Pulmonary Insulin-like Growth Factor I Delivery from Trehalose and Silk-Fibroin Microparticles

Insulin-like growth factor I (IGF-I) is a strong anabolic peptide with promising therapeutic value in muscle wasting diseases such as sarcopenia. We report a pulmonary IGF-I delivery system deploying silk-fibroin (SF) as carrier and in comparison to trehalose. Both IGF-I delivery systems were characterized regarding IGF-I integrity, IGF-I release profiles and aerodynamic properties. Transepithelial in vitro transport of IGF-I using the pulmonary Calu-3 model cell system followed comparable kinetics and mechanism of uptake as earlier demonstrated for insulin (INS), for which effective pulmonary delivery is known. Microparticles were spray-dried using either trehalose or SF, resulting in geometries allowing alveolar deposition. The effective IGF-I shuttling through the epithelial barrier of the lung was demonstrated in an ex vivo human lung lobe model, and expanded the exciting possibility of this administration route to this effective and anabolic peptide.