Browsing by Subject "hypertrophy"
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(2024)Congenital heart diseases develop during heart development and encompass structural abnormalities in the heart present at birth, with hypoplastic left heart syndrome (HLHS) representing a rare but life-threatening subtype. HLHS is characterised by the underdevelopment of left-sided heart structures, resulting in a major blood flow obstruction of the heart, impairing systemic circulation. Current knowledge of HLHS aetiology is scarce, which makes the development of effective treatments challenging. Therefore, identifying the disease mechanisms causing HLHS is essential. Notably, HLHS is linked with mutations in the NKX2-5 gene, which encodes for a cardiac transcription factor and has a pivotal role in heart development together with the transcription factor GATA4. This makes these genes intriguing research targets in HLHS. This study aims to enlighten how HLHS patient-derived human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) differ from those derived from healthy donors in terms of stress response by subjecting hiPSC-CMs to pro-hypertrophic stimuli, namely endothelin-1 (ET-1) and cyclic mechanical stretching. Additionally, the effects of GATA4-targeted compounds on these hypertrophy models were also studied, which included two inhibitors (3i-1262 and 3i-1000) and one activator (3i-0777) of GATA4-NKX2-5 interaction. Differentiation of CMs was performed using a small-molecule induction protocol based on sequential Wnt pathway activation and inhibition. The effects of ET-1 and cyclic mechanical stretching were analysed by High-content analysis for pro-B-type natriuretic peptide (proBNP) expression, and quantitative PCR for hypertrophic gene expression, respectively. Both ET-1 and cyclic mechanical stretching effectively induced hypertrophy in their respective models. This was observed in all cell lines as a higher hypertrophic response of proBNP in ET-1 exposed hiPSC-CMs and upregulation of hypertrophic genes NPPA and NPPB in stretched hiPSC-CMs. GATA4-targeted compounds did not show statistically significant effects on ET-1-induced hypertrophy or stretching-induced hypertrophic gene expression in any cell line, but various trends could be distinguished. As expected, both inhibitor compounds, 3i-1262 and 3i-1000, showed a tendency for antihypertrophic effects since they decreased the percentage of proBNP+ cells in all cell lines. Unexpectedly, the activator compound 3i-0777 also decreased the percentage of proBNP+ cells. We also observed that HLHS-disease cell line HEL 149 seemed to differ from the three other cell lines showing a phenotype that exhibits similar gene expression patterns as seen in heart failure patients. This was mainly observed as a statistically significantly lower basal MYH6 gene expression. However, the limited experimental setup of this study requires further experiments to detect significant differences and draw definitive conclusions regarding the effects of GATA4-targeted compounds on hypertrophic stimuli.
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(2023)Heart failure is a global health issue that can result from various factors, one of which is myocardial infarction. The adult human heart has limited regenerative capacity to cover the loss of cardiomyocytes after myocardial infarction with new cardiomyocytes. The main responses to the loss of cardiomyocytes are fibrotic scar formation and the hypertrophy of remaining cardiomyocytes. Prolonged hypertrophy eventually leads to heart failure. Current treatments for heart failure only relieve the symptoms. Inducing cardiac regeneration could be one possible way to prevent and treat heart failure. Thus, to develop medical treatments that enhance the regenerative capacity, a comprehensive understanding of precise cellular mechanisms behind heart regeneration is crucial. The objective of this study was to establish a high-content analysis method for human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) utilizing the Cell Painting assay to identify and categorize morphological alterations induced by various compounds in hiPSC-CMs. To evaluate the morphological impacts, dozens or even hundreds of cell features were measured at the same time. hiPSC-CMs were exposed to two hypertrophy inducers, endothelin-1 and angiotensin II, and to doxorubicin, which is known to be a cardiotoxic compound. In addition, the effects of a GATA4- targeting compound, C-2021, on hiPSC-CMs were examined. C-2021, was expected to have antihypertrophic effect on the cells. Previously used methods, proBNP staining and qPCR, were used to validate the novel method. According to proBNP staining and qPCR, endothelin-1 induced cardiomyocyte hypertrophy greater than angiotensin II. Compound C-2021 did not show statistically significant antihypertrophic properties after hypertrophic stimuli, but some tendency the alleviate the hypertrophy was noticed. Moreover, by utilizing different data processing programs a novel analysis method was developed. With this method, the different treatment groups were clustered based on the morphological alterations caused by compounds exposures. The hiPSC-CMs exposed to endothelin-1, angiotensin II or doxorubicin showed a different morphological profile compared to the control group hiPSC-CMs. Compound C-2021 was also observed to affect cell morphology. However, the data analysis still needs improvements in order to detect which cell features these compounds affect.
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