Effects of cigarette smoke in mice wound healing is strain dependent.

It has been clinically and experimentally shown that cigarette smokers suffer from impaired wound healing, but the mechanisms that lead to the alterations are not well understood. The aim of this study was to investigate if the effects of cigarette smoke exposure on excisional cutaneous wound healing are different depending on the strain (Swiss, BALB/c and C57BL/6 mice) studied. Male mice were exposed to smoke of nine whole cigarettes per day, 3 times/day, daily, for 10 days. In the 11th day a full-thickness excisional wound was performed. Control group was sham-exposed and also had a full-thickness excisional wound. The cigarette smoke exposure protocol was performed until euthanasia. Animals were euthanatized 14 days after wounding. Wound contraction was evaluated 7 and 14 days after lesion. Sections were stained with hematoxylin-eosin, Sirius red or toluidine blue and immunostained for alpha-smooth muscle actin. Smoke exposed animals presented delay in wound contraction, in fibroblastic and inflammatory cells recruitment and in myofibroblastic differentiation; those alterations were strain dependent. Cigarette smoke exposure also affected mast cells recruitment and neoepidermis thickness. In conclusion, the present study demonstrated that the effects of cigarette smoke in mice cutaneous wound healing are related to mice strain studied.

Overweight induced by high-fat diet delays rat cutaneous wound healing.

Prolonged wound healing is a complication that contributes to morbidity and mortality. Overweight people regularly undergo surgery and trauma, and often develop chronic wounds, but the effects of the adipose tissue excess on cutaneous wound healing are not well understood. This study tested the hypothesis that overweight induced by a high-fat diet impairs rat cutaneous wound healing. Male Wistar rats were fed with either a high-fat or a standard (control) diet. After 15 weeks, an excisional lesion was done and the animals were killed 21 d later. Wound contraction and re-epithelialization, blood pressure, glucose and retroperitoneal fat were evaluated. After killing, lesion and adjacent normal skin were formol-fixed and paraffin-embedded. Inflammatory infiltrate, myofibroblasts, collagen fibres and cellular proliferation were analysed and blood vessels were evaluated using stereological methods. There was no difference in blood pressure and glucose, but retroperitoneal fat increased in the high-fat diet group. Animals fed with the high-fat diet presented delayed wound contraction and re-epithelialization. It was found that 21 d after wounding, overweight induced by a high-fat diet increased the inflammatory infiltrate and delayed myofibroblastic differentiation, collagen deposition, epithelial and connective tissue cell proliferation, and angiogenesis. These findings support the hypothesis that a high-fat diet exerts negative effects on rat cutaneous wound healing, due mainly to the prolongation of the inflammatory phase.

Nitric oxide synthesis inhibition alters rat cutaneous wound healing.

BACKGROUND: Nitric oxide (NO) is an important molecule that participates in wound repair, but its effects on cutaneous wound healing are not well understood. The aim of this study was to investigate the effects of NO synthesis blockade on rat cutaneous wound healing by the administration of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor of NO synthases. METHODS: NO synthesis was inhibited by administration of L-NAME (20 mg/kg/day) in drinking water. An excisional wound was done, and the animals were killed 7, 14, and 21 days later. Wound contraction and blood pressure were evaluated. The lesion and adjacent skin were formalin fixed and paraffin embedded. Mast cells were quantified, and vessels were evaluated using stereological methods. RESULTS: L-NAME-treated animals presented delayed wound contraction, alterations in collagen organization, and neoepidermis thickness. The inhibition of NO synthesis increased mast cell migration 7 days after wounding, but decreased 21 days after wounding. Volume density of vessels was decreased in L-NAME-treated animals, 21 days after lesion. Surface density of vessels was frequently smaller in L-NAME-treated animals than in controls. CONCLUSIONS; The blockade of NO synthesis impaired cutaneous wound healing, acting in early and late phases of wound repair.

Blockade of beta1- and beta2-adrenoceptors delays wound contraction and re-epithelialization in rats.

1. The participation of sympathetic efferent fibres in wound healing is not well understood. The aim of the present study was to investigate the effects of beta(1)- and beta(2)-adrenoceptor blockade on rat excisional cutaneous wound healing. 2. Male rats were treated orally with propranolol dissolved in drinking water (50 mg/kg per day), whereas the control group received drinking water without propranolol. Propranolol was administered daily until rats were killed. A full-thickness excisional lesion was performed. The lesion area was measured to evaluate wound contraction. After rats had been killed, lesion and adjacent normal skin were formol fixed and paraffin embedded. Sections were stained with haematoxylin-eosin, Sirius red or Toluidine blue and immunostained for a-smooth muscle actin or proliferating cell nuclear antigen. 3. Propranolol-treated rats presented delayed wound contraction and epidermal healing and decreased hydroxyproline levels, collagen density and neo-epidermis thickness. Blockade of beta(1)- and beta(2)-adrenoceptors increased epidermal and connective tissue cell proliferation, polymorphonuclear leucocyte migration, myofibroblast density and mast cell migration. The volume density of blood vessels was increased and vessels were more dilated in propranolol-treated animals. 4. Thus, we conclude that beta(1)- and beta(2)-adrenoceptor blockade impairs cutaneous wound healing. This information should be considered by physicians during the treatment of patients who present with hypertension and problems in the healing process (such as venous ulcers).

Sympathetic denervation accelerates wound contraction but delays reepithelialization in rats.

Participation of the peripheral nervous system in wound healing is not well understood. The aim of this study was to investigate the effects of sympathetic denervation on rat excisional cutaneous wound healing. Male rats were chemically denervated with intraperitoneal administration of 6-hydroxydopamine (6-OHDA) in 1% ascorbic acid. 6-OHDA or vehicle was administered twice a week until euthanasia, beginning 7 days before wounding. A full-thickness excisional lesion was performed and the lesion area measured to evaluate wound contraction. After euthanasia, the lesion and adjacent normal skin were formalin-fixed and paraffin-embedded. Sections were stained with hematoxylin and eosin or toluidine blue, or immunostained for alpha-smooth muscle actin. Animals treated with 6-OHDA showed acceleration in wound contraction, increase in myofibroblastic differentiation, reduction in mast cell migration, and a delay in reepithelialization. To investigate the effects of neurogenic inflammation, a group of animals was treated with 6-OHDA only after the acute inflammatory phase, and these animals showed delayed wound contraction 3 and 7 days after wounding when compared to those treated before the lesion. In conclusion, the present study shows that sympathetic denervation affects cutaneous wound healing, probably by a decrease in neurogenic inflammation during the initial phase of healing and the absence of catecholamines throughout the final phase.

Fibrillin-1 and elastin are differentially expressed in hypertrophic scars and keloids.

Hypertrophic scars and keloids are two forms of excessive cutaneous scarring. Considering the importance of extracellular matrix elements in tissue repair, a morphological and quantitative analysis of the elastic system components (fibrillin-1 and elastin) was performed in normal skin, normal scars, hypertrophic scars, and keloids. In superficial and deep dermis, fibrillin-1 volume density was significantly higher in normal skin compared with normal scars, hypertrophic scars, and keloids. The fibrillin-1 volume density did not show differences between hypertrophic scars and keloids in superficial or deep dermis. In superficial dermis, elastin volume density was higher in normal skin compared with normal scars, hypertrophic scars, and keloids. In deep dermis, the elastin volume density was higher in keloids compared with normal skins, normal scars, and hypertrophic scars. We showed that the distribution of fibrillin-1 and elastin is disrupted in all kinds of scars analyzed, but there are two patterns: one for normal scars and another for excessive scars.

Role of apoptosis in the remodeling of cholestatic liver injury following release of the mechanical stress.

It has been known for a long time that portal fibrosis consecutive to experimental common bile duct ligation is reversible following obstacle removal, but the mechanisms involved remain unknown. We have studied the effect of bilioduodenal anastomosis and of simple biliary decompression on the remodeling of the lesion in bile duct-ligated rats. Rats were subjected to common bile duct ligation for 7 days or 14 days. Bilioduodenal anastomosis was performed after 14 days of bile duct ligation and animals sacrificed at intervals. In other animals, after 7 days or 14 days of ligation, the common bile duct was merely decompressed by bile aspiration and animals sacrificed 24 h later. Collagen deposition, alpha-smooth muscle actin expression and apoptosis were evaluated. Bile was collected and the bile acid profile assessed. After anastomosis, collagen deposition and alpha-smooth muscle actin expression decreased and were back to control values after 7 days. These parameters remained practically unchanged 24 h after biliary decompression. Bile duct ligation by itself induced apoptosis of some fibroblastic and bile ductular cells after 7 days; this was back to normal after 14 days. After anastomosis or decompression, apoptosis of both fibroblastic and bile ductular cells increased greatly and was accompanied by ultrastructural features of extracellular matrix degradation. Total bile acid content decreased after common bile duct ligation, the proportion of dihydroxylated bile acids decreasing and that of trihydroxylated bile acids increasing. Biliary decompression and anastomosis did not modify total concentration and composition of the biliary bile acid pool. In summary, we show that mere biliary decompression, by relieving the mechanical stress, is as effective as bilioduodenal anastomosis to induce apoptosis of portal cells that likely triggers portal fibrosis regression.