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Research Studies on Laser Therapy

 

SPINAL CORD INJURY RESEARCH STUDIES

CELLULAR INVASION FOLLOWING SPINAL CORD LESION AND LOW POWER LASER IRRADIATION.

Laser Med Surg Abstract issue, 2002: 11.
Byrnes K R, Waynant R W, Ilev I K et al.

In a rat experiment by Byrnes the spinal cord was hemisected at vertebral level T9. 810 nm laser was applied immediately after hemisection and daily for 14 days, 1589 J/cm2. Control rats received identical treatment, but without laser. The results indicate that laser therapy initially blocks cell invasion and activation of the injured spinal cord. Once laser therapy ceases at 14 days post-injury (the time point at which lesioned axons are reported to begin to sprout) there is a rebound increase in non-inflammatory cell invasion and activation that is visible 16 days postinjury.
These alterations in the spinal cord environment may contribute to the ability of lesioned axons to regenerate following injury.

TRANSPLANTATION OF EMBRYONAL SPINAL CORD NERVE CELLS CULTURED IN BIODEGRADABLE MICROCARRIERS FOLLOWED BY LOW POWER LASER IRRADIATION FOR THE TREATMENT OF TRAUMATIC PARAPLEGIA IN RATS.

Neur Res. 2002; 24.
Rochkind S, Shahar A, Alon M, Nevo Z.

In the study by Rochkind embryonal spinal cord nerve cells dissociated from rat fetuses, cultured in biodegradable microcarriers and embedded in hyaluronic acid, were implanted in the completely transsected spinal cords in 24 adult rats. 15 rats underwent 14 days of consecutive laser irradiation (780 nm, 250 mW, 30 minutes daily). 7 rats received the same treatment but without laser. Eleven of the 15 laser treated rats showed different degrees of active leg movements and gait performance compared to 4 of the 9 rats with implantation alone. In a control group of 7 rats with no therapy after the transsection of the spinal cord, six remained completely paralysed. Intensive axonal sprouting occurred in the laser group. In the control group the transsected area contained proliferating fibroblasts and blood capillaries only.

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DOUBLE-BLIND RANDOMIZED STUDY EVALUATING REGENERATION OF THE RAT TRANSECTED SCIATIC NERVE AFTER SUTURING AND POSTOPERATIVE LOW-POWER LASER TREATMENT.

Journal of reconstructive microsurgery. 2001; 17 (2): 133-137.
Shamir M H, Rochkind S, Sandbank J, Alon M.

This double-blind randomized study evaluated the therapeutic effect of low-power laser irradiation (LPLI) on peripheral nerve regeneration, after complete transection and direct anastomosis of the rat sciatic nerve. After this procedure, 13 of 24 rats received postoperative LPLI, with a wavelength of 780 nm laser, applied transcutaneously, 30 min daily for 21 consecutive days, to corresponding segments of the spinal cord and to the injured sciatic nerve.

Positive somatosensory evoked responses were found in 69.2 percent of the irradiated rats compared to 18.2 percent of the non-irradiated rats. Immunohistochemical staining in the lasertreated group showed an increased total number of axons and better quality of the regeneration process, due to an increased number of large-diameter axons compared to the non-irradiated control group. The study suggests that postoperative LPLI enhances the regenerative processes of peripheral nerves after complete transection and anastomosis.

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EFFECTS OF LASER IRRADIATION ON THE SPINAL CORD FOR THE REGENERATION OF CRUSHED PERIPHERAL NERVE IN RATS.

Lasers in Surgery and Medicine 2001, 28 (3): 216-219
Rochkind-S, Nissan-M, Alon-M et al.

The purpose of the study was to examine the recovery of the crushed sciatic nerve of rats after low- power laser irradiation applied to the corresponding segments of the spinal cord. After a crush injury to the sciatic nerve in rats, low-power laser irradiation was applied transcutaneously to corresponding segments of the spinal cord immediately after closing the wound by using 16mW, 632 nm He-Ne laser. The laser treatment was repeated 30 minutes daily for 21 consecutive days. The electrophysiologic activity of the injured nerves (compound muscle action potentials-- CMAPs) was found to be approximately 90% of the normal precrush value and remained so for up to a long period of time. In the control nonirradiated group, electrophysiologic activity dropped to 20% of the normal precrush value at day 21 and showed the first signs of slow recovery 30 day after surgery. The two groups were found to be significantly different during follow-up period (P 0.001). This study suggests that low-power laser irradiation applied directly to the spinal cord can improve recovery of the corresponding injured peripheral nerve.

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LIGHT THERAPY (LLLT) ALTERS GENE EXPRESSION AFTER ACUTE SPINAL CORD INJUR

K.R. Byrnes (1), R.W. Waynant (2), I.K. Ilev (2), B. Johnson (1), Pollard H. (1), Srivastava M. (1), Eidelman O. (1), Huang, W. (1), J.J. Anders (1)
1. Department of Anatomy, Physiology and Genetics, Uniformed Services University, Bethesda, MD, USA;
2. Center for Devices and Radiological Health, Food and Drug Administration, Rockville, MD, USA

Secondary injury in the spinal cord, which results in axonal degeneration, scar and cavity formation and cell death, occurs around the site of the initial trauma and is a primary cause for the lack of axonal regeneration observed after spinal cord injury (SCI). The immune response after SCI is under investigation as a potential mediator of secondary injury. Treatment of SCI with 810 nm light suppresses the immune response and improves axonal regeneration.
We hypothesize that these beneficial effects observed in the injured spinal cord are accompanied by alterations in gene expression within the spinal cord, particularly of those genes involved in secondary injury and the immune response. To test this hypothesis, a dorsal hemisection at vertebral level T9 was performed. The injured spinal cord from rat was then exposed to laser light (810nm, 150mW, 2,997 seconds, 0.3cm2 spot area, 1589 J/cm2) and spinal cord samples, including the injury site, were harvested at 6 and 48 hours and 4 days post-injury. Total RNA was extracted and purified from the lesioned spinal cord and cDNA copies were either labeled with [32P] for microarray analysis or amplified and analyzed with a polymerase chain reaction (PCR).

Microarray results revealed a suppression of genes involved in the immune response and excitotoxic cell death at 6 hours post-injury, as well as cell proliferation and scar formation at 48 hours post-injury in the light treated group. Analysis of the PCR products revealed that light treatment resulted in a significant suppression of expression of genes that normally peak between 6 and 24 hours post-injury, including the pro-inflammatory cytokine interleukin 6 (IL6), the chemokine monocyte chemoattractant protein 1 (MCP-1) and inducible nitric oxide synthase (iNOS; p<0.05). Genes expressed earlier than 6 hours post-injury, such as IL1b, tumor necrosis factor a (TNFa) and macrophage inflammatory protein 1a (MIP-1a) were not affected by light treatment.

Although the precise role some of these genes play in axonal regeneration after spinal cord injury is currently unclear, these data demonstrate that light therapy has an anti-inflammatory effect on the injured spinal cord, and may reduce secondary injury, thus providing a possible mechanism by which light therapy may result in axonal regeneration

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