Study of calcium dynamics in hiPSC-derived cardiomyocytes

Tiivistelmä – Referat – Abstract Cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs) provide a good model to study their function in human context. The hiPSC technology allows to create patient-specific cell lines. The cell lines can further be differentiated into any cell type retaining the same genetic information as the donor. Heart diseases such as Long QT syndrome (LQTS) and Non-compaction cardiomyopathy are caused due to mutations in ion channels in cardiac cells. The genetic abnormalities in these channels can cause life threatening arrhythmias. However, the diseases remain undiagnosed until later stage of the disease and the first sign could be sudden cardiac death. Hence, understanding the disease mechanism at a cellular level is crucial. The aim of the thesis is to study the functionality of cardiomyocytes from patient specific cells to analyse if the clinical representation of the diseases can be seen at the cellular level. An additional aim is to compare and study the Ca2+ transients in patient-derived and control cells. One way to study the functionality of cardiomyocytes is by Ca2+ imaging. The method involves live cell imaging of differentiated cardiomyocytes using fluorescent dyes (Fluo4 AM and Cal520). The Ca2+ transients of diseases such as LQTS and non-compaction cardiomyopathy are recorded and further analysed by Clampfit software. The main findings of this study include a) different Ca2+ dyes (Cal520 and Fluo4) had different profiles in control cardiomyocytes b) a significantly different profiles were observed between the SCN5A-mutant and control cardiomyocytes c) the effect of adrenaline was most significant at low doses and when exposed for a short time; prolonged exposure to adrenaline leads to adrenaline receptor desensitization. Moreover, different types of arrhythmias have been detected in cell lines such as oscillations, plateau abnormality, multiple peaks etc. In conclusion, detection of Ca2+ transients may be an indicator of heart diseases due to genetic mutations which will further help in taking preventive measures