AAV9-Mediated Targeting of Defined Neuronal Populations in Spinal Cord Through Intrathecal Injection

Area of Science:

• Neuroscience
• Molecular Biology
• Gene Therapy

Background:

• Adeno-associated viruses (AAVs) are effective vectors for gene delivery to the central nervous system (CNS).
• Targeting specific neuronal subtypes enhances precision and therapeutic potential in CNS gene therapy.

Purpose of the Study:

• To evaluate the efficacy of different promoters (CMV, hSyn, Hb9) in adeno-associated virus serotype 9 (AAV9) vectors for gene delivery to specific spinal cord neuronal populations.
• To investigate the impact of promoter choice and spinal cord segmental level on transgene expression patterns.

Main Methods:

• Intrathecal delivery of recombinant AAV9 vectors with CMV, hSyn, or Hb9 promoters in Wistar rats.
• Confocal microscopy evaluation of transgene expression in spinal cord laminae VII-X at cervical, thoracic, lumbar, and sacral levels.
• Quantitative analysis of transduced neurons and statistical comparison across promoters and spinal cord regions.

Main Results:

• hSyn promoter demonstrated consistent neuronal expression in lamina VII across all spinal levels, with higher transduction in cervical regions.
• CMV promoter drove higher expression in lamina VIII and X compared to hSyn and Hb9, but showed non-specific glial cell transduction.
• Hb9 promoter specifically restricted expression to motoneuron somata in lamina IX, indicating high specificity.

Conclusions:

• Promoter selection significantly influences AAV9-mediated gene expression patterns in the spinal cord.
• Hb9 promoter is optimal for specific motoneuron targeting, hSyn for broad neuronal expression, and CMV for robust but less specific expression.
• Rational promoter selection is crucial for developing effective spinal cord gene therapies for motor system disorders.