For both the incorporation of cells and future therapeutic applications the sterility of a biomaterial must be ensured. However, common sterilisation techniques are intense and often negatively impact on material physicochemical attributes, which can affect its suitability for tissue engineering and 3D printing. In the present study four sterilisation methods, autoclave, supercritical CO2 (scCO2) treatment, UV-and gamma () irradiation were evaluated regarding their impact on material properties and cellular responses. The investigations were performed on methyl cellulose (MC) as a component of an alginate/methyl cellulose (alg/MC) bioink, used for bioprinting embedded bovine primary chondrocytes (BPCs). In contrast to the autoclave, scCO2 and UV-treatments, the-irradiated MC resulted in a strong reduction in alg/MC viscosity and stability after extrusion which made this method unsuitable for precise bioprinting. Gel permeation chromatography analysis revealed a significant reduction in MC molecular mass only after-irradiation, which influenced MC chain mobility in the Ca 2+crosslinked alginate network as well as gel composition and microstructure. With regard to cell survival and proteoglycan matrix production, the results determined UV-irradiation and autoclaving as the best candidates for sterilisation. The scCO2-treatment of MC resulted in an unfavourable cell response indicating that this method needs careful optimisation prior to application for cell encapsulation. As proven by consistent FT-IR spectra, chemical alterations could be excluded as a cause for the differences seen between MC-treatments on alg/MC behaviour. This investigation provides knowledge for the development of a clinically appropriate 3D-printing-based fabrication process to produce bioengineered tissue for cartilage regeneration.

In contrast to other DNA damaging agents, ethanol/acetaldehyde generated DNA strand breaks without inducing ubiquitination of FANCD2, despite increasing protein levels in the nucleus. These data are consistent with recent reports that suggest the Fanconi anemia pathway plays an important role in the adult brain in response to DNA damage. Further work is required to establish what this role is, in particular the potential function of nonubiquitinated FANCD2 and its role in the DNA damage response in postmitotic neurons and neural precursor cells.

Objective: In previous research the use of hydrostatic pressure (HP) has been applied to enhance the formation of engineered cartilage, through the up-regulation of proteoglycan synthesis by mechanotransduction. However, the HP stimulation approach has been shown to vary between studies with a wide disparity in results, including anabolic, catabolic and non-responsive outcomes. To this end, a metaanalysis of HP publications using 3D cultured chondrocytes was performed to elucidate the key experiment factors involved in achieving a mechanotransducive response. Design: The effects of different HP regimes on proteoglycan production were investigated based on the following factors: static vs dynamic application, pressure magnitude, and experiment duration. Metaanalysis was performed on raw data taken from 11 publications which employed either aggrecan gene expression analysis or dimethyl methylene blue colorimetric assay. The measure of effect was calculated based on mean difference using a random effects model. Results: Analysis revealed that a significant anabolic response was most likely achieved when the following factors were employed; a static HP application, a magnitude within the mid-high physiological range of cartilage ( 5e10 MPa) and a study duration of !2 weeks. Conclusions: Thus, we propose that the selection of HP experiment factors can have a significant influence on engineered cartilage development, and that the results of this meta-analysis can be used as a basis for the planning of future HP experiments.