Potential for cellular stress response to hepatic factor VIII expression from AAV vector.

Area of Science:

• Gene Therapy
• Hematology
• Hepatology

Background:

• Hemophilia A and B are inherited bleeding disorders caused by deficiencies in coagulation factors VIII (FVIII) or IX.
• Adeno-associated virus (AAV) vector gene therapy shows promise for hemophilia B, but challenges remain for hemophilia A due to F8 cDNA size and FVIII protein secretion issues.
• Overexpression of FVIII can induce endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) in hepatocytes.

Purpose of the Study:

• To investigate whether AAV-mediated gene transfer of F8 in murine hepatocytes triggers the unfolded protein response (UPR).
• To assess the safety and immunogenicity of AAV gene transfer for hemophilia A at varying vector doses.

Main Methods:

• Engineered F8 transgene (BDD-FVIII, codon-optimized) for AAV vector generation.
• AAV gene delivery of F8 into C57BL/6 mice.
• Analysis of UPR markers, liver pathology, apoptosis, and FVIII immunogenicity at different vector doses.

Main Results:

• A mild activation of UPR markers was observed following F8 gene delivery at a specific vector dose.
• Increased vector dosing did not augment UPR activation.
• No significant liver pathology, apoptosis, or impact on FVIII immunogenicity was detected.

Conclusions:

• AAV-mediated F8 gene transfer in mice does not cause significant UPR-related liver toxicity.
• Engineered F8 transgenes in AAV vectors are a viable strategy for hemophilia A gene therapy.
• This approach holds potential for safe and effective therapeutic FVIII protein expression.