Thaís P. Amadeu

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.

Vascularization pattern in hypertrophic scars and keloids: a stereological analysis.

Wound healing is a complex process that does not always occur harmoniously and may lead to pathological scar development, such as hypertrophic scars and keloids. Considering that vascularization can play a role in the development of these scars, and that the literature is controversial, we performed a stereological analysis of dermal for vessels of normal skin, normal scars, hypertrophic scars, and keloids. The parameters studied concerned vessels: surface density, length density; for vessels and myofibroblasts: volume density, in papillary and reticular dermis. The pattern of dermal vascularization in normal skin and normal scar showed no differences. In papillary demis, the number of vessels was higher in hypertrophic scars and keloids than in normal skin (p < 0.05). Vessels of hypertrophic scars were more dilated than those of normal skin (p < 0.01). In reticular dermis, vessels were present in higher amount in hypertrophic scars and keloids than in normal skin (p < 0.025; p < 0.001, respectively). The pattern of vascularization did not show any differences between hypertrophic scars and keloids. Our results show that hypertrophic scars and keloids have a distinct pattern of vascularization compared to normal skin and normal scars. This indicates that abnormal vascularization can be involved in the development of hypertrophic scars and keloids.

S-nitrosoglutathione-containing hydrogel accelerates rat cutaneous wound repair

Background  Nitric oxide (NO) plays a key role in wound repair and S‐nitrosothiols like S‐nitrosoglutathione (GSNO) are well known NO donors.

Nitric oxide donor improves healing if applied on inflammatory and proliferative phase

BACKGROUND Nitric oxide (NO) is an important molecule synthesized during wound repair. Studies have reported the use of NO donors on cutaneous wound repair, but their effects in different phases of healing are still not elucidated. The aim of this work was to investigate the effects of topical application of a NO donor (S-nitrosoglutathione, GSNO)-containing hydrogel on excisional wounds in the inflammatory ((inf)), proliferative ((prol)), and inflammatory and proliferative phases ((inf+prol)) of rat cutaneous wound repair. MATERIAL AND METHODS In each group (control, GSNO(inf), GSNO(prol), and GSNO(inf+prol)), excisional wounds on the dorsal surface were made and wound contraction and re-epithelialization were evaluated. Fourteen days after wounding, wounds and adjacent skin were formalin-fixed and paraffin-embedded. Collagen fibers organization, mast cells, myofibroblasts and vessels were evaluated. RESULTS Wound contraction of the GSNO(inf+prol) group was faster than control, GSNO(inf), and GSNO(prol) groups, 5 and 7 d after wounding. Topical application of GSNO accelerated re-epithelialization 14 d after wounding, mainly in GSNO(inf+prol) group. In addition, the GSNO(inf+prol) group showed improved collagen fibers maturation and tissue organization, and lower amount of inflammatory cells in the superficial and deep areas of the granulation tissue, compared with the other groups. CONCLUSIONS NO is important in all phases of rat cutaneous wound repair, but if applied on inflammatory and proliferative phases, the improvement in wound healing (accelerating wound closure, wound re-epithelialization, and granulation tissue organization) is more impressive.

Topical S-nitrosoglutathione-releasing hydrogel improves healing of rat ischaemic wounds.

Topical application of the nitric oxide (NO) donor S‐nitrosoglutathione (GSNO) is known to exert beneficial effects on wound healing. The aim of this study was to evaluate, for the first time, the effect of topical application of GSNO on the healing of ischaemic wounds. Wistar rats were submitted to two parallels incisions on their backs; the skin was separated from the underlying tissue, the incisions were sutured and an excisional wound was made between the parallel incisions to create an ischaemic condition surrounding the wound. The animals were separated into a control group, which received a hydrogel vehicle without GSNO, and a GSNO‐treated group, which received a GSNO‐containing hydrogel. The animals were treated for 7 days consecutively with one daily application. The GSNO‐treated group displayed higher rates of wound contraction and re‐epithelization, lower amounts of inflammatory cells, an increase in collagen fibre density and organization and a decrease in the neovascularization compared to control. These results show that topical application of GSNO is effective in the treatment of ischaemic wounds, leading to a significant improvement in the wound healing. Therefore, topical GSNO‐containing hydrogels have potential for the therapeutic treatment of ischaemic diabetic and venous ulcers. Copyright

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 NG‐nitro‐l‐arginine methyl ester (l‐NAME), a non‐selective inhibitor of NO synthases.

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 α‐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.

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.

High Matrix Metalloproteinase Production Correlates with Immune Activation and Leukocyte Migration in Leprosy Reactional Lesions

ABSTRACT Gelatinases A and B (matrix metalloproteinase 2 [MMP-2] and MMP-9, respectively) can induce basal membrane breakdown and leukocyte migration, but their role in leprosy skin inflammation remains unclear. In this study, we analyzed clinical specimens from leprosy patients taken from stable, untreated skin lesions and during reactional episodes (reversal reaction [RR] and erythema nodosum leprosum [ENL]). The participation of MMPs in disease was suggested by (i) increased MMP mRNA expression levels in skin biopsy specimens correlating with the expression of gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α), (ii) the detection of the MMP protein and enzymatic activity within the inflammatory infiltrate, (iii) increased MMP levels in patient sera, and (iv) the in vitro induction of MMP-9 by Mycobacterium leprae and/or TNF-α. It was observed that IFN-γ, TNF-α, MMP-2, and MMP-9 mRNA levels were higher in tuberculoid than lepromatous lesions. In contrast, interleukin-10 and tissue inhibitor of MMP (TIMP-1) message were not differentially modulated. These data correlated with the detection of the MMP protein evidenced by immunohistochemistry and confocal microscopy. When RR and ENL lesions were analyzed, an increase in TNF-α, MMP-2, and MMP-9, but not TIMP-1, mRNA levels was observed together with stronger MMP activity (zymography/in situ zymography). Moreover, following in vitro stimulation of peripheral blood cells, M. leprae induced the expression of MMP-9 (mRNA and protein) in cultured cells. Overall, the present data demonstrate an enhanced MMP/TIMP-1 ratio in the inflammatory states of leprosy and point to potential mechanisms for tissue damage. These results pave the way toward the application of new therapeutic interventions for leprosy reactions.

Ultrasound accelerates healing of normal wounds but not of ischemic ones

To examine the influence of therapeutic ultrasound (US) on repair of standard and ischemic cutaneous lesions, full‐thickness excisional wounds were made in rats and treated with a US 3 MHz, 0.5 W/cm2 pulsed duty cycle. We used five experimental groups: control (received US powered off on the day of surgery, and on the second and fourth day), control US (received US on the day of surgery, and on the second and fourth day), ischemic (received US powered off on the day of surgery, and on the second and fourth day), ischemic US 3X (received US on the day of surgery, and on the second and fourth day) and ischemic US 5X (received US in the day of surgery, first, second, third and fourth day). The control US group showed acceleration in wound contraction 7 days after wounding, an increase in collagen density, and only focal inflammatory areas. Neo‐epidermis formation was more advanced in the control US group than in the control one. Wound contraction was delayed in the ischemic group when compared with the control group as well as the ischemic US 3X group, was but slightly accelerated in the ischemic US 5X group when compared with the ischemic group 7 days after wounding. Reepithelialization was delayed in both ischemic US groups when compared with the ischemic group. The number of inflammatory cells was higher in both US ischemic groups. We conclude that US therapy accelerates wound healing in normal wounds and delays wound healing in ischemic wounds.