Vascularised Cardiac Spheroids-on-a-Chip for Testing the Toxicity of Therapeutics

Microfabricated organ-on-a-chip tissue models are rapidly becoming the gold standard for the testing of safety and efficacy of therapeutics. A broad range of designs has emerged, but recreating microvascularised tissue models remains difficult in many cases. This is particularly relevant to mimic the systemic delivery of therapeutics, to capture the complex multi-step processes associated with trans-endothelial migration, uptake by targeted tissues and associated metabolic response. In this report, we describe the formation of microvascularised cardiac tissue spheroids embedded in microfluidic chips. The embedding of spheroids within vascularised multi-compartment microfluidic chips was investigated to identify the importance of the spheroid processing, and co-culture with pericytes on the integration of the spheroid within the microvascular networks formed. The architecture of the resulting models, the expression of cardiac and endothelial markers and the perfusion of the system was then investigated. The ability to retain beating over prolonged periods of time was quantified, over a period of 25 days, demonstrating not only perfusability but also functional performance of the tissue model. Finally, as a proof-of-concept of therapeutic testing, the toxicity of one therapeutic associated with cardiac disfunction was evaluated, identifying differences between direct in vitro testing on suspended spheroids and vascularised models.