Melt-electrowriting of 3D anatomically relevant scaffolds to recreate a pancreatic acinar unit in vitro

Melt-electrowriting (MEW) belongs to the group of advanced additive manufacturing techniques and consists of computer-aided design (CAD)-assisted polymer extrusion combined with a high-voltage supply to achieve deposition of polymeric fibers with diameters in the micrometric range (1 to 20 μm) similar to the size of natural extracellular matrix fibers. In this work, we exploit MEW to design and fabricate a three-dimensional (3D) model that resembles the morphology of the exocrine pancreatic functional unit without the need of supports, mandrels, or sacrificial materials. Optimized process parameters resulted in a MEW scaffold having regular fibers (19 ± 5 μm size) and an acinar cavity showing high shape fidelity. Then, human foreskin fibroblasts (HFF1) and human pancreatic ductal epithelial cells (HPDE), wild-type HPDE, and HPDE overexpressing KRAS oncogene were allowed to colonize the entire 3D structure and the acinar cavity. Thus, a physiologically relevant 3D model was created in vitro after 24 days using a co-culture protocol (14 days of HFF1 alone plus 10 days of HPDE and HFF1 co-culture). The effect of cell crosstalk within the MEW scaffolds was also assessed by monitoring HFF1 secretion of interleukin (IL)-6, a pro-inflammatory cytokine responsible for the inflammatory cascade occurring in pancreatic cancer. High levels of IL-6 were detected only when fibroblasts were co-cultured with the HPDE overexpressing KRAS. These findings confirmed that the MEW 3D in vitro model is able to recreate the characteristic hallmark of the pathological condition where cancer oncogenes mediate fibroblast activities.