9.1 Adipose tissue structure
White, brown, and beige fat differ in blood supply, cellularity, and promoter activity; mature adipocytes must be distinguished from the stromal vascular component.
9.2 AAV serotype selection
AAV8/9 is a common starting point. If necessary, use fat to screen capsids; systemic administration is prone to liver dominance.
9.3 Fat-specific promoter
ADIPOQ favors mature adipocytes, UCP1 favors brown/beige fat, and FABP4 may be expressed in other cells.
9.4 Administration method and dosage reference
Local injection into the fat pad: targeting white/brown fat. Mouse 1×10^11-2×10^11 vg/pad (AAV8), eWAT 30-50 μL/pad divided into 2 points, iBAT 20 μL/leaf (a total of 40 μL for two leaves), iWAT 25 μL/side; 30 G Hamilton (use 32 for BAT G fine injection), isoflurane anesthesia; AAV8 is the most efficient in transducing adipose tissue, the ADIPOQ promoter is specific for mature adipocytes, and the expression lasts for >4 weeks [9-2,9-5].
Subcutaneous/systemic administration: SC fat pad local regimen 2×10^10 vg/side, 25-30 μL/point; system 1×10^11-1×10^12 vg/animal. Brown fat (BAT) dosage is approximately 1×10^9-2×10^10 vg/pad. Each point of eWAT is ≤10 μL to prevent leakage into the abdominal cavity [9-4].
Coverage and limitations: mature adipocytes + stromal vascular component; off-targets include intraperitoneal leakage (eWAT) and high-dose hepatic spread. Adipocyte expression, liver off-target and metabolic phenotypes should be detected simultaneously; diet and temperature are important confounding factors [9-1].
9.5 Key research evidence
Jimenez et al. achieved in vivo AAV genetic engineering of white and brown adipose tissue in adult mice [9-2]; Bates et al. reviewed adipose tissue as an emerging target of AAV [9-1]; research on subcutaneous fat tropism gene therapy for congenital leptin defects demonstrates the SC pathway [9-4].
9.6 References for this chapter
[9-1] Bates R, Huang W, Cao L. Adipose tissue as an emerging target for AAV vectors. Mol Ther Methods Clin Dev. 2020;19:236-249. [H]
[9-2] Jimenez V, et al. AAV-mediated genetic engineering of white and brown adipose tissue. Diabetes. 2013;62:4012-4022. [F]
[9-3] Sancar G, et al. FGF1 and insulin control lipolysis by convergent pathways. Cell Metab. 2022;34:171-183.e6. [H]
[9-4] Subcutaneous administration of adipose-tropic gene therapy for congenital leptin deficiency. 2025. PMC12288548. [N]
[9-5] Direct aden-associated virus injection of murine adipose tissue. Methods Mol Biol. 2023. PMC10213077. [F]