Gene therapy for phenylketonuria mouse model using pseudotyped adeno‐associated virus vector

Abstract

Phenylketonuria (PKU) is an inherited metabolic disorder caused by a deficiency of phenylalanine hydroxylase. The accumulation of phenylalanine leads to severe mental and psychomotor retardation. Phenylalanine restriction diet can prevent irreversible damage if instituted from birth. Recently, we reported the cognitive outcome of biochemical and phenotypic reversal of PKU mouse model, Pahenu2, by the AAV 2-mediated gene delivery of a human PAH transgene (Pediatr Res 56:–284, 2004). However, the therapeutic effectiveness had been observed only in male PKU mice. No normalization in coat color or plasma phenylalanine level was observed in gene therapy on female PKU mice. In this study, we generated pseudotyped AAV2/8 vector encoding the human PAH gene. The rAAV2/8-hPAH vector was infused into female PKU mice via the hepatic portal vein. Six weeks after injection, the coat color change to black was clearly observed in female PKU as in male. Plasma phenylalanine level in female PKU mice decreased to 120_μM/L. The PAH enzyme activities of treated mouse liver increased to 65–70% of wild-type in female PKU mice, to 90–95% in male PKU mice. These corrections were sustained over 6 month. Furthermore, we observed rAAV2/8-hPAH treated female PKU mice can overcome maternal PKU syndrome. These results indicate that recombinant AAV 2/8 mediated gene therapy can be a useful therapeutic candidate for patients with PKU.