Lactadherin-mediated association of PS-exposing particles and cells in vitro by endothelial cells. (A) DiD-labeled MLVs containing either PS or EPG, preincubated in the presence or absence of lactadherin, were incubated with endothelial cells. Only in the case of PS-MLVs was enhanced association of lactadherin-preincubated MLVs (values ± SEM) seen. Association increased in time. (B) Multiphoton image of an endothelial cell with bound and internalized lactadherin-opsonized approximately 2 μm sized PS-MLVs (indicated by arrows) after 2 hours of incubation. Scale bar represents 5 μm. (C) Endothelial cell association of PKH-26–labeled aged erythrocytes with or without preincubation with lactadherin. Lactadherin enhanced endothelial cell association in a time-dependent manner (values ± SEM). (D) Multiphoton image of an endothelial cell with associated opsonized aged erythrocytes (indicated by arrows) after 4 hours of incubation. Scale bar represents 10 μm. (E) Endothelial cell association of PKH-26–labeled apoptotic tumor cells with or without preincubation with lactadherin (values ± SEM). Lactadherin enhanced endothelial cell association in a time-dependent manner. (F) Multiphoton image of endothelial cells with associated apoptotic tumor cells (indicated by arrows) that show a typical condensed nuclear staining after 4 hours of incubation. Scale bar represents 10 μm.