AAV8-LDLR Gene Therapy in Ldlr-KO and Homozygous Ldlr p.W483X Mice.

The low-density lipoprotein receptor (LDLR) plays a crucial role in cholesterol regulation and lipoprotein transport. Variations in the LDLR gene can cause familial hypercholesterolemia (FH), with homozygous familial hypercholesterolemia (HoFH) being the most severe form. HoFH is marked by elevated low-density lipoprotein cholesterol (LDL-C) levels and early onset of cardiovascular disease, often with a poor prognosis. Current treatment options for HoFH are limited by insufficient effectiveness and restricted availability. Gene therapy, which involves the delivery of functional LDLR genes, offers a promising and innovative approach that could significantly improve outcomes for patients with HoFH. In this study, the adeno-associated virus serotype 8 (AAV8) vector was used to deliver the LDLR gene specifically to hepatocytes. The vector was designed using the pAAV-TBG plasmid, incorporating a hepatocyte-specific thyroid hormone-binding globulin (TBG) promoter. Viral packaging was performed in HEK 293T cells, followed by virus collection, purification, and titration. Mice, including C57BL/6J, Ldlr-KO, and homozygous Ldlr p.W483X mice, were injected with low, medium, or high doses of the virus via the tail vein. The efficacy and safety of the AAV8-LDLR gene therapy were assessed through Western blot analysis, lipid profiling, and liver pathology. AAV8-mediated LDLR delivery effectively improved lipid levels in both Ldlr-KO and homozygous Ldlr p.W483X mice. LDL-C levels showed a sustained reduction over the 2-month observation period. Western blot analysis confirmed the expression of LDLR protein in the liver, while lipid profiling demonstrated significant reductions in total cholesterol, triglycerides, LDL-C, and high-density lipoprotein cholesterol levels. Liver histopathology revealed no significant differences in non-alcoholic fatty liver disease scores between groups, indicating a favorable safety profile, particularly at low and medium doses. AAV8-LDLR gene therapy shows considerable promise as an effective treatment for HoFH. Our results indicate that this therapy significantly reduces lipid levels while maintaining a favorable safety profile.