Muscle stem cells can act as antigen-presenting cells: implication for gene therapy

Area of Science:

• Gene therapy
• Immunology
• Muscle biology

Background:

• Adenoviral vectors are used for gene transfer.
• Promoters influence transgene expression and immune response.
• Muscle-specific promoters may offer advantages in gene therapy.

Purpose of the Study:

• To compare the efficiency of direct and ex vivo gene transfer using adenoviral vectors with different promoters (CMV vs. MCK).
• To investigate the impact of promoter choice on immune response and transgene expression in skeletal muscle.
• To evaluate the role of muscle-derived stem cells (MDSCs) in gene transfer and immune reactions.

Main Methods:

• Adenoviral vectors encoding luciferase under cytomegalovirus (CMV) or muscle creatine kinase (MCK) promoters were constructed.
• Direct intramuscular injection and ex vivo gene transfer using MDSCs were performed in mdx mice.
• Immune response and transgene expression levels were monitored over time.

Main Results:

• Direct injection of ADMCK (MCK promoter) resulted in lower immune response and more persistent transgene expression compared to ADCMV (CMV promoter).
• Ex vivo gene transfer using ADMCK-transduced MDSCs showed a weaker immune response and longer transgene expression than ADCMV-transduced MDSCs.
• The immune response in ex vivo transfer was linked to MDSC death or MDSCs acting as antigen-presenting cells (APCs).

Conclusions:

• Muscle-specific promoters, such as MCK, can significantly reduce immune responses in gene therapy for skeletal muscle.
• Restricting transgene expression to differentiated muscle cells prevents MDSCs from becoming APCs, improving ex vivo gene transfer efficiency.
• Utilizing muscle-specific promoters is a promising strategy to enhance the efficacy and durability of gene therapy for muscle disorders.