1. Background: Cell Types in the Heart
The heart mainly contains two major cell types: cardiomyocytes and cardiac fibroblasts. Cardiomyocytes are further divided into working cells and autorhythmic cells. Working cells are those that generate excitation upon external stimulation, including ventricular muscle cells and atrial muscle cells. Autorhythmic cells, in contrast, lack a stable resting potential and can spontaneously generate rhythmic excitation — mainly P cells (also called pacemaker cells) and Purkinje cells. Because the left ventricular wall is relatively thick, AAV injections for cardiac studies usually target the left ventricular wall.
2. Choosing the Injection Method, Dose and Promoter
There are several routes for AAV delivery to the heart. The two most frequently reported in the literature are intramyocardial injection and tail vein injection; both transduce the heart in vivo, with a total AAV amount of 1010–1011 vg. Intramyocardial injection is surgically demanding and somewhat more difficult; it is usually performed as small-volume, multi-site injection, 20 μL per site at 3–5 sites. Tail vein injection is easy to perform but slightly less specific than intramyocardial injection, with an injection volume of about 100 μL.
For in vivo cardiac AAV studies, AAV9 and AAV8 transduce the heart more efficiently than other serotypes, with AAV9 the most widely used. To achieve cardiac-specific expression of the gene of interest, the cardiac-specific promoters cTNT (cardiac troponin T) and α-MHC (α-myosin heavy chain) are recommended.
3. Case Study: Cardiomyocyte-Specific Gene Expression
- Data source
- Robust Cardiomyocyte-Specific Gene Expression Following Systemic Injection of AAV: In Vivo Gene Delivery Follows a Poisson Distribution
- Experimental animal
- 1-week-old C57BL/6 mice
- Injection route
- Jugular vein injection
- Serotypes
- AAV1 / AAV2 / AAV6 / AAV8 / AAV9
- Viral doses
- 3.15×109 vp; 1×1010 vp; 3.15×1010 vp; 1×1011 vp (volume about 20 μL)
- Detection time
- Frozen sections examined 4 weeks after injection
4. Selected WZBIO AAV Publications (Cardiac)
- Yin L et al. 2019. FBXL10 regulates cardiac dysfunction in diabetic cardiomyopathy via the PKC β2 pathway. J Cell Mol Med. 23(4): 2558–2567.
- Bing Li et al. 2018. Sirt1 Antisense Long Noncoding RNA Promotes Cardiomyocyte Proliferation by Enhancing the Stability of Sirt1. J Am Heart Assoc. 7(21): e009700.
- Zhong L et al. 2019. SM22α (Smooth Muscle 22α) Prevents Aortic Aneurysm Formation by Inhibiting Smooth Muscle Cell Phenotypic Switching Through Suppressing Reactive Oxygen Species/NF-κB (Nuclear Factor-κB). Arterioscler Thromb Vasc Biol. 39(1):e10-e25.
- Hu Y et al. 2019. Suppression of MicroRNA Let-7i-5p Promotes Cardiomyocyte Proliferation and Repairs Heart Function Post Injury by Targeting CCND2 and E2F2. Clin Sci (Lond). 133(3): 425-441.
- Wu QQ et al. 2019. The protective effect of high mobility group protein HMGA2 in pressure overload-induced cardiac remodeling. J Mol Cell Cardiol. 128:160-178.
