Engineering macrophage-derived exosomes for targeted paclitaxel delivery to pulmonary metastases: in vitro and in vivo evaluations.

Exosomes have recently emerged as a promising drug delivery system with low immunogenicity, high biocompatibility, and high efficacy of delivery. We demonstrated earlier that macrophage-derived exosomes (exo) loaded with a potent anticancer agent paclitaxel (PTX) represent a novel nanoformulation (exoPTX) that shows high anticancer efficacy in a mouse model of pulmonary metastases. We now report the manufacture of targeted exosome-based formulations with superior structure and therapeutic indices for systemic administration. Herein, we developed and optimized a formulation of PTX-loaded exosomes with incorporated aminoethylanisamide-polyethylene glycol (AA-PEG) vector moiety to target the sigma receptor, which is overexpressed by lung cancer cells. The AA-PEG-vectorized exosomes loaded with PTX (AA-PEG-exoPTX) possessed a high loading capacity, profound ability to accumulate in cancer cells upon systemic administration, and improved therapeutic outcomes. The combination of targeting ability with the biocompatibility of exosome-based drug formulations offers a powerful and novel delivery platform for anticancer therapy.