Abstract 601: Circulating Platelet Aggregate Damages Endothelial Cells in Culture
Background: The presence of circulating endothelial cells (CECs) in systemic circulation might be an indicator of endothelial damage and/or denudation, and thus the body’s response to repair and revascularization. Thus, we hypothesized that aggregated platelets (AgPlts) can disrupt and denude the endothelium, and contribute to the presence of CEC and EC-derived particles (ECDP). In this study, we used endothelial cells and sheep carotid artery segments.
Methods: Endothelial cells (sheep aortic and human umbilical vein) were grown in glass tubes and tagged with/without 0.5 μm fluorescent beads. These glass tubes as well as sheep carotid artery segments were connected to a Mini-Pump Variable Flow System to study the effect of circulating AgPlts on the endothelium. ECs in glass tube/artery segment were exposed to medium alone, non-aggregated platelets (NAgPlts), AgPlts and 90 micron polystyrene beads at a flow rate of 20-85 ml/minute for various time intervals (0, 30 seconds, 1, and 5 min). Collected effluents were cultured and incubated for 72 hrs to analyze the growth potential of dislodged but intact ECs. Inflammatory genes of the damaged endothelium were analyzed by RT-PCR and the presence of ECDP was further assessed by western blot analysis using an antibody to human von Willebrand factor (VWF).
Results: No ECs and ECDP were observed in effluents collected after injecting medium alone or medium and NAgPlts, whereas AgPlts and Polybeads drastically dislodged ECs and released ECs and ECDP in effluents. There were no ECs and ECDP in samples collected at 0 and 30 seconds. However, the number of ECs and EDCP in samples collected at 1 and 5 minutes was proportionately increased. Effluents collected when endothelial cell damage was seen showed an increased presence of VWF as compared to control effluents.
Conclusion: Our study demonstrates that circulating AgPlts denude the endothelium and release ECs and ECDP. Direct mechanical disruption and shear stress caused by circulating AgPlts could be the underlying mechanism of the observed endothelial damage. Moreover, a major source of the CECs in the blood circulation could be the damaged endothelium.
Author Disclosures: C. Aluganti Narasimhulu: None. M. Nandave: None. D. Bonilla: None. J. Singaravelu: None. Y. Ravi: None. S. Parthasarathy: None. S. Chittoor Bhaskar: None.
- © 2015 by American Heart Association, Inc.