Progressive slowdown/prevention of cellular senescence by CD9-targeted delivery of rapamycin using lactose-wrapped calcium carbonate nanoparticles

Abstract Cellular senescence(definition), a state of irreversible growth arrest and altered cell function, causes aging-related diseases. Hence, treatment modalities that could target aging cells would provide a robust therapeutic avenue. Herein, for the first time, we utilized CD9 receptors (overexpressed in senescent cells) for nanoparticle targeting in addition to the inherent β-galactosidase activity. In our study, CD9 monoclonal antibody-conjugated lactose-wrapped calcium carbonate nanoparticles loaded with mTOR(definition)-inhibiting drug studied for extending healthspan and lifespan." style="text-decoration:underline dotted; text-underline-offset:2px; cursor:help;">rapamycin(definition) (CD9-Lac/CaCO 3 /Rapa) were prepared for targeted rapamycin delivery to senescent cells. The nanoparticles exhibited an appropriate particle size (~130 nm) with high drug-loading capacity (~20%). In vitro drug release was enhanced in the presence of β-galactosidase suggesting potential cargo drug delivery to the senescent cells. Furthermore, CD9-Lac/CaCO 3 /Rapa exhibited high uptake and anti-senescence effects (reduced β-galactosidase and p53/p21/CD9/cyclin D1 expression, reduced population doubling time, enhanced cell proliferation and migration, and prevention of cell cycle arrest) in old human dermal fibroblasts. Importantly, CD9-Lac/CaCO 3 /Rapa significantly improved the proliferation capability of old cells as suggested by BrdU staining along with significant reductions in senescence-associated secretory phenotypes (IL-6 and IL-1β) ( P < 0.05). Altogether, our findings suggest the potential applicability of CD9-Lac/CaCO 3 /Rapa in targeted treatment of senescence.