Beating organs-on-chips as advanced preclinical tools for drug screening and disease modelling

Introduction Organs-on-Chip (OoC) have recently emerged as innovative in vitro tools holding the potential to improve prediction over human drug responses. Bringing into OoC models the entire complexity of native human tissue microenvironmental cues is still not trivial. Here we present new beating OoC, advanced miniaturized platforms integrating the native-like 3D mechanical microenvironment with an unprecedented level of precision. Device concept and Experimental procedure Our technology, uBeat, provides cells culture in 3D with highly controlled and tunable mechanical stimulation patterns. Relying on specific geometrical structures that modulate mechanical deformation exerted on 3D microtissues, uBeat allows achieving either uniaxial strain or confined compression. Based on uBeat, we developed two platforms: i) uHeart, a beating heart-on-chip integrating real-time electrophysiological measurements, and ii) uKnee, the first in vitro model of human osteoarthritic (OA) cartilage on chip. uHeart provides 3D human cardiac microtissues with a physiological cyclic uniaxial strain (i.e. 10%, 1Hz). Cardiomyocytes from human induced pluripotent stem cells (hiPSC-CMs) and human dermal fibroblast embedded in fibrin hydrogel and cultured within uHeart developed in synchronously beating and functional cardiac microtissues. This was demonstrated by electrophysiology studies conducted directly on-chip enabling the continuous monitoring of constructs’ electrical activity. uKnee provides 3D cartilage-like constructs with hyper-physiological (HP) compression (i.e. 30%, 1 Hz), sufficient to elicit OA pathogenesis in vitro. Upon generation of healthy cartilage microconstructs from human articular chondrocytes embedded in a poly(ethylene-glycol)-based hydrogel, HP compression was exploited to induce OA-like traits. HP stimulated constructs showed a shift in cartilage homeostasis towards catabolism, inflammation and hypertrophy, and the acquisition of a gene expression profile compatible with clinical evidences of OA. Both models were successfully exploited for drug screening purposes, by testing the effect of both well-known drugs and compounds under development. Conclusion Integration of specific 3D mechanical microenvironment resulted in OoC models with improved functionality and enhanced resemblance to pathological states. uBeat technology is highly versatile, being applicable to any organ/disease in which mechanical stimulation exerts a pathophysiological state. The proposed beating OoC thus represent new powerful and reliable preclinical tools for efficient in vitro drug screening and disease modelling. Acknowledgments Device manufacturing was partially performed at PoliFAB (Politecnico di Milano). This work was partially funded by MSCA IF (Grant #841975), SNF (Grant#310030_175660) and Cariplo Foundation (Grant#2018-0551).