Improved in vitro angiogenic behavior of human umbilical vein endothelial cells with oxidized polydopamine coating

Mussel inspired polydopamine (PDA) coatings have attracted a great deal of attention for their superior osteogenic property. Furthermore, recent investigations have demonstrated that vessel formation is crucial to bone regeneration. Hence, in the present study, the potential ability of polydopamine coatings with different oxidation degrees were systematically investigated in vitro to improve the angiogenic behavior of human umbilical vein endothelial cells (HUVECs). PDA was first coated on titanium (PDA-1#), and then oxidized by thermal treatment at 150 (PDA-2#) and 300 °C (PDA-3#), respectively. X-ray photoelectron spectroscopy (XPS) results revealed that phenolic hydroxyl (C-OH) and primary amino group (-NH₂) on PDA coatings deceased after oxidation, while quinone (C=O) increased. In vitro cell culture experiments suggested that PDA-2# sample was most beneficial for the adhesion, migration, and proliferation of HUVECs. Furthermore, HUVECs cultured on PDA-2# sample also exhibited best tube formation, CD31 expression, vascular endothelial growth factor (VEGF) secretion, as well as angiogenic-associated gene expression abilities. Our study suggests that moderate oxidation of PDA coating with balanced quinone and amino group has excellent potential to enhance bone vascularization, and is thus promising for clinical application in orthopedic implants.