Improved performance of a fully gutted adenovirus vector containing two full-length dystrophin cDNAs regulated by a...

Area of Science:

• Gene Therapy
• Molecular Biology
• Biotechnology

Background:

• Duchenne muscular dystrophy (DMD) is a severe genetic disorder caused by mutations in the dystrophin gene.
• Adenovirus-based gene transfer, particularly using helper-dependent adenoviruses (HDAd), shows promise for DMD treatment.
• Existing HDAd vectors require optimization to enhance dystrophin production and achieve sustained therapeutic effects.

Purpose of the Study:

• To construct and evaluate a novel, fully deleted HDAd vector (HDCBDys2x) for enhanced dystrophin gene transfer.
• To assess the efficiency and durability of dystrophin expression in dystrophin-deficient (mdx) mouse models.
• To investigate factors influencing transgene expression levels and immune responses.

Main Methods:

• Construction of a fully deleted HDAd vector (HDCBDys2x) carrying two human dystrophin cDNAs under a strong promoter.
• Infection of muscle cultures and intramuscular injection of HDCBDys2x into neonatal and adult mdx mice.
• Analysis of dystrophin expression levels, muscle fiber transduction, and humoral immune responses.

Main Results:

• HDCBDys2x demonstrated high dystrophin expression in muscle cultures and significant muscle fiber transduction in mdx mice.
• Neonatally injected mdx mice showed supranormal levels of transferred dystrophin, but expression was transient.
• Sustained dystrophin expression was observed in immunodeficient mice, and co-administration with first-generation adenovirus enhanced expression.

Conclusions:

• The developed HDCBDys2x vector achieves abundant dystrophin expression, representing an improvement for DMD gene therapy.
• Transient expression and humoral immune responses in immunocompetent mdx mice highlight challenges for long-term efficacy.
• Future strategies should focus on employing less immunogenic transgenes to achieve sustained therapeutic benefits.