Tissue fibrosis is a leading cause of mortality and is characterized by excessive protein deposition and altered tissue mechanical properties. In pathological fibrosis, as well as cancer related fibrosis, tissue pericytes and fibroblasts transition from a quiescent to a myofibroblastic phenotype. In vitro models are needed to better understand how these cells are influenced by their local microenvironment. Here, we developed a fibrous network platform to mimic the structure of the extracellular matrix, where fibers consist of cross-linked hyaluronic acid hydrogels with controlled cross-link density and mechanical properties. As a model myofibroblast precursor, primary hepatic stellate cells were seeded onto fibers with either low (soft) or high (stiff) cross-link density, either directly after isolation (quiescent) or following preculture on tissue culture plates (activated). In general, both quiescent and activated cells showed an increase in spreading, alpha smooth muscle actin expression, and the formation of multicellular clusters on soft fibers when compared to stiff fibers. Further, inhibition of alpha smooth muscle actin decreased activation of cells on soft fibers. This is likely due to fiber recruitment in soft fibers that increased local fiber density, whereas stiff fibers resisted recruitment. This work emphasizes the importance of substrate topography on cell-material interactions and shows that tunable fibrous hydrogels are a relevant culture platform for studying fibrosis and mechanotransduction in disease.
Keywords: electrospinning; fibrosis; hepatic stellate cells; hydrogel; myofibroblasts.