. The isolate KHV-TP30 was used testing the influence on process parameters, such as multiplicity of infection (MOI), time of infection (TOI) and time of harvest (TOH). Virus concentrations and infectivity at different time points of infection were examined using hydrolyzed probe qPCR (Gilad et al. 2004) and 50% tissue culture infectivity dose (TCID). The data obtained show that while the amount of the virus DNA remains constant after reaching its maximum, the infectivity of the virus decreases. Thus, especially, TOH can be crucial for generating a high-quality virus stock. Applying optimized parameters improved the infectivity of the harvested virus and reached a robust titre as high as 1.9 × 10 TCID/mL. To our knowledge, so far, there is no information in the peer-reviewed literature showing comparably high virus titres. Such virus yields not only facilitate conduction of further studies, including stability tests of the virus stock under various supplementation or disinfection trails, but also provide enough virus material to perform more detailed examinations of the infection mechanism.

Cholesterol is a major constituent of cell membranes and exhibits together with its oxidation products (oxysterols) several essential cellular functions. Additionally, it was recently shown to play a role during virus replication in fish. To investigate the involvement of cholesterol and oxysterols, for example, during a viral infection in fish cells, quantitative analysis of these analytes from cell cultures is necessary. A fast method based on solvent extraction followed by reversed‐phase high‐performance liquid chromatography with mass spectrometry for quantitation of cholesterol and seven oxysterols from cells and culture medium is described in this work. Detection limits were in the low ng/mL range, and the intra‐ and inter‐day precisions were above 87% for all analytes. A cholesterol content of approximately 10 μg per 2 × 106 cells, exceeding the concentration of oxysterols by at least 103‐fold, was determined for common carp brain cells. Furthermore, using the method established here, an uptake of externally supplied 25‐hydroxycholesterol by fish cells and its conversion to 7a,25‐dihydroxycholesterol could be shown. In summary, this is the first report on quantification of cholesterol and oxysterols from fish cell cultures, which can help in exploring their function during viral infections.