Gene editing has been used to repair the CFTR mutations in cultured patient intestinal stem cells50 and iPS cells that could be subsequently differentiated into epithelial cells.284,285 Although a long-standing challenge for gene therapy and gene editing for cystic fibrosis has been achieving efficient gene delivery to the lung epithelium, a recent study demonstrating functional correction of mice with cystic fibrosis following intranasal delivery of nanoparticles carrying triplex-forming peptide nucleic acid molecules is a very promising advance in this regard.286. This evidence concerns the gene CFTR and cystic fibrosis.