NGO-adsorbed LPA increased tip cell differentiation. (a) Wound healing assay of HUVECs cultured in basal culture medium without FBS or basal culture medium supplemented with NGO, NGO/LPA or LPA for 24 h. The wound areas (%) in the different groups were subjected to statistical analysis. (b) Tube formation assay in HUVECs cultured in basal culture medium in the absence or presence of NGO, NGO/LPA or LPA for 24 h. The results of quantitative analysis of the master segment length (μm) and numbers of nodes and meshes are presented in a histogram. (c) IF images showing CD34−and DLL4-positive cells in the groups. Scale bar, 100 μm. (d) Immunoblot analysis of KDR, CD34, and DLL4 in HUVECs treated with basal culture medium containing NGO, NGO/LPA or LPA for 24 h. Data represent the mean ± SD (n = 3). *p < 0.05, **p < 0.005.