BIODEGRADABLE HYDROGELS PRESENTING A GRADIENT OF siRNA FOR SPATIAL CONTROL OF CELL GENE EXPRESSION by MICHAEL CHRISTOPHER HILL

1 Chapter 1: Introduction 2 1.1. Overview 2 1.2. Hypothesis and Specific Aims 7 Chapter 2: Background 9 2.1. Importance of Gradients in Tissue Engineering 9 2.1.1. Morphogen gradients 9 2.1.2. Bone/cartilage interface 14 2.1.3. Bone /ligament and bone/tendon interfaces 18 2.2. RNA Interference and siRNA Delivery 22 2.2.1. Overview of RNA interference 22 2.2.2. Applications of siRNA in tissue engineering and regenerative medicine 25 2.2.3. Implications of siRNA gradients 27 Chapter 3: Materials and Methods 30 3.1. Synthesis of DEX-HEMA 30 3.2. Preparation of siRNA nanoparticles 33 3.3. Bioactivity evaluation of siRNA nanoparticle formulation 36 3.4. Fabrication of DEX-HEMA gradient hydrogels 37 3.5. Quantification of siRNA gradient 40 3.6. Release kinetics of siRNA from gradient hydrogels 42 3.7. Hydrogel swelling and degradation 43