Chemicals and reagents

Human apoAI and apoE3 were purchased from Athens Research and Technology (Athens, GA) and Leinco Technologies (St. Louis, MO), respectively. Transwell^™ polycarbonate membrane cell culture inserts (07200156 and 07200170); Pierce^™ Iodination Beads (PI28665); Zeba^™ Spin Desalting Columns, 7K MWCO (#89891); OptiMEM^™ Reduced Serum Medium; M-PER^™ Mammalian Protein Extraction Reagent; polyvinylidene fluoride (PVDF) membranes; and ECL plus chemiluminescence reagent were purchased from ThermoFisher Scientific (Waltham, MA). [1,2-³H(N)]-cholesterol (³H-Ch) and 125-Iodine (¹²⁵I) were obtained from American Radiolabeled Chemicals (St. Louis, MO) and PerkinElmer, Inc. (Waltham, MA), respectively. Freshly collected human blood was obtained from BiolVT (Fredrick, MD). Antibodies against caveolin-1, clathrin heavy chain 1 (CLTC), ALK1, ABCA1, apoE, apoB, and β-actin, as well as scrambled small interfering RNA (siRNA) and ABCA1 siRNAs (ABCsi), were purchased from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA). OptiPrep^™ Density Gradient Medium was obtained from Sigma-Aldrich (St. Louis, MO). Thiobarbituric acid-reacting substances (TBARS) assay kit was obtained from ZeptoMetrix Co. (Buffalo, NY). MAECs and the endothelium medium with growth factor supplement kit were obtained from Cell Biologics, Inc. (Chicago, IL). Human primary coronary artery endothelial cells (HCAECs) and vascular cell basal medium were purchased from American Type Culture Collection (ATCC) (Manassas, VA). The sixth to ninth passages of cells were used in the current study.