Stress-induced premature senescence is associated with a prolonged QT interval and recapitulates features of cardiac aging

Abstract

Rationale: Aging in the heart is a gradual process, involving continuous changes in cardiovascular cells, including cardiomyocytes (CMs), namely cellular senescence. These changes finally lead to adverse organ remodeling and resulting in heart failure. This study exploits CMs from human induced pluripotent stem cells (iCMs) as a tool to model and characterize mechanisms involved in aging. Methods and Results: Human somatic cells were reprogrammed into human induced pluripotent stem cells and subsequently differentiated in iCMs. A senescent-like phenotype (SenCMs) was induced by short exposure (3 hours) to doxorubicin (Dox) at the sub-lethal concentration of 0.2 µM. Dox treatment induced expression of cyclin-dependent kinase inhibitors p21 and p16, and increased positivity to senescence-associated beta-galactosidase when compared to untreated iCMs. SenCMs showed increased oxidative stress, alteration in mitochondrial morphology and depolarized mitochondrial membrane potential, which resulted in decreased ATP production. Functionally, when compared to iCMs, SenCMs showed, prolonged multicellular QTc and single cell APD, with increased APD variability and delayed afterdepolarizations (DADs) incidence, two well-known arrhythmogenic indexes. These effects were largely ascribable to augmented late sodium current (I NaL ) and reduced delayed rectifier potassium current (Ikr). Moreover sarcoplasmic reticulum (SR) Ca 2+ content was reduced because of downregulated SERCA2 and increased RyR2-mediated Ca 2+ leak. Electrical and intracellular Ca 2+ alterations were mostly justified by increased CaMKII activity in SenCMs. Finally, SenCMs phenotype was furtherly confirmed by analyzing physiological aging in CMs isolated from old mice in comparison to young ones. Conclusions: Overall, we showed that SenCMs recapitulate the phenotype of aged primary CMs in terms of senescence markers, electrical and Ca 2+ handling properties and metabolic features. Thus, Dox-induced SenCMs can be considered a novel in vitro platform to study aging mechanisms and to envision cardiac specific anti-aging approach in humans.

In need of age‐appropriate cardiac models: Impact of cell age on extracellular matrix therapy outcomes

“…On that note, we acknowledge that culturing cells for extended periods of time is not convenient regarding time and cost. As an alternative, DNA‐damaging agents, cardiotoxic drugs (i.e., doxorubicin) and oxidants (i.e., H 2 O 2 ) can be used to induce age‐independent premature senescence (SIPS), and mimic cardiac aging (Lazzarini et al, 2022). The use of SISP cells could offer an alternative in situations where invasive (i.e., patch clamp) or reseeding requiring (i.e., microelectrode array, MEA) qualitative methods are not suitable for advanced aged iCMs.…”

Priorities in Cardio-Oncology Basic and Translational Science

“… 35 , 36 Interestingly, cardiomyocytes also acquire the hallmarks of senescence when incubated with DOX, although almost all are postmitotic and, therefore, nonproliferating. 37 , 38 It is noteworthy that the concentrations of DOX that cause senescence in cardiac cell cultures are in the range of 50 to 500 nM, and DOX is detected at these levels in blood and tissues for most of the time after intravenous infusion. 39 , 40 By contrast, higher concentrations, which typically initiate apoptosis in vitro, correspond to the peak reached only shortly after intravenous administration.…”

“…For instance, growth differentiation factor 15 (GDF-15) is a SASP core protein and is synthesized by cardiomyocytes and endothelial cells undergoing senescence upon incubation with DOX and radiation, respectively. 38 , 47 In addition, GDF-15 concentrations increase in the months after DOX chemotherapy in women with breast cancer, 48 although the origin of GDF-15 is not yet clear.

Figure 1 SASP-Related Factors and Dox Cardiotoxicity Senescence-associated secretory phenotype (SASP)–related factors secreted by senescent cardiovascular cells can be measured in peripheral blood, and with further study, potentially can serve as biomarkers to select patients most likely to benefit from senescence-targeting interventions and to verify therapeutic efficacy.

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A new perspective on prostate cancer treatment: the interplay between cellular senescence and treatment resistance

“…In 1965, Hayflick’s discovery that normal human cells in culture have a limited capacity to divide, known as “Hayflick limit”, serves as a marker of cellular senescence, and the process is referred to as “replicative senescence” ( 33 ). Additionally, exposure to external stimuli such as reactive oxygen species (ROS) ( 34 ), DNA-damaging agents ( 35 ), or activated proto-oncogenes can induce stress-induced premature senescence (SIPS), resembling the senescent cell phenotype ( 36 , 37 ). Similarly, local ionizing radiation inflicts DNA damage in PCa cells, both directly and indirectly through increasing ROS, akin to chemotherapy effects ( 38 ).…”