PhD Candidate University Medical Center Goettingen Göttingen, Germany
Abstract: Takotsubo syndrome (TTS), also known as stress-induced cardiomyopathy, is characterized by acute left ventricular dysfunction, typically occurring in the absence of stenosis. Since a dysregulated central autonomic nervous system leading to excessive sympathetic stimulation is believed to play a role in the condition, TTS can be described as brain-heart syndrome. In previous studies, significantly elevated catecholamine levels in patients experiencing acute TTS were reported. Further, our previous research identified increased sensitivity to catecholamine-induced stress toxicity and a genetic predisposition in TTS using a TTS induced pluripotent stem cell (iPSC) cardiomyocytes (CM) model. This study aims to investigate whether iPSC-derived TTS sympathetic neurons (SN) influence iPSC-CM and whether they contribute to the development of TTS.
First, we established a 3-step protocol, including neuronal progenitor aggregates and 2D monolayer stages, based on Kirino et al. 2018. SN were generated from TTS-iPSC-lines harboring different genetic variants (e.g. AHNAK mutations). Immunohistochemical and transcript analyses proved the commitment to SN by increasing levels of PHOX2B, TH, and DBH while flow cytometry of 25-day-old cultures indicated ~80% of the population as autonomic progenitors. Finally, spontaneous and KCl-inducible noradrenaline release proved SN functionality. TTS-lines secrete more noradrenaline than wild-type or AHNAK-rescue lines. However, SN differentiation capacity needs to be further quantified. In the next step, we co-cultured SN and CM and observed higher beating frequency compared to CM monoculture, indicating basal stimulation of CMs by functional SN. Functional connectivity of SN and CM was further validated by an increased beating rate after nicotine stimulation of SN.
Overall, we developed an efficient protocol for differentiating functional iPSC-derived sympathetic neurons, enabling their co-culture with TTS-iPSC-cardiomyocytes to validate their functional interactions. Investigating the influence of TTS genetic predisposition on SN alongside CM is essential for identifying potential therapeutic targets for TTS. In the future, using a mix-and-match strategy, the impact of TTS-related neuronal mutations on the cardiac phenotype will be investigated.
