Transient Growth Factor Delivery Sustains Regenerated Axons after Spinal Cord Injury

Researchers explored whether continuous neurotrophin delivery is needed to maintain regenerating axons after spinal cord injury (SCI). They hypothesized that transient growth factor delivery might be sufficient to sustain axons. Using a tetracycline-inducible system, they controlled brain-derived neurotrophic factor (BDNF) expression in genetically modified fibroblasts. This allowed them to switch growth factor expression "on" or "off" at the injury site. The study found that brief growth factor delivery could indeed sustain regenerated axons in spinal cord lesions. This suggests the adult CNS can maintain axons extended by temporary growth factor exposure, possibly due to persistent Schwann cells.

• 1
  Transient growth factor delivery is sufficient to sustain long-term axonal projections into a site of SCI.
• 2
  BDNF protein levels could be positively regulated using an orally administered agent (doxycycline).
• 3
  Axon density in the graft remained high even after BDNF expression was turned off, suggesting a continued growth stimulus or synapse formation isn't required.