Inorganic Silica Nanoparticles Increase Lysosomal Biology and Protease Activity

The use of nanoparticles has revolutionized drug delivery by enabling targeted and controlled therapeutic release. However, their interactions with intracellular organelles, particularly lysosomes, are not yet fully understood. This study delineates the differential effects of two widely used nanocarriers-mesoporous silica (MSNs) and albumin (ANPs) nanoparticles-on lysosomal biology, with a focus on the expression and activity of cathepsins (CtsB and CtsD), which are key proteases involved in protein degradation and maintaining cellular balance. These two types of nanoparticles, differing in their material and degradability, exhibit distinct behaviors inside the cell. We demonstrate that inorganic MSNs cause significant changes in lysosomal function by altering lysosomal content and cathepsin levels, without triggering lysosomal membrane permeabilization-a typical response to organic particle stress. In contrast, ANPs-which are susceptible to lysosomal cathepsin degradation-induce milder changes in cathepsin expression and maintain lysosomal integrity. Our results highlight that the composition of nanocarriers plays a pivotal role in modulating lysosomal protease activity and maintaining overall cellular homeostasis, highlighting the importance of these parameters in the rational design of drug delivery platforms.