Preservation of acellular matrices represents a big challenge for the improvement of tissue engineering.In this work, a new method to preserve over time a decellularized esophageal scaffolds was explored.Dried and sterile acellular esophagi were obtained with a combined treatment of ethanol and a subsequent supercritical CO2 drying.Preservation of the extracellular matrix architecture, collagen content, and mechanical properties up to 6 months demonstrated the efficiency of the methodology with implications in natural scaffold storage.In vitro support of mesenchymal stem cells showed a promising indication to the further use of the technology in preclinical and clinical application.
Processes based on supercritical fluids, especially carbon dioxide, have been extensively investigated for their utility in pasteurizing milk, fruit and vegetable juices, raw vegetables, meat, and fish. This chapter initially reviews current issues in food pasteurization, then presents the thermodynamic fundamentals of supercritical fluid behavior and how SCFs can be utilized for pasteurization. The chapter includes possible mechanisms and models for the inactivation of a variety of hazardous microorganisms. This is followed by a comprehensive overview of specific studies of applications to a wide range of foodstuffs. Finally, the commercial viability of SCF pasteurization and the recent patent literature is discussed. The goal of this chapter is to enable both researchers and process developers to understand the scientific fundamentals behind the use of supercritical fluids for food pasteurization and assess the breadth of applications that have been considered.
Abstract Among the multiple metabolic signals involved in the establishment of the hepatic zonation, oxygen could play a key role. Indeed, depending on hepatocyte position in the hepatic lobule, gene expression and metabolism are differently affected by the oxygen gradient present across the lobule. The aim of this study is to understand whether an oxygen gradient, generated in vitro in our developed device, is sufficient to instruct a functional metabolic zonation during the differentiation of human embryonic stem cells (hESCs) from endoderm toward terminally differentiated hepatocytes, thus mimicking the in vivo situation. For this purpose, a microfluidic device was designed for the generation of a stable oxygen gradient. The oxygen gradient was applied to differentiating hESCs at the pre-hepatoblast stage. The definitive endoderm and hepatic endoderm cells were characterized by the expression of the transcription factor SOX-17 and alpha-fetoprotein (AFP). Immature and mature hepatocytes were characterized by hepatocyte nuclear factor 4-alpha (HNF-4α) and albumin (ALB) expression and also analyzed for cytochrome P450 (CYP3A4) zonation and glycogen accumulation through PAS staining. Metabolic zonated genes expression was assessed through quantitative real time PCR. Application of the oxygen gradient during differentiation induced zonated glycogen storage, which was higher in the hepatocytes grown in high pO 2 compared to those grown in low pO 2 . The mRNA levels of glutamine synthetase (GLUL), beta-catenin (CTNNB) and its direct target cyclin D1 (CCND1) showed significantly higher expression in the cells grown in low pO 2 compared to those grown in high pO 2 . On the contrary, carbamoyl-phosphate synthetase 1 (CPS1), ALB, the proliferative marker ki67 (MKI67) and cyclin A (CCNA) resulted to be significantly higher expressed in cells cultured in high pO 2 compared to those cultured in low pO 2 . These results indicate that the oxygen gradient generated in our device can instruct the establishment of a functional metabolic zonation in differentiating hESCs. The possibility to obtain differentiated hepatocytes in vitro may allow in the future to deepen our knowledge about the physiology/pathology of hepatocytes in relation to the oxygen content.
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The objective of the present study was to assess the potential synergistic effect between supercritical carbon dioxide (SC-CO2) and fresh culinary herbs (Coriandrum sativum and Rosmarinus officinalis) on the microbial inactivation of raw chicken meat. The microbiological inactivation was performed on Escherichia coli and natural flora (total mesophilic bacteria, yeasts, and molds). High pressure treatments were carried out at 40°C, 80 or 140 bar from 15 to 45 min. Microbial inactivation had a strong dependence on treatment time, achieving 1.4 log CFU/g reduction of E. coli after 15 min, and up to 5 log after 45 min, while a pressure increase from 80 up to 140 bar was not significant on the microbial inactivation. Mesophilic microorganisms were strongly reduced (>2.6 log CFU/g) after 45 min, and yeasts and molds were below the detection limits of the technique (<100 CFU/g) in most cases. The combination of fresh herbs together with SC-CO2 treatment did not significantly increase the inactivation of either E. coli or natural flora, which was similar to the SC-CO2 alone. The synergistic effect was obtained on the inactivation of E. coli using a proper concentration of coriander essential oil (EO) (0.5% v/w), while rosemary EO did not show a significant effect. Color analysis after the treatment showed an increment of lightness (L*), and a decrease of redness (a*) on the surface of the sample, making the product visually similar to cooked meat. Texture analysis demonstrated the modification of the texture parameters as a function of the process pressure making the meat more similar to the cooked one.
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