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The development of physiologically relevant intestinal models fueled by breakthroughs in primary cell-culture methods has enabled successful recapitulation of key features of intestinal physiology. These advances, paired with engineering methods, for example incorporating chemical gradients or physical forces across the tissues, have yielded ever more sophisticated systems that enhance our understanding of the impact of the host microbiome on human physiology as well as on the genesis of intestinal diseases such as inflammatory bowel disease and colon cancer. In this review we highlight recent advances in the development and usage of primary cell-derived intestinal models incorporating monolayers, organoids, microengineered platforms, and macrostructured systems, and discuss the expected directions of the field., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A significant effort is underway to develop biofuels as replacements for non-renewable fossil fuels. Among the various options, hydrogen is an attractive future energy carrier due to its potentially higher efficiency of conversion to usable power, low generation of pollutants and high energy density. There are a variety of technologies for biological hydrogen production; here, we concentrate on fermentative hydrogen production and highlight some recently applied approaches, such as response surface methodology, different reactor configurations and organisms that have been used to maximize hydrogen production rates and yields. However, there are significant remaining barriers to practical application, such as low yields and production rates, and we discuss several methods, including two stage processes and metabolic engineering, that are aimed at overcoming these barriers.

Tissue engineering is expected to help us outlive the failure of our organs by enabling the creation of tissue substitutes capable of fully restoring the original tissue function. Degenerative joint disease, which affects one-fifth of the US population and is the country's leading cause of disability, drives current research of actively growing, functional tissue grafts for joint repair. Toward this goal, living cells are used in conjunction with biomaterial scaffolds (serving as instructive templates for tissue development) and bioreactors (providing environmental control and molecular and physical regulatory signals). In this review, we discuss the requirements for engineering customized, anatomically-shaped, stratified grafts for joint repair and the challenges of designing these grafts to provide immediate functionality (load bearing, structural support) and long-term regeneration (maturation, integration, remodeling).

In this article, the current status of membrane bioreactor (MBR) technology for wastewater treatment is reviewed. Fundamental facets of the MBR process and membrane and process configurations are outlined and the advantages and disadvantages over conventional suspended growth-based biotreatment are briefly identified. Key process design and operating parameters are defined and their significance explained. The inter-relationships between these parameters are identified and their implications discussed, with particular reference to impacts on membrane surface fouling and channel clogging. In addition, current understanding of membrane surface fouling and identification of candidate foulants is appraised. Although much interest in this technology exists and its penetration of the market will probably increase significantly, there remains a lack of understanding of key process constraints such as membrane channel clogging, and of the science of membrane cleaning.

Sponges are a source of compounds with potential pharmaceutical applications. In this article, methods of sponge cell culture for production of these bioactive compounds are reviewed, and new approaches for overcoming the problem of metabolite supply are examined. The use of embryos is proposed as a new source of sponge material for cell culture. Stem cells are present in high amounts in embryos and are more versatile and resistant to infections than adult cells. Additionally, genetic engineering and cellular research on apoptotic mechanisms are promising new fields that might help to improve cell survival in sponge-cell lines. We propose that one topic for future research should be how to reduce apoptosis, which appears to be very high in sponge cell cultures.

Embryonic stem cells provide a potential resource for research and drug screening. To make such a resource feasible, it is necessary to generate cells of sufficient quality and quantity. The challenge is to expand cell numbers while maintaining the fidelity of phenotype and to control and direct differentiation to produce the cell type of interest in a format that is suitable for drug screening. At present, large-scale culturing of human ES cell lines is problematic and provides substantial challenges. This article provides an overview of current bioprocessing techniques that could be used to generate cells for drug discovery applications. This will generate further technical expertise that can be applied in the production of cells for potential therapeutic applications.

Cryogels are gel matrices that are formed in moderately frozen solutions of monomeric or polymeric precursors. Cryogels typically have interconnected macropores (or supermacropores), allowing unhindered diffusion of solutes of practically any size, as well as mass transport of nano- and even microparticles. The unique structure of cryogels, in combination with their osmotic, chemical and mechanical stability, makes them attractive matrices for chromatography of biological nanoparticles (plasmids, viruses, cell organelles) and even whole cells. Polymeric cryogels are efficient carriers for the immobilization of biomolecules and cells.

Increased knowledge of the molecular interactions that characterize the control of apoptosis is identifying possible novel approaches to inhibit cell death and generate enhanced viable cell biomass. The application of such approaches to recombinant mammalian cells promises to improve the cost-effectiveness of industrial-scale protein expression.