Apolipoprotein E (ApoE) is primarily produced by the liver and macrophages in the peripheral tissues, or by astrocytes and microglia in the central nervous system. ApoE transports lipoproteins, fat-soluble vitamins and cholesterol into the lymph systems, and then into the blood, preventing the accumulation of cholesterol-rich particles in the plasma. The function of ApoE protein has been widely studied in cardiovascular disease, lipid metabolism, and Alzheimer’s diseases.