Associations between traumatic stress symptoms, pain and bio-active components in burn wounds.

OBJECTIVE: Pain and traumatic stress symptoms often co-occur. Evidence suggests that the neuropeptide oxytocine and pro-inflammatory cytokines are associated with both stress and pain. The aim of this pilot study was to explore relations between self-reported pain and traumatic stress, oxytocin and three cytokines in burn wounds. METHODS: An observational study in three burn centres was performed. Patients were invited to participate in the study when deep dermal injury was suspected. Patients completed the Impact of Event Scale (IES), a self-report questionnaire assessing traumatic stress symptoms, and they rated their pain the day prior to surgery. During surgery, eschar (i.e., burned tissue) was collected and stored at -80 ° C until analysis. When the data collection was complete, oxytocin and cytokine levels were analysed. RESULTS: Eschar from 53 patients was collected. Pain and stress scores were available from 42 and 36 patients respectively. Spearman correlational analyses showed an association between lower oxytocin levels at wound site and a higher total IES score (r = -0.37) and pain (r = -0.32). Mann-Whitney U tests comparing groups scoring high or low on pain or stress confirmed these associations. CONCLUSION: These analyses lend support to a hormonal pathway that may explain how psychological distress affects pain at skin level in patients with traumatic stress symptoms.

In vitro cultured fetal fibroblasts have myofibroblast-associated characteristics and produce a fibrotic-like environment upon stimulation with TGF-ß1: Is there a thin line between fetal scarless healing and fibrosis?

Transforming growth factor-ß (TGF-ß) is a cytokine occurring in three isoforms with an important function in development and wound healing. In wound healing, prolonged TGF-ß signaling results in myofibroblast differentiation and fibrosis. In contrast, the developing second-trimester fetal skin contains high levels of all three TGF-ß isoforms but still has the intrinsic capacity to heal without scarring. Insight into TGF-ß signal transduction during fetal wound healing might lead to methods to control the signaling pathway during adult wound healing. In this study, we imitated wound healing in vitro by stimulating fibroblasts with TGF-ß1 and examining myofibroblast differentiation. The aim was to gain insight into TGF-ß signaling in human fibroblasts from fetal and adult dermis. First, TGF-ß1 stimulation resulted in similar or even more severe upregulation of myofibroblast-associated genes in fetal fibroblasts compared to adult fibroblasts. Second, fetal fibroblasts also had higher protein levels of myofibroblast-marker α-smooth muscle actin (α-SMA). Third, stimulated fetal fibroblasts in collagen matrices had higher protein levels of α-SMA, produced more of the fibrotic protein fibronectin splice-variant extra domain A (FnEDA), and showed enhanced contraction. Finally, fetal fibroblasts also produced significant higher levels of TGF-ß1. Altogether, these data show that in vitro cultured fetal fibroblasts have myofibroblast-associated characteristics and do produce a fibrotic environment. As healthy fetal skin has high levels of TGF-ß1, FnEDA, and collagen-III as well, these findings correlate with the in vivo situation. Therefore, our study demonstrates that there are similarities between fetal skin development and fibrosis and shows the necessity to discriminate between these processes.

Currently known risk factors for hypertrophic skin scarring: A review.

OBJECTIVE: The study aims to provide an overview of risk factors for hypertrophic scarring. BACKGROUND: Hypertrophic skin scarring remains a major concern in medicine and causes considerable morbidity. Despite extensive research on this topic, the precise mechanism of excessive scarring is still unknown. In addition, the current literature lacks an overview of the possible risk factors in the development of hypertrophic scars. METHODS: PubMed searches were performed on risk factors for hypertrophic scar (HTS) formation. RESULTS: Eleven studies suggesting nine factors associated with HTS formation were found. Studies concerning chemotherapy, age, stretch, infection, and smoking have a moderate to high strength of evidence, but some other factors have not been studied in a convincing manner or are still disputed. CONCLUSIONS: Risk factors for HTS formation are young age, bacterial colonization, and skin subjected to stretch. Chemotherapy, statins, and smoking seem to play a protective role in HTS formation.

Cell therapy for full-thickness wounds: are fetal dermal cells a potential source?

The application of autologous dermal fibroblasts has been shown to improve burn wound healing. However, a major hurdle is the availability of sufficient healthy skin as a cell source. We investigated fetal dermal cells as an alternative source for cell-based therapy for skin regeneration. Human (hFF), porcine fetal (pFF) or autologous dermal fibroblasts (AF) were seeded in a collagen-elastin substitute (Novomaix, NVM), which was applied in combination with an autologous split thickness skin graft (STSG) to evaluate the effects of these cells on wound healing in a porcine excisional wound model. Transplantation of wounds with NVM+hFF showed an increased influx of inflammatory cells (e.g., neutrophils, macrophages, CD4(+) and CD8(+) lymphocytes) compared to STSG, acellular NVM (Acell-NVM) and NVM+AF at post-surgery days 7 and/or 14. Wounds treated with NVM+pFF presented only an increase in CD8(+) lymphocyte influx. Furthermore, reduced alpha-smooth muscle actin (αSMA) expression in wound areas and reduced contraction of the wounds was observed with NVM+AF compared to Acell-NVM. Xenogeneic transplantation of NVM+hFF increased αSMA expression in wounds compared to NVM+AF. An improved scar quality was observed for wounds treated with NVM+AF compared to Acell-NVM, NVM+hFF and NVM+pFF at day 56. In conclusion, application of autologous fibroblasts improved the overall outcome of wound healing in comparison to fetal dermal cells and Acell-NVM, whereas application of fetal dermal fibroblasts in NVM did not improve wound healing of full-thickness wounds in a porcine model. Although human fetal dermal cells demonstrated an increased immune response, this did not seem to affect scar quality.

Transforming growth factor-ß (TGF-ß) signaling in healthy human fetal skin: a descriptive study.

BACKGROUND: TGF-ß plays an important role in growth and development but is also involved in scarring and fibrosis. Differences for this growth factor are known between scarless fetal wound healing and adult wound healing. Nonetheless, most of the data in this area are from animal studies or in vitro studies and, thus, information about the human situation is incomplete and scarce. OBJECTIVE: The aim of this study was to compare the canonical TGF-ß signaling in unwounded human fetal and adult skin. METHODS: Q-PCR, immunohistochemistry, Western Blot and Luminex assays were used to determine gene expression, protein levels and protein localization of components of this pathway in healthy skin. RESULTS: All components of the canonical TGF-ß pathway were present in unwounded fetal skin. Compared to adult skin, fetal skin had differential concentrations of the TGF-ß isoforms, had high levels of phosphorylated receptor-Smads, especially in the epidermis, and had low expression of several fibrosis-associated target genes. Further, the results indicated that the processes of receptor endocytosis might also differ between fetal and adult skin. CONCLUSION: This descriptive study showed that there are differences in gene expression, protein concentrations and protein localization for most components of the canonical TGF-ß pathway between fetal and adult skin. The findings of this study can be a starting point for further research into the role of TGF-ß signaling in scarless healing.

Minimal extracorporeal circulation (MECC) does not result in less hypertrophic scar formation as compared to conventional extracorporeal circulation (CECC) with dexamethasone.

INTRODUCTION: Cardiopulmonary bypass surgery is associated with a systemic inflammatory response through the interaction of air, blood and synthetic components in the bypass system and the physical trauma of surgery. An alternative cardiopulmonary bypass system, minimal extracorporeal circulation (MECC), has shown promising results in terms of reducing the inflammatory response. We hypothesized that this system may reduce pathological excessive scarring. To study this assumption, the effects of MECC and the effects of conventional extracorporeal circulation (CECC) with dexamethasone on skin scarring were compared in a standardized wound-healing model. METHODS AND RESULTS: Pre-sternal scars were evaluated prospectively at four and 12 months postoperatively. The height and width of the scars were measured, using a slide caliper and sonography. The scars were scored using the validated Patient and Observer Scar Assessment Scale. Additional risk factors for hypertrophic scar formation were identified by means of a questionnaire. During surgery, MECC was used in 45 patients and CECC/dexamethasone in 42 patients. Four months postoperatively, 22 patients of the MECC group (49%) and 18 patients in the CECC/dexamethasone group (43%) had developed hypertrophic scars. Twelve months postoperatively, the hypertrophic scars in four patients of the MECC group and in two patients of the CECC/dexamethasone group had become normotrophic. In 18 patients of the MECC group (38%) and 16 patients of the CECC group (41%) the scars remained hypertrophic at 12 months. These differences between the two groups were not statistically significant. CONCLUSION: MECC does not reduce hypertrophic scar formation compared with CECC with dexamethasone, but its use is more beneficial than the use of CECC/dexamethasone because of the circulatory and immunological advantages and because treatment with dexamethasone can be omitted.

The effect of a honey based gel and silver sulphadiazine on bacterial infections of in vitro burn wounds.

Bacterial contamination remains a constant threat in burn wound care. Topical treatments to combat contaminations have good bactericidal effects but can have detrimental effects for the healing process. Treatments with for example silver can increase healing times. Honey based products can be a good alternative as it is antibacterial and patient-friendly. We evaluated the bactericidal and cytotoxic effects of a honey based gel and silver sulphadiazine in a human burn wound model with Pseudomonas aeruginosa. After adding 10(5)colony forming units of P. aeruginosa, topical treatments were applied on the burn wound models. After 2, 12, 24, 28 and 70 h, bacteria were dislodged and counted by plating dilutions. Cytotoxic effects were evaluated histologically in samples of burn wound models treated topically for 3 weeks, without bacteria. L-Mesitran Soft significantly reduced the bacterial load (5-log reduction) up to 24h but did not completely eliminate bacteria from the burn wounds. After Flammazine(®) treatment, only a few colony forming units were observed at all time points. In contrast, re-epithelialization was significantly reduced after application of Flammazine(®) compared to L-Mesitran Soft or control. This in vitro model of burn wound infection can be used to evaluate topical treatments. L-Mesitran Soft is a good alternative for treating burn wounds but the slightly lower bactericidal activity in the burn wound model warrants a higher frequency of application.

A cytotoxic analysis of antiseptic medication on skin substitutes and autograft.

BACKGROUND: There is an increasing demand for the clinical application of human skin substitutes (HSSs) for treating ulcers, burns and surgical wounds. Due to this increasing demand and due to the simultaneous requirement for the administration of topical antiseptic medications, there is a need to determine potential cytotoxic effects of these medications on HSSs compared with autograft skin. OBJECTIVES: To perform such an evaluation. METHODS: Two different HSSs were used (autologous reconstructed epidermis on fibroblast-populated human dermis and allogeneic reconstructed epidermis on a fibroblast-populated rat collagen gel) and were compared with conventional full-thickness autograft. Twelve different antiseptics were applied topically to the stratum corneum in vitro for 24 h. The degree of cytotoxicity was analysed as detrimental changes in histology, metabolic activity (MTT assay) and RNA staining of tissue sections. RESULTS: The antiseptic medications tested showed different degrees of cytotoxicity. Acticoat, Aquacel Ag, Dermacyn, Fucidin, 0.5% silver nitrate solution and chlorhexidine digluconate were not cytotoxic for either HSS or autograft, and can therefore be used as required. Flamazine and zinc oxide cream resulted in moderate cytotoxicity. However, application of Betadine((R)), cerium-silver sulfadiazine cream, silver sulfadiazine cream with 1% acetic acid and Furacine resulted in a substantial decrease in cell viability and a detrimental effect on tissue histology when applied to autograft and especially to HSS. CONCLUSIONS: Due to the potential cytotoxic effect of some antiseptics on HSS, it is advised that clinicians balance the cytotoxicity of the medication, its antiseptic properties and the severity of colonization in choosing which one to apply.

Porcine wound models for skin substitution and burn treatment.

Skin regeneration is an important field of tissue engineering. Especially in larger burns and chronic wounds, present treatments are insufficient in preventing scar formation and promoting healing. Initial screening of potentially interesting products for skin substitution is usually done by in vitro tests. Before entering the clinic, however, in vivo studies in immunocompetent animals are necessary to prove efficacy and provide information on safety aspects. We have obtained extensive experience using the domestic pig as test animal for studies on skin replacement materials, including tissue engineered skin substitutes, and burn wound treatment. Two models are described: an excisional wound model for testing of dermal and epidermal substitutes and a burn wound model for contact and scald burns, which allows testing of modern wound dressings in comparison to the present gold standards in burn treatment. The results of these experiments show that in vivo testing was able to reveal (dis)advantages of the treatments which were not detected during in vitro studies.