Establishing how contraction modulates fibrotic remodelling and ECM homeostasis

The pathophysiology of heart failure is highly complex and different risk factors including inflammation, high blood pressure, myocardial infarction and diabetes contribute to disease development and progression. Despite different aetiologies, fibrosis is a common feature in >90% of heart failure patients, marked by excessive production of extracellular matrix (ECM) proteins. Presumably, the ECM remodelling negatively impacts the ability of the heart to contract and relax. In our lab we make use of human cardiac organoids (hCOs), a live contracting 3D model incorporating many important heart cells, including cardiomyocytes and fibroblasts. We can stimulate these organoids with profibrotic mediators to investigate how they influence gene and protein expression, signalling and cardiac function. For this project, we are interested in how cardiac contraction interacts with pro-fibrotic signalling. Preliminary results have shown that different pro-fibrotic stimuli induce functional changes within 1 hour of treatment, well before ECM remodelling occurs. It is unknown how these processes are linked. As an extension of this idea, we are interested in whether functional unloading (reducing contractility) can reverse ECM remodelling in the hCOs. Mechanical unloading in heart failure patients using a left ventricular assist device has been found to allow for some level of tissue remodelling. However, little is known about the mechanisms driving this response.

This project has 2 aims:

• to assess if cardiac dysfunction induced by profibrotic mediators contributes to the fibrotic ECM phenotype.
• to model the functional unloading response in the hCOs using contraction inhibitors to assess ECM remodelling.

This project will use human cardiac organoids to model the fibrotic ECM response following treatment with profibrotic stimuli. Contraction inhibitors will be used to interfere with hCO function after which functional and immunofluorescent protein detection analysis (using light and fluorescence microscopy) will be used to gain insights into the ECM remodelling.

There are many unknowns about the development of cardiac fibrosis and how ECM remodelling is regulated. This project will help us better understand the fundamental regulators of cardiac fibrosis. This knowledge could aid the identification of therapeutic targets and future development of antifibrotic therapies.