Co-targeting B-RAF and PTEN Enables Sensory Axons to Regenerate Across and Beyond the Spinal Cord Injury

Area of Science:

• Neuroscience
• Regenerative Medicine
• Spinal Cord Injury Research

Background:

• Adult mammalian primary sensory axons exhibit limited regeneration capacity following spinal cord injury (SCI).
• Insufficient intrinsic growth potential is a key barrier to axon regeneration after SCI.
• Previous studies indicated B-RAF activation and PTEN deletion promote axon regeneration in other nerve injuries.

Purpose of the Study:

• To investigate the efficacy of concurrently targeting B-RAF and PTEN in dorsal root ganglion (DRG) neurons for promoting dorsal column (DC) axon regeneration after SCI.
• To evaluate if this combined genetic targeting enhances the intrinsic growth potential of primary sensory axons post-SCI.

Main Methods:

• Genetic manipulation of B-RAF activation and PTEN deletion in DRG neurons of adult mice.
• Assessment of DC axon regeneration following SCI using histological analysis.
• Comparison of regeneration efficacy with pre-conditioning lesion strategies.

Main Results:

• Concurrent genetic targeting of B-RAF and PTEN enabled DC axons to regenerate beyond the SCI lesion site, with some reaching approximately 2 mm rostrally.
• This co-targeting strategy promoted more robust DC regeneration compared to a pre-conditioning lesion alone.
• The regenerative effect was additive when pre-conditioning lesion was combined with B-RAF/PTEN co-targeting.
• Post-injury targeting of B-RAF and PTEN also demonstrated enhanced DC axon regeneration.

Conclusions:

• Co-targeting B-RAF and PTEN effectively enhances the intrinsic growth potential of primary sensory axons after SCI.
• This dual genetic approach represents a promising novel strategy for promoting robust, long-distance regeneration of DC axons post-spinal cord injury.