Inhalable nano-structured microparticles for extracellular matrix modulation as a potential delivery system for lung...

The use of inhalable nanoparticulate-based systems in the treatment of lung cancer allows for efficient localized delivery to the lungs with less undesirable systemic exposure. For this to be attained, the inhaled particles should have optimum properties for deposition and at the same time avoid pulmonary clearance mechanisms. Drug delivery to solid tumors is furthermore challenging, due to dense extracellular matrix (ECM) formation, which hinders the penetration and diffusion of therapeutic agents. To this end, the aim of the current work is to develop an ECM-modulating nano-structured microparticulate carrier, that not only enables the delivery of therapeutic nanoparticles (NPs) to the lungs, but also enhances their intratumoral penetration. The system is composed of acetalated maltodextrin (AcMD) NPs embedded into a water-soluble trehalose/leucine matrix, in which collagenase was loaded with different mass concentrations (10 %, 30 % and 50 %). The collagenase-containing AcMD nano-structured microparticles (MPs) exhibited suitable median volume diameters (2.58 ± 1.35 to 3.01 ± 0.68 µm), hollow corrugated morphology, sufficient redispersibility, low residual moisture content (2.71 ± 0.17 % to 3.10 ± 0.20 %), and favorable aerodynamic properties (Mass median aerodynamic diameter (MMAD): 1.93 ± 0.06 to 2.80 ± 0.10 µm and fine particle fraction (FPF): 68.02 ± 6.86 % to 69.62 ± 2.01 %). Importantly, collagenase retained as high as 89.5 ± 6.7 % of its enzymatic activity after spray drying. MPs containing 10 % mass content of collagenase did not show signs of cytotoxicity on either human lung adenocarcinoma A549 cells or lung MRC-5 fibroblasts. The nanoparticle penetration was tested using adenocarcinoma A549/MRC-5 co-culture spheroid model, where the inclusion of collagenase resulted in deeper penetration depth of AcMD-NPs.