Factor IX expression in skeletal muscle of a severe hemophilia B patient 10 years after AAV-mediated gene transfer

• Published in: Blood Vol. 119; no. 13; pp. 3038 - 3041
• Main Authors: Buchlis, George, Podsakoff, Gregory M., Radu, Antonetta, Hawk, Sarah M., Flake, Alan W., Mingozzi, Federico, High, Katherine A.
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 29.03.2012; Americain Society of Hematology; American Society of Hematology
• Subjects: Adult; Biological and medical sciences; Brief Report; Dependovirus - genetics; Dependovirus - physiology; Factor IX - genetics; Factor IX - metabolism; Gene Expression; Gene Therapy; Gene Transfer Techniques; Genetic Therapy - methods; Genetic Vectors - administration & dosage; Genetic Vectors - genetics; Hematologic and hematopoietic diseases; Hemophilia B - genetics; Hemophilia B - metabolism; Hemophilia B - pathology; Hemophilia B - therapy; Humans; Male; Medical sciences; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; Organ Specificity - genetics; Platelet diseases and coagulopathies; Severity of Illness Index; Thrombosis and Hemostasis; Time Factors; Human; Hematology; Hemophilia B; Hemopathy; Dependovirus; Striated muscle; Hemophilia A; Genetic disease; Genetic transfer; Virus; Factor IX; Parvoviridae; Coagulopathy; Parvovirinae
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2011-09-382317

In previous work we transferred a human factor IX–encoding adeno-associated viral vector (AAV) into skeletal muscle of men with severe hemophilia B. Biopsy of injected muscle up to 1 year after vector injection showed evidence of gene transfer by Southern blot and of protein expression by IHC and immunofluorescent staining. Although the procedure appeared safe, circulating F.IX levels remained subtherapeutic (< 1%). Recently, we obtained muscle tissue from a subject injected 10 years earlier who died of causes unrelated to gene transfer. Using Western blot, IHC, and immunofluorescent staining, we show persistent factor IX expression in injected muscle tissue. F.IX transcripts were detected in injected skeletal muscle using RT-PCR, and isolated whole genomic DNA tested positive for the presence of the transferred AAV vector sequence. This is the longest reported transgene expression to date from a parenterally administered AAV vector, with broad implications for the future of muscle-directed gene transfer.