With the discovery of induced pluripotent stem cell (iPSCs) a wide range of cell types, including iPSC-derived cardiomyocytes (iPSC-CM), can now be generated from an unlimited source of somatic cells. These iPSC-CM are used for different purposes such as disease modelling, drug discovery, cardiotoxicity testing and personalised medicine. The 2D iPSC-CM models have shown promising results, but they are known to be more immature compared to in vivo adult cardiomyocytes. Novel approaches to create 3D models with the possible addition of other (cardiac) cell types are being developed. This will not only improve the maturity of the cells, but also leads to more physiologically relevant models that more closely resemble the human heart. In this review, we focus on the progress in the modelling of inherited cardiac arrhythmias in both 2D and 3D and on the use of these models in therapy development and drug testing.

Introduction: Little is known about the use of bioelectrical impedance analysis (BIA) in critically ill patients. The objective of this study was to evaluate the reproducibility of BIA measurements by comparing non-dominant versus dominant body-side measurements at 2 separate time points in healthy volunteers in order to extrapolate key elements that may be of relevance in critically ill patients.Material and methods: A prospective observational validation experiment was carried out in healthy volunteers. Full-body and segmental multiple frequency BIA measurements were carried out at the non-dominant and the dominant body side, consecutively, and on 2 separate occasions within 1 week. Parameters of interest were both raw data (impedance and phase angle) at the individual frequencies (5–50–100–200 kHz) and body fluid compartment volume estimations (total body water, extracellular water volume, intracellular water volume, volume excess).Results: A total of 42 measurements were performed in 22 volunteers. Median (interquartile range) age and time between measurements was 26 years (24; 35) and 2.07 days (1.00; 2.99), respectively. The intraclass-correlation coefficients (ICCs) for body fluid compartment volumes estimated by full-body BIA, were greatly above 90%, showing excellent agreement, except for volume excess which showed moderate agreement. Full-body raw impedance and phase angle measurements showed highly variable and much lower ICCs. For both estimated body fluid compartment volumes and raw measurements, segmental BIA showed also highly variable and low ICCs.Conclusions: Overall this study showed that in healthy volunteers, BIA-derived fluid parameters are reproducible, and differences can be attributed to the changes in clinical status.