Real-time monitoring of immediate drug response and adaptation upon repeated treatment in a microfluidic chip system.

Microfluidic tissue culture and organ-on-a-chip models provide efficient tools for drug testing in vivo and are considered to become the basis of in vitro test systems to analyze drug response, drug interactions and toxicity to complement and reduce animal testing. A major limitation is the efficient recording of drug action. Here we present an efficient experimental setup that allows long-term cultivation of cells in a microfluidic system in combination with continuous recording of luciferase reporter gene expression. The system combines a sensitive cooled luminescence camera system in combination with a custom build miniaturized incubation chamber. The setup allows to monitor time-dependent activation, but also the end of drug response. Repeated activation and recovery as well as varying durations of drug treatment periods can be monitored, and different modes of drug activity can be visualized.

In-Plate Cryopreservation of 2D and 3D Cell Models: Innovative Tools for Biomedical Research and Preclinical Drug Discovery.

Cell-based assays performed in multiwell plates are utilized in basic and translational research in a variety of cell models. The assembly of these multiwell platforms and their use is often laboratory specific, preventing the standardization of methods and the comparison of outputs across different analytical sites. Moreover, when cell models are based on primary cells with specialized culture requirements, including three-dimensional (3D) cell culture, their complexity and the need for manipulation by experienced operators can add significant cost and introduce long lead times to analysis, both of which are undesirable in any preclinical situation. To address this issue, we explored adaptations of cryopreservation technology that allow cells to be cryopreserved in-plate, ready for use in analysis, and have developed a method applicable to cells from different origins and different culture formats. Here we describe the application of this technology to conventional two-dimensional (2D) monolayers of human mesenchymal stem cells (MSCs) and human macrophages derived from primary monocytes, and to 3D cultures of hepatic organoids, colon organoids, and colon tumor organoids, each presented for cryopreservation in their obligate extracellular matrix. We demonstrated that cell viability, cell physiology, and cytotoxic sensitivity were maintained after cryopreservation, such that the models offer the means to uncouple model assembly from analytical use and to standardize cell models in product form for distribution to end users.

Bovine colon organoids: From 3D bioprinting to cryopreserved multi-well screening platforms.

Three-dimensional (3D) colon organoids, termed "colonoids", derived from adult stem cells represent a powerful tool in in vitro pharmaceutical and toxicological research. Murine and human colonoid models exist. Here we describe the establishment of bovine colonoids for agri-biotechnological applications, and extend the repertoire of colonoid culture options through proof-of-principle for bioprinting and novel in-plate cryopreservation technology. As a first step, we differentiated established long-term bovine colonoid cultures into mature colonoids. Tissue-specific differentiation was demonstrated by gene expression. Second, we investigated cryopreservation of colonoids in situ within an extracellular matrix in multi-well plates. Upon controlled thawing, cryopreserved 3D cultures grew at similar rates to unfrozen colonoids. Cytotoxic sensitivity to staurosporine was not significantly different between in situ freeze-thawed and unfrozen control cultures. Third, scalability of colonoid culture assembly by extrusion bioprinting into multi-well plates using GelMA bioink was assessed. With optimised bioprinting and crosslinking parameters, colonoids in GelMA were printed into 96 well culture plates and remained viable and proliferative post-print. For tissue-relevant in vitro studies we furthermore established differentiated colonoid-derived monolayer cultures on permeable membranes. Taken together, we outline novel in vitro approaches to study the ruminant colonic epithelium and introduce in-plate cryopreservation as convenient alternative to conventional in-vial cryopreservation.

Different Regulation of Interleukin-1 Production and Activity in Monocytes and Macrophages: Innate Memory as an Endogenous Mechanism of IL-1 Inhibition.

Production and activity of interleukin (IL)-1ß are kept under strict control in our body, because of its powerful inflammation-promoting capacity. Control of IL-1ß production and activity allows IL-1 to exert its defensive activities without causing extensive tissue damage. Monocytes are the major producers of IL-1ß during inflammation, but they are also able to produce significant amounts of IL-1 inhibitors such as IL-1Ra and the soluble form of the decoy receptor IL-1R2, in an auto-regulatory feedback loop. Here, we investigated how innate immune memory could modulate production and activity of IL-1ß by human primary monocytes and monocyte-derived tissue-like/deactivated macrophages in vitro. Cells were exposed to Gram-negative (Escherichia coli) and Gram-positive (Lactobacillus acidophilus) bacteria for 24 h, then allowed to rest, and then re-challenged with the same stimuli. The presence of biologically active IL-1ß in cell supernatants was calculated as the ratio between free IL-1ß (i.e., the cytokine that is not bound/inhibited by sIL-1R2) and its receptor antagonist IL-1Ra. As expected, we observed that the responsiveness of tissue-like/deactivated macrophages to bacterial stimuli was lower than that of monocytes. After resting and re-stimulation, a memory effect was evident for the production of inflammatory cytokines, whereas production of alarm signals (chemokines) was minimally affected. We observed a high variability in the innate memory response among individual donors. This is expected since innate memory largely depends on the previous history of exposure or infections, which is different in different subjects. Overall, innate memory appeared to limit the amount of active IL-1ß produced by macrophages in response to a bacterial challenge, while enhancing the responsiveness of monocytes. The functional re-programming of mononuclear phagocytes through modulation of innate memory may provide innovative approaches in the management of inflammatory diseases, as well as in the design of new immunization strategies. In this respect, the interindividual variability in innate memory suggests the need of a personalized assessment.

Innate Immune Memory: The Latest Frontier of Adjuvanticity.

Recent findings in the field of immune memory have demonstrated that B and T cell mediated immunity following infections are enhanced by the so-called trained immunity. This effect has been most extensively investigated for the tuberculosis vaccine strain Bacillus Calmette-Guérin (BCG). Epidemiological studies suggest that this vaccine is associated with a substantial reduction in overall child mortality that cannot be solely explained by prevention of the target disease but that it seems to rely on inducing resistance to other infections. Upon infection or vaccination, monocytes/macrophages can be functionally reprogrammed so as to display an enhanced defensive response against unrelated infections. Epigenetic modifications seem to play a key role in the induction of this "innate memory." These findings are revolutionising our knowledge of the immune system, introducing the concept of memory also for mammalian innate immunity. Thus, vaccines are likely to nonspecifically affect the overall immunological status of individuals in a clinically relevant manner. As a consequence, future vaccine strategies ought to take into account the contribution of innate memory through appropriate design of formulations and administration scheduling.