The expanding applications of nonviral genomic medicines in the lung remain restricted by delivery challenges. Here, leveraging a high-throughput platform, we synthesize and screen a combinatorial library of biodegradable ionizable lipids to build inhalable delivery vehicles for messenger RNA and CRISPR–Cas9 gene editors. Lead lipid nanoparticles are amenable for repeated intratracheal dosing and could achieve efficient gene editing in lung epithelium, providing avenues for gene therapy of congenital lung diseases. A high-throughput screen improves lipid nanoparticle delivery of gene editors in the lung.
Researchers are developing lipid nanoparticles that may target the lungs. The particles are made of molecules that contain two parts: a positively charged head group and a long lipid tail. The positive charge of the head group helps the particles interact with negatively charged mRNA, and also helps the mRNA escape from cellular structures that engulf the particles once they enter the cells. In tests on mice, the researchers showed that they could use the particles to deliver mRNA encoding CRISPR/Cas9 components designed to turn off a genetically encoded stop signal in the animals' lung cells. When this stop signal is removed, a gene for a fluorescent protein lights up. Measuring this fluorescent signal allows researchers to determine what percentage of cells have successfully expressed the mRNA. After one dose of mRNA, about 40% of lung epithelial cells were transfected, the researchers found. Two doses brought the level to more than 50% and three doses to 60%. The most important targets for treating lung disease are two types of epithelial cells called club cells and hair cells, and each was transfected at about 15%. These particles could offer an inhalable treatment for cystic fibrosis and other lung diseases.