The hierarchical micro-/nanotextured topographies promote the proliferation and angiogenesis-related genes expression in human umbilical vein endothelial cells by initiation of Hedgehog-Gli1 signaling.

The hierarchical microtextured/nanotextured topographies have been recognized to have better tissue integration properties, but the underlying mechanisms are only partially understood. Hedgehog signaling plays a pivotal role in developmental and homeostatic angiogenesis. We suppose that the Hedgehog-Gli1 signaling may play a significant role in the response of endothelial cells to microtextured/nanotextured topographies (MNTs). To confirm this hypothesis, we produced the MNTs decorated with TiO2 nanotubes of two different diameters (25 and 70 nm), and the proliferation, apoptosis, angiogenesis-related genes expression and Hedgehog signaling activity of human umbilical vein endothelial cells (HUVECs) grown onto these MNTs were measured. Our results showed that the MNTs induced significantly high expression of Sonic Hedgehog (SHH), Smoothened (SMO) and GLI1 in the HUVECs as well as high activation of Hedgehog-Gli1 signaling, compared to the smooth surface. The HUVECs grown on the MNTs showed significantly high levels of adhesion, proliferation and expression of angiogenesis-related genes, including angiopoietin-1 (ANG-1), vascular endothelial growth factor (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2) and endothelial nitric oxide synthase (ENOS); these enhancements were attenuated by siRNA-mediated depletion of SMO, which indicated a significant role of Hedgehog-Gli1 signaling in mediating the enhanced effect of the MNTs on the angiogenic potential of HUVECs. This study may contribute to the modification of biomaterial surfaces for better tissue integration and clinical performance.