Low‐Level Laser Therapy for Closed‐Head Traumatic Brain Injury in Mice: Effect of Different Wavelengths

Abstract

Background and Objectives Traumatic brain injury (TBI) affects millions worldwide and is without effective treatment. One area that is attracting growing interest is the use of transcranial low-level laser therapy (LLLT) to treat TBI. The fact that near-infrared light can penetrate into the brain would allow non-invasive treatment to be carried out with a low likelihood of treatment-related adverse events. LLLT may treat TBI by increasing respiration in the mitochondria, causing activation of transcription factors, reducing inflammatory mediators and oxidative stress, and inhibiting apoptosis. Study Design/Materials and Methods We tested LLLT in a mouse model of closed-head TBI produced by a controlled weight drop onto the skull. Mice received a single treatment with continuous-wave 665, 730, 810, or 980 nm lasers (36 J/cm2 delivered at 150 mW/cm2) 4-hour post-TBI and were followed up by neurological performance testing for 4 weeks. Results Mice with moderate-to-severe TBI treated with 665 and 810 nm laser (but not with 730 or 980 nm) had a significant improvement in Neurological Severity Score that increased over the course of the follow-up compared to sham-treated controls. Morphometry of brain sections showed a reduction in small deficits in 665 and 810 nm laser treated mouse brains at 28 days. Conclusions The effectiveness of 810 nm agrees with previous publications, and together with the effectiveness of 660 nm and non-effectiveness of 730 and 980 nm can be explained by the absorption spectrum of cytochrome oxidase, the candidate mitochondrial chromophore in transcranial LLLT.

Low-Level Laser Therapy Effectively Prevents Secondary Brain Injury Induced by Immediate Early Responsive Gene X-1 Deficiency

“…Our current investigations extend previous findings confirming the beneficial effects of LLLT on a novel head trauma model with closed skull and scalp. 11,12 The results argue strongly for the great potential of LLLT as a convenient preventative strategy for TBI in the clinics. This is particularly of clinical significance for mTBI.…”

“…10 Exposure of the injured head to the laser greatly improved the neurologic performance of the injured mice as compared with untreated mice. 11,12 It is generally believed that the pathogenesis of secondary brain injury involves a complex cellular and molecular cascade in association with inadequate mitochondrial function, blood-brain barrier disruption, neuroinflammation, oxidative stress, cell death, and so on. 3 Owing to the complicated pathogenesis, no single animal model can recapitulate all aspects of the pathogenesis observed in humans so far.…”

Significant Improvements in Cognitive Performance Post-Transcranial, Red/Near-Infrared Light-Emitting Diode Treatments in Chronic, Mild Traumatic Brain Injury: Open-Protocol Study

“…36 Multiple animal studies using mice, show significantly better recovery of motor and cognitive function after NIR transcranial low-level laser therapy when treated in the acute post-injury phase. [37][38][39][40] Most of this work has suggested improved energy kinetics and decreased inflammation as possible mechanisms for acute neuroprotection. Energetics may also have a role in the chronic phase of injury.…”

Análise da expressão e mecanismos de ação das proteínas Akt, Hsp90, mTOR e ciclina D1 em cultura de células de carcinoma epidermoide humano e células displásicas após irradiação com laser em baixa intensidade

“…O aumento da atividade mitocondrial muitas vezes encontrado em células que tiveram contato com LLLT (262)(263)(264)(265)(266) é, na realidade, importante para o estabelecimento de alguns tratamentos, como o de traumatismo craniano (174) e de regeneração de células nervosas (267) . Isto porque um aumento da atividade das mitocôndrias leva à consequente geração de ATP e aceleração do metabolismo celular (261) , tornando-se importante para a reparação tecidual frente a injúrias, por exemplo (268)(269)(270) .…”

“…Esta terapia vem crescendo no campo do derrame cerebral (170,171) , injuria traumática do cérebro (172)(173)(174) , doenças neurodegenerativas (175) , e lesões de medula espinal (176) .…”