Table 2.

Potential CRISPR/Cas9 Gene-Editing Approaches in the Lung

	Prenatal Gene Editing	Postnatal In Vivo Gene Editing	Postnatal Ex Vivo Gene Editing
Target cells	Developing progenitor cells	In situ tissue-specific stem cells (i.e., basal cells for cystic fibrosis and alveolar type II cells for surfactant protein deficiency)	Harvested stem cells
Advantages	Higher efficiency	Relative technical ease	Patient specific
	Immune tolerance		Avoids in vivo viral exposure
	Disease prevention		Ability to select for corrected cells before engraftment
Limitations	Technical difficulties including specialized equipment	Lower efficiency	Challenges with reengraftment
Application	Genetic surfactant protein deficiency	Cystic fibrosis, alpha-1 antitrypsin deficiency	Depends on availability of engraftment assay but could include cystic fibrosis