Protective Effect of 940 nm Laser on Gamma-Irradiated Mice

Abstract

Objective: The purpose of this study was to investigate the radioprotective features of 940 nm laser on the life span of mice, and absolute counts of blood cells and their proportions in gamma-irradiated mice. Background data: An important feature of laser light is activation of mitotic division and differentiation of cells, which may be useful in activation of hematopoiesis in gamma-irradiated organisms. Materials and methods: Mice were randomly assigned to 11 groups according to the type(s) of influence. Generally, mice were irradiated in three different ways: with laser at different fluences, with gamma irradiation, or by combination of laser at different fluences and gamma irradiation in a different order. Mice were treated with 940 nm laser at 3, 12, or 18 J/cm 2 and/or a lethal dose of gamma irradiation (8.7 Gy). Each group was randomly subdivided into two subgroups, in which the life span of the mice and blood cell counts (on 12th and 45th day after gamma irradiation) were analyzed. Results: Laser (940 nm) at a fluence of 3 J/cm 2 significantly prolonged the life span of gammairradiated mice ( p < 0.05). In the same group, counts of white blood cells, lymphocytes, and neutrophils were higher on day 12 than in the gamma group. On day 45 after gamma irradiation, some signs of hematopoiesis repair were found in blood. There were no significant differences in counts of erythrocytes, monocytes, neutrophils, or the proportion of neutrophils between this group and the control group. Conclusions: In summary, 940 nm laser at a fluence of 3 J/cm 2 demonstrates radioprotective features in an experiment with lethally irradiated mice. Mechanisms responsible for this effect will be investigated in further studies.

Radioreparative Effect of Diode Laser on Leukopoiesis Recovery: A Pilot Study

“…As a result of this impact, the mice in group C had a greater number of WBCs than the mice in group B. This effect of laser therapy corresponded with results from our previous experiment [20] and may have led to the more effective regeneration of hematopoiesis and the prolonged lifespan of mice even after irradiation with a lethal dose of gamma radiation.…”

“…We did not organize a group of healthy mice irradiated with laser radiation only, because the primary aim of our study was to explore the effectiveness of laser treatment in the recovery of leukopoiesis post-irradiation and proposed that such a group would not provide direct information relevant to this specific research question. In our prior research we had already demonstrated that high-power laser treatment can reduce the counts of certain peripheral blood cells (absolute counts of white blood cells, lymphocytes, neutrophils, and monocytes) in a dose-dependent manner [20]. These fallouts helped us to explain the results in the group irradiated by gamma radiation 24 h after laser therapy [20].…”

“…This was observed in our experiment. In our previous work [20], we investigated the effect of the order of irradiation by a 940 nm laser and the influence of its energy density on the survival and recovery of hematopoiesis in mice irradiated with a lethal dose of IR. It was shown that a single laser treatment of the gamma-irradiated mice (3 J/cm 2 , 20 Hz, and 5 W) resulted in survival and lifespan extensions and statistically significantly, 2.33 to 3.33 times, higher WBC, LYM, and NEU counts on day 12 after gamma irradiation, compared to mice that did not receive the laser therapy.…”

“…As mentioned earlier, in the mammalian organism, granulocytes and LYMs are involved in the protection of the organism against pathogens, which, by their action on the irradiated organism, can lead to a lethal outcome. In our previous experiment [20], we observed two groups of mice irradiated with gamma radiation and a laser. The absolute numbers of NEUs and LYMs were higher than in the other groups.…”

“…In our previous experiment, a 940 nm, 5 W, 20 Hz, 3 J/cm 2 energy density laser was shown to prolong the lifespan of mice exposed to a lethal dose of gamma radiation (8.7 Gy) when used 24 h after gamma irradiation. In addition, laser therapy with the above parameters increased the absolute numbers of leukocytes (LEUs), including granulocytes, lymphocytes (LYMs), and T-lymphocytes (T-LYMs), in the peripheral blood by 1.5-3.67 times on day 12, compared to the group of gamma-irradiated animals [20].…”