Abstract 17172: Adiponectin Promoter Elements Combined with Liver-Specific microRNA-122 Target Sequences Specifically Target Adipose Tissue for Gene Transfer with Intravenous Delivery an AAV8 Vector
Objective: To develop an in vivo, systemic method of gene transfer specifically targeting adipose tissue. We assessed the hypothesis that systemic adeno-associated virus (AAV)-mediated vector delivery can transfer genes specifically to adipose tissue.
Background: Obesity is a major risk factor for developing coronary heart disease. Adipose is an endocrine organ critical to energy intake and expenditure. Available data on adipose is limited, in part, because of the difficulties in adapting experimental techniques to a tissue with high lipid content. Few studies have investigated in vivo gene transfer in adipose tissue, and these studies used subcutaneous injections in obese mice.
Method and Results: Tail vein IV injections of a luciferase expression vector in healthy C57BL/6 mice revealed that AAV serotype 8 (AAV8) best targeted adipose tissue. Tail vein injections of AAV8 were used to administer all subsequent vectors in five mice per vector. Mice were sacrificed 2-3 weeks after injection, and tissues were analyzed for transgene expression. Systemic delivery of a vector containing the GFP gene under control of a CMV promoter induced GFP transgene expression in most tissues tested, including subcutaneous, omental, gonadal, and brown fat depots. To restrict GFP expression to adipose depots, the CMV promoter was replaced with an adiponectin enhancer/promoter to make Adipo-GFP AAV. Systemic delivery of Adipo-GFP AAV induced GFP expression in all adipose depots tested. GFP expression in non-adipose tissues was negligible except for liver. To ameliorate unwanted liver expression, target sites for liver specific microRNA -122 were incorporated into the vector to make Adipo-GFP-miR122 AAV. Mice injected with Adipo-GFP-miR122 AAV no longer expressed GFP in liver, yet they expressed GFP in adipose tissue. Furthermore, mature adipocytes isolated from adipose tissue express GFP, indicating Adipo-GFP-miR122 vector targets mature adipocytes for transgene expression.
Conclusion: AAV8-mediated systemic delivery of a specifically designed adipose expression vector can selectively target adipose tissue for in vivo gene transfer. This novel approach has therapeutic potential in obesity and downstream complications like insulin resistance and diabetes.
- © 2011 by American Heart Association, Inc.