Cystic fibrosis (CF) is a life-threatening, inherited chronic disease that affects the lungs and digestive system of 30,000 children and adults in the US [1]. Lung disease results from clogging of the airways due to mucus build-up, decreased mucociliary clearance, chronic inflammation and bacterial infection [2]. Pseudomonas aeruginosa is the main causative agent of morbidity and mortality in CF patients [3]. For the treatment of CF-associated infections, antibiotics represent the standard approach [3,4]. However, the efficacy of antibiotics is severely limited by dosing/delivery kinetics and multi-drug resistance, and many of the current antibiotics are ineffective in eradicating the bacteria once chronic infection is established [3-6]. Therefore, there is a significant and urgent need for the development of new strategies that can deliver payloads in a targeted fashion to eradicate bacterial infections in the CF lung.

The objective of this project is to engineer biodegradable porous and hollow polymeric particles delivering active bacteriophages to reduce CF-associated infections. Our central hypothesis is that phage-presenting particles will be efficiently delivered to the infected airway where the phages will infect and kill bacteria to eradicate the infection. We have formulated this hypothesis based on the ability of lytic phage to infect and destroy microorganisms, but not mammalian cells, and our expertise in engineering bioactive biomaterials. Particle size and density will be tuned to allow for efficient pulmonary delivery of phage to the small airways via inhalation. This research will provide a simple and innovative strategy to eradicate bacterial infections in the CF lung. We are well prepared to undertake the proposed research because of the combined expertise of our team in materials engineering and CF biology.

Aim 1. Evaluate lung delivery, residence time and safety of bacteriophage-loaded porous poly(lactic-co-qlycolic) acid (PLGA} particles. PLGA is a FDA-approved biodegradable polymer with an excellent record of safety [7]. Furthermore, PLGA particles have been used for drug delivery to the lung in animal models with minimal inflammatory or toxicity complications [7-11]. We will optimize particle formulation, including size, density and degradation rate, of PLGA particles to allow maximum loading of bacteriophages and deep lung deposition. The lung deposition patterns and residence time will be evaluated by testing particles in healthy mice. Particles distribution and safety (local inflammation and clearance) will be evaluated at various time points.

Aim 2. To examine the ability of phage-presenting particles to reduce infection in a murine model of lung infection in healthy and CF mice. Chronic infection of bacteria in a mouse model of infected lung in both healthy and CF mice will be established, first using the CFTR knockout mouse and then repeated using the model expressing delF508-CFTR. Once chronic infection is established, promising formulations of phage-loaded particles from aim 1 will be tested to evaluate treatment efficacy and survival.