Pancreatic ductal adenocarcinoma (PDAC) is one of the most overlooked cancers despite its dismal median survival time of 6 months. The biggest challenges in improving patient survival are late diagnosis due to lack of diagnostic markers, and limited treatment options due to almost complete therapy resistance. The past decades of research identified the dense stroma and the complex interplay/crosstalk between the cancer- and the different stromal cells as the main culprits for the slow progress in improving patient outcome. For better ex vivo simulation of this complex tumor microenvironment the models used in PDAC research likewise need to become more diverse. Depending on the focus of the investigation, several in vitro and in vivo models for PDAC have been established in the past years. Particularly, 3D cell culture such as spheroids and organoids have become more frequently used. This review aims to examine current PDAC in vitro models, their inherent limitations, and their successful implementations in research.

Highlights We described a straightforward and highly reproducible 3D culturing method to investigate the intercellular crosstalk between pancreatic cancer and pancreatic stellate cells (PSCs)/cancer associated fibroblasts (CAFs). Pancreatic ductal adenocarcinoma (PDAC) is therapy resistant and characterized by a desmoplastic microenvironment with low functional vascularization. As a consequence, this cancer type is nutrition-poor. Using expression profiling, we compared the common culturing condition using ten percent fetal bovine serum (FBS) with 0.1percent FBS and found that PDAC cells when grown together with PSCs/CAFs change into a more aggressive subtype, independent of the FBS concentration in the medium. Depending on the FBS concentration, the PSCs/CAFs display a shift from a myofibroblastic CAF (myCAF) to a more inflammatory CAF (iCAF) phenotype in co-culture with PDAC cells. We demonstrate that the pharmacotranscriptomic signatures as well as the chemoresistance of the PDAC cells change significantly upon co-culture with PSCs/CAFs.

BackgroundPreterm newborns typically require supplemental oxygen but hyperoxic conditions also damage the premature lung. Oxygen-induced lung damages are mainly studied in newborn mouse models using oxygen concentrations above 75% and looking at short-term effects. Therefore, we aimed at the investigation of long-term effects and their dependency on different oxygen concentrations.MethodsNewborn mice were exposed to moderate vs. severe hyperoxic air conditions (50 vs. 75% O2) for 14 days followed by a longer period of normoxic conditions. Lung-related parameters were collected at an age of 60 or 120 days.ResultsSevere hyperoxia caused lower alveolar density, enlargement of parenchymal air spaces and fragmented elastic fibers as well as higher lung compliance with peak airflow limitations and higher sensitivity to ventilation-mediated damages in later life. However, these long-term lung structural and functional changes did not restrict the voluntary physical activity. Also, they were not accompanied by ongoing inflammatory processes, increased formation of reactive oxygen species (ROS) or altered expressions of antioxidant enzymes (superoxide dismutases, catalase) and lung elasticity-relevant proteins (elastin, pro-surfactant proteins) in adulthood. In contrast to severe hyperoxia, moderate hyperoxia was less lung damaging but also not free of long-term effects (higher lung compliance without peak airflow limitations, increased ROS formation).ConclusionsSevere but not moderate neonatal hyperoxia causes emphysematous lungs without persisting oxidative stress and inflammation in adulthood. As the existing fragmentation of the elastic fibers seems to play a pivotal role, it indicates the usefulness of elastin-protecting compounds in the reduction of long-term oxygen-related lung damages.

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