Far-Infrared Therapy Accelerates Diabetic Wound Healing via Recruitment of Tissue Angiogenesis in a Full-Thickness Wound Healing Model in Rats

Abstract

Far-infrared ray (FIR) therapy has been applied in the tissue regeneration field. Studies have revealed that FIR could enhance wound healing. However, the biological effects of FIR on diabetic wounds remain unclear. Our study aims to investigate whether FIR could accelerate diabetic wound healing and analyze the biomechanisms. A dorsal skin defect (area, 6 × 5 cm2) in a streptozotocin (STZ)-induced diabetes rodent model was designed. Thirty-two male Wistar rats were divided into 4 groups (n = 8 each subgroup). Group 1 consisted of sham, non-diabetic control; group 2, diabetic control without treatment; group 3, diabetic rats received 20 min FIR (FIR-20, 20 min per session, triplicate/weekly for 4 weeks) and group 4, diabetic rats received 40 min FIR (FIR-40, 40 min per session, triplicate in one week for 4 weeks). The wound healing was assessed clinically. Skin blood flow was measured by laser Doppler. The vascular endothelial growth factor (VEGF), 8-hydroxy-2-deoxyguanosine (8-OHdG), eNOS, and Ki-67, were analyzed with immunohistochemical (IHC) staining. Laser Doppler flowmetry analysis of the blood flow of wounding area revealed the blood flow was higher in diabetic rats who received 40 min FIR (FIR-40) as compared to that in FIR-20 group. The wounding area was significantly reduced in the FIR-40 group than in the diabetic control groups. Histological findings of peri-wounding tissue revealed a significant increase in the neo-vessels in the FIR-treated groups as compared to the controls. IHC staining of periwounding biopsy tissue showed significant increases in angiogenesis expressions (VEGF, eNOS, and EGF), cell proliferation (Ki-67), and suppressed inflammatory response and oxygen radicles (CD45, 8-OHdG) expressions in the FIR-treated groups as compared to that in controls. Treatment with the optimal dosage of FIR significantly facilitated diabetic wound healing and associated with suppressed pro-inflammatory response and increased neovascularization and tissue regeneration.

Effects of far‐infrared radiation lamp therapy on recovery from a simulated soccer‐match in elite female soccer players

“…However, some possible mechanisms could be speculated from previous animal and in vitro studies. 17,[32][33][34][35] FIR was reported to influence cell membrane potentials and mitochondrial metabolism by thermal and non-thermal effects, 21 increased blood circulation, 35 tissue regeneration, 34 upregulation of calcium-dependent nitric oxide and calmodulin, 33 providing positive effects on antioxidative, anti-inflammatory, and analgesic activities. 16,17 FIR can penetrate muscle about 4 cm deep, and has been shown to reduce edema and facilitate removal of metabolic bi-products by non-heating effect.…”

“…The mechanisms underpinnings of the FIR lamp therapy effects on muscle damage and performance parameters were not investigated in the current study. However, some possible mechanisms could be speculated from previous animal and in vitro studies 17,32–35 . FIR was reported to influence cell membrane potentials and mitochondrial metabolism by thermal and non‐thermal effects, 21 increased blood circulation, 35 tissue regeneration, 34 upregulation of calcium‐dependent nitric oxide and calmodulin, 33 providing positive effects on antioxidative, anti‐inflammatory, and analgesic activities 16,17 .…”

Improved extremity tissue oxygenation with short-term exposure to textiles embedded with far infrared light emitting thermoactive particles in patients with diabetes mellitus

“… 6 While the exact mechanisms are unknown, studies of FIR therapy in diabetes suggest an effect through nitric oxide regulation, reduced oxidative stress and inflammation, and, over time, increased neovascularization. 21 …”

“…and inflammation, and, over time, increased neovascularization. 21 FIR emitting textiles are interwoven with thermoactive mineral particles. They are purported to work by absorbing natural body heat and then re-emitting energy back to the skin as FIR light.…”

Compare the effectiveness of extracorporeal shockwave and hyperbaric oxygen therapy on enhancing wound healing in a streptozotocin‐induced diabetic rodent model

“…The animal model followed that of our previous reports. 20,22,23 The dorsum of the rat was shaved, and the palpable hip joints were used as anatomical landmarks for defining the base of the wound defect, which consisted of a full-thickness skin defect measuring 6 Â 5 cm 2 . The edge of the wound defect was stitched and set up with 4-0 silk stitches to forestall wound contracture.…”