Probing and Overcoming Extracellular Barriers to Inhaled Nanomedicine

drug delivery;gene delivery;particle tracking;biological barrier;cystic fibrosis;mucus;pulmonary disease;nanomedicine;Biomedical Engineering

Schuster, Benjamin Samuel

Johns Hopkins University

关键词: drug delivery;    gene delivery;    particle tracking;    biological barrier;    cystic fibrosis;    mucus;    pulmonary disease;    nanomedicine;    Biomedical Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/39312/SCHUSTER-DISSERTATION-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Inhaled nanoparticles are a promising technology for delivering therapeutic molecules to the lungs to treat diseases such as cystic fibrosis (CF) and lung cancer. This dissertation focuses on characterizing and overcoming a critical extracellular barrier to inhaled nanomedicine: the mucus gel that coats the lung airway epithelium. Mucus is an adhesive meshwork that can trap particles and facilitate their removal from the lungs via mucociliary clearance. Although this defense mechanism protects the lungs from pathogens and particulate pollution, it can also prevent inhaled drug and gene nanoparticles from reaching their target. We therefore investigated strategies to improve particle penetration through human lung mucus. To measure nanoparticle transport, we used multiple particle tracking, a high resolution microscopy technique for quantifying movement of individual particles.First, we examined how particle size and surface chemistry affect mobility in respiratory mucus. We prepared polymeric nanoparticles densely coated with low molecular weight polyethylene glycol (PEG) to minimize muco-adhesion, and compared their transport to that of uncoated, muco-adhesive particles in respiratory mucus collected from endotracheal tubes of surgical patients without pulmonary comorbidities. We found that 100 and 200 nm diameter PEG-coated particles rapidly penetrated respiratory mucus, at rates exceeding their uncoated counterparts by more than one order of magnitude. In contrast, coated and uncoated particles 500 nm in diameter were sterically immobilized by the mucus mesh. These findings identify small size and adhesion-resistant surface as design criteria for therapeutic, respiratory-mucus-penetrating nanoparticles.Next, we studied viruses – nature’s nanoparticles – for CF lung gene therapy. We investigated whether CF sputum acts as a barrier to adeno-associated virus (AAV) gene vectors including AAV2, the serotype tested in CF clinical trials, and AAV1, a leading candidate for future trials. We found that sputum strongly impeded diffusion of AAV, regardless of serotype, and may thereby inhibit access to target cells. However, an AAV2 mutant engineered to have reduced heparin binding diffused twice as fast as AAV2 on average, presumably because of reduced adhesion to sputum. We also discovered that the mucolytic N-acetylcysteine could markedly enhance AAV diffusion. These studies offer strategies for increasing AAV penetration through sputum to improve clinical outcomes.