Abstract：
Photobiomodulation therapy (PBM) has shown positive effects when applied locally to modulate the inflammatory process and facilitate muscle repair. However, the available literature on the mechanisms of action of vascular photobiomodulation (VPBM), a non-invasive method of vascular irradiation, specifically in the context of local muscle repair, is limited. Thus, this study aimed to assess the impact of vascular photobiomodulation (VPBM) using a low-level laser (LLL) on the inflammatory response and the process of skeletal muscle repair whether administered prior to or following cryoinjury-induced acute muscle damage in the tibialis anterior (TA) muscles. Wistar rats (n = 85) were organized into the following experimental groups: (1) Control (n = 5); (2) Non-Injury + VPBM (n = 20); (3) Injured (n = 20); (4) Pre-VPBM + Injury (n = 20); (5) Injury + Post-VPBM (n = 20). VPBM was administered over the vein/artery at the base of the animals\' tails (wavelength: 780 nm; power: 40 mW; application area: 0.04 cm2; energy density: 80 J/cm2). Euthanasia of the animals was carried out at 1, 2, 5, and 7 days after inducing the injuries. Tibialis anterior (TA) muscles were collected for both qualitative and quantitative histological analysis using H&E staining and for assessing protein expression of TNF-α, MCP-1, IL-1β, and IL-6 via ELISA. Blood samples were collected and analyzed using an automatic hematological analyzer and a leukocyte differential counter. Data were subjected to statistical analysis (ANOVA/Tukey). The results revealed that applying VPBM prior to injury led to an increase in circulating neutrophils (granulocytes) after 1 day and a subsequent increase in monocytes after 2 and 5 days, compared to the Non-Injury + VPBM and Injured groups. Notably, an increase in erythrocytes and hemoglobin concentration was observed in the Non-Injury + VPBM group on days 1 and 2 in comparison to the Injured group. In terms of histological aspects, only the Prior VPBM + Injured group exhibited a reduction in the number of inflammatory cells after 1, 5, and 7 days, along with an increase in blood vessels at 5 days. Both the Prior VPBM + Injured and Injured + VPBM after groups displayed a decrease in myonecrosis at 1, 2, and 7 days, an increase in newly-formed and immature fibers after 5 and 7 days, and neovascularization after 1, 2, and 7 days. Regarding protein expression, there was an increase in MCP-1 after 1 and 5 days, TNF-α, IL-6, and IL-1β after 1, 2, and 5 days in the Injured + VPBM after group when compared to the other experimental groups. The Prior VPBM + Injured group exhibited increased MCP-1 production after 2 days, in comparison to the Non-Injury + VPBM and Control groups. Notably, on day 7, the Injured group continued to show elevated MCP-1 protein expression when compared to the VPBM groups. In conclusion, VPBM effectively modulated hematological parameters, circulating leukocytes, the protein expression of the chemokine MCP-1, and the proinflammatory cytokines TNF-α and IL-1β, ultimately influencing the inflammatory process. This modulation resulted in a reduction of myonecrosis, restoration of tissue architecture, increased formation of newly and immature muscle fibers, and enhanced neovascularization, with more pronounced effects when VPBM was applied prior to the muscle injury.
摘要：
光生物调节疗法（PBM）在局部应用以调节炎症过程并促进肌肉修复时显示出积极作用。然而,关于血管光生物调节(VPBM)作用机制的现有文献，一种非侵入性的血管照射方法，特别是在局部肌肉修复的背景下，是有限的。因此，这项研究旨在评估使用低水平激光(LLL)进行血管光生物调节(VPBM)对胫骨前肌(TA)冷冻损伤诱导的急性肌肉损伤之前或之后炎症反应和骨骼肌修复过程的影响.将Wistar大鼠(n=85)分为以下实验组:(1)对照(n=5);(2)非损伤+VPBM(n=20);(3)损伤(n=20);(4)VPBM前+损伤(n=20);(5)损伤+VPBM后(n=20)。在动物尾部的静脉/动脉上施用VPBM(波长:780nm;功率:40mW;施用面积:0.04cm2;能量密度:80J/cm2)。在诱导损伤后1、2、5和7天进行动物的安乐死。收集胫骨前（TA）肌肉进行定性和定量组织学分析，使用H＆E染色和评估TNF-α的蛋白表达，MCP-1,IL-1β,和IL-6通过ELISA。收集血液样品并使用自动血液分析仪和白细胞分类计数器进行分析。对数据进行统计分析(ANOVA/Tukey)。结果表明，在损伤前应用VPBM导致1天后循环中性粒细胞（粒细胞）增加，2天和5天后单核细胞随后增加，与非损伤+VPBM和损伤组相比。值得注意的是,与损伤组相比,非损伤+VPBM组在第1天和第2天观察到红细胞和血红蛋白浓度增加.在组织学方面，只有先前的VPBM+损伤组在1、5和7天后显示炎症细胞数量减少，随着5天血管的增加。先前的VPBM+损伤组和损伤后的VPBM在第1、2和7天显示出心肌坏死的减少，5天和7天后，新形成的和未成熟的纤维增加，以及1、2和7天后的新生血管形成。关于蛋白质表达，1天和5天后MCP-1增加，TNF-α,当与其他实验组比较时,损伤+VPBM后1、2和5天后的IL-6和IL-1β。先前的VPBM+损伤组显示2天后MCP-1产生增加，与非损伤+VPBM和对照组相比。值得注意的是,在第7天,当与VPBM组相比时,损伤组继续显示升高的MCP-1蛋白表达。总之,VPBM有效调节血液学参数，循环白细胞，趋化因子MCP-1、促炎细胞因子TNF-α和IL-1β的蛋白表达,最终影响炎症过程。这种调节导致了心肌坏死的减少，组织结构的恢复，新的和未成熟的肌肉纤维的形成增加，增强了新生血管形成，当在肌肉损伤之前应用VPBM时，效果更明显。
