Proliferation and functionality of human umbilical vein endothelial cells on angiopoietin-1 immobilized 316L stainless steel

Angiopoietin-1 (Ang-1), a vascular-specific growth factor secreted from periendothelial cells, has drawn increasing attention in clinical applications because it can promote the reconstruction of blood vessels and has an anti-inflammatory effect compared with vascular endothelial growth factor (VEGF). In this study, Ang-1 was firstly covalently conjugated onto polydopamine (PDA) coated 316L stainless steel (SS), aiming at developing an Ang-l modified surface for endothelialization. The results of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) measurements confirmed the successful immobilization of Ang-1. Quartz crystal microbalance with dissipation (QCM-D) studies demonstrated that ∼154 ng cm−2 of Ang-1 were bonded onto the PDA surface. To confirm its functionality, the effects of the Ang-1-modified coating on the growth behavior of human umbilical vein endothelial cells (HUVECs) were studied. As a result, the Ang-1 functionalized surface significantly enhanced endothelial cell adhesion, proliferation and migration. It was also found the Ang-1 functionalized coating could promote the release of nitric oxide (NO), secretion of prostacyclin-2 (PGI2) and inhibit the apoptosis of HUVECs. These data effectively suggested angiopoietin-1 could potentially be applied not only in neovascularization such as ischemic reperfusion and vascularization of tissue engineering scaffolds, but also in surface modification of cardiovascular implant materials for re-endothelialization.