Cutaneous Healing Research Articles

Examining the contribution of surrounding intact skin during cutaneous healing.

Severe cutaneous wounds expose the body to the external environment, which may lead to impairments in bodily functions and increased risk of infection. There is a need to develop skin substitutes which could effectively promote complete skin regeneration following an injury. Murine models are used to test such skin substitutes, but their healing involves contraction of the dermis not found in human wounds. We have previously described a device called a dome, which comes in two models, that is used to prevent skin contraction in mice. One model provides a physical barrier to minimize contraction, and the other model has additional perforations in the barrier to allow cellular contribution from the surrounding intact skin. Taking advantage of an enhanced version of these two models, we compared granulation tissue formation, the extent of vascularization, and the transition to myofibroblastic phenotype between the models. We enhanced the dome by developing a twist open cap dome and applied the two models of the dome into the excisional wound biopsy in mice. We demonstrate that the dome can be used to prevent skin contraction in mice. The control model prevented skin contraction while barricading the contribution of surrounding intact skin. When not barricaded, the intact skin enhances wound healing by increasing the number of myofibroblasts and neovascularization. Using a novel model of inhibition of skin contraction in rodents, we examined the contribution from the surrounding intact skin to granulation tissue formation, myofibroblastic differentiation, and neovascularization during the course of skin healing in mice.

Defective Black Nano-Titania Thermogels for Cutaneous Tumor-Induced Therapy and Healing.

Current challenges in cutaneous tumor therapy are healing the skin wounds resulting from surgical resection and eliminating possible residual tumor cells to prevent recurrence. To address this issue, bifunctional biomaterials equipped with effective tumor therapeutic capacity for skin cancers and simultaneous tissue regenerative ability for wound closure are highly recommended. Herein, we report an injectable thermosensitive hydrogel (named BT-CTS thermogel) with the integration of nanosized black titania (B-TiO2- x, ∼50 nm) nanoparticles into a chitosan (CTS) matrix. The B-TiO2- x nanocrystal exhibits a crystalline/amorphous core-shell structure with abundant oxygen vacancies, which endows the BT-CTS thermogels with simultaneous photothermal therapy (PTT) and photodynamic therapy (PDT) effects under single-wavelength near-infrared laser irradiation, leading to an excellent therapeutic effect on skin tumors in vitro and in vivo. Moreover, the BT-CTS thermogel not only supports the adhesion, proliferation, and migration of normal skin cells but also facilitates skin tissue regeneration in a murine chronic wound model. Therefore, such BT-CTS thermogels with easy injectability, excellent thermostability, and simultaneous PTT and PDT efficacy as well as tissue regenerative activity offers a promising pathway for the healing of cutaneous tumor-induced wounds.

A polyethylenimine-based diazeniumdiolate nitric oxide donor accelerates wound healing.

Nitric oxide (NO) plays a pivotal role in the cutaneous healing process and a topical supplement of NO is beneficial for wound repair. In this work, a novel polyethylenimine (PEI) based diazeniumdiolate nitric oxide donor was prepared. The obtained polymer (PEI-PO-NONOate) was characterized by Fourier transform infrared (FTIR) spectroscopy, UV-vis absorption spectra, and nuclear magnetic resonance (NMR). The PEI-PO-NONOate polymer was stable under anhydrous conditions at different temperatures. A total of 0.57 μmol gaseous NO was released from 1.0 mg of the PEI-PO-NONOate polymer in PBS of pH 7.4 and it presented a proton-driven release pattern. Furthermore, the PEI-PO-NONOate polymer exhibited a controlled release profile sustained for over 30 hours within the polyethylene glycol (PEG) mixture system. Cytotoxicity evaluation was performed on L929 cells. Full-thickness excisional cutaneous wound models of mice were prepared and the PEI-PO-NONOate polymer was applied to investigate its effects on wound healing. The results revealed that the PEI-PO-NONOates exhibited good biocompatibility. It was also found that the PEI-PO-NONOate polymer promoted cutaneous wound healing and closure with enhanced granulation tissue formation, collagen deposition, and angiogenesis, as compared to the control. In summary, a novel nitric oxide releasing polymer with high loading efficiency and a controlled release profile was developed which presented the potential for application in the acceleration of cutaneous wound healing.

Chitosan hydrogels containing nanoencapsulated phenytoin for cutaneous use: Skin permeation/penetration and efficacy in wound healing

Although phenytoin is an antiepileptic drug used in the oral treatment of epilepsy, its off-label use as a cutaneous healing agent has been studied in recent years due to the frequent reports of gingival hyperplasia after oral administration. However, the cutaneous topical application of phenytoin should prevent percutaneous skin permeation. Therefore, the aim of this study was to evaluate the in vitro skin permeation/retention and in vivo effects of nanocapsules and nanoemulsions loaded with phenytoin and formulated as chitosan hydrogels on the healing process of cutaneous wounds in rats. The hydrogels had adequate pH values (4.9–5.6) for skin application, drug content of 0.025% (w/w), and non-Newtonian pseudoplastic rheological behaviour. Hydrogels containing nanocapsules and nanoemulsions enabled improved controlled release of phenytoin and adhesion to skin, compared with hydrogels containing non-encapsulated phenytoin. In vitro skin permeation studies showed that phenytoin permeation to the receptor compartment, and consequently the risk of systemic absorption, may be reduced by nanoencapsulation without any change in the in vivo performance of phenytoin in the wound healing process in rats.

Role of Schwann cells in cutaneous wound healing.

Dermal wound healing is the process of repairing and remodeling skin following injury. Delayed or aberrant cutaneous healing poses a challenge for the health care system. The lack of detailed understanding of cellular and molecular mechanisms involved in this process hampers the development of effective targeted treatments. In a recent study, Parfejevs et al.-using state-of-the-art technologies, including in vivo sophisticated Cre/loxP techniques in combination with a mouse model of excisional cutaneous wounding-reveal that Schwann cells induce adult dermal wound healing. Strikingly, genetic ablation of Schwann cells delays wound contraction and closure, decreases myofibroblast formation, and impairs skin re-epithelization after injury. From a drug development perspective, Schwann cells are a new cellular candidate to be activated to accelerate skin healing. Here, we summarize and evaluate recent advances in the understanding of Schwann cells roles in the skin microenvironment.

High in situ mRNA levels of IL-22, TFG-β, and ARG-1 in keloid scars

Keloid scars are currently considered a chronic inflammatory process and no longer a benign skin tumor. Keloids are defined as highly inflamed, hyperproliferative pathological scars. Growth factors and cytokines have important functions in the keloid inflammatory etiopathogenesis. The aim of this study was to analyze the in situ expression of cytokines and growth factors in keloid scars in comparison with that in normal scars. Among them, we specifically assessed TGF-β, FGF, IL-33, IL-22, ARG-1, ARG-2, iNOS, VIP, VIP-R1, TAC, and TAC-R1. A total of 98 biopsies were evaluated, including of 53 keloid and 45 normal scars. The age of patients with keloids ranged from 11 to 73 years, with a mean age of 28 years and predominance of the female gender (58.5% of the total patients). Around 64.15% of the patients belonged to the black ethnic group. Evaluated keloids were most commonly located in the earlobe because of ear piercing, representing 73.6% of the cases. We found significantly greater expression of TGF-β, IL-22, and ARG-1 in keloids when compared with that in normal scars. As for IL-33, ARG-2, and VIP-R1, despite the higher number of mRNA copies found in keloids, this difference was not significant. Furthermore, FGF, iNOS, VIP, TAC, and TAC-R1 mRNA levels were not detectable, and therefore these results were inconclusive in this study. Considering these results, understanding the cellular and molecular mechanisms that control the inflammatory response during cutaneous healing may promote the development of strategies to improve the treatment of patients with keloids.

Identification of mRNA of the Inflammation-associated Proteins CXCL8, CXCR2, CXCL10, CXCR3, and β-Arrestin-2 in Equine Wounded Cutaneous Tissue: a Preliminary Study

Horses often sustain cutaneous wounds and healing can be prolonged and difficult to treat. Compared to body wounds, limb wounds heal slower and are more likely to develop exuberant granulation tissue. Differences in healing rates and exuberant granulation tissue formation is attributed to abnormal cytokine profiles. CXCL8 and its receptor CXCR2 are involved in acute inflammation whereas CXCL10 and its receptor CXCR3 are involved in inflammation resolution. β- arrestin-2 regulates inflammation through internalization of G-protein coupled receptors (GPCRs) including CXCR2 and CXCR3. Gene expression of these five inflammation associated proteins have not been previously identified in equine cutaneous tissue and may play a role in dysregulation of inflammation in equine limb wounds. The mRNA expression levels were measured using QuantiGene Plex Assay from cutaneous biopsies collected from surgically created wounds on the limb and thorax on days 0, 1, 2, 7, 14, and 33 from two horses. The mRNA expression levels were measured in mean fluorescent intensity and graphed. We were successful in identifying all five proteins for the first time in equine cutaneous tissue. Preliminary results suggest that there are different expression patterns for CXCL8, CXCR2 and β-arrestin-2 between the limb and thorax but not for CXCL10 and CXCR3. Differential regulation of CXCL8, CXCR2 and β-arrestin-2 may further explain why limb wounds heal differently than body wounds and warrants further investigation.

Microbial Host Interactions and Impaired Wound Healing in Mice and Humans: Defining a Role for BD14 and NOD2.

Chronic wounds cause significant patient morbidity and mortality. A key factor in their etiology is microbial infection, yet skin host-microbiota interactions during wound repair remain poorly understood. Microbiome profiles of noninfected human chronic wounds are associated with subsequent healing outcome. Furthermore, poor clinical healing outcome was associated with increased local expression of the pattern recognition receptor NOD2. To investigate NOD2 function in the context of cutaneous healing, we treated mice with the NOD2 ligand muramyl dipeptide and analyzed wound repair parameters and expression of antimicrobial peptides. Muramyl dipeptide treatment of littermate controls significantly delayed wound repair associated with reduced re-epithelialization, heightened inflammation, and up-regulation of murine β-defensins 1, 3, and particularly 14. We postulated that although murine β-defensin 14 might affect local skin microbial communities, it may further affect other healing parameters. Indeed, exogenously administered murine β-defensin 14 directly delayed mouse primary keratinocyte scratch wound closure invitro. To further explore the role of murine β-defensin 14 in wound repair, we used Defb14-/- mice and showed they had a global delay in healing invivo, associated with alterations in wound microbiota. Taken together, these studies suggest a key role for NOD2-mediated regulation of local skin microbiota, which in turn affects chronic wound etiology.

Growth hormone-releasing peptide 6 prevents cutaneous hypertrophic scarring: early mechanistic data from a proteome study.

Hypertrophic scars (HTS) and keloids are forms of aberrant cutaneous healing with excessive extracellular matrix (ECM) deposition. Current therapies still fall short and cause undesired effects. We aimed to thoroughly evaluate the ability of growth hormone releasing peptide 6 (GHRP6) to both prevent and reverse cutaneous fibrosis and to acquire the earliest proteome data supporting GHRP6's acute impact on aesthetic wound healing. Two independent sets of experiments addressing prevention and reversion effects were conducted on the classic HTS model in rabbits. In the prevention approach, the wounds were assigned to topically receive GHRP6, triamcinolone acetonide (TA), or vehicle (1% sodium carboxy methylcellulose [CMC]) from day 1 to day 30 post-wounding. The reversion scheme was based on the infiltration of either GHRP6 or sterile saline in mature HTS for 4 consecutive weeks. The incidence and appearance of HTS were systematically monitored. The sub-epidermal fibrotic core area of HTS was ultrasonographically determined, and the scar elevation index was calculated on haematoxylin/eosin-stained, microscopic digitised images. Tissue samples were collected for proteomics after 1 hour of HTS induction and treatment with either GHRP6 or vehicle. GHRP6 prevented the onset of HTS without the untoward reactions induced by the first-line treatment triamcinolone acetonide (TA); however, it failed to significantly reverse mature HTS. The preliminary proteomic study suggests that the anti-fibrotic preventing effect exerted by GHRP6 depends on different pathways involved in lipid metabolism, cytoskeleton arrangements, epidermal cells' differentiation, and ECM dynamics. These results enlighten the potential success of GHRP6 as one of the incoming alternatives for HTS prevention.

Skin and scale regeneration after mechanical damage in a teleost

Skin wound healing has been widely studied in mammalian models but the information on teleost cutaneous healing is sparse and frequently considered in the context of viral or bacterial infections or parasitic infestations in aquaculture. In the present study a detailed time course (0 h, 6 h, 1, 2, 3 and 4 days) coupled to morphology and gene expression analysis revealed rapid regeneration of skin without scarring in a marine teleost after a superficial wound caused by the loss of a large area of scales. The integrity of the integument, as assessed by quantification of extracellular matrix (ECM) gene transcripts (fn1a, colIα1, colVα2, colXα1, ogn1, ogn2, crtac1a, cyr61, pcna, krt2 and mmp9) was restored within 2 days. Epithelial-mesenchyme interactions assessed by expression of edar and shh were associated with epidermal closure, the re-establishment of the basement membrane and also scale eruption. Histological observations suggested tissue re-epithelialization was independent of inflammation and that transcripts representing the humoral and cellular elements of the immune response (mpo, cyba and csf1r, cd48 and cd200) were modulated in the early stages of sea bream (Sparus aurata) skin repair after injury. Overall, the results indicate that after superficial skin damage tissue reconstitution started immediately with re-epithelialization, followed by ECM deposition and finally tissue maturation, indicating that in the skin regenerative process, reconstitution of the physical barrier was the priority over other integument functions, including immune surveillance.

Evaluation of wound healing effect of alginate films containin g Aloe vera ( Aloe barbadensis Miller) gel.

A new alginate dressing with Aloe vera gel was developed and used to study its cutaneous healing effect in vivo by surgical wounds in Wistar rats. The aloe-alginate film was characterized by Fourier-transform infrared spectroscopy, mechanical properties, scanning electron microscopy, hydration rate, and calcium release. The aloe-alginate film demonstrated desirable physical and mechanical characteristics for wound dressing application. The animals were divided in three groups (n = 20): gauze bandage, alginate film, and aloe-alginate film. The histological analysis on the 3rd, 7th, 14th, and 22nd days after the treatment showed that the aloe-alginate films modulated the inflammatory phase and decreased the quantity of macrophages when compared to the alginate film group and the control (gauze bandage). The evaluation of collagen fibers showed a decrease in type III and increase in type I fibers on group treated with aloe-alginate film suggesting an improvement in the progression of the healing process.

Statin Therapy Negatively Impacts Skeletal Muscle Regeneration and Cutaneous Wound Repair in Type 1 Diabetic Mice.

Those with diabetes invariably develop complications including cardiovascular disease (CVD). To reduce their CVD risk, diabetics are generally prescribed cholesterol-lowering 3-hydroxy-methylglutaryl coenzyme A reductase inhibitors (i.e., statins). Statins inhibit cholesterol biosynthesis, but also reduce the synthesis of a number of mevalonate pathway intermediates, leading to several cholesterol-independent effects. One of the pleiotropic effects of statins is the reduction of the anti-fibrinolytic hormone plasminogen activator inhibitor-1 (PAI-1). We have previously demonstrated that a PAI-1 specific inhibitor alleviated diabetes-induced delays in skin and muscle repair. Here we tested if statin administration, through its pleiotropic effects on PAI-1, could improve skin and muscle repair in a diabetic rodent model. Six weeks after diabetes onset, adult male streptozotocin-induced diabetic (STZ), and WT mice were assigned to receive control chow or a diet enriched with 600 mg/kg Fluvastatin. Tibialis anterior muscles were injured via Cardiotoxin injection to induce skeletal muscle injury. Punch biopsies were administered on the dorsal scapular region to induce injury of skin. Twenty-four days after the onset of statin therapy (10 days post-injury), tissues were harvested and analyzed. PAI-1 levels were attenuated in statin-treated diabetic tissue when compared to control-treated tissue, however no differences were observed in non-diabetic tissue as a result of treatment. Muscle and skin repair were significantly attenuated in Fluvastatin-treated STZ-diabetic mice as demonstrated by larger wound areas, less mature granulation tissue, and an increased presence of smaller regenerating muscle fibers. Despite attenuating PAI-1 levels in diabetic tissue, Fluvastatin treatment impaired cutaneous healing and skeletal muscle repair in STZ-diabetic mice.

Dermal fibroblast in cutaneous development and healing.

The skin is the largest organ of the body and is composed of two layers: the overlying epidermis and the underlying dermis. The dermal fibroblasts originate from distinct locations of the embryo and contain the positional identity and patterning information in the skin. The dermal fibroblast progenitors differentiate into various cell types that are fated to perform specific functions such as hair follicle initiation and scar formation during wound healing. Recent studies have revealed the heterogeneity and plasticity of dermal fibroblasts within skin, which has implications for skin disease and tissue engineering. The objective of this review is to frame our current understanding and provide new insights on the origin and differentiation of dermal fibroblasts and their function during cutaneous development and healing. WIREs Dev Biol 2018, 7:e307. doi: 10.1002/wdev.307 This article is categorized under: Birth Defects > Organ Anomalies Signaling Pathways > Cell Fate Signaling Adult Stem Cells, Tissue Renewal, and Regeneration > Regeneration Nervous System Development > Vertebrates: Regional Development.

The inhibition of 5-Lipoxygenase (5-LO) products leukotriene B4 (LTB4) and cysteinyl leukotrienes (cysLTs) modulates the inflammatory response and improves cutaneous wound healing

To analyze the participation of the enzyme 5-lipoxygenase (5-LO) in skin repair, WT wounds were compared to those in 5-LO deficient mice (5-LO−/−), which presented faster closure and reduced inflammatory infiltrate in the skin, together with increased CD4 regulatory T cells markers in the draining lymph nodes. The 5-LO−/− wounds also had diminished TNF-α, CCL11, CCL7, CCL2, CXCL9, CCR1 and CXCR2 mRNA expression in the lesions, besides differential extracellular matrix remodeling. Furthermore, when cysteinyl leukotriene (cysLT) and leukotriene (LTB4) receptors were antagonized in WT mice, there was a remarkable reduction in TNF-α expression and faster skin healing, similarly to the findings in 5-LO−/− animals. Finally, our results suggested that 5-LO products, in special cysLT and LTB4, underline skin inflammation that follows skin injury and their neutralization may be an important strategy to improve cutaneous healing.

Contribution of therapeutic education to the prevention of pressure ulcers in spinal cord injury

Spinal cord injuries (SCI) are not chronic illness, but a new state of life that requires several adaptations. It seems particularly interesting to apply the concept of therapeutic patient education (TPE) on SCI to prevent the occurrence of pressure ulcers (PU). The aim of our study was to evaluate the contribution of TPE in SCI to prevent the occurence of PU. It was a prospective study. Two groups of SCI were randomized to 25 subjects. The first group (G1) had the usual advices and the second group (G2) had a TPE according to a guide that we established. All patients had an initial assessment of their knowledge and a second one three months later. Fifty patients were included. There was no statistically significant difference between two groups concerning age, sex and ASIA score. There were no patients with urinary incontinence in either group. The initial assessment revealed moderately knowledge in both groups regarding mechanisms of onset of PU, its complications, its risk factors, monitoring of the skin condition, areas of risk to be monitored, relief of fulcrums, signs of PU and the role of good body hygiene. The knowledge was considered bad for the items risk of the tobacco on cutaneous healing, situations conducing to the appearance of pressure scores, warning signs prior to the occurrence of PU, quality control of the support surfaces in the prevention of PU, the role of balanced nutrition, the choice of clothes and adapted sheets and how to deal with redness of the skin. At the three-month evaluation, we found a statistically significant improvement in G2 responses. Thirteen patients in G1 developed PU. Only 3 patients in G2 developed PU. Our study showed the efficacy of TPE of SCI in order to improve their knowledge and consequently their practices for the prevention of PU. Therefore the patient must participate at his own care.

Wound healing in Piaractus mesopotamicus supplemented with chromium carbochelate and Saccharomyces cerevisiae

A cicatrização e reparação de tecidos são mecanismos essenciais para garantir a sobrevivência e saúde de qualquer indivíduo. O objetivo deste trabalho foi avaliar o impacto da suplementação com carboquelato de cromo (CC) e Saccharomyces cerevisiae (SC) sobre a cicatrização no peixe tropical Piaractus mesopotamicus. Para isto, os peixes foram distribuídos em quatro grupos: controle (sem tratamento), suplementados com 18 mg/kg de carboquelato de cromo, 0,3% de S. cerevisiae e associação de ambos os suplementos. Após 105 dias de alimentação, foram realizadas incisões na pele de espessura completa (2,0 x 1,0 x 0,25 cm) removendo epiderme e derme. Avaliações macroscópicas e microscópicas foram realizadas 1, 3, 7, 14, 21, 28 e 35 dias após a indução das feridas, para monitorar a taxa de cicatrização. As bordas opostas das feridas avançaram gradualmente a cada dia, demonstrando o aumento progressivo do processo de cicatrização ao longo do tempo. O processo inflamatório foi exacerbado e expansivo, com aumento no número de células mucosas e cromatóforos. Apesar deste processo, não foram observadas diferenças significativas na retração das feridas e nos parâmetros microscópicos entre os grupos. Peixes suplementados com CC ou Sc apresentaram rápida reepitelização, maior grau de organização de fibras colágenas e de neovascularização inicial. Concluiu-se que a suplementação com S. cerevisiae ou carboquelato de cromo melhora aspectos específicos do processo cicatricial no pacu.

Halloysite and chitosan oligosaccharide nanocomposite for wound healing.

The present work is focused on the development of halloysite and chitosan oligosaccharide nanocomposite for wound healing. It considers a therapeutic option for difficult to heal skin lesions and burns. The significance of the research considers two fundamental aspects: the first one is related to the development of a self-assembled nanocomposite, formed by spontaneous ionic interaction, while the second one is related to the possibility to find an effective treatment for cutaneous non healing lesions. The characterization of this hybrid system involves a multidisciplinary approach considering integrated techniques of solid state investigation and advanced electron microscopies, and in vitro/in vivo models to understand biocompatibility and proliferation properties (enhancement of in vitro fibroblast motility, proliferation and migration, and of in vivo burn healing), to understand safety and effectiveness of the developed nanocomposite.

Abstract 519: Inhibition of von Willebrand Factor Activity Does Not Delay Cutaneous Wound Healing

Introduction: Physiologically, von Willebrand Factor (VWF) recruits platelets to sites of injury by binding to exposed collagen and platelet GPIbα, particularly at sites of high shear. VWF is critical to hemostasis, since complete deficiency leads to bleeding as severe as hemophilia. Conversely, VWF plays a key role in arterial thrombosis, as in myocardial infarction and stroke. Despite being an attractive therapeutic target, no agents directed against VWF are currently available. Our group is testing an RNA aptamer that blocks VWF binding to GPIbα as an antithrombotic. We have previously shown that leukocyte influx and cutaneous healing are impaired in a mouse model of hemophilia. We have also found that wound healing is delayed in mice given target specific oral anticoagulants. The purpose of the current study was to determine whether inhibiting VWF would similarly impair wound healing. Methods: We used C57BL/6J mice administered vehicle or VWF aptamer. At the dose selected, aptamer prolonged the saphenous vein bleeding time for the expected 10 day healing period. Healing was assessed in a skin punch biopsy model. Wound size was measured daily, and following sacrifice the wound area harvested for histology. Inflammation (in the absence of tissue injury) was induced by topical application of cantharidin for 24 hours, followed by tissue harvesting. Results: The in vivo efficacy of the aptamer was verified, since bleeding remained prolonged to a level slightly less severe than hemophilia at the end of the experiment (10 days after wounding). There was no difference in time to healing between control and aptamer-treated mice, with all wounds healed at 10 days. There was also no statistically significant difference in wound size at any time. Cantharidin induced a similar level of cellular influx in treated and control mice. Aptamer-treated mice exhibited a slight amount of inflammation-induced hemorrhage, though not the gross hemorrhage observed in thrombocytopenic mice. Conclusion: Inhibition of VWF activity does not delay cutaneous wound closure, despite inducing a severe hemostatic defect. Compared to other antithrombotic strategies, an aptamer against VWF could avert some undesirable side effects on host defense and tissue repair.

395 Redefining colour and redness in cutaneous healing and scarring: Quantitative evaluation of erythema and pigmentation in human skin corroborated by immunohistochemical analysis

395 Redefining colour and redness in cutaneous healing and scarring: Quantitative evaluation of erythema and pigmentation in human skin corroborated by immunohistochemical analysis

935 Early-stage induction of ERK1/2 and NFkB pathways is essential for more rapid cutaneous healing in mice

935 Early-stage induction of ERK1/2 and NFkB pathways is essential for more rapid cutaneous healing in mice