Light promotes regeneration and functional recovery and alters the immune response after spinal cord injury

Lasers Surg Med. 2005 Mar;36(3):171-85. doi: 10.1002/lsm.20143.


Background and objectives: Photobiomodulation (PBM) has been proposed as a potential therapy for spinal cord injury (SCI). We aimed to demonstrate that 810 nm light can penetrate deep into the body and promote neuronal regeneration and functional recovery.

Study design/materials and methods: Adult rats underwent a T9 dorsal hemisection, followed by treatment with an 810 nm, 150 mW diode laser (dosage = 1,589 J/cm2). Axonal regeneration and functional recovery were assessed using single and double label tract tracing and various locomotor tasks. The immune response within the spinal cord was also assessed.

Results: PBM, with 6% power penetration to the spinal cord depth, significantly increased axonal number and distance of regrowth (P < 0.001). PBM also returned aspects of function to baseline levels and significantly suppressed immune cell activation and cytokine/chemokine expression.

Conclusion: Our results demonstrate that light, delivered transcutaneously, improves recovery after injury and suggests that light will be a useful treatment for human SCI.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Axons / physiology*
  • Cytokines / metabolism
  • Ectodysplasins
  • Female
  • Glial Fibrillary Acidic Protein / metabolism
  • Immunohistochemistry
  • Leukocyte Common Antigens / metabolism
  • Locomotion / radiation effects
  • Low-Level Light Therapy*
  • Macrophages / metabolism
  • Membrane Proteins / metabolism
  • Nerve Regeneration / physiology*
  • Neuroglia / metabolism
  • Nitric Oxide Synthase / metabolism
  • Radiotherapy Dosage
  • Rats
  • Rats, Sprague-Dawley
  • Recovery of Function / physiology*
  • Spectrophotometry
  • Spinal Cord Injuries / physiopathology
  • Spinal Cord Injuries / radiotherapy*
  • T-Lymphocytes / metabolism


  • Cytokines
  • EDA protein, human
  • Ectodysplasins
  • Glial Fibrillary Acidic Protein
  • Membrane Proteins
  • Nitric Oxide Synthase
  • Leukocyte Common Antigens