4-(5-benzo(1-3)dioxol-5-yl-4-pyridin-2-yl-1h-imidazol-2-yl)benzamide and Heart-Failure

We have created a novel in-vitro platform to study reverse remodeling of engineered heart tissue (EHT) after mechanical unloading. EHTs were created by seeding decellularized porcine myocardial sections with a mixture of primary neonatal rat ventricular myocytes and cardiac fibroblasts. Each end of the ribbon-like constructs was fixed to a plastic clip, allowing the tissues to be statically stretched or slackened. Inelastic deformation was introduced by stretching tissues by 20% of their original length. EHTs were subsequently unloaded by returning tissues to their original, shorter length. Mechanical characterization of EHTs immediately after unloading and at subsequent time points confirmed the presence of a reverse-remodeling process, through which stress-free tissue length was increased after chronic stretch but gradually decreased back to its original value within 9 days. When a cardiac myosin inhibitor was applied to tissues after unloading, EHTs failed to completely recover their passive and active mechanical properties, suggesting a role for actomyosin contraction in reverse remodeling. Selectively inhibiting cardiomyocyte contraction or fibroblast activity after mechanical unloading showed that contractile activity of both cell types was required to achieve full remodeling. Similar tests with EHTs formed from human induced pluripotent stem cell-derived cardiomyocytes also showed reverse remodeling that was enhanced when treated with omecamtiv mecarbil, a myosin activator. These experiments suggest essential roles for active sarcomeric contraction and fibroblast activity in reverse remodeling of myocardium after mechanical unloading. Our findings provide a mechanistic rationale for designing potential therapies to encourage reverse remodeling in patient hearts.

Topics: Actomyosin; Animals; Animals, Newborn; Benzamides; Benzylamines; Cardiac Myosins; Cell Line; Dioxoles; Heart Failure; Humans; Induced Pluripotent Stem Cells; Myocardial Contraction; Myocardium; Myocytes, Cardiac; Myofibroblasts; Rats; Rats, Sprague-Dawley; Receptor, Transforming Growth Factor-beta Type I; Sarcomeres; Signal Transduction; Swine; Tissue Engineering; Tissue Scaffolds; Uracil; Urea; Ventricular Remodeling

Cytokine-like 1 (Cytl1) is a secreted protein that is involved in diverse biological processes. A comparative modeling study indicated that Cytl1 is structurally and functionally similar to monocyte chemoattractant protein 1 (MCP-1). As MCP-1 plays an important role in cardiac fibrosis (CF) and heart failure (HF), we investigated the role of Cytl1 in a mouse model of CF and HF. Cytl1 was upregulated in the failing mouse heart. Pressure overload-induced CF was significantly attenuated in cytl1 knock-out (KO) mice compared to that from wild-type (WT) mice. By contrast, adeno-associated virus (AAV)-mediated overexpression of cytl1 alone led to the development of CF in vivo. The endothelial-mesenchymal transition (EndMT) and the transdifferentiation of fibroblasts (FBs) to myofibroblasts (MFBs) have been suggested to contribute considerably to CF. Adenovirus-mediated overexpression of cytl1 was sufficient to induce these two critical CF-related processes in vitro, which were completely abrogated by co-treatment with SB-431542, an antagonist of TGF-β receptor 1. Cytl1 induced the expression of TGF-β2 both in vivo and in vitro. Antagonizing the receptor for MCP-1, C-C chemokine receptor type 2 (CCR2), with CAS 445479-97-0 did not block the pro-fibrotic activity of Cytl1 in vitro. Collectively, our data suggest that Cytl1 plays an essential role in CF likely through activating the TGF-β-SMAD signaling pathway. Although the receptor for Cyt1l remains to be identified, Cytl1 provides a novel platform for the development of anti-CF therapies.

Topics: Animals; Aorta; Benzamides; Cell Transdifferentiation; Constriction, Pathologic; Dioxoles; Disease Models, Animal; Endomyocardial Fibrosis; Fibroblasts; Gene Expression Regulation; Heart Failure; Humans; Male; Mice; Mice, Knockout; Myocardial Infarction; Myocardial Reperfusion Injury; Myofibroblasts; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptors, CCR2; Receptors, Cytokine; Receptors, Transforming Growth Factor beta; Signal Transduction; Smad Proteins; Transforming Growth Factor beta2