Development of a Human Induced Pluripotent Stem Cell Derived Myocardium on a Chip and Its Use to Diagnose and Treat Ischemic Reperfusion Injury in Cardiovascular Disease

Cardiovascular diseases (CVD) have been the leading cause of death in the developed world for nearly 100 years, responsible for nearly 18 million deaths yearly, more deaths than all forms of cancer combined. The majority of CVD related deaths are due to myocardial infarction (MI). Additionally, the only viable long-term solution for undiagnosed MIs and the remaining CVDs is heart transplant, in which nearly 70% of potential donor organs are deemed unusable. The major mechanism of damage for both MI as well as that which occurs during organ procurement and transplantation is ischemic/reperfusion injury (I/R). Due to an extreme limit on viable human hearts available for transplant, let alone research, the use of animal models has become a common alternative for CVD study. Unfortunately, due to differences in human and animal physiology and pathology, results from such studies are often inconclusive or contradictive to one another.

In recent decades, tissue engineering has developed model tissues utilizing human derived cells to better mimic human physiology in vitro. This reduces species to species variability as well as ethical concerns regarding usage of clinically precious human organs. Several studies have utilized tissue engineered methods for studying human myocardium, however they have been restricted to specific characterization and/or pharmaceutical screening rather than recapitulating a physiologically relevant human heart tissue model. It is imperative that a physiologically relevant model is developed to better diagnose and treat CVD, specifically MI and heart transplant, as being able to accurately identify and understand the underlying mechanisms of I/R in human physiology is crucial for CVD treatment and prevention.

The main goal of this dissertation was to develop a high throughput physiologically relevant human derived myocardium tissue model to investigate novel diagnosis and treatment methods of I/R in both MI and heart transplantation. Towards this goal, we first developed a microfluidic human heart anoxia and reperfusion tissue (HEART) model using human induced pluripotent stem cell derived cardiomyocytes (iCMs) and endothelial cells (iECs) and observed that cells seeded in the HEART retained their canonical cell specific markers and functionality and were able to survive within the device for up to 7 days under flow giving physiological wall shear stresses. We then utilized the HEART to validate the therapeutic potential of adipose derived mesenchymal stem cell (ASC) secretome (ASC-S) in an organ transplant scenario. We showed that the detrimental effect of cardioplegic solution was mainly limited to iCMs, and the inclusion of ASC-S was able to ameliorate this via the oxidative stress pathway. Finally, we developed an in vitro MI model for the HEART and compared miRNA expression to MI patients using a near real-time miRNA concentration sensor, and observed that the HEART was able to closely mimic clinical miRNA expression through both the ischemic and reperfusion stages of MI. The novel HEART provides researchers with a modular and physiologically relevant in vitro tool for the development of novel diagnostic and therapeutic approaches to CVD.