Culturing of Cardiac Fibroblasts in Engineered Heart Matrix Reduces Myofibroblast Differentiation but Maintains Their Response to Cyclic Stretch and Transforming Growth Factor beta 1

Isolation and culturing of cardiac fibroblasts (CF) induces rapid differentiation toward a myofibroblast phenotype, which is partly mediated by the high substrate stiffness of the culture plates. In the present study, a 3D model of Engineered Heart Matrix (EHM) of physiological stiffness (Youngs modulus similar to 15 kPa) was developed using primary adult rat CF and a natural hydrogel collagen type 1 matrix. CF were equally distributed, viable and quiescent for at least 13 days in EHM and the baseline gene expression of myofibroblast-markers alfa-smooth muscle actin (Acta2), and connective tissue growth factor (Ctgf) was significantly lower, compared to CF cultured in 2D monolayers. CF baseline gene expression of transforming growth factor-beta1 (Tgf beta 1) and brain natriuretic peptide (Nppb) was higher in EHM-fibers compared to the monolayers. EHM stimulation by 10% cyclic stretch (1 Hz) increased the gene expression of Nppb (3.0-fold), Ctgf (2.1-fold) and Tgf beta 1 (2.3-fold) after 24 h. Stimulation of EHM with TGF beta 1 (1 ng/mL, 24 h) induced Tgf beta 1 (1.6-fold) and Ctgf (1.6-fold). In conclusion, culturing CF in EHM of physiological stiffness reduced myofibroblast marker gene expression, while the CF response to stretch or TGF beta 1 was maintained, indicating that our novel EHM structure provides a good physiological model to study CF function and myofibroblast differentiation

The labyrinth of life-styles

The increasing complexity of multi-cultural society has given rise to the thought that traditional (demographic and socio-economic) variables are no longer sufficient to substantiate policy development and planning in the housing sector. The concept of life-style is presumed to add to the description and prediction of the demand side, thus enabling housing strategies that are consistent with more dynamic and differentiated preferences. The usefulness of life-styles for policy development was studied in a literature review, in particular of research in the Netherlands. The study shows that the current significance of the concept is doubtful for various reasons: the indefiniteness of life-styles; the static and simplified view of society that is often presented, which is partly caused by the methods used; the uncertain relation to types of residential environment; and the unproven necessity of using life-styles alongside or as a substitute for more traditional variables. Recommendations are offered for future research on this subject. © The Author(s) 200