UCLA

The goal of this work is to understand the role of the microenvironment on cardiovascular differentiation. I sought to investigate the role of extracellular matrix (ECM) proteins on early cardiovascular differentiation and specifically the role of ECM proteins and three-dimensional (3D) environment using an engineered scaffold that mimics the cardiovascular progenitor cell (CPC) niche. Chapter one provides background and outlines the significance of this work. Chapter two describes the development of a 3D scaffold used for later studies. I examined the role of a 3D hydrogel on the induction of CPCs from murine embryonic stem (mES) cells and characterized integrin expression in both undifferentiated and partially differentiated mES cells. These results show that the addition of a 3D element in the microenvironment significantly increases the amount of CPCs induced from mES cells. Chapter three investigates the role of the microenvironment on cell fate commitment of CPCs. This work demonstrates the effects of both ECM proteins and the addition of a 3D scaffold to CPC culture on both vascular endothelial cell and smooth muscle cell differentiation. I also developed a method to create CPC-derived layered tissue engineered vascular grafts. Chapter four extends this work into a human induced pluripotent stem (hiPS) cell model. I show the effects of the microenvironment do influence cardiac differentiation in a human model, but with differing results from the mouse studies. I also show that the addition of fibronectin in 3D scaffold can greatly enhance vascular differentiation, and that cardiac differentiation is time sensitive.

This works provides insight into the role of the microenvironment on cardiovascular differentiation in both mouse and human stem cell models, introduces a method to create layered tissue engineered vascular grafts, and raises new questions and directions for future work in the area of cardiovascular tissue engineering and cardiovascular differentiation.