Application of interpenetrating alginate-collagen polymer network to understand cancer-associated fibroblasts (CAFs) behaviour in 3D

Research on the tumor microenvironment had become increasingly popular, as the current drugs and therapies hardly meet clinical expectations. Tumor is a heterogeneous complex, which consists many kinds of stroma cells. Cancer associated fibroblasts (CAF) is the main cell type with tumor stroma. It had been demonstrated that CAF will interact with cancer cells via secreting growth factor and cytokines promoting cancer cells activities, such as proliferation, invasiveness, and metastasis. In addition, the tumor stroma will keep changing during tumor progression, such as crosslinking density and extracellular matrix (ECM) deposition, which will affect tumor itself. However, there are no studies on the effects of stroma influencing CAF. In this study, we fabricated collagen/alginate (Col/Al) interpenetrate network (IPN) hydrogel with different mechanical properties to mimic the tumor microenvironment to study breast CAF activities. Rheology and SEM results showed that the un-cross-linked Col/Al hydrogel present porous structure and was with around 50 Pascals of storage modulus, which was similar to healthy breast tissue stroma. However, the cross-linked Col/Al hydrogel presented porous but more bundled structure and was with around 300 Pascals of storage modulus, which was quite close to the tumor in its late stage. Interestingly, cells showed different morphology with the different hydrogel, spread shape in un-cross-linked hydrogel and round shape in Col/Al hydrogel. Therefore, we hypothesize that the CAF morphology change will influence CAF activities and further affect cancer cells behaviors. The rt-PCR results confirmed that the CAF would have different gene expression. Spread cells would lower IL-6 expression compared to the round cells. CAF is a main source of IL-6, which always affect cancer cells activities. The cancer cells invasiveness results of MB-231 breast cancer cells treated with conditioned medium derived from different CAF-encapsulated hydrogels did not demonstrate much significant difference. This might be due to the different proliferation state of CAFs within hydrogel. Overall, the CAF stroma study has proven significant and could potentially provide new target and direction for the future of cancer therapy.Bachelor of Engineering (Materials Engineering