LLLT at 670 nm positively influences all phases of rat skin wound healing.

ABSTRACT:The use of a simple and reproducible model is inevitable for objective statement of the effects of external factors on wound healing. Hence, present study was conducted to establish an excisional model of skin wound healing in corticosteroid treated, and streptozotocine induced diabetic rats as well as to standardized the semi-quantitative and quantitative evaluation of selected parameters. Round full thickness skin wounds were performed on the back of male Sprague-Dawley rats. Animals were sacrificed two, six, and fourteen days after surgery. Sections were stained with hematoxylin-eosin and van Gieson. Both semi-quantitative (wound reepithelization; presence of: inflammatory cells, fibroblasts, new wessels, and collagen) and quantitative methods (polymorphonuclear leucocytes/tissue macrophages ratio, percentage of re-epithelization, area of the granulation tissue) were used to evaluate the histological changes during wound healing. As compared to the control group the wound healing process of both experimental groups was decelerated. Interestingly, wound reepithelization and angiogenesis were significantly inhibited only in the steroid rats while epithelization was accelerated in diabetic rats. In conclusion, when compared to primary sutured wound healing it can be concluded that the excisional model is more appropriate for histological assessment of the effect of various factors on wound healing. In addition, administration of corticosteroids represents simple and inexpensive model of a complex skin wound healing impairment.

Optimal parameters of low-level laser therapy (LLLT) for wound healing are still discussed. Hence, our study was aimed to compare effects of different power densities of LLLT at 635 nm in rats. Four, round, full-thickness, skin wounds were made on the backs of 48 rats that were divided into two groups (non-steroid laser-treated and steroid laser-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm(2)) each with different power density (1 mW/cm(2), 5 mW/cm(2), and 15 mW/cm(2)), whereas the fourth wound served as a control. Two days, 6 days, and 14 days after surgery, eight animals from each group were killed and samples were removed for histological evaluation. In the non-steroid laser-treated rats, significant acceleration of epithelization and collagen synthesis 2 days and 6 days after surgery was observed in stimulated wounds. In steroid laser-treated rats, 2 days and 14 days after surgery, a decreased leucocyte/macrophage ratio and a reduction in the area of granulation tissue were recorded, respectively. In conclusion, LLLT, by the method we used, improved wound healing in the non-steroid laser-treated rats, but it was useless after corticosteroid treatment.

Vidinsk˘ B., P. Gal, T. Toporcer, F. Longauer, L. Lenhardt, N. Bobrov, J. Sabo: Histological Study of the First Seven Days of Skin Wound Healing in Rats. Acta Vet. Brno 2006, 75: 197-202.The aim of this study was to elaborate a histological model of incisional skin wound healing in Sprague-Dawley rats. Under aseptic conditions two paravertebral full thickness skin incisions were performed on the back of 42 anesthetized male rats. Histological sections from tissue specimens were stained by hematoxylin and eosin, van Gieson, PAS + PSD, Mallory's phosphotungstic hematoxylin and azur and eosin and evaluated during the first seven days after surgery. Histological evaluation revealed that the regeneration of injured epidermis was completed five days after surgery. The inflammatory phase was recorded during the first three days of healing with the culmination of this phase between day one and day two. The beginning of the proliferative phase was dated to the first day and the peak during day five and day six. The initiation of the maturation and remodeling phase of the healing process was observed six days after wounding. At the layer of striated muscle, the centronucleated cells were described for the first time six days after surgery. The wound healing process of rat skin was histologically described during the first seven days. Results of this work can serve as an experimental model for further research using external pharmacological and physical factors (laser light, magnetic field) by which the wound healing can be favourably influenced.Sprague-Dawley rats, inflammatory phase, proliferative phase, maturation in remodeling phase, histology

The aim of our study was to evaluate the changes of interstitial pH and flavin adenine dinucleotide (FAD)/reduced nicotinamide adenine dinucleotide (NADH) ratio in healing skin wounds using fluorescence spectroscopy in Sprague Dawley rats. In the experiment, excisional and incisional models of wound healing were used. The florescein as the pH-sensitive probe using excitation spectra (lambda(Em) = 535 nm) was used for the measurement of pH changes, and synchronous fluorescence spectra (Deltalambda = 60 nm) for the monitoring of FAD/NADH ratio changes were measured from the surfaces of healing wounds. Increase of interstitial pH and FAD/NADH ratio was recorded during the time interval from the 15th to the 65th minute after surgery. The decrease of pH between the 48th and the 72nd hour after surgery as well as the increase of FAD/NADH ratio between the 72nd and the 96th hour of wound healing were recorded. The results indicate that the use of fluorescence spectroscopy may be considered as a valuable tool for noninvasive in vivo monitoring of selected redox parameters in the early phases of wound healing.