BACE1 and Alzheimer disease: Dendritic cell-derived exosomes, functionalized with neuron-specific rabies viral glycoprotein (RVG) peptide expressing Lamp2b, have been used to specifically deliver siRNA against BACE1, a therapeutic target for AD, to neurons, microglia, and oligodendrocytes in the brain, resulting in the specific knockdown of BACE1 [17].