Micro/nanoscale bubble-mediated mucolytic conditioning of the lung model of cystic fibrosis enhances nanoparticle transport through the mucus.

Abstract

Cystic fibrosis (CF) is a monogenic disease with severe pulmonary manifestations. Nanoparticle carriers of drug and gene therapeutics for CF are being studied, but only few can traverse the highly concentrated, disulfide-crosslinked airway mucus in the CF lung. Here, we developed mucolytic-associated polydisperse micro/nanoscale bubble formulations (MNB) that couple reducing chemistry (tris(2-carboxyethyl)phosphine, TCEP) with an ultrasound-responsive carrier to disrupt mucus. We evaluated the penetration of a model nanocarrier through a CF-mimetic mucus hydrogel following MNB-TCEP treatment. Under the same reducing-equivalent dosing, MNB-TCEP markedly enhanced penetration of 200 nm anionic nanoparticles relative to both PBS and free TCEP. In the more restrictive thick-mucus condition, therapeutic ultrasound increased anionic nanoparticle penetration approximately 3.5-fold in the MNB-TCEP group relative to its no-ultrasound counterpart, without statistically significant effects on PBS or free TCEP controls. MNB-TCEP also retained diagnostic ultrasound visibility in gel phantoms and produced airway-associated echogenicity in ex vivo porcine lungs within fluid-accessible, non-aerated imaging windows. Moreover, MNB-TCEP with or without ultrasound did not reduce acute viability of ex vivo tracheal biopsies under the tested regimens. Introduction of an AAV1 reporter suggested that bubble-ultrasound conditioning may increase localized reporter-positive nuclei in airway epithelium. Together, these data identify mucolytic-associated MNB formulations as a theranostic strategy to enhance nanocarrier access through CF-mimetic mucus, with exploratory tissue-level data supporting further evaluation for gene-delivery applications.