Light Promotes Regeneration and Functional Recovery and Alters the Immune Response After Spinal Cord Injury

Lasers in Surgery and Medicine 36:171–185 (2005)

Kimberly R. Byrnes PhD, Ronald W. Waynant PhD, Ilko K. Ilev,PhD, Xingjia Wu,BS, Lauren Barna,BS, Kimberly Smith, Reed Heckert,BS, Heather Gerst, BS and Juanita J. Anders,PhD.

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 ¼ 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 Spinal Cord Injury.  

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