Gene Therapy for Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an inherited metabolic disorder characterized by high levels of plasma low density lipoproteins (LDL) and an increased risk of premature atherosclerosis and coronary heart disease. LDL receptor (LDLr) deficiency is the most prevalent cause of FH. Therefore, hepatocyte-directed LDLr gene transfer constitutes an important strategy for the treatment of this monogenetic disease. Nowadays, homozygous FH patients are treated with lipid-lowering drugs complemented by plasma or LDL apheresis. Liver transplantation can restore metabolism of apolipoprotein B containing lipoproteins, but requires lifelong immunosuppression to prevent organ rejection. Recently, significant progress in gene transfer technology has encouraged investigators to further develop LDLr gene transfer approaches for the treatment of FH. In experimental animal models of FH, LDLr overexpression following viral vector-based gene transfer has been shown to be associated with long-term stable correction of hyperlipidemia, with attenuation of atherosclerosis progression, and in certain cases even with lesion regression. The first part of this review provides a thorough overview of familial hypercholesterolemia including its diagnosis, lipoprotein metabolism, and current management. In the second part, we critically review experimental LDLr gene transfer studies demonstrating the progress that has been made from the initial proof of principle studies to recent investigations showing dramatic regression of atherosclerosis in experimental models.