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


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.


CONCLUSIONS
Our results demonstrate that light, delivered transcutaneously, improves recovery after injury and suggests that light will be a useful treatment for human SCI.
Byrnes
Kimberly R
KR
Department of Anatomy, Physiology & Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA. krb27@georgetown.edu
Waynant
Ronald W
RW
Ilev
Ilko K
IK
Wu
Xingjia
X
Barna
Lauren
L
Smith
Kimberly
K
Heckert
Reed
R
Gerst
Heather
H
Anders
Juanita J
JJ
D000818:Animals; D001369:Axons / Q000502:physiology*; D016207:Cytokines / Q000378:metabolism; D053331:Ectodysplasins; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008124:Locomotion / Q000528:radiation effects; D028022:Low-Level Light Therapy; D008264:Macrophages / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009416:Nerve Regeneration / Q000502:physiology*; D009457:Neuroglia / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011879:Radiotherapy Dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology*; D013053:Spectrophotometry; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000532:radiotherapy*; D013601:T-Lymphocytes / Q000378:metabolism
D016207:Cytokines; C506018:EDA protein, human; D053331:Ectodysplasins; D005904:Glial Fibrillary Acidic Protein; D008565:Membrane Proteins; D019001:Nitric Oxide Synthase; D017493:Leukocyte Common Antigens