Idiopathic pulmonary fibrosis (IPF) is a fatal chronic lung disease characterized by gradual alveolar epithelial damage and irredeemable fibrotic remodeling, with a median survival time of only 3 to 5 years after diagnosis. Although pirfenidone (PFD) and nintedanib (NTD) are currently the only approved IPF therapeutic drugs, because they are orally administered drugs, there is a fatal barrier that the amount of drugs reaching the lungs is limited due to liver metabolism and systemic circulation processes, resulting in reduced drug efficacy. To overcome these challenges, we developed a stealth-biomimetic drug delivery system composed of poly lactic-co-glycolic acid (PLGA) nanoparticles encapsulating NTD (NTD-NPs), which are coated with mesenchymal stem (MSC) cell-derived membrane vesicles (CMVs) engineered with polyethylene glycol (PEGylated-CMVs-NPs). NTD was chosen because it effectively blocks the fibrosis signaling pathway, and it is hydrophobic, making it easy to form into NPs.

NTD-NPs nanoparticles were synthesized using a single-emulsification solvent evaporation method and characterized for size distribution, zeta potential, encapsulation efficiency, stability, and toxicity. Before CMVs from MSCs, MSCs were PEGylated and isolated using hypotonic solutions. The extrusion process was used for making PEGylated-CMVs-NPs, and characterized and evaluated for its therapeutic function. Further, PEGylated-CMVs-NPs were intratracheally delivered to bleomycin-induced idiopathic pulmonary fibrosis and evaluated for their recovery.

We chose PLGA as the core material due to its biodegradability, biocompatibility, and suitability for encapsulating hydrophobic drugs. To reduce immunogenicity and enhance the targeting of fibrotic lung tissue, the nanoparticle surface was cloaked with membranes derived from mesenchymal stem cells (MSCs). For further improvement in mucosal penetration and to avoid clearance by alveolar macrophages, the membrane was PEGylated. Our PEGylated-CMVs-NPs showed stable colloidal properties with a uniform size of around 200 nm and a negative zeta potential. Cellular uptake assays found significantly reduced phagocytosis by RAW264.7 macrophages while maintaining efficient delivery to MRC-5 fibroblast cells. Furthermore, in the bleomycin-induced IPF mouse model, our PEGylated-CMVs-NPs showed effective accumulation in fibrotic lung tissues and a notable reduction in immune cell infiltration, collagen deposition, and fibrotic gene expression (TGF-β1, α-SMA, Col1a1), compared to free drug and uncoated nanoparticles. Crucially, no appreciable systemic toxicity was noted during treatment.

Altogether, our PEGylated-CMVs-NPs platforms combine immune evasion, mucosal permeability, targeted delivery, and sustained drug release, and appear to be a promising therapeutic approach for IPF and other fibrotic lung diseases. These results have a high potential for clinical translation.