Genotoxic effect induced by hydrogen peroxide in human hepatoma cells using comet assay

Background: Hydrogen peroxide is a common reactive oxygen intermediate generated by variousforms of oxidative stress. Aims: The aim of this study was to investigate the DNA damage capacity ofH2O2 in HepG2 cells. Methods: Cells were treated with H2O2 at concentrations of 25 μM or 50 μM for5 min, 30 min, 40 min, 1 h or 24 h in parallel. The extent of DNA damage was assessed by the cometassay. Results: Compared to the control, DNA damage by 25 μM and 50 μM H2O2 increasedsignificantly with increasing incubation time up to 1 h, but it was not increased at 24 h. Conclusions:Our Findings confirm that H2O2 is a typical DNA damage inducing agent and thus is a good modelsystem to study the effects of oxidative stress. DNA damage in HepG2 cells increased significantlywith H2O2 concentration and time of incubation but later decreased likely due to DNA repairmechanisms and antioxidant enzyme

EHOSINUSOSCOPIJA AS NONINVASIVE DIAGNOSTICAL METHOD

A-scan ultrasonography is non-invasive diagnostics methods. Its show excellent result and first in exploring a maxillar sinus, especially significance in children which is most common case for reduction of hearing in conduction type

The regulatory challenge of 3D bioprinting

New developments in additive manufacturing and regenerative medicine have the potential to radically disrupt the traditional pipelines of therapy development and medical device manufacture. These technologies present a challenge for regulators because traditional regulatory frameworks are designed for mass manufactured therapies, rather than bespoke solutions. 3D bioprinting technologies present another dimension of complexity through the inclusion of living cells in the fabrication process. Herein we overview the challenge of regulating 3D bioprinting in comparison to existing cell therapy products as well as custom-made 3D printed medical devices. We consider a range of specific challenges pertaining to 3D bioprinting in regenerative medicine, including classification, risk, standardization and quality control, as well as technical issues related to the manufacturing process and the incorporated materials and cells

Evaluation of sterilisation methods for bio-ink components: gelatin, gelatin methacryloyl, hyaluronic acid and hyaluronic acid methacryloyl

Reliable and scalable sterilisation of hydrogels is critical to the clinical translation of many biofabrication approaches, such as extrusion-based 3D bioprinting of cell-laden bio-inks. However sterilisation methods can be destructive, and may have detrimental effects on the naturally-derived hydrogels that constitute much of the bio-ink palette. Determining effective sterilisation methods requires detailed analysis of the effects of sterilisation on relevant properties such as viscosity, printability and cytocompatibility. Yet there have been no studies specifically exploring the effects of sterilisation on bio-inks to date. In this work, we explored the effects of various sterilisation techniques on four of the most widely used bio-ink components: gelatin, gelatin methacryloyl, hyaluronic acid, and hyaluronic acid methacrylate. Autoclaving was the most destructive sterilisation method, producing large reductions in viscosity and in mechanical properties following crosslinking. Filter sterilisation caused some reduction in rheological properties of GelMA due to removal of higher molecular weight components, but did not affect photocrosslinking. Ethylene oxide (EtO) was the least destructive sterilisation method in terms of rheological properties for all materials, had no detrimental effect on the photocrosslinkable methacrylate/methacrylamide groups, and so was chosen for more detailed examination. In biological analyses, we found that EtO treatment successfully eradicated a bacterial challenge of E. coli, caused no decrease in viability of human mesenchyman stem cells (hMSCs), and had no effect on their rate of proliferation. Finally, we found that EtO-treated hydrogels supported encapsulated hMSCs to differentiate towards the chondrogenic lineage, and to produce new cartilage matrix. Our results bring to light various effects that sterilisation can have on bio-inks, as well as highlighting EtO sterilisation as a method which minimises degradation of properties, while still promoting biological function