Bio-fabricated alginate tumor-like hydrogels to enhance understanding of prostate-specific micro-environments in vitro

Engineered three-dimensional (3D) in vitro models are useful tools for closely mimic human tissue-specific tumor microenvironments (TME) and to provide key information on cell-material interactions. In this work we aimed at engineering prostate-specific in vitro models to help in discerning specific cell-material interactions at the interface during prostate cancer (PCa) progression, focusing on modelling both biomechanical and biochemical traits of the prostate extracellular matrix (ECM) within PCa progression. Here, we functionalized alginates and obtained PCa-specific hydrogels for 3D culture and ease evaluation of markers used to assess PCa progression in human prostate cancer cells (i.e., PC-3 cells). Alginate-based hydrogels were modified with laminin-like peptides (i.e., IKVAV, AG73) and tailored in physical and mechanical properties to closely mimic the PCa ECM, with mechanical properties in the range of 2.5-13 kPa (the stiffer value matching advanced/metastatic PCa). To engineer the heterogeneity of advanced PCa, cancer-associated fibroblasts (hTERT PF179T CAF) were selected as stromal cellular component and co/cultured with PC-3 cells. We formulated prostate bioinks for extrusion-based bioprinting (EBB) and 3D printed engineered PCa in vitro models to study the effect of the microenvironment on the expression of key markers in PC-3 cells, considering the pivotal role of epithelial-to-mesenchymal transition (EMT) in PCa progression. Cells cultured in prostate-specific hydrogels showed higher cell proliferation and viability, whereas CD44 and Vimentin expression evidenced a higher metastatic potential in PC-3 cells cultured in stiffer and laminin-enriched hydrogels. The selected PCa TMEs used in this work showed PC-3 cells expressing increased levels of Vimentin when co-cultured with CAFs, which also correlates with CD44 expression. Results suggests positive correlations with clinical findings, underlying that tumor biomechanics holds potential for better understand cancer pathobiology and that new 3D in vitro models are urged to unveil how ECM traits regulate PCa progression.