Organ-on-Chips for Studying Tissue Barriers: Standard Techniques and a Novel Method for Including Porous Membranes Within Microfluidic Devices.

A relevant number of organ-on-chips is aimed at modeling epithelial/endothelial interfaces between tissue compartments. These barriers help tissue function either by protecting (e.g., endothelial blood-brain barrier) or by orchestrating relevant molecular exchanges (e.g., lung alveolar interface) in human organs. Models of these biological systems are aimed at characterizing the transport of molecules, drugs or drug carriers through these specific barriers. Multilayer microdevices are particularly appealing to this goal and techniques for embedding porous membranes within organ-on-chips are therefore at the basis of the development and use of such systems. Here, we discuss and provide procedures for embedding porous membranes within multilayer organ-on-chips. We present standard techniques involving both custom-made polydimethylsiloxane (PDMS) membranes and commercially available plastic membranes. In addition, we present a novel method for fabricating and bonding PDMS porous membranes by using a cost-effective epoxy resin in place of microfabricated silicon wafers as master molds.

GZMKhigh CD8+ T effector memory cells are associated with CD15high neutrophil abundance in non-metastatic colorectal tumors and predict poor clinical outcome.

CD8+ T cells are a major prognostic determinant in solid tumors, including colorectal cancer (CRC). However, understanding how the interplay between different immune cells impacts on clinical outcome is still in its infancy. Here, we describe that the interaction of tumor infiltrating neutrophils expressing high levels of CD15 with CD8+ T effector memory cells (TEM) correlates with tumor progression. Mechanistically, stromal cell-derived factor-1 (CXCL12/SDF-1) promotes the retention of neutrophils within tumors, increasing the crosstalk with CD8+ T cells. As a consequence of the contact-mediated interaction with neutrophils, CD8+ T cells are skewed to produce high levels of GZMK, which in turn decreases E-cadherin on the intestinal epithelium and favors tumor progression. Overall, our results highlight the emergence of GZMKhigh CD8+ TEM in non-metastatic CRC tumors as a hallmark driven by the interaction with neutrophils, which could implement current patient stratification and be targeted by novel therapeutics.