Structural coupling of cardiomyocytes and noncardiomyocytes: quantitative comparisons using a novel micropatterned cell pair assay

Abstract

Pedrotty DM, Klinger RY, Badie N, Hinds S, Kardashian A, Bursac N. Structural coupling of cardiomyocytes and noncardiomyocytes: quantitative comparisons using a novel micropatterned cell pair assay. Am J Physiol Heart Circ Physiol 295: H390 -H400, 2008. First published May 23, 2008; doi:10.1152 doi:10. /ajpheart.91531.2007controlled studies of the structural and functional interactions between cardiomyocytes and other cells are essential for understanding heart pathophysiology and for the further development of safe and efficient cell therapies. We established a novel in vitro assay composed of a large number of individual micropatterned cell pairs with reproducible shape, size, and region of cell-cell contact. This assay was applied to quantify and compare the frequency of expression and distribution of electrical (connexin43) and mechanical (N-cadherin) coupling proteins in 5,000 cell pairs made of cardiomyocytes (CMs), cardiac fibroblasts (CFs), skeletal myoblasts (SKMs), and mesenchymal stem cells (MSCs). We found that for all cell pair types, side-side contacts between two cells formed 4.5-14.3 times more often than end-end contacts. Both connexin43 and N-cadherin were expressed in all homotypic CM pairs but in only 13.4 -91.6% of pairs containing noncardiomyocytes, where expression was either junctional (at the site of cell-cell contact) or diffuse (inside the cytoplasm). CM expression was exclusively junctional in homotypic pairs but predominantly diffuse in heterotypic pairs. Noncardiomyocyte homotypic pairs exhibited diffuse expression 1.7-8.7 times more often than junctional expression, which was increased 2.6 -4.4 times in heterotypic pairs. Junctional connexin43 and N-cadherin expression, respectively, were found in 38.6 Ϯ 7.3 and 39.6 Ϯ 6.2% of CM-MSC pairs, 21.9 Ϯ 5.0 and 13.6 Ϯ 1.9% of CM-SKM pairs, and in only 3.8 -9.6% of CM-CF pairs. Measured frequencies of protein expression and distribution were stable for at least 4 days. Described studies in micropatterned cell pairs shed new light on cellular interactions relevant for cardiac function and cell therapies. micropatterning; coculture; stem cell; gap junction MYOCARDIAL INFARCTION RESULTS in an irreversible cardiomyocyte loss followed by replacement fibrosis and, often, progression to congestive heart failure. Cellular cardiomyoplasty, the transplantation of exogenous cells into the damaged heart, was recently proposed as an alternative approach for the treatment of postinfarction disease (35). Despite the initial promise of the transplantation of skeletal myoblasts and bone marrow-derived stem cells (1, 32), the latest results of double-blind placebocontrolled clinical trials have been more ambiguous (45). One main recognized obstacle to understanding the mechanisms of repair and designing more efficient therapies has been the difficulty in tracking and systematically studying the structural and functional interactions between the implanted cells and host cardiomyocytes in situ. Importantly, although a number of novel cardiogenic cell types a...

Optical mapping of cryoinjured rat myocardium grafted with mesenchymal stem cells

“…This finding is consistent with others showing that MSCs have the ability to express Cx-43 and Cx-45 in vivo (10,14) and in vitro (2,19,21,32). Moreover, it has been shown that MSCs are able to functionally couple with other cells (21,32).…”

Hypoxia-stimulated cardiac fibroblast production of IL-6 promotes myocardial fibrosis via the TGF-β1 signaling pathway

“…Clarifying the structural and functional interactions between CMs and FBs is essential to understand the pathophysiological heart. 15 Meléndez et al 16 showed that IL-6 infusion, both in vivo and in vitro, in rats resulted in myocardial remodeling with considerable fibrosis within the myocardium, and the soluble IL-6 receptor in combination with IL-6 was essential to increase the collagen concentration by isolated cardiac FBs. IL-6 also has a role in mediating the phenotypic conversion to myofibroblasts.…”

Cooperative coupling of cell-matrix and cell–cell adhesions in cardiac muscle

“…In Day 1 and 4 μtissues, the cell-cell junction had a sigmoid-like contour, similar to yin-yang interfaces observed in migrating endothelial cells constrained to FN islands (17) and diagonal interfaces in patterned myocyte pairs (36). To quantify this, we measured junction geometry while varying μtissue length to width ratio (μLW) (Fig.…”