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Background: The use of plasma rather than serum for determination of cardiac troponins can improve turnaround time and potentially avoid incomplete serum separation that may produce falsely increased results. We investigated the influence of incomplete serum separation and the effect of heparin-plasma on cardiac troponin concentrations. Methods: Serum and heparin-plasma samples were drawn simultaneously from 100 patients (50 patients with acute coronary syndrome and 50 patients after open heart surgery) and measured on three different analytical systems, two for determination of cardiac troponin I (cTnI; Abbott AxSYM and Bayer ACS:Centaur) and one for cardiac troponin T (cTnT; Roche Elecsys cTnT STAT). Serum samples were reanalyzed after a second centrifugation to assess the influence of incomplete serum separation. Results: Mean results (± 95% confidence interval) in heparin-plasma compared with serum were 101% ± 2% (AxSYM cTnI), 94% ± 3% (ACS:Centaur cTnI), and 99% ± 3% (Elecsys cTnT). Differences >20% were seen in 11% of results on the ACS:Centaur, 9% of results on Elecsys cTnT, and 2% of results on the AxSYM. For the Elecsys cTnT assay, the magnitude of the difference between serum and plasma was independent of the absolute concentration and confined to individual samples, and was reversed by treatment with heparinase. A second centrifugation had no effect on serum results by any of the assays. Conclusion: The concentrations of troponins measured in heparin-plasma are markedly lower than in serum in some cases.

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Migrating cells like coronary smooth muscle cells in restenosis change their cell shape and form cellular protrusions called filopodia. A prerequisite for filopodia formation is the rearrangement of the actin cytoskeleton. An essential role of the 78-kDa protein Moesin is described for Rho- and Rac-dependent assembly of actin filaments. In vivo Moesin is not observed in mature smooth muscle cells. The objective of this study was to demonstrate that Moesin is upregulated in migrating coronary smooth muscle cells during restenosis development. In vivo expression of Moesin was upregulated in neointimal coronary smooth muscle cells of dilated porcine coronary arteries compared to the undilated left circumflex coronary artery of the same swine. Concordant to these results Moesin expression was upregulated in migrating and invading human arterial smooth muscle cells in vitro analyzed by FACS, Western blotting and RT-PCR. In addition, the invasive potential of Moesin-positive Mel Im cells transfected with Moesin sense DNA increased by 28% as compared to mock-transfected control, whereas antisense transfected cells had a decreased invasive potential of 32%. Transfection of Moesin-negative HepG2 with Moesin sense cDNA increased the invasive potential by 43%. Finally, transfection of human arterial smooth muscle cells with Moesin sense cDNA caused an increased invasive potential of 30%. Transfection of haSMCs with antisense cDNA decreased the invasive potential by 37% in comparison to mock-transfected control. These results demonstrate for the first time an upregulation of Moesin expression in coronary smooth muscle cells of the neointima after arterial injury. The increased migrative and invasive potential of cells transfected with Moesin confirmed the functional role of Moesin in cell migration. This indicates an important role of Moesin during restenosis development.