  A distinct feature of pancreatic ductal adenocarcinoma (PDAC) is a prominent
tumor microenvironment (TME) with remarkable cellular and spatial heterogeneity
that meaningfully impacts disease biology and treatment resistance. The dynamic
crosstalk between cancer cells and the dense stromal compartment leads to
spatially and temporally heterogeneous metabolic alterations, such as acidic pH
that contributes to drug resistance in PDAC. Thus, monitoring the extracellular
pH metabolic fluctuations within the TME is crucial to predict and to quantify
anticancer drug efficacy. Here, a simple and reliable alginate-based 3D PDAC
model embedding ratiometric optical pH sensors and cocultures of tumor (AsPC-1)
and stromal cells for simultaneously monitoring metabolic pH variations and
quantify drug response is presented. By means of time-lapse confocal laser
scanning microscopy (CLSM) coupled with a fully automated computational
analysis, the extracellular pH metabolic variations are monitored and
quantified over time during drug testing with gemcitabine, folfirinox, and
paclitaxel, commonly used in PDAC therapy. In particular, the extracellular
acidification is more pronounced after drugs treatment, resulting in increased
antitumor effect correlated with apoptotic cell death. These findings highlight
the importance of studying the influence of cellular metabolic mechanisms on
tumor response to therapy in 3D tumor models, this being crucial for the
development of personalized medicine approaches.
