We then mimicked cholesterol efflux from astrocytes by replacing the AD and control CSFs with synthetic rHDL-APOE3 and rHDL-APOE4 nanoparticles, following the method depicted in Figure 1A. When comparing cholesterol efflux between the two rHDL nanoparticles, both synthetic rHDL-APOE3 and rHDL-APOE4 induced cholesterol efflux from astrocytes at similar levels. The gene discussed is APOE; the disease is Alzheimer disease.