Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society
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Highly reactive metabolites, such as oxygen free radicals, initiate a cascade of inflammatory processes in thermally damaged skin, leading to enhanced tissue loss and delayed wound healing. The extent of tissue necrosis in the zone of stasis is of prognostic significance in the wound healing process. In this study, the effect of oxygen free radical removal by recombinant human-Cu/Zn-superoxide dismutase, given in three different formulations during the inflammatory postburn phase and wound repair, was examined. ⋯ Edema formation, size of lesions, deepening of necrosis, and reepithelialization were examined. Results indicate that superoxide dismutase treatment resulted in reduced and faster recruitment of edema formation, smaller wound sizes, and minor tissue necrosis compared to the controls, thus resulting in significantly faster reepithelialization after 3 weeks. These animal studies on the efficacy of liposomal oxygen free radical scavenger showed accelerated wound healing in all parameters tested.
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Comparative Study
Effects of nitric oxide releasing poly(vinyl alcohol) hydrogel dressings on dermal wound healing in diabetic mice.
Healing of chronic wounds such as diabetic foot ulcers is a significant clinical problem. Methods of accelerating healing in these difficult lower extremity sites include use of growth factor-loaded gels, hyperbaric oxygen, grafts, and artificial skin replacements. Nitric oxide (NO) has been proposed as a possible active agent for enhancing wound healing. ⋯ By days 10 to 13 this delay was no longer apparent. Granulation tissue thickness within the wounds at days 8 and 15 and scar tissue thickness after wound closure were increased in animals exposed to higher dose NO hydrogels. The results of this study suggest that exogenous NO released from a hydrogel wound dressing has potential to modulate wound healing.
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Comparative Study
Increased collagen deposition in an uncomplicated surgical wound compared to a minimal subcutaneous test wound.
Little information is currently available concerning the relationship between results obtained in humans from surgical test wounds and results from wound models. Therefore, to evaluate human wound healing parameters, tubings of expanded polytetrafluoroethylene were implanted in a subcutaneous test wound in the arm of 47 volunteers and 20 patients undergoing hernia repair. The surgical patients also had implants left in the surgical wound cavity. ⋯ The variability of the results was 40% lower in the subcutaneous test wound than in the surgical wound. There was no significant difference in hydroxyproline deposition between the volunteers and the patients undergoing hernia repair. In patients undergoing minor surgery without signs of compromised healing the expanded polytetrafluoroethylene test wound in the arm reflects the deposition of non-collagenous protein, but not collagen, within the surgical wound.
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Aging has been anecdotally reported to result in prolonged wound healing. Measurement of punch biopsy wound closure in young (4 month old) and old (36 month old) rats indicated there was a significant delay in wound closure by old rats during the early phase of repair, after which closure rates were equivalent. The delay in granulation tissue accumulation in older animals could involve premature programmed cell death (apoptosis); however, apoptotic fibroblasts in sponge granulation tissue and tissue culture were less abundant in samples from old rats relative to young rats. ⋯ Gelatin zymography indicated a greater abundance of matrix metalloproteinase-2 in supernatants from gels containing skin fibroblasts from old rats. Taken together, these results suggest that the age-associated healing delay in the rat may not be related to the appearance or abundance of distinct myofibroblast or apoptotic cell populations. Proteolysis may have a significant role in delayed wound healing in aged animals.