Heart disease is a staggering clinical and public health problem and the leading cause of death for both men and women in Western countries. The underlying pathomechanism of nearly all aetiologies relates to altered contractility and cardiac tissue tension but also gene expression changes and epigenomic remodelling. Within the sarcomere, the fundamental contractile unit in striated muscle, the giant protein titin is the major source of cardiac passive tension. Since sarcomeres are connected to the nucleus, I hypothesise that titin passive tension is transmitted to the nucleus and sensed by the mechano-sensitive nuclear lamina, affecting chromatin structure and gene expression, similar to cytoskeleton passive tension in nonmuscle cells. I will test this hypothesis in human cardiomyocytes derived from induced pluripotent stem cells (hiPSC-CMs) with either a low or high titin-derived passive tension by editing the titin gene locus. I will also investigate whether changes of titin tension affect sarcomere-resident chromatin remodellers: Smyd1, Smyd2, and HP1γ. Combining fluorescence and super-resolution imaging with chromatin-immunoprecipitation sequencing and RNA sequencing, I will delineate a comprehensive map of titin-derived epigenetic remodelling in hiPSC-CMs. The TiGER project will dissect a complex biophysical mechanism leveraging on hiPSC-CMs as they represent an exceptional platform to unveil human cardiac-specific phenomena that require extensive gene editing, culture, and imaging. As titin-derived passive tension changes during development, physiology, and disease, TiGER’s results could have major implications for cardiac pathophysiology and could unlock future compelling research avenues. I will explore this novel role for titin as an epigenetic remodeller under the supervision of Prof. Dr. Gotthardt, a world-leading expert of cardiac mechanotransduction and titin at the Max Delbrück Center (MDC) in Berlin.

Stem cells and organoids have revolutionized our ability to build tissues and organ-like structures ‘in a dish’. Organoid models of a wide range of human tissues are increasingly applied to drug and treatment development and to fundamental and translational studies. However, the challenge of simultaneously growing more than one different tissues in a single functional organoid remains. Human neuromuscular organoids (NMOs) represent a landmark discovery toward building more complex and physiologically relevant human tissues in vitro. NMOs closely capture the cellular repertoire and structural and functional properties of the neuromuscular system, but, similar to other organoids, they do not reach adult tissue stages of maturation, at least in part, due to lack of connectivity and in vivo-like sensory inputs, including bioelectrical cues, essential in physiological phenomena. In a multi-disciplinary approach, the eNeuroMus project aims to test the hypothesis that delivery of brain-like input, currently excluded from NMO models, will enhance the complexity and maturation status of NMOs toward adult tissue stages. To this end, NMOs will be interfaced with conformable multielectrode arrays, based on organic conducting polymers, to expose NMOs to brain-like input via electrical stimulation and to record NMO electrophysiological activity in a growth stage-dependent manner. To decipher the effects of electrical stimulation on tissue maturation, electrophysiology assays will be combined with cutting-edge technologies, including spatial transcriptomics, optogenetics and advanced imaging. This analysis pipeline will result in a rich dataset, unravelling the long-term effects of electrical stimulation and the molecular pathways involved in the maturation of human neuromuscular organoids. Overall, the eNeuroMus project will deliver a novel and sophisticated framework for engineering the next generation of biohybrid organoids as tools for modelling human development and disease.