No tumour-initiating risk associated with scAAV transduction in newborn rat liver.
Delivery of recombinant adeno-associated virus (rAAV) vectors to the newborn liver is followed by a rapid loss of episomal vector copies because of hepatocyte proliferation. In selected hepatocytes, integration of rAAV genomes can lead to a sustained expression of the transgene. The safety of in vivo gene therapy with single-stranded AAV vectors has been questioned in a study reporting a high incidence of hepatocellular carcinoma, associated with provirus integration events in mice that receive an single-stranded AAV injection at birth. To investigate the tumour-initiating potential of the newly established self-complementary AAV (scAAV) vectors in the liver, groups of newborn rats received intravenous injection of a scAAV vector encoding the green fluorescent protein (GFP), or were injected with phosphate-buffered saline (PBS) or diethylnitrosamine (DEN), a well-known liver tumour initiator. The rats were fed on a diet containing 2-acetylaminofluorene, a potent liver tumour-promoting agent to accelerate the carcinogenic process. After 2 months, the animals were killed and their livers analysed. Preneoplastic nodules were identified by glutathion S-transferase-p (GSTp) staining, and GFP expression was detected by immunohistochemistry. Vector genome integration events were analysed. The numbers of GSTp-positive foci were comparable in the PBS and the scAAV-GFP groups and significantly higher in the DEN group. The proportion of GSTp-positive foci that also expressed GFP was low and in the range expected for random occurrence. No specific integration hot spots were detected by linear amplification-mediated-PCR in transduced liver. In conclusion, scAAV transduction of newborn rat liver does not trigger preneoplastic lesions suggesting an absence of liver tumourigenesis.
INSERM UMR1064, Centre de Recherche en Transplantation et en Immunologie, Université de Nantes, CHU Hôtel Dieu, Nantes, France.
V
V
Gauttier
V
V
Pichard
D
D
Aubert
C
C
Kaeppel
M
M
Schmidt
N
N
Ferry
S
S
Conchon
D000818:Animals; D000229:Dependovirus / Q000235:genetics*; D015316:Genetic Therapy / Q000009:adverse effects*; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D022781:Hepatocytes / Q000473:pathology* / Q000821:virology; D008099:Liver / Q000378:metabolism / Q000473:pathology* / Q000821:virology; D051379:Mice; D009369:Neoplasms / Q000235:genetics / Q000473:pathology / Q000821:virology; D051381:Rats; D014161:Transduction, Genetic
D049452:Green Fluorescent Proteins