Biodegradable microparticles designed to efficiently reach and act on cystic fibrosis mucus barrier

Cystic fibrosis (CF) is a progressive genetic disease caused by mutations in the gene that produces the CF transmembrane conductance regulator (CFTR) protein. The malfunction of the CFTR protein causes a thick buildup of mucus in the lungs that clogs the airways and traps bacteria, thus leading to infections, extensive lung damage and respiratory failure. Micro-delivery systems are currently being investigated as an efficient way to cross the viscous and complex architecture of the CF mucus. In this study, we produced synthetic and natural microparticles (MPs) based on poly(dl‑lactide‑co‑glycolide) (PLGA) or gellan gum through tailored water/oil emulsion procedures. Morphological and physico-chemical characterizations were carried out on both classes of MPs showing particles having diameters within suitable ranges to reach the CF airways. In vitro biocompatibility tests were also performed on both MPs using a human lung cancer cell line (A549) demonstrating that treatment with MPs induces no cytotoxic effects. Both classes of MPs were loaded with a mucolytic agent (N‑acetyl cysteine, NAC) and their release kinetics evaluated using high performance liquid chromatography (HPLC). The analysis pointed out that the amount of NAC released from MPs resulted in a dose-dependent increment, with a rapid release kinetic to satisfy the requirement for inducing an early mucus degradation. Finally, mucolytic action of NAC-loaded MPs was evaluated in an artificial sputum model through its rheological analysis obtaining the lowest viscosity profile after the addition of drug-loaded MPs. Taken together, gained results allowed us to select suitable MPs as potential drug targeting platforms having a mucolytic action for CF treatment.