Synergistic Effects of Photobiomodulation Therapy with Combined Wavelength on Diabetic Wound Healing In Vitro and In Vivo.

Objective: The difficulty in chronic diabetic wound healing remains the focus of clinical research. Photobiomodulation therapy (PBMT) with different wavelengths could exert different effects on wound healing, but the effects of combined red and blue light (BL) remained unclear. Methods: Diabetic rat wound model and diabetic wounded endothelial cell model were established to observe possible effects of PBMT using combined wavelengths for wound healing. Cells and animals were separated into four groups exposed to red and/or BL. Cell viability, apoptosis, and migration, as well as the expression level of nitric oxide (NO), vascular endothelial growth factor, interleukin-6, and tumor necrosis factor-α were measured in vitro. Diabetic rats were evaluated for wound closure rates, collagen deposition, inflammation intensity, and density of neovascularization after light irradiation. Results: PBMT using combined wavelengths significantly sped up the healing process with increasing angiogenesis density, collagen deposition, and alleviating inflammation in vivo. Moreover, combined wavelength irradiation promoted cell proliferation and migration, and NO production, as well as reduced reactive oxygen species and inflammation in vitro. Conclusions: PBMT using combined wavelengths performed a synergistic effect for promoting diabetic wound healing and would be helpful to explore a more efficient pattern toward chronic wound healing.

Postconditioning With Red-Blue Light Therapy Improves Survival of Random Skin Flaps in a Rat Model.

BACKGROUND: Random skin flap ischemic necrosis is a serious challenge in reconstructive surgery. Photobiomodulation is a noninvasive effective technique to improve microcirculation and neovascularization. Photobiomodulation with red or blue light has been separately proven to partially prevent skin flap necrosis, but the synergistic effect of red and blue light not been elucidated. Our experiment evaluated the impact of postconditioning with red-blue light therapy on the viability of random flaps. METHODS: Thirty Sprague-Dawley male rats (male, 12 weeks) with a cranially based random pattern skin flap (3 × 8 cm) were divided into 3 groups: control group, red light group, and red-blue light group. On postoperative day 7, flap survival was observed and recorded using transparent graph paper, flaps were obtained and stained with hematoxylin and eosin, and microvessel density was measured. Micro-computed tomography was used to measure vascular volume and vascular length. On days 0, 3, and 7 after surgery, blood flow was measured by laser Doppler. To investigate the underlying mechanisms, the amount of nitric oxide (NO) metabolites in the flap tissue was assessed on days 3, 5, and 7 after surgery. RESULTS: The mean percentage of skin flap survival was 59 ± 10% for the control group, 69 ± 7% for the red light group, and 79 ± 9% for the red-blue light group (P < 0.01). The microvessel density was 12.3 ± 1.2/mm2 for the control group, 31.3 ± 1.3/mm2 for the red light group, and 36.5 ± 1.4/mm2 for the red-blue light group (P < 0.01). Both vascular volume and total length in the red-blue light group showed significantly increased compared with the red light and control group (P < 0.01). Blood flow in the red-blue light treated flap showed significantly increased at postsurgery days 3 and 7 compared with the red light and control group (P < 0.01). The level of the NO metabolites was significantly increased in flap tissues belonging to the red-blue light group compared with the other 2 groups (P < 0.01). CONCLUSIONS: This study showed that postconditioning with red-blue light therapy can enhance the survival of random skin flap by improving angiogenesis and NO releasing.

Shape and site dependent in vivo degradation of Mg-Zn pins in rabbit femoral condyle.

A type of specially designed pin model of Mg-Zn alloy was implanted into the full thickness of lesions of New Zealand rabbits' femoral condyles. The recovery progress, outer surface healing and in vivo degradation were characterized by various methods including radiographs, Micro-CT scan with surface rendering, SEM (scanning electron microscope) with EDX (Energy Dispersive X-ray analysis) and so on. The in vivo results suggested that a few but not sufficient bridges for holding force were formed between the bone and the implant if there was a preexisting gap between them. The rapid degradation of the implantation in the condyle would result in the appearance of cavities. Morphological evaluation of the specially designed pins indicated that the cusp was the most vulnerable part during degradation. Furthermore, different implantation sites with distinct components and biological functions can lead to different degradation rates of Mg-Zn alloy. The rate of Mg-Zn alloy decreases in the following order: implantation into soft tissue, less trabecular bone, more trabecular bone, and cortical bone. Because of the complexities of in vivo degradation, it is necessary for the design of biomedical Mg-Zn devices to take into consideration the implantation sites used in clinics.