Biology subjects

Maione, A. S.

Publications and source records attributed to Maione, A. S..

3 recordsLinked to original sources

bioRxiv2025

Cellular consequences of non-ablative radiotherapy, a novel approach to ventricular tachycardias

BackgroundRadiotherapy (RT) with a single focused application of ionizing radiation (STAR) has been suggested as a non-invasive alternative to radiofrequency in ablating ventricular tachycardia (VT). Emerging data reveal that STAR may suppress VT without substrate destruction, by enhancing impulse conduction instead, through increased expression of NaV1.5 channels and connexin 43. AimsTo investigate electrophysiology and intracellular Ca2+ dynamics in cardiomyocytes (CMs) from mice subjected to in-vivo RT. The emerging data led us to evaluate biochemical changes potentially linking electrophysiological response to ionizing irradiation. MethodsCMs isolated 2 weeks after RT with low-dose (15 Gy) or high-dose (25 Gy) were compared to those of sham-treated mice (CTRL). We evaluated: i) INaT and INasus properties; ii) AP parameters, including the prevalence of Early After-Depolarizations (EADs); iii) intracellular Ca2+ dynamics; iv) CaMKII phosphorylation and v) ROS content. Results25 Gy RT i) increased INaT and, to a larger extent, INasus (increased INasus/INaT ratio); ii) increased AP amplitude, +dV/dtmax and duration (APD) and facilitated EADs; iii) depressed intracellular Ca2+ dynamics. 15 Gy RT had similar but smaller effects (dose-dependency). 25 Gy RT reduced CaMKII phosphorylation but increased cell ROS content, thus providing a mechanism for INaL enhancement. ConclusionsThe results support the view that STAR may supress VT by increasing conduction velocity, with APD prolongation providing an additional mechanism. On the other hand, INasus enhancement (likely by ROS) and Ca2+ handling depression may impair electrical stability and contractility in the irradiated region.

physiology↗

bioRxiv2024

An iPSC-derived bio-inspired scaffold modelling the structure and the effects of extracellular matrix in cardiac fibrosis

Cardiac fibrosis occurs following insults to the myocardium and is characterized by the abnormal accumulation of non-compliant extracellular matrix (ECM), which compromises cardiomyocyte contractile activity and eventually leads to heart failure. This phenomenon is driven by the differentiation of cardiac fibroblasts (cFbs) into myofibroblasts and results in changes in ECM biochemical, structural and mechanical properties. The lack of predictive in vitro models of heart fibrosis has so far hampered the search for innovative treatments. Here, we devised a single-step decellularization protocol to obtain and thoroughly characterize the biochemical and micro-mechanical properties of the ECM secreted by activated cFbs differentiated from human induced pluripotent stem cells (iPSCs). We activated iPSC-derived cFbs to the myofibroblast phenotype by tuning basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-{beta}1) signalling and confirmed that activated cells acquired key features of myofibroblast phenotype, like SMAD2/3 nuclear shuttling, the formation of aligned alpha-smooth muscle actin (-SMA)-rich stress fibres and increased focal adhesions (FAs) assembly. Next, we used Mass Spectrometry, nanoindentation, scanning electron and confocal microscopy to unveil the characteristic composition and the visco-elastic properties of the abundant, collagen-rich ECM deposited by cardiac myofibroblasts in vitro. Finally, we demonstrated that the fibrotic ECM activates mechanosensitive pathways in iPSC-derived cardiomyocytes, impacting on their shape, sarcomere alignment, phenotype, and calcium handling properties. We thus propose human bio-inspired decellularized matrices as animal-free, isogenic cardiomyocyte culture substrates recapitulating key pathophysiological changes occurring at the cellular level during cardiac fibrosis.

cell biology↗

bioRxiv2023

Early consequences of the phospholamban mutation PLN-R14del+/- in a transgenic mouse model

AimsThe heterozygous phospholamban (PLN) mutation R14del (PLN R14del+/-) is associated with a severe arrhythmogenic cardiomyopathy (ACM) developing in the adult. "Superinhibition" of SERCA2a by PLN R14del is widely assumed to underlie the pathogenesis, but alternative mechanisms such abnormal energy metabolism have also been reported. This work aims to 1) to evaluate Ca2+ dynamics and energy metabolism in a transgenic (TG) mouse model of the mutation prior to cardiomyopathy development; 2) to test whether they are causally connected. Methods and ResultsCa2+ dynamics, energy metabolism parameters, reporters of mitochondrial integrity, energy and redox homeostasis were measured in ventricular myocytes of 8-12 weeks-old, phenotypically silent, TG mice. Mutation effects were compared to pharmacological PLN antagonism and analysed during modulation of sarcoplasmic reticulum (SR) and cytosolic Ca2+ compartments. Transcripts and proteins of relevant signalling pathways were evaluated. The mutation was characterized by hyperdynamic Ca2+ handling, similar to that induced by PLN antagonism. Albeit all components of energy metabolism were depressed at rest, functional signs of mitochondrial damage or energy starvation were absent and cell energy charge was preserved. The response of mitochondrial O2 consumption to SERCA2a blockade was lost in mutant myocytes (SR-mitochondrial uncoupling) and ER-stress signalling was activated. Conclusions1) PLN R14del+/- loses its ability to inhibit SERCA2a, which argues against SERCA2a superinhibition as a mechanism of ACM; 2) depression of resting energy metabolism may at least partly reflect impairment of SR-mitochondrial coupling; 3) ER-stress may be an early factor in the pathogenesis.

physiology↗