Delivery of siRNA Silencing P-gp in Peptide-Functionalized Nanoparticles Causes Efflux Modulation at the Blood–Brain Barrier

Explore the use of transferrin-receptor peptide-functionalized nanoparticles (NPs) targeting blood-brain barrier (BBB) as siRNA carriers to silence P-glycoprotein (P-gp).Permeability experiments were assessed through a developed BBB cell-based model; P-gp mRNA expression was evaluated in vitro; rhodamine 123 permeability was assessed after cell monolayer treatment with siRNA NPs.Beyond their ability to improve siRNA permeability through the BBB by twofold, 96-h post-transfection, functionalized polymeric NPs successfully reduced P-gp mRNA expression up to 52%, compared with nonfunctionalized systems. Subsequently, the permeability of rhodamine 123 through the human BBB model increased up to 27%.Developed BBB-targeted NPs induced P-gp downregulation and consequent increase on P-gp substrate permeability, revealing their ability to modulate drug efflux at the BBB.