Organ-on-a-chip technology: turning its potential for clinical benefit into reality

•Organ-on-a-chip technology has the potential to improve the success of drug discovery.•Environmental cues and inter-organ communication increase physiological relevance.•Organotypic effects depend on model composition and on chip sensing technology.•The gain of confidence for human translation of ‘on-chip’ effects is emerging.•Multi-disciplinary networks are driving the evolution of organ-on-a-chip approaches.