Delayed Wound Contraction Research Articles

Pseudomonas aeruginosa virulence proteins pseudolysin and protease IV impede cutaneous wound healing

AbstractThe intricate biological process of cutaneous wound healing is achieved through precise and highly programmed events. Dermal fibroblasts and keratinocytes play a significant role in the process of reepithelialization during wound healing. Pathogenic bacteria such as Pseudomonas aeruginosa (P. aeruginosa) may delay the proliferative phase of wound repair by secreting their proteins leading to delayed or impaired wound healing. We have analyzed three virulent strains of P. aeruginosa isolated from the wound environment which also differed in their ability to produce biofilms. Mass spectrometric analysis of differentially expressed secreted proteins by three virulent strains of P. aeruginosa revealed peptides from pseudolysin and protease IV expressed from lasB and prpL genes. Pseudolysin and protease IV recombinant proteins were tested for their ability to modulate wound healing in several cell types of wound microenvironment in in vitro and in vivo models. Both pseudolysin and protease IV inhibited migration and survival of fibroblasts, keratinocytes, and endothelial cells. In three dimensional spheroid endothelial models and matrigel assays these proteins impeded sprouting and tube formation. In a mouse model of excision wound, pseudolysin and protease IV treatment showed reduced collagen content, inhibited neovascularization and epithelialization, and delayed wound contraction. Furthermore, pseudolysin and protease IV treatment resulted in a significant increase in plasma IL-6 levels when compared to vehicle control and control, suggesting the induction of a state of prolonged inflammation. Taken together, our data indicate pseudolysin and protease IV secreted from biofilm producing and antibiotic resistant P. aeruginosa in wound microenvironment produce both local and systemic effects that is detrimental to the maintenance of tissue homeostasis. Hence, these proteins may serve as potential therapeutic targets toward better clinical management of wounds.

Low mortality oxidative stress murine chronic wound model

IntroductionInvestigators have struggled to produce a reliable chronic wound model. Recent progress with antioxidant enzyme inhibitors shows promise, but mortality rates are high. We modified the dosage and administration of...

Exercise prior to, but not concomitant with, stress reverses stress-induced delayed skin wound healing.

Stress-induced prolonged inflammation impairs cutaneous wound healing. Exercise may inhibit this effect via an anti-inflammatory mechanism. Our aim was to investigate the effect of moderate exercise on skin wound healing in chronically stressed mice. Mice were trained five times per week on a treadmill or received no training. Mice underwent daily rotational stress from the 6th week until euthanasia. During the 8th week, two wounds were created in the dorsum and collected 10 days later. A control group only received wounds. Exercise was performed prior to and simultaneous with stress for 2 weeks or only prior to stress. Stress increased normetanephrine levels 10 days after wounding, resulting in an increased amount of inflammatory cells and reduced expression of inflammatory cytokines as well as angiogenesis, myofibroblast differentiation and matrix deposition. Concomitant exercise and stress potentiated these effects, intensifying the delayed wound contraction. When exercise was performed only prior to stress, however, the mice showed reduced inflammatory cells in granulation tissue 10 days after wounding and improved wound healing compared with animals with exercise and concomitant stress. Moderate exercise in association with stress potentiates the stress effect; however, when exercise was performed prior to stress, wound healing was improved.

Injected biodegradable polyurethane scaffolds support tissue infiltration and delay wound contraction in a porcine excisional model.

The filling of wound cavities with new tissue is a challenge. We previously reported on the physical properties and wound healing kinetics of prefabricated, gas-blown polyurethane (PUR) scaffolds in rat and porcine excisional wounds. To address the capability of this material to fill complex wound cavities, this study examined the in vitro and in vivo reparative characteristics of injected PUR scaffolds employing a sucrose porogen. Using the porcine excisional wound model, we compared reparative outcomes to both preformed and injected scaffolds as well as untreated wounds at 9, 13, and 30 days after scaffold placement. Both injected and preformed scaffolds delayed wound contraction by 19% at 9 days and 12% at 13 days compared to nontreated wounds. This stenting effect proved transient since both formulations degraded by day 30. Both types of scaffolds significantly inhibited the undesirable alignment of collagen and fibroblasts through day 13. Injected scaffolds were highly compatible with sentinel cellular events of normal wound repair cell proliferation, apoptosis, and blood vessel density. The present study provides further evidence that either injected or preformed PUR scaffolds facilitate wound healing, support tissue infiltration and matrix production, delay wound contraction, and reduce scarring in a clinically relevant animal model, which underscores their potential utility as a void-filling platform for large cutaneous defects. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1679-1690, 2016.

The Effect of Local Rho-Kinase Inhibition on Murine Wound Healing

The process of cutaneous wound healing and contraction is a complex orchestra of temporally and spatially controlled signaling moieties and pathways. Rho-kinase (ROCK) has been implicated as a key downstream effector of transforming growth factor β1 (TGF-β1) signal transduction, which ultimately coordinates α-smooth muscle actin (α-SMA)-mediated wound contraction. Previous in vitro studies of ROCK inhibition have demonstrated decreased fibroblast contraction and epithelial advancement after wounding. In vivo systemic ROCK inhibition revealed modest late wound healing attenuation in contrast to α-SMA knock-out rodents. The goal of this investigation was to explore the effect of local delivery of a ROCK inhibitor on an in vivo murine model of wound healing. Full-thickness cutaneous wounds were created in 24 white mice and were treated daily with local topical delivery of 100 μL of 10(-4) M ROCK inhibitor (Y27632) or saline control. Percent wound surface area over time and compensatory epithelial advancement was quantified. After 12 days, tissue was harvested for assessment of inflammatory cellular density, immunohistochemistry for α-SMA, and TGF-β protein expression. Wounds subjected to local ROCK inhibition were significantly larger than controls at early time points, and this effect of delayed wound contraction in ROCK-inhibited wounds persisted for 7 days after wounding (P < 0.05). The effect of ROCK inhibition on delay of wound contraction was normalized at day 12. There was no significant difference between control and ROCK-inhibited groups in the area of the nascent epithelium beyond the wound margin, wound inflammatory cellular density, and TGF-β1 expression. However, ROCK inhibition led to as statistically significant decrease in α-SMA stress fiber formation compared to controls [32.5% (3.5%) vs 17.4% (2.6%); P < 0.05]. Local delivery of a ROCK inhibitor delayed the time course of murine wound contraction in a manner similar to that previously reported in α-SMA knock-out rodents, thus demonstrating an effective method for in vivo ROCK inhibition. Accordingly, α-SMA stress fiber formation was inhibited in treated wound beds without altering local inflammation, TGF-β1 expression, or epithelial wound edge advancement.

Nicotine affects cutaneous wound healing in stressed mice

Stress is an important condition of modern life. Nicotine addiction can modulate the physiological response to stress. Cutaneous healing is a complex process resulting in scar formation, which can be delayed by stress. Therefore, the aim of this study was to investigate the effects of nicotine administration on cutaneous wound healing in chronically stressed mice. Male mice were submitted to rotational stress, whereas control animals were not subjected to stress. These stressed and control animals were treated with a transdermal nicotine patch that was changed every day. A full-thickness excisional lesion was also generated, and 14days later, lesions had recovered. However, the Stress+Nicotine group presented a delay in wound contraction. These wounds showed a decrease in inflammatory cell infiltration and lower expression of transforming growth factor-β (TGF-β), whereas there was an increase in angiogenesis and tumor necrosis factor-α (TNF-α) expression. In vitro fibroblast migration was also impaired by the nicotine treatment of stressed-stimulated cells. In conclusion, nicotine administration potentiates the delay in wound closure observed in mice submitted to stress.

Both obesity-prone and obesity-resistant rats present delayed cutaneous wound healing

Diet-induced overweight rats exhibit delayed cutaneous healing; however, when receiving an obesogenic diet, some rats are susceptible to developing the overweight phenotype, whereas others are resistant. We investigated cutaneous healing in diet-induced obesity (DIO)-prone and diet-resistant (DR) rats. Male rats were fed with a standard (control) or a high-saturated fat (30 % fat, w/w) diet for 20 weeks. Then, the experimental group was subdivided into DIO (n 17) and DR (n 16) groups. An excision lesion was made, and the animals were killed 7 or 14 d later. The average body weight was 29 and 25 % higher in the DIO group compared with the C and DR groups. Retroperitoneal fat was higher in the DIO group than in the control and DR groups (518 and 92 %) and was higher in the DR group than in the control group (223 %). The DIO group presented glucose intolerance, and both the DIO and DR groups presented delayed wound contraction (50 %) and re-epithelialisation (20 %). Compared with the DR group, the DIO group displayed higher amounts of inflammatory cells as well as higher levels of lipid peroxidation (P < 0·05). Myofibroblastic differentiation and vessel remodelling were delayed in both the DIO and DR groups. Nitrite levels were lower in the DIO group (340 % less) than in the DR group. TNF-α expression was increased in the DIO group (130 %) compared with the DR group. Our results showed that DIO as well as DR rats present delays in cutaneous wound healing, even though the DR group does not have an overweight phenotype.

Cutaneous wound healing of chronically stressed mice is improved through catecholamines blockade

Stress impairs cutaneous wound healing; however, it is unclear how beta-adrenoceptors participates in alterations induced by stress on skin wound repair. Therefore, the aim of this study was to investigate the effects of propranolol, a non-selective beta-blocker, administration on cutaneous wound healing of chronically stressed mice. Male mice were spun at 115 rpm for 15 min every hour from three days before wounding until euthanasia. Control animals were not submitted to stress. Stressed and control animals were treated with propranolol dissolved in water; controls received only water. Propranolol administration began one day before wounding and was continued daily until euthanasia. A full-thickness excisional lesion was performed. Seven and fourteen days later, animals were killed, and lesions were formalin-fixed and paraffin-embedded. Sections were stained with hematoxylin-eosin and immunostained against F4/80 to quantify macrophages, alpha-smooth muscle actin to quantify the myofibroblast density and proliferating cell nuclear antigen to quantify the cell proliferation. Furthermore, matrix metalloproteinases (MMP)-2 and MMP-9 activity, nitrite and hydroxyproline levels and tumor necrosis factor-alpha (TNF-alpha) expression were measured in wound. Stress and control + propranolol groups presented a delay in wound contraction, re-epithelialization, F4/80-positive macrophages, neutrophils and mast cells infiltration, cellular proliferation, angiogenesis, myofibroblastic differentiation, MMP-2 and MMP-9 activation and TNF-alpha expression, whereas an increase in the nitrite levels. Stress + propranolol group presented results similar to control group. In conclusion, stress impairs cutaneous wound healing in mice through beta1- adrenoceptors and beta2-adrenoceptors activation.

Matrix metalloproteinase inhibition delays wound healing and blocks the latent transforming growth factor-β1-promoted myofibroblast formation and function

The ability to regulate wound contraction is critical for wound healing as well as for pathological contractures. Matrix metalloproteinases (MMPs) have been demonstrated to be obligatory for normal wound healing. This study examined the effect that the broad-spectrum MMP inhibitor BB-94 has when applied topically to full-thickness skin excisional wounds in rats and its ability to inhibit the promotion of myofibroblast formation and function by the latent transforming-growth factor-beta1 (TGF-beta1). BB-94 delayed wound contraction, as well as all other associated aspects of wound healing examined, including myofibroblast formation, stromal cell proliferation, blood vessel formation, and epithelial wound coverage. Interestingly, BB-94 dramatically increased the level of latent and active MMP-9. The increased levels of active MMP-9 may eventually overcome the ability of BB-94 to inhibit this MMP and may explain why wound contraction and other associated events of wound healing were only delayed and not completely inhibited. BB-94 was also found to inhibit the ability of latent TGF-beta1 to promote the formation and function of myofibroblasts. These results suggest that BB-94 could delay wound closure through a twofold mechanism; by blocking keratinocyte migration and thereby blocking the necessary keratinocyte-fibroblast interactions needed for myofibroblast formation and by inhibiting the activation of latent TGF-beta1.

Ccn2/Ctgf Overexpression Induced by Cigarette Smoke during Cutaneous Wound Healing is Strain Dependent

Cigarette smoke has been associated with poor healing in several studies, but the precise mechanisms involving this impairment are still not elucidated. The aim of this work was to investigate cigarette smoke exposure effects on initial phases of cutaneous healing in mice, focusing mainly on gene expression of two molecules involved in wound repair (Ccn2/Ctgf and Tgfb1) and to study if these effects are strain dependent. Mice were exposed to the smoke of nine cigarettes per day, three times per day, for ten days. In the eleventh day an excisional wound was made. The control group was sham-exposed. The cigarette smoke exposure protocol was performed until euthanasia, seven days after wounding. Wound contraction was evaluated. Sections were stained with hematoxylin-eosin, Sirius red, and toluidine blue, and also immunostained for alpha-smooth muscle actin. Gene expression of Ccn2/Ctgf and Tgfb1 was evaluated by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). Smoke-exposed animals presented delay in wound contraction; fibroblastic, inflammatory, and mast cell recruitment; re-epithelialization; myofibroblastic differentiation; and Ccn2/Ctgf and Tgfb1 gene expression. Those alterations were strain dependent. This work confirmed the deleterious effects of cigarette smoke exposure on mouse cutaneous healing depending on mouse strain and links these effects to an overexpression of Ccn2/Ctgf.

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.

Delay of cutaneous wound closure by morphine via local blockade of peripheral tachykinin release

Topically applied morphine is routinely used to alleviate pain in cutaneous wounds such as burns and pressure sores. Evidence suggests the topical administration of exogenous opioid drugs may impair wound closure. This study examined the effects of topical morphine on a standardized model of cutaneous wound healing in the rat. Full-thickness 4 mm diameter circular skin flaps were excised from the intrascapular region of male Sprague-Dawley rats. IntraSite™ ® Gel infused with either morphine-sulfate, neurokinin-1 (NK-1) or neurokinin-2 (NK-2) receptor antagonists, substance P (SP), neurokinin A (NKA), SP + morphine-sulfate, or NKA + morphine-sulfate was applied to the wound twice daily. Results demonstrated a significant overall delay in the time course of wound contraction in morphine-treated animals when compared with gel-only treated controls. The delay in wound contraction seen in morphine-treated animals increased in a concentration-dependent manner. Topical application of NK-1 or NK-2 receptor antagonists mimicked the effects of morphine in delaying wound closure, suggesting topical opioids impair wound closure via the inhibition of SP and NKA release peripherally into the healing wound. Additionally, no significant delays in closure were seen in rats receiving morphine combined with SP or NKA, demonstrating the ability of each neuropeptide to attenuate the effects of morphine in delaying wound closure and restore normal wound closure rates. The combination of SP or NKA and morphine-sulfate for wound therapy may provide local analgesia while maintaining normal closure rates.

Ascorbic acid increases healing of excision wounds of mice whole body exposed to different doses of γ-radiation

Because of the practical importance of acute radiation exposure associated with combined injuries, it is imperative to investigate the efficacy of cost-effective nutritional factors in the reconstruction of irradiated wounds. Therefore, effect of pretreatment of ascorbic acid was studied on the healing of excised wounds in mice exposed to 2, 4, 6 and 8 Gy whole body γ-radiation. A full-thickness wound was created on the dorsum of the irradiated mice and the progression of wound contraction was monitored by capturing video images of the wound at various varying days after irradiation. Irradiation caused a dose dependent delay in wound contraction and wound healing time, while ascorbic acid pretreatment resulted in a significant acceleration in the rate of wound contraction and a decrease in the mean wound healing time. To understand the mechanism of healing, collagen, hexosamine, DNA, nitrite and nitrate contents were measured in the granulation tissue of wounded mice treated with ascorbic acid before exposure to 6 Gy γ-radiation. Ascorbic acid treatment prior to irradiation enhanced the synthesis of collagen, hexosamine, DNA, nitrite and nitrate contents. The histological assessment of wound biopsy revealed an improved collagen deposition, and increase in fibroblast and vascular densities. The present study demonstrates that ascorbic acid pretreatment has a beneficial effect on the irradiated wound and could be a substantial therapeutic strategy to accelerate wound repair in irradiated wounds and in the cases of combined injury situations.

Fibrin/platelet plug counteracts cutaneous wound contraction: The hypothesis of “skipping stone”

Cutaneous wound contraction and epithelialization act collaboratively to minimize the exposed wound surface. However excessive wound contraction is undesirable due to the resultant disfigurement and scarring. Fibrin clot has greater stiffness than surrounding tissue and mechanical strain further enhances its stiffness. On the contrary, skin exhibits diminished stiffness when affected by high strain rates. Therefore during early stages of wound healing, the contractile wound border is confronted by fibrin clot forming a high strain region in the interface of contractile tissue and fibrin clot--which is evidenced by computer simulation. Due to the stress relaxation property of skin, the contractile strain is partly neutralized. Meanwhile, gradually the stiffness of fibrin clot decreases which is followed by another cycle of wound contraction. This cyclic pattern of contraction resembles the movement of a stone over water or "skipping stone". The stone bounces repeatedly when thrown across the surface of water with reduction of jumping altitude with each bounce till the stone stops completely. This hypothesis is further supported by the observed initial delay in wound contraction and the chronological correlation of enhanced wound contraction with loss of superficial eschar and substitution of fibrin clot with granulation tissue. Also there is evidence that fibrin inhibits fibroblast-mediated contraction of collagen. Furthermore, modest increase in wound contraction rate in fibrinogen deficient mice and fibrin-mediated diminished wound contraction are agreement with the proposed hypothesis.

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

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. 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. 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 β1‐ AND β2‐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).

Mechanical and humoral factors in wound healing

Summary As wound contraction can be prevented by full-thickness skin graft and enhanced by licking and since saliva contains growth-promoting macromolecules, we have studied the mechanical and humoral aspects of wound healing. Standardized burn and freeze-produced wounds were produced in rats. Contraction did not occur in wounds caused by freezing (n = 30), while burn wounds (n = 30) contracted to less than one-third of the original size in 3 weeks. If the centres of the freeze-produced wounds (n = 12) were excised, contraction would then occur and proceed at the same rate as open wounds (n = 12). The collagen contents of the burn wounds (n = 24) showed a greater initial loss followed by rapid replacement, while that of the freeze-produced wounds (n = 24) demonstrated a slower removal and more gradual replacement. Submandibular sialadenectomized mice (n = 34) and sham controls (n = 34) had excision of a standard sized patch of sacral skin. Through a separate abdominal incision polyvinyl sponges of known weight were introduced subcutaneously into all the animals. Mice without the submandibular salivary glands showed a slower rate of wound contraction than the sham controls (P&amp;lt;0.001). However, this delay in wound contraction was abolished if sialadenectomized mice were caged with mice having intact salivary glands. Collagen synthesis as determined by the hydroxyproline concentrations in the polyvinyl sponges were the same in both groups of animals irrespective of cage environment. Further standard sacral wounds in submandibular sialadenectomized mice (n = 120) were treated with different salivary components. Only high molecular weight nerve growth factor was able to accelerate wound contraction in these sialadenectomized animals to control values. In conclusion, the degree of wound contraction following injury is dependent on the integrity of the matrix, while the initiation of contraction is likely to be chemically induced.

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.

Role of curcumin, a naturally occurring phenolic compound of turmeric in accelerating the repair of excision wound, in mice whole-body exposed to various doses of γ-radiation

The healing of irradiated wounds has always been a central consideration in medical practice because radiation disrupts normal response to injury, leading to a protracted recovery period. The quest for clinically effective wound healing agents is important in the medical management of irradiated wounds. Therefore, the present study was conceptualized to investigate the effect of curcumin (natural yellow, diferuloylmethane), a major yellow pigment and an active component of turmeric on wound healing in mice exposed to whole-body γ-radiation. A full-thickness wound was created on the dorsum of mice whole-body irradiated to 2, 4, 6, or 8 Gy. The progression of wound contraction was monitored periodically by capturing video images of the wound. The collagen, hexosamine, DNA, nitric oxide, and histological profiles were evaluated at various postirradiation days in mice treated and not treated with curcumin before exposure to 0 or 6 Gy. The whole-body exposure resulted in a dose-dependent delay in wound contraction and prolongation of wound healing time. Irradiation caused a significant reduction in collagen, hexosamine, DNA, and nitric oxide synthesis. Pretreatment with curcumin significantly enhanced the rate of wound contraction, decreased mean wound healing time, increased synthesis of collagen, hexosamine, DNA, and nitric oxide and improved fibroblast and vascular densities. This study demonstrates that curcumin pretreatment has a conducive effect on the irradiated wound and could be a substantial therapeutic strategy in initiating and supporting the cascade of tissue repair processes in irradiated wounds.