Despite continuous advances in studying human diseases and drug screening methodology, only a small fraction of drug candidates achieve approval for clinical use due to the lack of efficacy and/or adverse effects. A major challenge in studying human diseases and in identifying drug candidates that target these diseases, is the lack of an effective model that captures different aspects of human physiology. Studies are still heavily reliant on monolayer cell cultures or on animal models, neither of which can fully recapitulate the human body and its disease stages. Microphysiological systems/organs-on-a-chip (MPS/OOC) are designed to bridge the gap between monolayer cell culture and animal models. This body of research aims to develop novel MPS/OOC supported by a true living human vasculature to mimic human organ functions, model human diseases, and utilize these platforms to advance drug discovery and development.