(145e) Platelet Adhesion to Fibrinogen Patterned Substrates

Platelet adhesion to the vessel wall during vascular injury is mediated by platelet glycoproteins binding to their respective ligands on the vascular wall. In this study we investigated the role that ligand spacing plays in regulating platelet interactions with fibrinogen under hemodynamic flow.  To regulate the size and distance between patches of fibrinogen we developed a photolithography based technique to fabricate patterns (e.g. lines, dots) of proteins surrounded by a protein repellant layer of poly(ethylene glycol). We demonstrate that when mepacrine labeled whole blood is perfused over substrates patterned with 4 micron wide lines of fibrinogen, platelets selectively adhere to the areas of patterned fibrinogen. Using fluorescent microscopy we demonstrate that the amount of platelet coverage (5% - 35%) and the ability of thrombi to grow laterally was dependent upon the distance (3 - 30 microns) between parallel lines of fibrinogen. We also report on the effects of fibrinogen patch size on platelet adhesion by varying the size of the protein patch (2 – 8 microns) available for adhesion. The technique described in this paper provides an effective way to fabricate patterned protein surfaces for use in novel platelet adhesion assays under physiologic flow conditions.