Table 3.

Comparison of human cell models relevant for CF therapeutic application.

Cell models	Established immortalized cell lines	Pulmonary				Gut
		HBE		Nasal		Intestinal
		Bronchial ALI	Bronchial organoid	Nasal ALI	Nasal organoid	Rectal biopsies	Rectal organoid	Organoid 2-D monolayer
Patient-specific	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Tissue source	-	Lung explants Bronchial brushing/biopsies Bronchoalveolar lavage fluid		Nasal brushing/curettage		Rectal biopsies
Invasiveness of sample acquisition	-	+++		+		++
Easy-to-culture	- Flexible - Easy to manipulate	- Limited expansion and differentiation potential (decreases as a function of passage)				- Long term expanding cultures
		- ALI cultures take 4 weeks to form pseudostratified epithelium -No standardized protocol available for airway organoids				- Long term expanding cultures -Established and standardized protocol for organoid -Monolayer in development phase
Phenocopies CF lung	No (prone to artifact)	Yes (gold standard)	Yes	Yes	Yes	No	No	No
Phenocopies CF intestine	No	No	No	No	No	Yes	Yes	Yes
CFTR functional readout	- Ussing - Halide assay	- Ussing	- FIS	- Ussing	- FIS	ICM	- FIS/SLA	Ussing
Assay dynamic range	Large	Moderate	Moderate	Small	Small	Large	Large	Large
Biochemical/physiological readout	- CFTR western blotting	- CFTR western blotting - ASL -CBF	- CFTR western blotting	- CFTR western blotting	- CFTR western blotting		- CFTR western blotting
Drug screening	- High-throughput - Hit-to-lead drug development	- Mid-throughput - Checkpoint before drugs enter clinical trial/use	Exploratory	Mid-throughput	Exploratory	Low-throughput	Mid-throughput	Exploratory
Predictive value	++	+++	Exploratory	Exploratory	Exploratory	++	++	Exploratory

+++, High; ++, Moderate; +, Low; 2-D, 2-Dimensional; ALI, Air-liquid interphase; ASL, Airway surface liquid; CBF, Cilia beating frequency; FIS, Forskolin-induced swelling; HBE, Human bronchial epithelial; ICM, Intestinal current measurement; SLA, Steady-state lumen area.