A fibronectin‐fibrinogen‐tropoelastin coating reduces smooth muscle cell growth but improves endothelial cell function

Abstract

Reendothelialization of the stent surface after percutaneous coronary intervention (PCI) is known to be an important determinant of clinical outcome. We compared the effects of biological stent coatings, fibronectin, fibrinogen and tropoelastin, on human umbilical vein endothelial cell (HUVEC) and vascular smooth muscle cell (VSMC) characteristics. Umbilical cord arterial segments were cultured on coated surfaces and VSMC outgrowth (indicating proliferation and migration) was measured after 12 days. mRNA was isolated from HUVEC and VSMC cultured on these coatings and gene expression was profiled by QPCR. Procoagulant properties of HUVEC were determined by an indirect chromogenic assay which detects tissue factor activity. The varying stent coatings influence VSMC outgrowth: 31.2 ± 4.0 mm2 on fibronectin, 1.6 ± 0.3 mm2 on tropoelastin and 8.1 ± 1.5 mm2 on a mixture of fibronectin/fibrinogen/tropoelastin, although HUVEC migration remains unaffected. Culturing HUVEC on tropoelastin induces increased expression of VCAM-1 (13.1 ± 4.4 pg/ml), ICAM-1 (5.1 ± 1.3 pg/ml) and IL-8 (11.6 ± 3.1 pg/ml) compared to fibronectin (0.7 ± 0.2, 0.8 ± 0.2, 2.3 ± 0.5 pg/ml, respectively), although expression levels on fibronectin/fibrinogen/tropoelastin remain unaltered. No significant differences in VCAM-1, ICAM-1 and IL-8 mRNA expression are found in VSMC. Finally, HUVEC cultured on tropoelastin display a fivefold increased tissue factor activity (511.6 ± 26.7%), compared to cells cultured on fibronectin (100 ± 3.9%) or fibronectin/fibrinogen/tropoelastin (76.3 ± 25.0%). These results indicate that tropoelastin inhibits VSMC migration but leads to increased inflammatory and procoagulant markers on endothelial cells. Fibronectin/fibrinogen/tropoelastin inhibits VSMCs while compensating the inflammatory and procoagulant effects. These data suggest that coating a mixture of fibronectin/fibrinogen/tropoelastin on a stent may promote reendothelialization, while keeping unfavourable processes such as restenosis and procoagulant activity limited.

Electrodeposited Gels Prepared from Protein Alloys

“…Recombinant human tropoelastin, displaying a wide range of biological activities, is especially suitable for mediation of the cell responses to biomaterials [2,4–5,25–26]. Our results confirmed that the addition of tropoelastin constituents to silk-tropoelastin alloys promoted the attachment of HEFs and the endothelialization by HUVECs.…”

“…Furthermore, while cell proliferation was observed on all the three tropoelastin-containing samples, films contain higher ratio of tropoelastin tend to facilitate the formation of a better integrated endothelium (Figure 6C). This result confirmed that, in addition to enhanced cell attachment, the tropoelastin components in the protein alloys had a positive impact on accelerated HUVEC endothelialization [26]. …”

“…Our results confirmed that the addition of tropoelastin constituents to silk-tropoelastin alloys promoted the attachment of HEFs and the endothelialization by HUVECs. Re-endothelialization is a crucial aspect of wound healing after vascular injury and similarly after stenting [26]. Furthermore, cellular binding domains as well as other specific biofunctional motifs can be easily integrated into the assembled gels through genetic engineering techniques [30,31].…”

Tropoelastin Enhances Nitric Oxide Production by Endothelial Cells

“…This hemocompatibility has led to translational studies with tropoelastin coatings on metallic vascular stents which present tropoelastin's cell attachment functionality, allowing for enhanced endothelialization, decreased smooth muscle cell proliferation and stent hemocompatibility [3,11,12]. These effects are seen both in vitro and following implantation, where in vivo studies confirm that tropoelastin coatings preferentially enhance endothelialization, while suppressing underlying smooth muscle cell infiltration and hyperproliferation [13]. With the accelerating use of tropoelastin materials for vascular applications, it is increasingly important to broaden the understanding of tropoelastin cell signaling mechanisms.…”

Smooth muscle-specific drug targets for next-generation drug-eluting stent

“…have found that tropoelastin treatment only inhibits VSMC migration but leads to increased inflammatory response in EC. However, combined treatment with fibronectin, fibrinogen and tropoelastin inhibits VSMCs while reducing the inflammatory effects on EC (17). Therefore, coating a mixture of fibronectin/fibrinogen/tropoelastin on a stent may promote re-endothelialization and induce a better vascular repair following vascular intervention.…”