Abstract
Background: Arrhythmogenic Cardiomyopathy (ACM) is a multifactorial genetic heart disease characterized by the progressive loss of the myocardium and its substitution with fibro-fatty tissue. In the worst case, this compromised state can lead to a patient's sudden cardiac death, but there is a variety of different outcomes depending on the patient genetic background, disease severity and penetrance. Emerging evidence about the involvement of Cardiac Stromal Cells (CStC) points to an active role of mitochondria in ACM pathogenesis (Lippi et al. 2023, Volani et al. 2022, van Opbergen et al. 2019). Thus, the current project employs primary CStC from several patients (ACM) and healthy donors (CTRL) to unravel whether mitochondrial function is altered and how that is linked to disease etiology and progression.
Methods: CStC were cultured either in basal medium (BM) or adipogenic medium (AM), a stressor needed to unmask the ACM phenotype. Mitochondrial-related analyses, such as ultrastructure, membrane potential, network connection, respiratory capacity, redox status and electron transport chain (ETC) proteins, were performed at day (d) 0 in BM and at d3, d7, d15 after AM.
Results: Mitochondria appear visually healthy in ACM and CTRL both in BM and AM, with no variation in mitochondrial membrane potential, fusion/fission mechanisms, mitochondrial density, and ETC protein expression. Despite that, mitochondrial network is more fragmented in ACM compared to CTRL in BM, possibly explaining the observation of a decreased mitochondrial respiratory capacity. Interestingly, mitochondrial respiratory capacity significantly increases in ACM compared to CTRL after 7 days of AM; the latter could relate to the augmented presence of intracellular lipids in ACM. Finally, preliminary analysis of ROS revealed no major differences in BM, although it suggests cellular redox remodelling at d3 of AM.
Conclusion: This is the first study that performed a comprehensive analysis of mitochondrial morphology, dynamics, function and redox status in primary cardiac stromal cells from human subjects with different genetic backgrounds to provide evidence for mitochondrial changes as co-factors in the disease progression.
Funding Acknowledgments: Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This research was funded by the Department of Innovation, Research and University of the Autonomous Province of Bolzano-South Tyrol (Italy), and by the Joint Project Südtirol- FWF (Italy-Austria).