Airway-to-Go: An Ex Vivo Cystic Fibrosis Airway Model and Bioreactor System for High Throughput Gene Therapy Screening

Despite three decades of progress since the cystic fibrosis
transmembrane
conductance regulator (CFTR) gene was discovered, there is still no
gene therapeutic cure for the lethal pulmonary component of cystic
fibrosis (CF). Existing CF models fall short of capturing all aspects
of CF lung disease: animal models either develop gastrointestinal-only
disease or are prohibitively expensive for large-scale experiments,
while cell culture models lack both 3D tissue context and the thick
inflammatory exudate barrier to airway-side delivery. To maximize
translational potential, CF gene therapeutics must be tested on a
model that captures all genotypic and phenotypic aspects of CF lung
disease. Here, we combine three key innovations(i) a grab-and-go,
real-time, imaging-enabled bioreactor, (ii) an optimized tissue culture
protocol for human and porcine airway explants, and (iii) a biophysical-bioelectrical
barrier model of CFto build the Airway-to-Go, a platform uniquely
suited to high-throughput screening of candidate gene therapies for
CF. Our air–liquid interface bioreactor design provides an
even distribution of nebulized material and interfaces with a range
of nondestructive monitoring technologies, including bioluminescence
imaging, bioimpedance monitoring, and fluorescence microscopy in two
planes. A Pneumacult-based tissue culture method enabled by new tissue
holders supports both porcine and human CF airway explant structure
and function for as long as 10 weeks. Disease model components that
mimic the bioelectrical (via CFTR inhibition) and biophysical (via
bioartificial mucus addition) barriers to gene delivery influence
tissue inflammatory state and gene uptake, without causing toxicity.
When these components were combined for a demonstrative gene delivery
study using viral vectors, nondestructive readouts of gene delivery
success revealed differences in gene uptake and expression due to
CF-mimetic biophysical and bioelectrical barriers. This work establishes
a built-for-purpose platform to accelerate translation of CF gene
therapeutics, using porcine and human tissue explants as a steppingstone
to clinical trials.