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Bioengineered coagulation factor VIII enables long-term correction of murine hemophilia A following liver-directed adeno-associated viral vector delivery.

Brown HC, Wright JF, Zhou S, Lytle AM, Shields JE, Spencer HT, Doering CB - Mol Ther Methods Clin Dev (2014)

Bottom Line: Through bioengineering approaches, a novel fVIII molecule, designated ET3, was developed and shown to improve biosynthetic efficiency 10- to 100-fold.Due to the large size of the expression cassette, AAV-ET3 genomes packaged into viral particles as partial genome fragments.Despite this potential limitation, a single peripheral vein administration of AAV-ET3 into immune-competent hemophilia A mice resulted in correction of the fVIII deficiency at lower vector doses than previously reported for similarly oversized AAV-fVIII vectors.

View Article: PubMed Central - PubMed

Affiliation: Graduate Program in Molecular and Systems Pharmacology, Laney Graduate School, Emory University , Atlanta, Georgia, USA.

ABSTRACT
Clinical data support the feasibility and safety of adeno-associated viral (AAV) vectors in gene therapy applications. Despite several clinical trials of AAV-based gene transfer for hemophilia B, a unique set of obstacles impede the development of a similar approach for hemophilia A. These include (i) the size of the factor VIII (fVIII) transgene, (ii) humoral immune responses to fVIII, (iii) inefficient biosynthesis of human fVIII, and (iv) AAV vector immunity. Through bioengineering approaches, a novel fVIII molecule, designated ET3, was developed and shown to improve biosynthetic efficiency 10- to 100-fold. In this study, the utility of ET3 was assessed in the context of liver-directed, AAV-mediated gene transfer into hemophilia A mice. Due to the large size of the expression cassette, AAV-ET3 genomes packaged into viral particles as partial genome fragments. Despite this potential limitation, a single peripheral vein administration of AAV-ET3 into immune-competent hemophilia A mice resulted in correction of the fVIII deficiency at lower vector doses than previously reported for similarly oversized AAV-fVIII vectors. Therefore, ET3 appears to improve vector potency and mitigate at least one of the critical barriers to AAV-based clinical gene therapy for hemophilia A.

No MeSH data available.


Related in: MedlinePlus

Phenotypic correction of the bleeding diathesis. Hemophilia A mice treated with rAAV-HCR-ET3 were subjected to a tail transection bleeding assay to test for phenotypic correction. For clarity, mice are grouped by vector dose: High (8e12–2e13 vp/kg), medium (2e12–8e12 vp/kg) low (6.3e10–1e12 vp/kg) and no treatment control.
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fig6: Phenotypic correction of the bleeding diathesis. Hemophilia A mice treated with rAAV-HCR-ET3 were subjected to a tail transection bleeding assay to test for phenotypic correction. For clarity, mice are grouped by vector dose: High (8e12–2e13 vp/kg), medium (2e12–8e12 vp/kg) low (6.3e10–1e12 vp/kg) and no treatment control.

Mentions: Correction of the hemophilia A bleeding phenotype was assessed by tail transection bleeding assay on animals that received varying doses of rAAV-HCR-ET3 (Figure 6). Overall, mice that received rAAV-HCR-ET3 treatment demonstrated less blood loss than saline-treated control mice. Specifically, all mice that received one of the high vector doses (8e12–2e13 vp/kg) showed no detectable blood loss while mice that received medium (1e12–4e12 vp/kg) or low (6.2e10–5.0e11 vp/kg) doses demonstrated dose responsive decreases in blood loss that, both as individual groups and as a whole, were significantly less than saline treated controls (P < 0.005, Mann–Whitney U-test).


Bioengineered coagulation factor VIII enables long-term correction of murine hemophilia A following liver-directed adeno-associated viral vector delivery.

Brown HC, Wright JF, Zhou S, Lytle AM, Shields JE, Spencer HT, Doering CB - Mol Ther Methods Clin Dev (2014)

Phenotypic correction of the bleeding diathesis. Hemophilia A mice treated with rAAV-HCR-ET3 were subjected to a tail transection bleeding assay to test for phenotypic correction. For clarity, mice are grouped by vector dose: High (8e12–2e13 vp/kg), medium (2e12–8e12 vp/kg) low (6.3e10–1e12 vp/kg) and no treatment control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4362354&req=5

fig6: Phenotypic correction of the bleeding diathesis. Hemophilia A mice treated with rAAV-HCR-ET3 were subjected to a tail transection bleeding assay to test for phenotypic correction. For clarity, mice are grouped by vector dose: High (8e12–2e13 vp/kg), medium (2e12–8e12 vp/kg) low (6.3e10–1e12 vp/kg) and no treatment control.
Mentions: Correction of the hemophilia A bleeding phenotype was assessed by tail transection bleeding assay on animals that received varying doses of rAAV-HCR-ET3 (Figure 6). Overall, mice that received rAAV-HCR-ET3 treatment demonstrated less blood loss than saline-treated control mice. Specifically, all mice that received one of the high vector doses (8e12–2e13 vp/kg) showed no detectable blood loss while mice that received medium (1e12–4e12 vp/kg) or low (6.2e10–5.0e11 vp/kg) doses demonstrated dose responsive decreases in blood loss that, both as individual groups and as a whole, were significantly less than saline treated controls (P < 0.005, Mann–Whitney U-test).

Bottom Line: Through bioengineering approaches, a novel fVIII molecule, designated ET3, was developed and shown to improve biosynthetic efficiency 10- to 100-fold.Due to the large size of the expression cassette, AAV-ET3 genomes packaged into viral particles as partial genome fragments.Despite this potential limitation, a single peripheral vein administration of AAV-ET3 into immune-competent hemophilia A mice resulted in correction of the fVIII deficiency at lower vector doses than previously reported for similarly oversized AAV-fVIII vectors.

View Article: PubMed Central - PubMed

Affiliation: Graduate Program in Molecular and Systems Pharmacology, Laney Graduate School, Emory University , Atlanta, Georgia, USA.

ABSTRACT
Clinical data support the feasibility and safety of adeno-associated viral (AAV) vectors in gene therapy applications. Despite several clinical trials of AAV-based gene transfer for hemophilia B, a unique set of obstacles impede the development of a similar approach for hemophilia A. These include (i) the size of the factor VIII (fVIII) transgene, (ii) humoral immune responses to fVIII, (iii) inefficient biosynthesis of human fVIII, and (iv) AAV vector immunity. Through bioengineering approaches, a novel fVIII molecule, designated ET3, was developed and shown to improve biosynthetic efficiency 10- to 100-fold. In this study, the utility of ET3 was assessed in the context of liver-directed, AAV-mediated gene transfer into hemophilia A mice. Due to the large size of the expression cassette, AAV-ET3 genomes packaged into viral particles as partial genome fragments. Despite this potential limitation, a single peripheral vein administration of AAV-ET3 into immune-competent hemophilia A mice resulted in correction of the fVIII deficiency at lower vector doses than previously reported for similarly oversized AAV-fVIII vectors. Therefore, ET3 appears to improve vector potency and mitigate at least one of the critical barriers to AAV-based clinical gene therapy for hemophilia A.

No MeSH data available.


Related in: MedlinePlus