Effectiveness of a Regenerative Epithelial Suspension (RES), on the pigmentation of split-thickness skin graft donor sites in children: the dRESsing pilot randomised controlled trial protocol

BACKGROUND

Paediatric donor site wounds are often complicated by dyspigmentation following a split-thickness skin graft. These easily identifiable scars can potentially never return to normal pigmentation. A Regenerative Epidermal Suspension (RES) has been shown to improve pigmentation in patients with vitiligo, and in adult patients following a burn injury. Very little is known regarding the efficacy of RES for the management of donor site scars in children.

METHODS AND ANALYSIS

A pilot randomised controlled trial of 40 children allocated to two groups (RES or no RES) standard dressing applied to donor site wounds will be conducted. All children aged 16 years or younger requiring a split thickness skin graft will be screened for eligibility. The primary outcome is donor site scar pigmentation 12 months after skin grafting. Secondary outcomes include re-epithelialisation time, pain, itch, dressing application ease, treatment satisfaction, scar thickness and health-related quality of life. Commencing 7 days after the skin graft, the dressing will be changed every 3-5 days until the donor site is ≥ 95% re-epithelialised. Data will be collected at each dressing change and 3, 6 and 12 months post skin graft.

ETHICS AND DISSEMINATION

Ethics approval was confirmed on 11 February 2019 by the study site Human Research Ethics Committee (HREC) (HREC/18/QCHQ/45807). Study findings will be published in peer-reviewed journals and presented at national and international conferences. This study was prospectively registered on the Australian New Zealand Clinical Trials Registry (available at https://anzctr.org.au/ACTRN12620000227998.aspx).

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry [Available at https://anzctr.org.au/ACTRN12620000227998.aspx].

Early intervention of carbon dioxide fractional laser in hypertrophic scar through TGFβ-1/ Smad3 signaling pathway

Hypertrophic scars are usually the result of surgical trauma or burn,and more common in individuals with a darker skin color. They appear as red and raised lesions around the wound that continually expand over a period of weeks or months, causing itching, pain, burning sensation and discomfort. Severe scarring affects interpersonal and social relationships, and decreases the quality of life of the patients.The aim of this study was to evaluate the effect of carbon dioxide fractional laser as an early intervention against hypertrophic scars using a rabbit ear scar model, and explore the role of the TGFβ-1/ Smad3 signaling pathway in scar hyperplasia. Four wounds were made into each ear of rabbits, and divided into the untreated control and three laser-treatment groups. The experimental groups received laser intervention once, twice and thrice respectively. laser treatment significantly inhibited the formation of hypertrophic scars, and maximum benefits were seen in the wounds that received three laser treatments. Immunohistochemical staining showed that the in situ expression of TGFβ-1 and Smad3 in the scars decreased by varying degrees after laser intervention, and was most obvious after three laser interventions. Furthermore, the expression levels were the lowest at the end of 6 months after modeling. Therefore, we can assume that early intervention with carbon dioxide fractional laser can prevent formation of hypertrophic scars by regulating the TGF-β1/Smad3 pathway.

Treatment of hypopigmented burn hypertrophic scars with short-term topical tacrolimus does not lead to repigmentation

OBJECTIVES

Dyschromia is an understudied aspect of hypertrophic scar (HTS). The use of topical tacrolimus has successfully shown repigmentation in vitiligo patients through promotion of melanogenesis and melanocyte proliferation. It was hypothesized that HTSs treated with topical tacrolimus would have increased repigmentation compared to controls.

METHODOLOGY

Full-thickness burns in red Duroc pigs were either treated with excision and meshed split-thickness skin grafting or excision and no grafting, and these wounds formed hypopigmented HTSs (n = 8). Half of the scars had 0.1% tacrolimus ointment applied to the scar twice a day for 21 days, while controls had no treatment. Further, each scar was bisected with half incurring fractional ablative CO2 laser treatment before topical tacrolimus application to induce laser-assisted drug delivery (LADD). Pigmentation was evaluated using a noninvasive probe to measure melanin index (MI) at Days 0 (pretreatment), 7, 14, and 21. At each timepoint, punch biopsies were obtained and fixed in formalin or were incubated in dispase. The formalin-fixed biopsies were used to evaluate melanin levels by H&E staining. The biopsies incubated in dispase were used to obtain epidermal sheets. The ESs were then flash frozen and RNA was isolated from them and used in quantitative reverse transcription polymerase chain reaction for melanogenesis-related genes: Tyrosinase (TYR), TYR-related protein-1 (TYRP1), and dopachrome tautomerase (DCT). Analysis of variance test with Šídák's multiple comparisons test was used to compare groups.

RESULTS

Over time, within the grafted HTS and the NS group, there were no significant changes in MI, except for Week 3 in the -Tacro group. (+Tacro HTS= pre = 685.1 ± 42.0, w1 = 741.0 ± 54.16, w2 = 750.8 ± 59.0, w3 = 760.9 ± 49.8) (-Tacro HTS= pre = 700.4 ± 54.3, w1 = 722.3 ± 50.7, w2 = 739.6 ± 53.2, w3 = 722.7 ± 50.5). Over time, within the ungrafted HTS and the NS group, there were no significant changes in MI. (+Tacro HTS= pre = 644.9 ± 6.9, w1 = 661.6 ± 3.3, w2 = 650.3 ± 6.2, w3 = 636.3 ± 7.4) (-Tacro HTS= pre = 696.8 ± 8.0, w1 = 695.8 ± 12.3, w2 = 678.9 ± 14.0, w3 = 731.2 ± 50.3). LADD did not lead to any differential change in pigmentation compared to the non-LADD group. There was no evidence of increased melanogenesis within the tissue punch biopsies at any timepoint. There were no changes in TYR, TYRP1, or DCT gene expression after treatment.

CONCLUSION

Hypopigmented HTSs treated with 0.1% tacrolimus ointment with or without LADD did not show significantly increased repigmentation. This study was limited by a shorter treatment interval than what is known to be required in vitiligo patients for repigmentation. The use of noninvasive, topical treatments to promote repigmentation are an appealing strategy to relieve morbidity associated with dyschromic burn scars and requires further investigation.

Evaluation of Facial Trauma Scars After Treating by Refining Plastic Surgery Techniques: A Follow-Up Study

BACKGROUND

Although early debridement and refining plastic surgery techniques have been shown to be effective in the treatment of facial scars after trauma, their postoperative outcomes have not been quantitatively evaluated by the relevant Scar Cosmesis Assessment and Rating (SCAR) Scale. This study was designed to provide a fair assessment of the appearance and local symptoms of scars after treatment by refining plastic surgery techniques and to share the operational skills of surgical repairs.

PATIENTS AND METHODS

Patients who received refining plastic surgery techniques were followed up, and facial scars were taken as high-definition photos, which were presented to 6 professional observers, 6 lay observers, and patients themselves to score the facial scars, including: scar spread, erythema, dyspigmentation, track marks or suture marks, hypertrophy/atrophy, itch and pain according to the SCAR.

RESULTS

There were 56 patients who met the inclusion criteria and 25 agreed to participate in the study. No hypertrophic scar was found, and all patients were satisfied with the scar control effect. The scores showed that the treatment was achieved good results in scar spread (pro group: 0.85±0.55, lay group: 0.96±0.68, patients: 0.92±0.64), erythema (pro group: 0.34±0.26, lay group: 0.45±0.37, patients: 0.32±0.48), hypertrophy/atrophy (pro group: 0.21±0.27, lay group: 0.21±0.31, patients: 0.32±0.48), and there was no significant difference in the scores of the 3 observation groups ( P >0.05). However, it is difficult to eliminate dyspigmentation (pro group: 0.29±0.26, lay group: 0.30±0.30, patients: 0.40±0.50), track marks or suture marks (pro group: 0.45±0.33, lay group: 0.59±0.30, patients: 0.36±0.49). Two (8%) patients complained of itch and 1 (4%) patient complained of both itch and pain in the past 24 hours.

CONCLUSIONS

The appearance of facial scars is satisfactory, the local symptoms are mild, and the evaluation among different aesthetics is affirmative after receiving refining plastic surgery techniques, which is just in line with the purpose of seeking beauty for the patients, and meanwhile can provide a good foundation for the comprehensive treatment of late scars, so that the treatment plan should be promoted.

Scar Management and Dyschromia: A Summary Report from the 2021 American Burn Association State of the Science Meeting

Burn scars, and in particular, hypertrophic scars, are a challenging yet common outcome for survivors of burn injuries. In 2021, the American Burn Association brought together experts in burn care and research to discuss critical topics related to burns, including burn scars, at its State of the Science conference. Clinicians and researchers with burn scar expertise, as well as burn patients, industry representatives, and other interested stakeholders met to discuss issues related to burn scars and discuss priorities for future burn scar research. The various preventative strategies and treatment modalities currently utilized for burn scars were discussed, including relatively noninvasive therapies such as massage, compression, and silicone sheeting, as well as medical interventions such as corticosteroid injection and laser therapies. A common theme that emerged is that the efficacy of current therapies for specific patient populations is not clear, and further research is needed to improve upon these treatments and develop more effective strategies to suppress scar formation. This will necessitate quantitative analyses of outcomes and would benefit from creation of scar biobanks and shared data resources. In addition, outcomes of importance to patients, such as scar dyschromia, must be given greater attention by clinicians and researchers to improve overall quality of life in burn survivors. Herein we summarize the main topics of discussion from this meeting and offer recommendations for areas where further research and development are needed.

Reducing Risks of Facial Scarring

Risk factors for the formation of facial scars include skin type, ethnicity, scar location, and certain medical conditions that contribute to poor or delayed healing. Risk of scar can be reduced with appropriate surgical planning, including proper placement and design of incisions, meticulous skin closure, aseptic technique, and wound care to improve healing. Common pathologic scars include hypertrophic scars and keloid scars, each of which has unique approaches to surgical revision and medical treatment due to their respective risks of recurrence. Topical scar therapies, medical therapies, and surgical revision techniques for improvement in final scar appearance are discussed.

Treatment of burn hypertrophic scar with fractional ablative laser-assisted drug delivery can decrease levels of hyperpigmentation

BACKGROUND

Laser treatments have been used to treat a variety of scar symptoms, including the appearance of scars following burn injury. One such symptom is hyperpigmentation. There are several qualitative and quantitative measures of assessing improvement in hyperpigmentation over time. The Patient and Observer Scar Assessment Scale (POSAS) and Vancouver Scar Scale (VSS) are two scales that describe characteristics of scar such as pigmentation level. These scales are limited by their qualitative nature. On the other hand, spectrophotometers provide quantitative measures of pigmentation. Prior studies have reported that laser can change scar pigmentation, but no quantitative values have been reported. The current study examines changes in scar melanin index after CO₂ fractional ablative laser scar revision (FLSR) via noninvasive probe measurement in patients of various Fitzpatrick skin types (FST).

MATERIALS AND METHODS

Patients with scars of various sizes and etiologies were treated with FLSR. A database was constructed including 189 patients undergoing laser treatment. From this pool, individuals were selected based on the criteria that they completed at least two laser sessions and had Melanin index measurements for both of these sessions and the pre-operative visit. This criteria resulted in 63 patients of various FST in the cohort. Melanin index, POSAS-Observer (O) and -Patient (P) pigmentation and color scores and VSS-pigmentation scores were examined over time. Demographic information (age of patient at time of first treatment, age of scar at time of first treatment, use of laser-assisted drug delivery (LADD), gender, FST, and Ethnicity) were collected from the medical record. Patients were grouped as "responder" if their Melanin index indicated decreased levels of hyperpigmentation after FLSR treatment in more than half of their total number of visits and "nonresponder" if it did not.

RESULTS

The majority of patients were responders (41/63). In responder patients, measurements of Melanin index showed significantly improved levels of hyperpigmentation in hypertrophic scars after two FLSR sessions (p < 0.05). Age of patient, gender, FST, age of scar, ethnicity, or type of drug delivered by LADD did not predict responder grouping. POSAS-O and -P pigmentation/color scores showed improved scores after two FLSR sessions within the responder group. POSAS-P color scores showed improved scores after two and three FLSR sessions in the nonresponder group. VSS pigmentation scores showed improved scores after three FLSR sessions in the responder group only.

CONCLUSION

Based on Melanin index values, FLSR leads to improvements in hyperpigmentation in certain patients.

Laser-assisted drug delivery of synthetic alpha melanocyte stimulating hormone and L-tyrosine leads to increased pigmentation area and expression of melanogenesis genes in a porcine hypertrophic scar model

OBJECTIVES

One symptom of hypertrophic scar (HTS) that can develop after burn injury is dyschromia with hyper- and hypopigmentation. There are limited treatments for these conditions. Previously, we showed there is no expression of alpha melanocyte stimulating hormone (α-MSH) in hypopigmented scars, and if these melanocytes are treated with synthetic α-MSH in vitro, they respond by repigmenting. The current study tested the same hypothesis in the in vivo environment using laser-assisted drug delivery (LADD).

METHODS

HTSs were created in red Duroc pigs. At Day 77 (pre), they were treated with CO₂ fractional ablative laser (FLSR). Synthetic α-MSH was delivered as a topical solution dissolved in  l-tyrosine (n = 6, treated). Control scars received LADD of  l-tyrosine only (n = 2, control). Scars were treated and examined weekly through Week 4. Digital images and punch biopsies of hyper, hypo-, and normally pigmented scar and skin were collected. Digital pictures were analyzed with ImageJ by tracing the area of hyperpigmentation. Epidermal sheets were obtained from punch biopsies through dispase separation and RNA was isolated. qRT-PCR was run for melanogenesis-related genes: tyrosinase (TYR), tyrosinase-related protein-1 (TYRP1), and dopachrome tautomerase (DCT). Two-way ANOVA with multiple comparisons and Dunnett's correction compared the groups.

RESULTS

The areas of hyperpigmentation were variable before treatment. Therefore, data is represented as fold-change where each scar was normalized to its own pre value. Within the LADD of NDP α-MSH + l-tyrosine group, hyperpigmented areas gradually increased each week, reaching 1.3-fold over pre by Week 4. At each timepoint, area of hyperpigmentation was greater in the treated versus the control (1.04 ± 0.05 vs. 0.89 ± 0.08, 1.21 ± 0.07 vs. 0.98 ± 0.24, 1.21 ± 0.08 vs. 1.04 ± 0.11, 1.28 ± 0.11 vs. 0.94 ± 0.25; fold-change from pre-). Within the treatment group, pretreatment, levels of TYR were decreased -17.76 ± 4.52 below the level of normal skin in hypopigmented scars. After 1 treatment, potentially due to laser fractionation, the levels decreased to -43.49 ± 5.52. After 2, 3, and 4 treatments, there was ever increasing levels of TYR to almost the level of normally pigmented skin (-35.74 ± 15.72, -23.25 ± 6.80, -5.52 ± 2.22 [p < 0.01, Week 4]). This pattern was also observed for TYRP1 (pre = -12.94 ± 1.82, Week 1 = -48.85 ± 13.25 [p < 0.01], Weeks 2, 3, and 4 = -34.45 ± 14.64, -28.19 ± 4.98, -6.93 ± 3.05 [p < 0.01, Week 4]) and DCT (pre = -214.95 ± 89.42, Week 1 = -487.93 ± 126.32 [p < 0.05], Weeks 2, 3, and 4 = -219.06 ± 79.33, -72.91 ± 20.45 [p < 0.001], -76.00 ± 24.26 [p < 0.001]). Similar patterns were observed for scars treated with LADD of  l-tyrosine alone without NDP α-MSH. For each gene, in hyperpigmented scar, levels increased at Week 4 of treatment compared to Week 1 (p < 0.01).

CONCLUSIONS

A clinically-relevant FLSR treatment method can be combined with topical delivery of synthetic α-MSH and l-tyrosine to increase the area of pigmentation and expression of melanogenesis genes in hypopigmented HTS. LADD of  l-tyrosine alone leads to increased expression of melanogenesis genes. Future studies will aim to optimize drug delivery, timing, and dosing.

Proceedings of the 2021 American Burn Association State and Future of Burn Science Meeting

Periodically, the American Burn Association (ABA) has convened a State of the Science meeting on various topics representing multiple disciplines within burn care and research. In 2021 at the request of the ABA President, meeting development was guided by the ABA's Burn Science Advisory Panel (BSAP) and a subgroup of meeting chairs. The goal of the meeting was to produce both an evaluation of the current literature and ongoing studies, and to produce a research agenda and/or define subject matter-relevant next steps to advance the field(s). Members of the BSAP defined the topics to be addressed and subsequently solicited for nominations of expert speakers and topic leaders from the ABA's Research Committee. Current background literature for each topic was compiled by the meeting chairs and the library then enhanced by the invited topic and breakout discussion leaders. The meeting was held in New Orleans, LA on November 2nd and 3rd and was formatted to allow for 12 different topics, each with two subtopics, to be addressed. Topic leaders provided a brief overview of each topic to approximately 100 attendees, followed by expert-lead breakout sessions for each topic that allowed for focused discussion among subject matter experts and interested participants. The breakout and topic group leaders worked with the participants to determine research needs and associated next steps including white papers, reviews and in some cases collaborative grant proposals. Here, summaries from each topic area will be presented to highlight the main foci of discussion and associated conclusions.

Angiogenic gene characterization and vessel permeability of dermal microvascular endothelial cells isolated from burn hypertrophic scar

Hypertrophic scar (HTS) formation is a common challenge for patients after burn injury. Dermal microvascular endothelial cells (DMVECs) are an understudied cell type in HTS. An increase in angiogenesis and microvessel density can be observed in HTS. Endothelial dysfunction may play a role in scar development. This study aims to generate a functional and expression profile of HTS DMVECs. We hypothesize that transcript and protein-level responses in HTS DMVECs differ from those in normal skin (NS). HTSs were created in red Duroc pigs. DMVECs were isolated using magnetic-activated cell sorting with ulex europaeus agglutinin 1 (UEA-1) lectin. Separate transwell inserts were used to form monolayers of HTS DMVECs and NS DMVECs. Cell injury was induced and permeability was assessed. Gene expression in HTS DMVECS versus NS DMVECs was measured. Select differentially expressed genes were further investigated. HTS had an increased area density of dermal microvasculature compared to NS. HTS DMVECs were 17.59% less permeable than normal DMVECs (p < 0.05). After injury, NS DMVECs were 28.4% and HTS DMVECs were 18.8% more permeable than uninjured controls (28.4 ± 4.8 vs 18.8 ± 2.8; p = 0.11). PCR array identified 31 differentially expressed genes between HTS and NS DMVECs, of which 10 were upregulated and 21 were downregulated. qRT-PCR and ELISA studies were in accordance with the array. DMVECs expressed a mixed profile of factors that can contribute to and inhibit scar formation. HTS DMVECs have both a discordant response to cellular insults and baseline differences in function, supporting their proposed role in scar pathology. Further investigation of DMVECs is warranted to elucidate their contribution to HTS pathogenesis.

Laser Treatment of Hypopigmentation in Scars: A Review

BACKGROUND

Despite history of multiple treatment modalities, repigmentation of hypopigmented scars remains a difficult clinical problem.

OBJECTIVE

The purpose of this review is to evaluate the literature on laser and combination laser plus adjunct topical therapy for hypopigmented burn and traumatic scars.

MATERIALS AND METHODS

A search on PubMed and on Oxford Academic was conducted with additional relevant literature obtained from reference lists.

RESULTS

Treatment regimens that address hypopigmentation within scars were reviewed. A combination of nonablative fractional or ablative fractional laser treatment with topical prostaglandin analogue with or without topical retinoid were found to result in superior repigmentation.

CONCLUSION

Reliable improvement of hypopigmentation in scars after laser treatment is challenging. Laser can achieve success in some cases. Ultraviolet laser can achieve modest repigmentation; however, results are short-lived and require continued re-treatment. Modest improvement in pigmentation is seen with nonablative fractional laser or ablative fractional laser alone and enhanced repigmentation is demonstrated when combining fractional laser resurfacing with topical application of synthetic prostaglandin analogues and other known modulators of melanogenesis.

In-depth examination of hyperproliferative healing in two breeds of Sus scrofa domesticus commonly used for research

Background

Wound healing can result in various outcomes, including hypertrophic scar (HTS). Pigs serve as models to study wound healing as their skin shares physiologic similarity with humans. Yorkshire (Yk) and Duroc (Dc) pigs have been used to mimic normal and abnormal wound healing, respectively. The reason behind this differential healing phenotype was explored here.

Methods

Excisional wounds were made on Dc and Yk pigs and were sampled and imaged for 98 days. PCR arrays were used to determine differential gene expression. Vancouver Scar Scale (VSS) scores were given. Re-epithelialization was analyzed. H&E, Mason's trichrome, and immunostains were used to determine cellularity, collagen content, and blood vessel density, respectively.

Results

Yk wounds heal to a "port wine" HTS, resembling scarring in Fitzpatrick skin types (FST) I-III. Dc wounds heal to a dyspigmented, non-pliable HTS, resembling scarring in FST IV-VI. Gene expression during wound healing was differentially regulated versus uninjured skin in 40/80 genes, 15 of which differed between breeds. Yk scars had a higher VSS score at all time points. Yk and Dc wounds had equivalent re-epithelialization, collagen disorganization, and blood vessel density.

Conclusions

Our findings demonstrate that Dc and Yk pigs can produce HTS. Wound creation and healing were consistent among breeds, and differences in gene expression were not sufficient to explain differences in resulting scar phenotype. Both pig breeds should be used in animal models to investigate novel therapeutics to provide insight into a treatment's effectiveness on various skin types.

Promoter Methylation Status in Pro-opiomelanocortin Does Not Contribute to Dyspigmentation in Hypertrophic Scar

Burn injuries frequently result in hypertrophic scars (HTSs), specifically when excision and grafting are delayed due to limited resources or patient complications. In patient populations with dark baseline pigmentation, one symptom of HTS that often occurs is dyspigmentation. The mechanism behind dyspigmentation has not been explored, and, as such, prevention and treatment strategies for this morbidity are lacking. The mechanism by which cells make pigment is controlled at the apex of the pathway by pro-opiomelanocortin (POMC), which is cleaved to its products alpha-melanocyte-stimulating hormone (α-MSH) and adrenocorticotropin hormone (ACTH). α-MSH and ACTH secreted by keratinocytes bind to melanocortin 1 receptor (MC1R), expressed on melanocytes, to initiate melanogenesis. POMC protein expression is upregulated in hyperpigmented scar compared to hypopigmented scar by an unknown mechanism in a Duroc pig model of HTS. POMC RNA levels, as well as the POMC gene promoter methylation status were investigated as a possible mechanism. DNA was isolated from biopsies obtained from distinct areas of hyper- or hypopigmented scar and normal skin. DNA was bisulfite-converted, and amplified using two sets of primers to observe methylation patterns in two different CpG islands near the POMC promoter. Amplicons were then sequenced and methylation patterns were evaluated. POMC gene expression was significantly downregulated in hypopigmented scar compared to normal skin, consistent with previously reported protein expression levels. There were significant changes in methylation of the POMC promoter; however, none that would account for the development of hyper- or hypopigmentation. Future work will focus on other areas of POMC transcriptional regulation.

Hypopigmented burn hypertrophic scar contains melanocytes that can be signaled to re-pigment by synthetic alpha-melanocyte stimulating hormone in vitro

There are limited treatments for dyschromia in burn hypertrophic scars (HTSs). Initial work in Duroc pig models showed that regions of scar that are light or dark have equal numbers of melanocytes. This study aims to confirm melanocyte presence in regions of hypo- and hyper-pigmentation in an animal model and patient samples. In a Duroc pig model, melanocyte presence was confirmed using en face staining. Patients with dyschromic HTSs had demographic, injury details, and melanin indices collected. Punch biopsies were taken of regions of hyper-, hypo-, or normally pigmented scar and skin. Biopsies were processed to obtain epidermal sheets (ESs). A subset of ESs were en face stained with melanocyte marker, S100β. Melanocytes were isolated from a different subset. Melanocytes were treated with NDP α-MSH, a pigmentation stimulator. mRNA was isolated from cells, and was used to evaluate gene expression of melanin-synthetic genes. In patient and pig scars, regions of hyper-, hypo-, and normal pigmentation had significantly different melanin indices. S100β en face staining showed that regions of hyper- and hypo-pigmentation contained the same number of melanocytes, but these cells had different dendricity/activity. Treatment of hypo-pigmented melanocytes with NDP α-MSH produced melanin by microscopy. Melanin-synthetic genes were upregulated in treated cells over controls. While traditionally it may be thought that hypopigmented regions of burn HTS display this phenotype because of the absence of pigment-producing cells, these data show that inactive melanocytes are present in these scar regions. By treating with a pigment stimulator, cells can be induced to re-pigment.

Galectin-1 production is elevated in hypertrophic scar

Upon healing, burn wounds often leave hypertrophic scars (HTSs) marked by excess collagen deposition, dermal and epidermal thickening, hypervascularity, and an increased density of fibroblasts. The Galectins, a family of lectins with a conserved carbohydrate recognition domain, function intracellularly and extracellularly to mediate a multitude of biological processes including inflammatory responses, angiogenesis, cell migration and differentiation, and cell-ECM adhesion. Galectin-1 (Gal-1) has been associated with several fibrotic diseases and can induce keratinocyte and fibroblast proliferation, migration, and differentiation into fibroproliferative myofibroblasts. In this study, Gal-1 expression was assessed in human and porcine HTS. In a microarray, galectins 1, 4, and 12 were upregulated in pig HTS compared to normal skin (fold change = +3.58, +6.11, and +3.03, FDR <0.01). Confirmatory qRT-PCR demonstrated significant upregulation of Galectin-1 (LGALS1) transcription in HTS in both human and porcine tissues (fold change = +7.78 and +7.90, P <.05). In pig HTS, this upregulation was maintained throughout scar development and remodeling. Immunofluorescent staining of Gal-1 in human and porcine HTS showed significantly increased fluorescence (202.5 ± 58.2 vs 35.2 ± 21.0, P <.05 and 276.1 ± 12.7 vs 69.7 ± 25.9, P <.01) compared to normal skin and co-localization with smooth muscle actin-expressing myofibroblasts. A strong positive correlation (R = .948) was observed between LGALS1 and Collagen type 1 alpha 1 mRNA expression. Gal-1 is overexpressed in HTS at the mRNA and protein levels and may have a role in the development of scar phenotypes due to fibroblast over-proliferation, collagen secretion, and dermal thickening. The role of galectins shows promise for future study and may lead to the development of a pharmacotherapy for treatment of HTS.

Light or Dark Pigmentation of Engineered Skin Substitutes Containing Melanocytes Protects Against Ultraviolet Light-Induced DNA Damage In Vivo

Engineered skin substitutes (ESS) containing autologous fibroblasts and keratinocytes provide stable wound closure in patients with large, full-thickness burns, but are limited by hypopigmentation due to absence of added melanocytes. DNA damage caused by ultraviolet radiation (UV) increases risk for skin cancer development. In human skin, melanocytes provide pigmentation that protects skin from UV-induced DNA damage. This study investigated whether inclusion of human melanocytes (hM) affects the response of ESS to UV in vivo. Specifically, pigmentation and formation of cyclobutane pyrimidine dimers (CPDs), the most prevalent UV-induced DNA photoproduct, were analyzed. Three groups of ESS were prepared with fibroblasts and keratinocytes, ± melanocytes, and grafted orthotopically to immunodeficient mice: ESS without melanocytes (ESS-hM), ESS with light skin-derived (Caucasian) melanocytes (ESS+hM-L), and ESS with dark skin-derived (African-American) melanocytes (ESS+hM-D). Pigmentation of ESS+hM-L and ESS+hM-D increased significantly after grafting; pigmentation levels were significantly different among groups. Mean melanocyte densities in ESS+hM-L and ESS+hM-D were similar to each other and to densities in normal human skin. After 8 weeks in vivo, grafts were irradiated with 135 mJ/cm2 UV; non-UV-treated mice served as controls. UV modestly increased pigmentation in the ESS+hM groups. UV significantly increased CPD levels in ESS-hM, and levels in ESS-hM were significantly greater than in ESS+hM-L or ESS+hM-D. The results demonstrate that light or dark melanocytes in ESS decreased UV-induced DNA damage. Therefore, melanocytes in ESS play a photoprotective role. Protection against UV-induced DNA damage is expected to reduce skin cancer risk in patients grafted with ESS containing autologous melanocytes.

Effect of sulfur mustard on melanogenesis in vitro

The chemical warfare agent sulfur mustard (SM) affects all cells in the epidermis including melanocytes which are responsible for melanin synthesis. After exposure to SM, pigment abnormalities like hypo- and hyperpigmentation can occur. The underlying molecular pathomechanisms of SM exposure on human melanogenesis have not been elucidated so far. In our study, we investigated the effect of SM on human melanocytes and melanogenesis. Normal human epidermal melanocytes (NHEM) were used as in vitro model and they were exposed to different concentrations of SM (4.5 μM-100 μM). Melanin production was analyzed by absorption measurements at 405 nm. In addition, quantitative real-time PCR (qPCR) and Western blot experiments were performed to determine the expression of essential melanogenesis-related proteins including tyrosinase (TYR), tyrosinase-related protein (TRP) 1 and 2 and microphthalmia transcription factor (MITF). Our findings demonstrated that exposure to low SM concentrations increased melanin synthesis accompanied with an increase in protein expression. In contrast, high SM concentrations led to decreased melanin content and a downregulation in expression of all investigated melanogenesis-associated proteins. We concluded that low SM concentrations may cause hyperpigmentation while high SM concentrations decreased melanin content which may explain hypopigmented skin areas in SM exposed patients.