Complete Atherosclerosis Regression After Human ApoE Gene Transfer in ApoE-Deficient/Nude Mice

Abstract

Abstract-The apolipoprotein E (apoE)-deficient mouse is a relevant animal model of human atherosclerosis. Although the prevention of atherosclerosis development has been documented after somatic gene transfer into animal models, regression of lesions remains to be demonstrated. Thus, we used this genetically defined mouse model nn the nude background to show atherosclerosis regression. ApoE-deficient nude mice were infected with 5ϫ10 8 or 10 9 plaque-forming units of a first-generation adenovirus encoding human apoE cDNA. The secretion of human apoE resulted in a rapid decrease of total cholesterol, which normalized the hypercholesterolemic phenotype within 14 days (from 600Ϯ100 to Ͻ100 g/mL). Transgene expression was observed during a period of Ͼ4 months, with a normalization of cholesterol and triglyceride levels during 5 months. At that time, we successfully reinjected the recombinant adenovirus and observed the appearance of the human protein as well as the correction of lipoprotein phenotype. In mice killed 6 months-after the first infection, we observed a dose-dependent regression of fatty streak lesions in the aorta. We showed sustained expression of a transgene with a first-generation adenoviral vector and a correction of dyslipoproteinemia phenotype leading to lesion regression. These data demonstrate that somatic gene transfer can induce plaque regression.

Does Therapeutic Intervention Achieve Slowing of Progression or Bona Fide Regression of Atherosclerotic Lesions?

“…The nude athymic mice are deficient for cellular immunity, and because of their immunodeficient background, the adenovirus-mediated gene transfer and the expression of apoE lasted for Ͼ4 months. 40 In these 17-week-old mice, a dose-dependent regression of fatty streak lesions occurred during 4 months after the gene transfer. 40 In another model system, namely, LDL receptordeficient mice, liver-directed gene transfer of apoA-I was performed.…”

“…In a more complex study, apoE -/-mice were generated on the nude background as a new mouse model for atherosclerosis. 40 Human apoE cDNA was transferred to these mice with a first-generation adenoviral vector. The nude athymic mice are deficient for cellular immunity, and because of their immunodeficient background, the adenovirus-mediated gene transfer and the expression of apoE lasted for Ͼ4 months.…”

Inhibition of atherosclerosis in apolipoprotein-E-deficient mice following muscle transduction with adeno-associated virus vectors encoding human apolipoprotein-E

“…17,37,38 The restoration of normal cholesterolaemic levels and protection against atherosclerosis has been achieved in apoE -/-animal models by the gene transfer of human apoE, using retroviral, adenoviral and plasmid expression vectors. 22,23,26,[39][40][41] As a platform for secretion of therapeutic proteins into the circulation, muscle has been used extensively in rAAVmediated gene transfer yielding sustained transgene expression in the absence of immune clearance of transduced cells. 29,[31][32][33][34][35] We have examined the feasibility of targeting muscle as a platform for the secretion of anti-atherogenic proteins by the transfection of mouse myoblast cultures with rAAV-based plasmid vectors containing apoA1 and LCAT cDNAs.…”

“…In a recent study, apoE -/-nude mice were treated with a first generation adenovirus containing human apoE cDNA and complete regression of atherosclerosis was demonstrated 6 months after injection. 26 As these animals were immune deficient, no immune response was mounted against the adenovirus vector and recognition of human apoE as a neoantigen was minimal which resulted in prolonged transgene expression.…”

“…For studies showing quantitative regression of atherosclerotic plaques, recourse to immunodeficient athymic apoE -/-mice was required. 26 Recombinant adeno-associated viruses (rAAVs) are attractive candidate vectors for gene therapy as they are defective and non-pathogenic, 27 can transduce both dividing and non-dividing cells, and are devoid of viral structural genes which diminishes the risk of adverse host immune responses. 28,29 In particular, the use of skeletal muscle as a heterologous site for gene delivery with rAAV vectors has gained increasing importance as a platform for the secretion of therapeutic transgene products into the circulation.…”