Micro-electrode channel guide (µECG) technology: an online method for continuous electrical recording in a human beating heart-on-chip.

Cardiac toxicity still represents a common adverse outcome causing drug attrition and post-marketing withdrawal. The development of relevantin vitromodels resembling the human heart recently opened the path towards a more accurate detection of drug-induced human cardiac toxicity early in the drug development process. Organs-on-chip have been proposed as promising tools to recapitulatein vitrothe key aspects of thein vivocardiac physiology and to provide a means to directly analyze functional readouts. In this scenario, a new device capable of continuous monitoring of electrophysiological signals from functionalin vitrohuman hearts-on-chip is here presented. The development of cardiac microtissues was achieved through a recently published method to control the mechanical environment, while the introduction of a technology consisting in micro-electrode coaxial guides allowed to conduct direct and non-destructive electrophysiology studies. The generated human cardiac microtissues exhibited synchronous spontaneous beating, as demonstrated by multi-point and continuous acquisition of cardiac field potential, and expression of relevant genes encoding for cardiac ion-channels. A proof-of-concept pharmacological validation on three drugs proved the proposed model to potentially be a powerful tool to evaluate functional cardiac toxicity.

Engineering an Environment for the Study of Fibrosis: A 3D Human Muscle Model with Endothelium Specificity and Endomysium.

The integration of vascular structures into in vitro cultured tissues provides realistic models of complex tissue-vascular interactions. Despite the incidence and impact of muscle-wasting disorders, advanced in vitro systems are still far from recapitulating the environmental complexity of skeletal muscle. Our model comprises differentiated human muscle fibers enveloped by a sheath of human muscle-derived fibroblasts and supported by a vascular network with mural-like cells. Here, we demonstrate the induction of muscle-specific endothelium and the self-organization of endomysial muscle fibroblasts mediated by endothelial cells. We use this model to mimic the fibrotic environment characterizing muscular dystrophies and to highlight key signatures of fibrosis that are neglected or underestimated in traditional 2D monocultures. Overall, this vascularized meso-scale cellular construct finely recapitulates the human skeletal muscle environment and provides an advanced solution for in vitro studies of muscle physiology and pathology.

Structural analysis and ion translocation mechanisms of the muscle-type acetylcholine receptor channel.

PURPOSE: The aim of this work is to analyze the conformational changes in the acetylcholine receptor caused by channel opening and to investigate the electrostatic profile during ion translocation through the channel. METHODS: A computational model of the human muscle-type acetylcholine receptor (AChR) was built and used to analyze channel structure and its interactions with different ions. Using the Torpedo AChR crystal structure as a homologous template, the 3D structure of the human muscle-type AChR was reconstructed. RESULTS: This first model is optimized and an open structure of the channel is generated using Normal Mode Analysis in order to assess morphologic and energetic differences between open and closed structures. In addition, the issue of ion translocation is investigated in further detail. Results elucidate different aspects of the channel: channel gate structure, channel interactions with translocating ions, differences between muscle-type AChR and previous neuronal-type AChR models. CONCLUSIONS: The model constructed here is ideal for further computational studies on muscle-type AChR and its pathologic mutations.