Laser scanning cytometry: A novel method for the detection of platelet-endothelial cell adhesion

Background: Adherence of platelets to endothelial cells may be a significan t event in the development of vascular thrombosis. Existing models, which e xamine platelet-endothelial cell interactions, compromise endothelial cell integrity or use radioactivity to identify platelets that adhere to endothe lial cells. We report a novel method for in vitro detection of platelet-end othelial cell adhesion that allows endothelial cells to remain as an intact monolayer and for visualization of individual platelets. Methods: Fluorescently labeled platelets were incubated with a confluent mo nolayer of endothelial cells. Laser scanning cytometry (LSC) identified pla telets bound to endothelial cells based on their fluorescent signals. Results: LSC detection of platelets reliably reproduced well-described find ings of thrombin-induced platelet-endothelial cell adhesion. Results demonstrating reduced adhesion with a glycoprotein IIb-IIIa-specifi c blocking monoclonal antibody confirmed the specificity of the LSC detecti on of platelet-endothelial cell adhesion. Conclusions: LSC is a novel method for detecting platelet-endothelial cell adhesion. Its advantages over other methods are: (a) endothelial cells rema in undisturbed and adherent throughout; (b) the ability to detect individua l bound platelets and subpopulations; (c) the ability to store images and s lides and then relocate, revisualize, and reanalyze individual cells or cel l populations of interest; and (d) no radioactivity. Cytometry 43:308-313, 2001. (C) 2001 Wiley-Liss, Inc.