Cell-Penetrating Peptide Nanofibers Boost Lung Drug Delivery by Up to 10-Fold

Supramolecular cell-penetrating peptides (CPPs) that self-assemble into nanofibers were coated onto PLGA nanoparticles to create nanocomposites. Cellular uptake was quantified in primary lung epithelial cells, macrophages, and endothelial cells and compared to naked PLGA and monomeric CPP-modified nanoparticles. Cell entry mechanisms were investigated through inhibitor studies. Mucus permeation was assessed. The formulation was tested for stability after freeze-drying and nebulization.

Pulmonary drug delivery is one of the most important frontiers in medicine — from treating asthma and COPD to delivering gene therapies for cystic fibrosis and mRNA therapeutics for respiratory infections. Current nanoparticle systems are limited by poor mucus penetration and cellular uptake. By leveraging the self-assembling properties of cell-penetrating peptides to create a nanofiber coating, this approach provides a significant upgrade to standard PLGA nanoparticles with proven translational characteristics.

The intersection of peptide nanotechnology and pulmonary drug delivery is an active area of innovation. This work demonstrates that self-assembling peptide nanofibers can dramatically outperform individual cell-penetrating peptides — the supramolecular organization creates a multivalent surface that enhances cell interactions. As inhaled therapeutics gain importance (especially after COVID-19 highlighted pulmonary drug delivery), this nanocomposite platform could become a versatile tool for delivering nucleic acids, proteins, and small molecules to the lungs.

All studies are in vitro — no animal inhalation studies or in vivo pulmonary delivery data are presented. The 10-fold enhancement was in endothelial cells, while lung epithelial cells showed a more modest 3-fold improvement. The specific cell-penetrating peptide sequences used are not detailed in the abstract. Long-term stability of the freeze-dried formulation and potential immunogenicity of the peptide nanofibers in the lungs are not addressed. The drug payload capacity and release kinetics with actual therapeutic cargo are not characterized.