ABSTRACT
Biomaterials allow for the precision control over the combination and release of cargo needed to engineer cell outcomes. These capabilities are particularly attractive as new candidate therapies to treat autoimmune diseases, conditions where dysfunctional immune cells create pathogenic tissue environments during attack of self-molecules termed self-antigens. Here we extend past studies showing combinations of a small molecule immunomodulator co-delivered with self-antigen induces antigen-specific regulatory T cells. In particular, we sought to elucidate how different ratios of these components loaded in degradable polymer particles shape the antigen presenting cell (APC) -T cell interactions that drive differentiation of T cells toward either inflammatory or regulatory phenotypes. Using rapamycin (rapa) as a modulatory cue and myelin self-peptide (myelin oligodendrocyte glycoprotein- MOG) - self-antigen attacked during multiple sclerosis (MS), we integrate these components into polymer particles over a range of ratios and concentrations without altering the physicochemical properties of the particles. Using primary cell co-cultures, we show that while all ratios of rapa:MOG significantly decreased expression of co-stimulation molecules on dendritic cells (DCs), these levels were insensitive to the specific ratio. During co-culture with primary T cell receptor transgenic T cells, we demonstrate that the ratio of rapa:MOG controls the expansion and differentiation of these cells. In particular, at shorter time points, higher ratios induce regulatory T cells most efficiently, while at longer time points the processes are not sensitive to the specific ratio. We also found corresponding changes in gene expression and inflammatory cytokine secretion during these times. The in vitro results in this study contribute to in vitro regulatory T cell expansion techniques, as well as provide insight into future studies to explore other modulatory effects of rapa such as induction of maintenance or survival cues.
ABSTRACT
Tannic acid (TA) has been previously shown to have anticancer potential for breast cancer but its effects on melanoma have not yet been investigated. Similarly, stiffness of the tumor microenvironment is known to have a profound effect on breast cancer metastasis, but little is known about its role on melanoma. The goal of the current study is to investigate the synergistic effects of TA and matrix stiffness on melanoma progression. A375 melanoma cells with metastatic potential were cultured on TA crosslinked uncompacted (UC; soft) and electrochemically compacted (ECC; stiff) collagen gels and the effects of TA on gel morphology, mechanical properties, and cellular response (i.e. morphology and proliferation) were evaluated. SEM results showed that TA crosslinking induced merging of collagen fibrils that resulted in decrease in pore size of both UC and ECC collagen gels. Tensile testing showed that TA crosslinking significantly (p < 0.05) improved the mechanical properties of ECC collagen gels. Results from Alamar blue assay showed that TA preferentially inhibited the proliferation of A375 melanoma cells compared to the non-cancerous NIH 3T3 fibroblasts on UC collagen gels. However, on ECC collagen gels, preferential effect of TA was not prevalent as proliferation of both cell types was inhibited to a similar extent. When comparing the two gel types, inhibition of A375 melanoma cell proliferation was more pronounced on TA crosslinked UC collagen gels compared to TA crosslinked ECC collagen gels. Overall, these results suggest that TA incorporated into UC collagen gels may more selectively inhibit the proliferation of melanoma cells, and that matrix stiffness is an important driver of tumor proliferation and progression.
