There were no statistically significant differences in the degree of positive staining of the various integrins examined in the cardiovascular system before and after LVAD support. The results obtained were similar in tissues obtained from IHD patients and from DCM patients. Perlecan was expressed on the membrane of the cardiomyocytes (Fig. 2). In both patient groups, the expression in the pre-LVAD situation was significantly less than in the controls. Only in IHD patients LVAD support resulted in some increase; however, the expression remained below control levels. Messenger RNA expression of integrin-α1, -α3, -α5, -α6, -α7, -α10, -α11, -β1, -β3, -β5, and -β6 were tested by Q-PCR.

Statistically significant

changes in mRNA expression due to LVAD support were only observed in 5 out of 11 integrins tested (Fig. 3) in either one or both patient groups. However, these 5 integrins did not show significant differences PLX3397 nmr with the healthy controls (both pre- and post-LVAD) except for integrin-α6 in DCM patients. In this case the pre-LVAD level is significantly lower than control mTOR activity level (Fig. 3). Expression of integrin-α1, -α6 and -α10 mRNA significantly increased after LVAD support in DCM patients compared to pre-LVAD. The observed increase was 0.98-fold (P=.014), 1.40-fold, (P=.007), and 2.47-fold (P=.023), respectively. In IHD patients significant increases in mRNA expression were seen after LVAD support for integrin-α6 and -β6; 23-fold (P=.046) and 9.34-fold (P=.026), respectively, whereas a decrease (0.41-fold, P=.039) was measured for integrin-α5. Integrins mediate interactions between cells, basal membrane and the extracellular matrix (ECM) that are essential for several out cellular processes. Intact integrin function has been related to anti-apoptotic signaling and cell survival [16], induction of post-infarct cell migration and

myocardial repair [17], activation and regeneration involving epithelial–mesenchymal transition [18], as well as to a normal progression of cardiomyocytes through the cell cycle [19]. Structural remodeling of the ventricular wall in patients with heart failure involves changes in the ECM [5], [6] and [20], cardiomyocytes, and basal membranes [13]. The changes observed in the patient group of this study were the same as described by Bruggink et al. [13] and [20]. Since integrins form the contact between cells and their surrounding matrix and are important in the mechanotransduction of the contracting cardiomyocytes, it might be expected that if changes in the ECM occur this will be reflected in integrin expression in the myocardium. Furthermore, it has been described that LVAD support in heart failure patients leads to at least partial normalization of the heart condition [8] and [9] among others reflected in changes in regulatory miRNA expression [7].