High-dose ultraviolet light exposure reduces scar hypertrophy in a rabbit ear model

Wound care practices following in-office cutaneous surgery among family physicians in Canada

OBJECTIVE

Family physicians (FPs) in Canada routinely perform in-office cutaneous surgery. There is strong evidence to support a moist wound healing environment, resulting in faster healing times and improved cosmesis. However, the wound care practices of FPs have not been previously studied. We aimed to examine the postoperative wound care practices of FPs after in-office cutaneous surgery.

METHOD

An online survey was distributed to Canadian FPs to determine post-surgical wound care practices. The survey examined moist versus dry wound healing and the reasons for these recommendations were explored. Additional wound care practices were also studied. Appropriate statistical analyses were undertaken.

RESULTS

A total of 573 (91.5%) FPs completed the survey. Just under half (49.2%) of FPs recommended moist wound healing to their patients, while the remaining respondents (50.8%) recommended dry wound healing. The most endorsed reason for both moist and dry wound care recommendations was prior training (63.1% and 65.3%, respectively). Most physicians (57.2%) recommended the use of a cream or ointment postoperatively. While there appeared to be consensus on recommending sun avoidance after cutaneous surgery (77.7%), additional wound care practices varied, including: the use of dressings; cleansing practices; smoking cessation; reduction in physical activity; photoprotection; water exposure; and scar treatment/cosmetic use.

CONCLUSION

Almost half of FPs in Canada responding to the survey did not recommend moist wound healing despite strong evidence to support this practice. We also noted a diverse range of postoperative wound care practices after in-office cutaneous surgery. Therefore, these results highlight a critical need for consistent wound care recommendations following cutaneous surgery for FPs in Canada.

Chinese expert consensus on clinical prevention and treatment of scar. BURNS & TRAUMA 2018;6:27. [PMID: 30263894 PMCID: PMC6154406 DOI: 10.1186/s41038-018-0129-9]

Following injury, Asian skin has a tendency toward hyperpigmentation and scar formation than Caucasians. A standardized algorithm tailored to Asian patients, especially Chinese patients, is in great demand. Twelve independent, self-selected academic and military physicians from the department of burn/trauma, plastic surgery and dermatology with extensive experience in treating scars were assembled on January 17, 2015, establishing the consensus panel. This consensus was then appraised, drafted, reviewed, and finalized during the following 3 years, aiming to standardize and improve scar prevention and treatment in China. Hopefully, it may also provide some advices and references for the management of scarring in Asian patients.

Hypertrophic Scarring in the Rabbit Ear: A Practical Model for Studying Dermal Fibrosis

Excessive fibrous tissue deposition after injury in the form of hypertrophic scar remains a major clinical challenge. The development of an animal model for such scarring has been extremely difficult because of a major difference between the healing process in laboratory animals and humans. Here, we describe the rabbit ear model for excessive dermal scarring which has some clinical and histological resemblance to human hypertrophic scar. Since its development, this model has been widely used to study the cellular and molecular biology of hypertrophic scarring and evaluate the efficacy of new therapeutic agents.

Sodium channel Nax is a regulator in epithelial sodium homeostasis

The mechanisms by which the epidermis responds to disturbances in barrier function and restores homeostasis are unknown. With a perturbation of the epidermal barrier, water is lost, resulting in an increase in extracellular sodium concentration. We demonstrate that the sodium channel Nax functions as a sodium sensor. With increased extracellular sodium, Nax up-regulates prostasin, which results in activation of the sodium channel ENaC, resulting in increased sodium flux and increased downstream mRNA synthesis of inflammatory mediators. Nax is present in multiple epithelial tissues, and up-regulation of its downstream genes is found in hypertrophic scars. In animal models, blocking Nax expression results in improvement in scarring and atopic dermatitis-like symptoms, both of which are pathological conditions characterized by perturbations in barrier function. These findings support an important role for Nax in maintaining epithelial homeostasis.

Effect of P144® (Anti-TGF-β) in an "In Vivo" Human Hypertrophic Scar Model in Nude Mice

Background

Hypertrophic scars are one of the most important complications in surgery due to their cosmetic and functional impairments. Previous studies in tissue fibrotic disorders have shown promising results by inhibiting the biological activity effect of Transforming Growth Factor-beta 1 (TGF-β1). The aim of the current study was to determine the clinical effect of the inhibition of TGF-β1 signaling in human hypertrophic scars implanted in nude mice by topical application of an inhibitor of TGF-β1 (P144®).

Material and Methods

A total of 30 human hypertrophic scars were implanted in 60 nude mice. The animals were divided in two groups, group A (placebo) and group B (treatment). Group C (basal) was considered as the preimplanted scar samples and they were not implanted in the nude mice. After the shedding period, topical application of a lipogel containing placebo (group A) or P144 (group B) was daily administered during two weeks. The animals were sacrificed upon completion of the study. Total area, thickness and collagen fibers area were measure and compared across all groups. Immunohistochemistry was also performed in order to quantify collagen type I and type III and elastic fiber expressions present in the dermis.

Results

Successful shedding was achieved in 83,3% of the xenografts. The mean time for shedding was 35±5.4 days. Statistically significant differences were found in the total area, collagen fibers area and thickness between the groups. Increased elastic fibers and decreased collagen I were found in the P144-treated group compared to the basal group.

Conclusion

Topical application of an inhibitor of TGF-β1 may promote scar maturation and clinical improvement of hypertrophic scar morphology features in an “in vivo” model in nude mice after two weeks of treatment.

Hydration status regulates sodium flux and inflammatory pathways through epithelial sodium channel (ENaC) in the skin

Although it is known that the inflammatory response that results from disruption of epithelial barrier function after injury results in excessive scarring, the upstream signals remain unknown. It has also been observed that epithelial disruption results in reduced hydration status and that the use of occlusive dressings that prevent water loss from wounds decreases scar formation. We hypothesized that hydration status changes sodium homeostasis and induces sodium flux in keratinocytes, which result in activation of pathways responsible for keratinocyte-fibroblast signaling and ultimately lead to activation of fibroblasts. Here, we demonstrate that perturbations in epithelial barrier function lead to increased sodium flux in keratinocytes. We identified that sodium flux in keratinocytes is mediated by epithelial sodium channels (ENaCs) and causes increased secretion of proinflammatory cytokines, which activate fibroblast via the cyclooxygenase 2 (COX-2)/prostaglandin E2 (PGE2) pathway. Similar changes in signal transduction and sodium flux occur by increased sodium concentration, which simulates reduced hydration, in the media in epithelial cultures or human ex vivo skin cultures. Blockade of ENaC, prostaglandin synthesis, or PGE2 receptors all reduce markers of fibroblast activation and collagen synthesis. In addition, employing a validated in vivo excessive scar model in the rabbit ear, we demonstrate that utilization of either an ENaC blocker or a COX-2 inhibitor results in a marked reduction in scarring. Other experiments demonstrate that the activation of COX-2 in response to increased sodium flux is mediated through the PIK3/Akt pathway. Our results indicate that ENaC responds to small changes in sodium concentration with inflammatory mediators and suggest that the ENaC pathway is a potential target for a strategy to prevent fibrosis.

Effects of botulinum toxin type A on expression of genes in keloid fibroblasts

BACKGROUND

Invasive growth of fibroblast cells, which is regulated by multiple biological factors, is the key event in the pathophysiology of keloid scars. Recent studies have suggested that botulinum toxin type A (BoNT-A) could inhibit invasive growth of keloids. However, the molecular mechanisms are unknown.

OBJECTIVE

The authors explore the effect of BoNT-A on the expression of genes relevant to invasive growth in keloid fibroblasts.

METHODS

With 112 genes that were relevant to invasive growth, the authors utilized microarray analysis to study messenger RNA expression profiles in keloid fibroblasts treated with BoNT-A. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to confirm the microarray results.

RESULTS

Analyses from microarray and qRT-PCR revealed that the S100A4 gene was upregulated and that the TGF-β1, VEGF, MMP-1, and PDGFA genes were downregulated in fibroblasts treated with BoNT-A.

CONCLUSIONS

The BoNT-A altered expression levels of S100A4, TGF-β1, VEGF, MMP-1, and PDGFA genes in keloid fibroblasts provide a useful clue for exploring the function of BoNT-A and finding a novel treatment for keloid scarring.

In vivo inhibition of hypertrophic scars by implantable ginsenoside-Rg3-loaded electrospun fibrous membranes

Clinically, hypertrophic scarring (HS) is a major concern for patients and has been a challenge for surgeons, as there is a lack of treatments that can intervene early in the formation of HS. This study reports on a Chinese drug, 20(R)-ginsenoside Rg3 (GS-Rg3), which can inhibit in vivo the early formation of HS and later HS hyperplasia by inducing the apoptosis of fibroblasts, inhibiting inflammation and down-regulating VEGF expression. Implantable biodegradable GS-Rg3-loaded poly(l-lactide) (PLA) fibrous membranes were successfully fabricated using co-electrospinning technology to control drug release and improve drug utilization. The in vivo releasing time of GS-Rg3 lasts for 3 months, and the drug concentration released in rabbits can be controlled by varying the drug content of the electrospun fibers. Histological observations of HE staining indicate that GS-Rg3/PLA significantly inhibits the HS formation, with obvious improvements in terms of dermis layer thickness, epidermis layer thickness and fibroblast proliferation. The results of immunohistochemistry staining and Masson's trichrome staining demonstrate that GS-Rg3/PLA electrospun fibrous membranes significantly inhibit HS formation, with decreased expression of collagen fibers and microvessels. VEGF protein levels are much lower in the group treated with GS-Rg3/PLA eletrospun membranes compared with other groups. These results demonstrate that GS-Rg3 is a novel drug, capable of inhibiting the early formation of HS and later HS hyperplasia. GS-Rg3/PLA electrospun membrane is a very promising new treatment for early and long-term treatment of HS.

Electrospun poly(L-lactide) fiber with ginsenoside rg3 for inhibiting scar hyperplasia of skin

Hypertrophic scarring (HS) has been considered as a great concern for patients and a challenging problem for clinicians as it can be cosmetically disfiguring and functionally debilitating. In this study, Ginsenoside Rg3/Poly(l-lactide) (G-Rg3/PLLA) electrospun fibrous scaffolds covering on the full-thickness skin excisions location was designed to suppress the hypertrophic scar formation in vivo. SEM and XRD results indicated that the crystal G-Rg3 carried in PLLA electrospun fibers was in amorphous state, which facilitates the solubility of G-Rg3 in the PLLA electrospun fibrous scaffolds, and solubility of G-Rg3 in PBS is increased from 3.2 µg/ml for pure G-Rg3 powders to 19.4 µg/ml for incorporated in PLLA-10% fibers. The released G-Rg3 content in the physiological medium could be further altered from 324 to 3445 µg in a 40-day release period by adjusting the G-Rg3 incorporation amount in PLLA electrospun fibers. In vitro results demonstrated that electrospun G-Rg3/PLLA fibrous scaffold could significantly inhibit fibroblast cell growth and proliferation. In vivo results confirmed that the G-Rg3/PLLA electrospun fibrous scaffold showed significant improvements in terms of dermis layer thickness, fibroblast proliferation, collagen fibers and microvessels, revealing that the incorporation of the G-Rg3 in the fibers prevented the HS formation. The above results demonstrate the potential use of G-Rg3/PLLA electrospun fibrous scaffolds to rapidly minimize fibroblast growth and restore the structural and functional properties of wounded skin for patients with deep trauma, severe burn injury, and surgical incision.

Splinting Strategies to Overcome Confounding Wound Contraction in Experimental Animal Models

SIGNIFICANCE

Clinical healing by secondary intention frequently occurs in skin that is firmly anchored to underlying (human) connective tissue. Small animals (rodents) are extensively utilized to model human cutaneous wound healing, but they heal by wound contraction, a process that is limited in the human and confounds quantitative and qualitative evaluation of experimental wound repair.

RECENT ADVANCES

To alleviate wound contraction in loose-skinned species, practical solutions include choosing anatomical sites with firmly attached dermis and subcutis (e.g., rabbit ear) or performing mechanical fixation of the skin by using one of a number of devices or splints. In each case, the wound volume remains relatively constant, allowing the histomorphometric or biomolecular quantification of the cellular response under well-controlled, experimental conditions. In addition, the defined aperture of the splinted wound allows the placement of a variety of materials, including scaffolds, cells, and biologically active formulations into the wound site in an effort to potentiate the healing response and abrogate scarring. In contrast, production of larger experimental wounds or the deliberate distraction of wound margins can be used to model a hypertrophic response.

CRITICAL ISSUES

Device design parameters should consider ease of application, durability, and lack of interference with the normal influx of local and circulating cells to the wound site.

FUTURE DIRECTIONS

Improved methods of securing flexible splints would provide a more efficient experimental platform. These devices could also incorporate optical or electronic sensors that report both the mechanical and physiological status of the healing.

Localized controlled release of stratifin reduces implantation-induced dermal fibrosis

Localized controlled release of anti-fibrogenic factors can potentially prevent tissue fibrosis surrounding biomedical prostheses, such as vascular stents and breast implants. We have previously demonstrated that therapeutic intervention with topically applied stratifin in a rabbit ear fibrotic model not only prevents dermal fibrosis but also promotes more normal tissue repair by regulating extracellular matrix deposition. In this work, the anti-fibrogenic effect of a controlled release form of stratifin was investigated in the prevention of fibrosis induced by dermal poly(lactic-co-glycolic acid) (PLGA) microsphere/poly(vinyl alcohol) (PVA) hydrogel implants. Pharmacodynamic effects were evaluated by histopathological examination of subcutaneous tissue surrounding implanted composites. Controlled release of stratifin from PLGA microsphere/PVA hydrogel implants significantly moderated dermal fibrosis and inflammation by reducing collagen deposition (30%), total tissue cellularity (48%) and infiltrated CD3(+) immune cells (81%) in the surrounding tissue compared with the stratifin-free implants. The controlled release of stratifin from implants markedly increased the level of matrix metalloproteinase-1 expression in the surrounding tissue, which resulted in less collagen deposition. These stratifin-eluting PLGA/PVA composites show promise as coatings to decrease the typical fibrosis exhibited around implanted biomedical prostheses, such as breast implants and vascular stents.

The effect of surgical denervation on prevention of excessive dermal scarring: a study on rabbit ear hypertrophic scar model

BACKGROUND

Previous reports have suggested that the extent of wound contraction, epithelisation and total healing time were influenced by denervation of tissues. In this article, we studied for the first time the effect of sensory denervation on prevention of excessive dermal scarring.

MATERIALS AND METHODS

Sixteen New Zealand white rabbits were used. Denervation of the right ears was performed by surgical excision of two main sensory nerves. Dissections were also performed on left ears without any nerve excision for the control group. After 14 days of follow-up and confirmation of tissue denervation, an excessive dermal scarring model as defined by Morris et al. was made by surgery on both ears. Twenty-eight days after making the wounds, the tissues were extirpated for analyses. The scars were evaluated by the scar elevation index (SEI), epithelisation time and inflammatory cell count.

RESULTS

The SEI of the denervated side scars was significantly lower than that of the non-denervated side. The rate and timing of total epithelisation and inflammatory cell count between groups yielded no difference.

CONCLUSIONS

In this study, the surgical denervation skin reduced scarring. It was suggested that understanding the exact role of sensory nerves and neural mediators in excessive dermal scarring is necessary for the prevention and treatment of scarring.

Intradermal tacrolimus prevent scar hypertrophy in a rabbit ear model: a clinical, histological and spectroscopical analysis

BACKGROUND

Keloids and hypertrophic scars (HSc) affect 4.5-16% of the population. Thus far, the different approaches of keloid treatment are not very efficient, with a 50% relapse rate and many ongoing researches are looking for simple, safe and more efficient therapeutic methods. Tacrolimus is an immunomodulator that could be useful in treating keloid.

OBJECTIVES

The objective of this study is to evaluate the effectiveness of Tacrolimus in inhibiting HSc formation on rabbits' ears model and to check optical skin spectroscopy in tissue characterization.

METHODS

Our study was carried out on 20 New-Zealand female white rabbits. HSc were obtained by wounding rabbits' ear. These wounds were treated with intradermal injections of tacrolimus (0.2-0.5 mg/cm(2)) or a vehicule. The assessment of treatment efficacy was performed by clinical examinations, histological assay and skin spectrometry.

RESULTS

Tacrolimus did not induce general or local side-effects. The scar elevation index in treated subjects was half less than that of the untreated ones. Furthermore, dermal thickness and inflammatory cellular density were both significantly smaller for treated scars than for the control ones. In vivo optical skin spectroscopy can characterize hypertrophic and normal skin with high sensibility and specificity.

CONCLUSION

Intradermal injection of tacrolimus at 0.5 mg/cm(2) is an efficient way to prevent HSc in our experiment model and its tolerance is correct. Optical spectroscopy could be a good non-invasive tool to evaluate HSc treatment. These promising results might be proposed for patients suffering from keloid.