After successful characterization of siRNA-LNPs by size (∼70 nm diameter), polydispersity index (< 0.3), zeta potential (∼neutral), and siRNA encapsulation efficiency (> 99 %) (Table S1), we decided to validate, as a proof of concept, whether our siAR-LNPs could knock down the AR gene in vitro, both at the mRNA (Fig. 1a) and protein levels (Fig. 1b), in two prostate cancer cell lines that express the AR wild type (PC346C and LNCaP). Here, AR is linked to Familial prostate cancer.