Directing the Self-assembly of Tumour Spheroids by Bioprinting Cellular Heterogeneous Models within Alginate/Gelatin Hydrogels.

Human tumour progression is a dynamic process involving diverse biological and biochemical events such as genetic mutation and selection in addition to physical, chemical, and mechanical events occurring between cells and the tumour microenvironment. Using 3D bioprinting we have developed a method to embed MDA-MB-231 triple negative breast cancer cells, and IMR-90 fibroblast cells, within a cross-linked alginate/gelatin matrix at specific initial locations relative to each other. After 7 days of co-culture the MDA-MB-231 cells begin to form multicellular tumour spheroids (MCTS) that increase in size and frequency over time. After ~15 days the IMR-90 stromal fibroblast cells migrate through a non-cellularized region of the hydrogel matrix and infiltrate the MDA-MB-231 spheroids creating mixed MDA-MB-231/IMR-90 MCTS. This study provides a proof-of-concept that biomimetic in vitro tissue co-culture models bioprinted with both breast cancer cells and fibroblasts will result in MCTS that can be maintained for durations of several weeks.

Effect of graphene oxide on bacteria and peripheral blood mononuclear cells.

BACKGROUND: Driven by the potential biological applications of graphene, many groups have studied the response of cells exposed to graphene oxide (GO). In particular, investigations of bacteria indicate that there are 2 crucial parameters, which so far have only been investigated separately: GO size and exposure methodology. Our study took into account both parameters. We carefully characterized the samples to catalog sizes and structural properties, and tested different exposure methodologies: exposure in saline solution and in the presence of growth media. Furthermore, we performed experiments with peripheral blood mononuclear cells exposed to our GO materials. METHODS: Atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize the morphology and composition of different samples of GO: GO-H2O, GO-PBS and GO-MG. Our samples had 2D sizes of ~100 nm (GO-H2O and GO-PBS) and >2 µm (GO-MG). We tested antibacterial activity and cytotoxicity toward peripheral blood mononuclear cells of 3 different GO samples. RESULTS: A size-dependent growth inhibition of Escherichia coli (DH5 α) in suspension was found, which proved that this effect depends strongly on the protocol followed for exposure. Hemocompatibility was confirmed by exposing peripheral blood mononuclear cells to materials for 24 hours; viability and apoptosis tests were also carried out. CONCLUSIONS: Our experiments provide vital information for future applications of GO in suspension. If its antibacterial properties are to be potentiated, care should be taken to select 2D sizes in the micrometer range, and exposure should not be carried out in the presence of grow media.

Coupling aerobic biodegradation of methanol vapors with heterologous protein expression of endochitinase Ech42 from Trichoderma atroviride in Pichia pastoris.

Methanol is included among the most hazardous air pollutants, and an effort of vapors biofiltration by using microbial consortiums has been reported. The aim of this work was to couple the methanol vapors biodegradation with the production of recombinant endochitinase (ech42) from Trichoderma atroviride in Pichia pastoris transformed with the pPIC-ech42 plasmid. After carrying out batch experiments at 0.5% (w/v) of methanol concentration, the recombinant P. pastoris Mut(+) strain was selected because it showed methanol biodegradation rates similar to those of wild type GS115 strain (39 g/m(3)h), but 15% higher than the transformed Mut(S) strain. In addition, the recombinant Ech42 protein production was higher in Mut(+) than Mut(S). After various methanol vapor concentrations were evaluated, the maximum recombinant protein recovery was 317 mg/l and the volumetric methanol consumption rate was 88.7 g/m(3)h at 0.5% (w/v) of methanol concentration. This research underlines the promising application of linking methanol vapors biodegradation with the production of recombinant protein with high biotechnological interests.