Efficient Gene Transfer into Cardiac Myocytes Using Adeno-Associated Virus (AAV) Vectors

Adeno-associated virus (AAV) vectors, derived from a non-pathogenic parvovirus, are considered to be an appropriate gene transfer vehicle for both dividing and non-dividing cells. In the present study, we investigated whether the rat heart could be efficiently transduced with AAV vectors. Rat cardiac myocytes (CM) were infected with AAV-lacZ vector containingβ-galactosidase (β-gal) genein vitro, and the expression ofβ-gal in CM was evaluated by X-gal staining andβ-gal ELISA. With increasing multiplicities of infection (MOI), more than 60% of CM were stained positively with X-gal, and theβ-gal expression increased to 31.1±4.6 ng/mg protein in a MOI-dependent manner (MOI: 104to 106particles/cell). Theβ-gal expression was also increased in an incubation period-dependent manner (1–24 h).β-gal expression was maximal at day 3 and then gradually decreased with time. However,β-gal expression at day 14 was almost the same level as that at day 1 (45.5±5.9v55.2±6.2 ng/mg protein). Excised rat right ventricular papillary muscles were also infected with AAV-lacZex vivo. When theβ-gal expression was evaluated by X-gal staining, more than 80% of CM in the papillary muscles were stained positively, indicating efficient gene transfer into CM using AAV vectors. These findings suggest that AAV vectors are promising for cardiac gene therapy.