Endothelial cells undergo morphological, biomechanical, and dynamic changes in response to tumor necrosis factor-α

The immune response triggers a complicated sequence of events, one of which is release of the cytokine tumor necrosis factor-alpha (TNF-alpha) from stromal cells, for example monocytes and macrophages. In this work we investigated the biophysical effects of TNF-alpha on endothelial cells (ECs), including changes in cell morphology, biomechanics, migration, and cytoskeletal dynamics. We found that TNF-alpha induces a wide distribution of cell area and aspect ratio, with these properties increasing on average during treatment. Interestingly, aspect ratio peaks after approximately 10 h of exposure to TNF-alpha, corresponding also to a peak in exerted traction forces. Meanwhile, ECs treated with TNF-alpha soften, and we associate this with significant increases in estimated cellular volume. In addition, our evaluation of migratory dynamics revealed an inverse correlation between cell aspect ratio and migration speed after TNF-alpha treatment, suggesting that cell shape may be an important functional regulator of EC migration during an inflammatory response. Finally, we addressed the basic mechanics of how the reorganization of F-actin filaments occurs during TNF-alpha treatment, and observed a dynamic shift of existing actin filaments. Together, our results suggest a functional link between EC morphology, biomechanics, migration, and cytoskeletal dynamics during an inflammatory response.