TNF-α and TGF-β synergistically stimulate elongation of human endothelial cells without transdifferentiation to smooth muscle cell phenotype

We earlier reported synergy between tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) for apoptosis in human umbilical vein endothelium (HUVEC). Here, we study morphological change by circularity measurement of HUVEC surviving this cytokine induced synergistic apoptosis. Contrasting with reports by others studying bovine endothelium, HUVEC did not change morphology in response to TGF-β1. TNF-α markedly elongated cells (p<0.001) and this further increased with combination of the two cytokines (p<0.001), while elongation was accompanied by increased actin stress fibres. Transdifferentiation of HUVEC to a smooth muscle cell phenotype as reported elsewhere was excluded in the current study.