Efficacy of an Adeno-associated Virus 8-Pseudotyped Vector in Glycogen Storage Disease Type II

Abstract

Glycogen storage disease type II (GSD-II; Pompe disease) causes death in infancy from cardiorespiratory failure. The underlying deficiency of acid alpha-glucosidase (GAA; acid maltase) can be corrected by liver-targeted gene therapy in GSD-II, if secretion of GAA is accompanied by receptor-mediated uptake in cardiac and skeletal muscle. An adeno-associated virus (AAV) vector encoding human (h) GAA was pseudotyped as AAV8 (AAV2/8) and injected intravenously into immunodeficient GSD-II mice. High levels of hGAA were maintained in plasma for 24 weeks following AAV2/8 vector administration. A marked increase in vector copy number in the liver was demonstrated for the AAV2/8 vector compared to the analogous AAV2/2 vector. GAA deficiency in the heart and skeletal muscle was corrected with the AAV2/8 vector in male GSD-II mice, consistent with receptor-mediated uptake of hGAA. Male GSD-II mice demonstrated complete correction of glycogen storage in heart and diaphragm with the AAV2/8 vector, while female GSD-II mice had correction only in the heart. A biomarker for GSD-II was reduced in both sexes following AAV2/8 vector administration. Therefore, GAA production with an AAV2/8 vector in a depot organ, the liver, generated evidence for efficacious gene therapy in a mouse model for GSD-II.

Pompe disease diagnosis and management guideline

“…Studies demonstrate that expression of the acid alpha glucosidase gene within muscle cells or in some cases secretion of GAA from liver leads to a reduction of the glycogen storage abnormality in the mice. Moreover, these studies showed that the immune response to the expressed enzyme in AAV-treated Pompe mice treated can be reduced in some cases117,121 or be influenced by tissue specific expression 118,119…”

Heart-targeted adeno-associated viral vectors selected by in vivo biopanning of a random viral display peptide library

“…40 Tissue directed in vivo gene transfer has also been attempted by systemic application of pseudotyped AAV6, AAV8 or AAV9 vectors. 38,39,[42][43][44][45] Besides the fact that there is only a limited number of vector serotypes available, by far lower than the variety of potential tissue targets, these serotype-based targeted vectors also have limited or no specificity for the tissue of interest. In congruence with this assumption, our data showed that the library-derived vectors presented here were more specific than AAV serotype 9 (at least with respect to biodistribution of the genomes), which is known to confer efficient transduction of heart tissue.…”

Stbd1 is highly elevated in skeletal muscle of Pompe disease mice but suppression of its expression does not affect lysosomal glycogen accumulation

“…Total RNA extraction and reverse transcription were performed as described [14]. Real-time PCR was performed using LightCycler 480 (Roche Diagnostics, Indianapolis, IN) and primers 5′-TGAGCCCTGA ACCTTCCGATC-3′ (forward) and 5′-GTGCTGTCGTCCATTCTCTGA-3′ (reverse).…”

“…Real-time PCR was performed using LightCycler 480 (Roche Diagnostics, Indianapolis, IN) and primers 5′-TGAGCCCTGA ACCTTCCGATC-3′ (forward) and 5′-GTGCTGTCGTCCATTCTCTGA-3′ (reverse). β-actin was used as internal control [14].…”

“…RIPA extracts of tissues were analyzed by Western blotting [14]. Primary antibodies used: rabbit anti mouse Stbd1, gift from Dr. Peter J. Roach, Indiana University [8]; LAMP2 and rabbit anti PYGM (Abcam); rabbit anti glycogen synthase (Cell Signaling); goat anti GAPDH (Novus Biologicals); rabbit anti LC3B; and HRP-conjugated mouse anti β-actin (Sigma-Aldrich).…”