Abstract 18155: Immobilised apoA-I and High-Density Lipoproteins are Anti-Thrombotic and Exert Anti-Inflammatory Effects in Vascular Smooth Muscle Cells
Aim: The clinical efficacy of current endovascular stents is limited by thrombosis and inflammation-induced restenosis. Plasma activated coating (PAC) is able to covalently bind proteins to stainless steel (SS) surfaces in their bioactive state. High density lipoproteins (HDL) and its main apolipoprotein constituent apoA-I regulate key biological processes involved in restenosis and thrombosis, highlighting their potential for immobilization on PAC-coated SS stent surfaces. We hypothesized that covalently bound apoA-I or reconstituted HDL (rHDL) to PAC-coated SS will retain its biological properties and improve stent patency.
Methods and Results: The covalent binding of apoA-I or rHDL to SS and PAC-coated SS was confirmed by incubation with 125I labelled apoA-I or rHDL, followed by boiling in SDS to remove passively bound protein. Levels of bound radiolabelled apoA-I and rHDL were 704 and 89 cpm for SS, which increased significantly to 3669 and 3176 cpm for PAC, respectively. Thrombosis formation under static conditions was assessed by scanning electron microscopy which revealed thrombus formation was strikingly reduced in PAC-coated samples and completely absent in PAC+apoA-I and PAC+rHDL samples, while extensive thrombi formed on the SS samples at all time points. Thrombus formation under flow conditions using a Chandler Loop showed PAC, PAC+apoA-I and PAC+rHDL samples had 97.8%, 97% and 94% lower thrombus weights, compared to SS samples, respectively (p<0.05). Smooth muscle cell (SMC) and endothelial cell (EC) attachment was measured by crystal violet staining and showed that immobilized apoA-I and rHDL on PAC-coated SS reduced SMC attachment by 70% and 80%, respectively, p<0.05. Conversely, EC attachment was increased by 36% on PAC+apoA-I (p<0.05). Chemokine expression (CCL2, CCL5 and CX3CL1) of TNF-α stimulated SMCs grown on immobilised apoAI and rHDL was measured by qPCR and had significantly attenuated TNF-α-induced increases in CCL2 (40 & 47%), CCL5 (27 & 30%) and CX3CL1 (36 & 36%), p<0.05.
Conclusion: ApoA-I and rHDL covalently bind to PAC-coated SS surfaces and retain anti-thrombotic and anti-inflammatory properties. This may represent a novel site-directed approach to increase stent patency.
Author Disclosures: L.Z. Vanags: None. J. Tan: None. J. Michael: None. M. Bilek: None. S. Wise: None. C. Bursill: None.
- © 2014 by American Heart Association, Inc.