The Applications and Challenges of the Development of In Vitro Tumor Microenvironment Chips

The tumor microenvironment (TME) plays a critical, yet mechanistically elusive role in tumor development and progression, as well as drug resistance. To better understand the pathophysiology of the complex TME, a reductionist approach has been employed to create in vitro microfluidic models called “tumor chips”. Herein, we review the fabrication processes, applications, and limitations of the tumor chips currently under development for use in cancer research. Tumor chips afford capabilities for real-time observation, precise control of microenvironment factors (e.g. stromal and cellular components), and application of physiologically relevant fluid shear stresses and perturbations. Applications for tumor chips include drug screening and toxicity testing, assessment of drug delivery modalities, and studies of transport and interactions of immune cells and circulating tumor cells with primary tumor sites. The utility of tumor chips is currently limited by the ability to recapitulate the nuances of tumor physiology, including extracellular matrix composition and stiffness, heterogeneity of cellular components, hypoxic gradients, and inclusion of blood cells and the coagulome in the blood microenvironment. Overcoming these challenges and improving the physiological relevance of in vitro tumor models could provide powerful testing platforms in cancer research and decrease the need for animal and clinical studies

Quantifying Alpha and Beta Acids in Hops

The bitter flavor in beer is largely due to the α- and β-acid content found in the female cones of the hop plant, Humulus lupulus. This is because hops are often added to the mashed malted barely and boiled during the production of beer. During this process, the modestly bitter α-acids (humulone, cohumulone, and adhumulone) undergo thermal isomerization, making a much more bitter flavor. Meanwhile, the β-acids (lupulone, colupulone and adlupulone) are oxidized, making them significantly less bitter than the α-acids. Therefore, since alpha and beta acids largely contribute to the flavor of the beer, it is important that brewers know the concentration of these acids and can correlate growing conditions. In this experiment, the objective was to quantify the α- and β-acid content in hops samples provided by local collaborators to the International Calibration Extract 3 (ICE-3) standard