PROJECT SUMMARY Millions of people are affected by chronic conditions, and the number will continue to rise due to increased life expectancy. These diseases, including wet age-related macular degeneration (AMD), rely on frequent local injections for disease management. Frequent injections required for maximum therapeutic efficacy are associated with barriers to care including patient discomfort, high treatment costs, and risk of complications. There is a clinical need to reduce injection frequency while maintaining treatment efficacy for these chronic diseases to improve treatment outcomes and quality of life for these patients. The overall objective of this project is to develop a tunable, injectable, biodegradable microcapsule delivery device that has the potential to sustain release of therapeutics of varying molecular weights for at least 12 months. Theoretical modeling will be combined with in vitro and in vivo experimental studies to optimize the microcapsule system and predict therapeutic release. In Aim 1, microcapsule porosity will be modulated using two methods to tune therapeutic release. Release of therapeutics of varying molecular weights, including anti-VEGF (vascular endothelial growth factor) and triamcinolone acetonide (TA), will be evaluated at least 12 months. Therapeutic release rates and bioactivity will be assessed in vitro by evaluating samples using ELISA, Ultra Performance Liquid Chromatography (UPLC), endothelial cell tube formation assays, and inhibition of inflammatory markers in retinal cells. An in silico model for drug release dependent on porosity and drug size will be refined. In Aim 2, microcapsule outer polymer layer thickness will be modulated to tune therapeutic release. Long-term release rates and bioactivity of anti-VEGF and TA will be evaluated in vitro. The in silico model will be refined and validated for drug release dependent on capsule layer thickness. In Aim 3, microcapsule biocompatibility and pharmacokinetic distribution of the therapeutics will be evaluated in vivo. The microcapsule will first be evaluated for 1 month for short-term biocompatibility. Then, fluorescently labeled therapeutics will be loaded into optimized microcapsules and compared to blank capsules and therapeutic only controls for 12 months. Fluorophotometry will be used to quantitatively assess therapeutic concentrations released over time and will be compared to assays conducted on extracted ocular tissues at study termination. Results will be compared to published studies for effective therapeutic concentrations. This study will also provide 12 month in vivo safety data. The in silico model will be refined to include measurements of therapeutic concentrations in the vitreous and retina to predict in vivo distribution coupled to drug release from a capsule. Additionally, a computational tool will be developed for optimizing capsule layer thickness and porosity for specified release duration, pharmacokinetic tissue distribution, a...