Role of three-dimensional matrix stiffness in regulating the response of human neural cells to toxins

Recent studies have highlighted the strong influence of microenvironmental stiffness on various cell fates including proliferation, migration, and differentiation in both two- and three-dimensional culture conditions. Our study attempts to understand the role of 3D microenvironmental stiffness on cell cytotoxic response using neural glioblastoma U-87 cells encapsulated in alginate hydrogel matrices of varying stiffness as the model system. Interestingly, we observed that cells encapsulated in soft alginate matrices were more sensitive to the toxic chemicals relative to cells encapsulated in stiffer matrices. The observed dependence of toxic responses on matrix stiffness was also seen for other neural cell lines including U-251 glioblastoma and IMR-32 neuroblastoma cells. Given the established involvement of Rho GTPases in mediating mechanosensitive cell responses, we also performed the toxicity assays using U-87 cells expressing constitutively active mutants of the Rho GTPase RhoA. Under these conditions, the toxic responses were similar for U-87 cells cultured in both soft and stiff matrices. These results suggest a strong role of mechanotransductive signaling on the response of neural cells to toxins. We believe that determining the role of substrate stiffness on the toxic response of neural cells will be crucial to the development of optimal in vitro cell-based screens of neurotoxicity