Hypertrophic scar, wound contraction and hyper-hypopigmentation

Advancements in skin grafting: Development and application of a novel two-blade dermatome for concurrent split-thickness and dermal graft harvesting

This investigation delineates the evolution and prospective utilisation of an innovative two-blade dermatome, designed for the concurrent harvesting of a conventional split-thickness skin graft (STSG) and an additional dermal graft within the same surgical harvest. Historically, the extraction of dermal grafts has encountered substantial technical impediments, contributing to its limited acceptance and utilisation in clinical practice. The prototype dermatome, introduced in this technical note, offers a solution that could facilitate the more extensive adoption of dermal grafting techniques. The dermal segment of an STSG, obtained as a second graft, confers four notable advancements: First, employing solely the dermal component for grafting and repositioning the uppermost skin flap to the donor site, markedly diminishes donor site morbidity. Second, owing to its elasticity, the dermal graft reduces the need for meshing, thereby enhancing cosmetic outcomes. Third, utilising both the uppermost skin layer and a deeper dermal layer for the recipient site can reduce donor site areas. Fourth, the dermal segment of the graft can serve as a dermal matrix in reconstructive procedures, potentially reducing the need for an allogenic dermal matrix and obviating the subsequent STSG; the dermal graft may heal independently, eliminating the need for an additional conventional STSG. The findings of this study, predicated on the application of a first-generation two-blade dermatome on four cadavers, demonstrate the feasibility of extracting at least two distinct grafts with pre-determined thicknesses in a single, technically less challenging, surgical harvest procedure. In conclusion, this proof-of-concept research elucidates the feasibility of a two-blade dermatome, capable of simultaneously yielding at least one conventional STSG and one dermal graft, thereby simplifying skin graft harvesting. Although these preliminary investigations were conducted on human cadavers, the results hold promise for the development of two-blade dermatomes and represent a significant advancement in skin graft harvesting. Further research is imperative to refine the prototype and to broaden our comprehension of the potential applications of dermal grafting in various clinical scenarios.

The effects of TGF-β1 and IFN-α2b on decorin, decorin isoforms and type I collagen in hypertrophic scar dermal fibroblasts

Hypertrophic scars (HTS) develop from an excessive synthesis of structural proteins like collagen and a decreased expression of proteoglycans such as decorin. Previous research has demonstrated that decorin expression is significantly down-regulated in HTS, deep dermal tissue, and thermally injured tissue, reducing its ability to regulate pro-fibrotic transforming growth factor-beta 1 (TGF-β1) and normal fibrillogenesis. However, treatment of HTS fibroblasts with interferon-alpha 2b (IFN-α2b) has been shown to reduce excessive collagen synthesis and improve HTS by reducing serum TGF-β1 levels. The expression of decorin isoforms in HTS is currently unknown and the effects of TGF-β1 and IFN-α2b on decorin, decorin isoform expression and type 1 collagen are of great interest to our group. Dermal fibroblasts were treated with TGF-β1 and/or IFN-α2b, for 48 h. The expression and secretion of decorin, decorin isoforms and type 1 collagen were quantified with reverse transcription-quantitative polymerase chain reaction, immunofluorescence staining and enzyme-linked immunosorbent assays. The mRNA expression of decorin and each isoform was significantly reduced in HTS fibroblasts relative to normal skin. TGF-β1 decreased the mRNA expression of decorin and decorin isoforms, whereas IFN-α2b showed the opposite effect. IFN-α2b significantly inhibited TGF-β1's effect on the mRNA expression of type I collagen alpha 1 in papillary dermal fibroblasts and overall showed relative effects of inhibiting TGF-β1. These data support that a further investigation into the structural and functional roles of decorin isoforms in HTS pathogenesis is warranted and that IFN-α2b is an important agent in reducing fibrotic outcomes.

Transoral endoscopic thyroidectomy vestibular approach as a novel technique for pediatric populations: Results from a single surgeon

Background

The transoral endoscopic thyroidectomy vestibular approach (TOETVA) is increasingly being adopted worldwide because of its many advantages. However, there are few reports on the effectiveness and safety of TOETVA in children. In this study, we report the results of the application of TOETVA on 27 pediatric patients in Vietnam. To the best of our knowledge, this is also the largest sample size of the TOETVA technique performed by a single surgeon on pediatric patients worldwide. Patients and methods: From June 2020 to February 2022, we performed TOETVA on 27 pediatric patients (≤ 18 years old). The outcomes of the procedure were retrospectively reviewed.

Results

Our study was conducted on 27 pediatric patients, of whom 24 were female (88.9%). The mean age was 16.3 ± 2 (range 10-18). Fifteen patients had benign thyroid nodules with a mean nodule size of 31.6 ± 7.1 (range 20-50mm), and 12 patients had papillary thyroid carcinoma with a mean nodule size of 10.2 ± 5.6 (range 4-19mm). All 27 patients underwent successful TOETVA without any conversion to open surgery. The 15 patients with benign thyroid nodules had lobectomies with a mean operative time of 83.3 ± 10.5 (range 60-105 minutes). Among the 12 patients diagnosed with thyroid cancer, ten had a lobectomy, isthmusectomy, and central neck dissection, with a mean operative time of 89.8 ± 5.7 (range 80-100 minutes). The other two underwent total thyroidectomy with central lymph node dissection with a mean operative time of 132.5 minutes. The mean hospital stay was 4.7 ± 0.9 (range 3-7 days). No patient had permanent complications, such as hypocalcemia, recurrent laryngeal nerve injury, or mental nerve injury. The rates of temporary recurrent laryngeal nerve injury and mental nerve injury were 3.7% and 11.1% respectively.

Conclusions

TOETVA may be a feasible and safe surgical method for children with thyroid disease. However, we recommend that only high-volume thyroid surgeons with experience in TOETVA should perform TOETVA on the pediatric population.

The feasibility of negative pressure wound therapy versus standard dressings in paediatric hand and foot burns protocol: a pilot, single-centre, randomised control trial

INTRODUCTION

The goal of paediatric hand and foot burn management is hypertrophic scar and/or contracture prevention. The risk of scar formation may be minimised by integrating negative pressure wound therapy (NPWT) as an acute care adjunct as it decreases the time to re-epithelialisation. NPWT has known associated therapeutic burden; however, this burden is hypothesised to be outweighed by an increased likelihood of hypertrophic scar prevention. This study will assess the feasibility, acceptability and safety of NPWT in paediatric hand and foot burns with secondary outcomes of time to re-epithelialisation, pain, itch, cost and scar formation.

METHODS AND ANALYSIS

This is a single-site, pilot randomised control trial. Participants must be aged ≤ 16 years, otherwise well and managed within 24 h of sustaining either a hand or foot burn. Thirty participants will be randomised to either standard care (Mepitel®-a silicone wound interface contact dressing-and ACTICOAT™-a nanocrystalline silver-impregnated dressing) or standard care plus NPWT. Patients will be reviewed until 3 months post-burn wound re-epithelialisation, with measurements taken at dressing changes to assess primary and secondary outcomes. Surveys, randomisation and data storage will be done via online platforms and physical data storage collated at the Centre for Children's Health Research, Brisbane, Australia. Analysis will be performed using the Stata statistical software.

ETHICS AND DISSEMINATION

Queensland Health and Griffith University Human Research ethics approval including a site-specific assessment was obtained. The findings of this study will be disseminated through clinical meetings, conference presentations and peer reviewed journals.

TRIAL REGISTRATION

Registered with the Australian and New Zealand Clinical Trials Registry (ACTRN12622000044729, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=381890&isReview=true , registered 17/01/2022).

Remote-Access Thyroidectomy in the Pediatric Population: a Systematic Review

INTRODUCTION

Remote-access thyroidectomy has been reported in the pediatric population in a limited fashion.

METHODS

This was a systematic review in PubMed and Scopus for pediatric remote-access thyroidectomy.

RESULTS

Seventy-eight articles were identified and screened, of which 13 met the inclusion criteria, including 231 patients; 70% of publications reported six or fewer patients. The mean age was 15.3 years (range 5-19). Sixty percent of surgeries were total thyroidectomy. Transaxillary robotic approach was most commonly performed (48.9%). Sixty-seven percent of the cases were operated on for a malignancy. Tumor size ranged between 0.4 and 1.8 cm. Recurrent laryngeal nerve injury rate was 1.9%. Transient and permanent hypocalcemia rates were 23.9% and 2.2%, respectively.

CONCLUSION

Pediatric remote-access thyroidectomy is not widely employed currently. Comparative studies with better quality are needed to establish its safety. Among selected pediatric patients, it can provide an alternative to open approaches, especially when neck scar is of major concern.

Mapping the 3D remodeling of the extracellular matrix in human hypertrophic scar by multi-parametric multiphoton imaging using endogenous contrast

The hypertrophic scar is an aberrant form of wound healing process, whose clinical efficacy is limited by a lack of understanding of its pathophysiology. Remodeling of collagen and elastin fibers in the extracellular matrix (ECM) is closely associated with scar progression. Herein, we perform label-free multiphoton microscopy (MPM) of both fiber components from human skin specimens and propose a multi-fiber metrics (MFM) analysis model for mapping the structural remodeling of the ECM in hypertrophic scars in a highly-sensitive, three-dimensional (3D) manner. We find that both fiber components become wavier and more disorganized in scar tissues, while content accumulation is observed from elastin fibers only. The 3D MFM analysis can effectively distinguish normal and scar tissues with better than 95% in accuracy and 0.999 in the area under the curve value of the receiver operating characteristic curve. Further, unique organizational features with orderly alignment of both fibers are observed in scar-normal adjacent regions, and an optimized combination of features from 3D MFM analysis enables successful identification of all the boundaries. This imaging and analysis system uncovers the 3D architecture of the ECM in hypertrophic scars and exhibits great translational potential for evaluating scars in vivo and identifying individualized treatment targets.

Comparison of the Robotic Bilateral Axillo-Breast Approach and Conventional Open Thyroidectomy in Pediatric Patients: A Retrospective Cohort Study

Background: Operations for pediatric thyroid nodules are more complicated, and usually lead to longer scars, which may impair life quality in the long term. Bilateral axillo-breast approach robotic thyroidectomy (BABA RT) may provide a better alternative to conventional open thyroidectomy (COT) for pediatric thyroid nodules. Our study aimed at comparing the surgical and oncological outcomes of BABA RT and COT in pediatric patients. Methods: The data of 49 pediatric patients who consecutively underwent BABA RT or COT (20:29) between July 1998 and November 2021 in our center were retrospectively analyzed, including demographics, surgery extent, surgical outcomes, pathological characteristics, and oncological outcomes. Results: All BABA RT procedures were completed successfully without conversion to open operation. The BABA RT group consisted of 5 benign and 15 malignant cases, while the COT group consisted of 19 benign and 10 malignant cases. The operation time, drain removal time, and number of lymph nodes harvested by central lymph node dissection or lateral lymph node dissection were equivalent in the BABA RT and COT groups. Notably, the postoperative hospital stay of the BABA RT group was shorter than that of the COT group (8.5 [interquartile ranges (IQRs): 3] vs. 11 [IQR: 8] days, p = 0.008). The aesthetic score of the BABA RT group was much higher than that of the COT group (9 [IQR: 1] vs. 6 [IQR: 1], p < 0.001). There was no significant difference between the BABA RT and COT groups in hypoparathyroidism rate (transient, 5 vs. 4; permanent, 1 vs. 0). There was one case of chyle leakage in the COT group and no other complications in any group, such as recurrent laryngeal nerve injury. With a median follow-up of 101 (IQR: 189) months, one case of local relapse and one case of pulmonary metastasis in the COT group were documented. Conclusion: In the hands of experienced surgeons, robotic BABA thyroidectomy can be a safe and effective option for both benign and malignant thyroid nodules in children, including those with lymph node metastasis. Robotic BABA thyroidectomy can offer a better and faster postoperative course and a much better cosmetic result, which is crucial for pediatric thyroid patients.

Assessment of Hair Density and Sub-epidermal Tissue Thickness in Burn Scars Using High-Definition Ultrasound Imaging

Burn scars show significant differences in structure, pigment, and hair density/sparsity from unburned skin, yet no formal documentation of these changes can be found in the literature. Evaluation of these differences is essential to assessing future intervention outcomes. The study was a prospective controlled clinical trial. Included were 19 adult burn survivors (18-63 years old, average age 47; 15 male, 4 female, 14 Caucasian, 2 African American, 1 Hispanic; 11 flame burns, 5 scald burns, 2 grease burns and 1 electrical burn, 2%-60% TBSA) with conspicuous, mature scars. All study subjects had either skin-grafted or nongrafted scars, as well as healthy skin in the same body area, to control for intraindividual variability. All scars were at least 9 months old and at a minimum 2 × 2 cm2 in size. On each individual, at least one nongrafted scar or one grafted scar and healthy skin was imaged with a high-definition ultrasound device (Longport, Inc., Glen Mills, PA, 35MHz probe, 1500 m/s). Vancouver scar scale was assessed. Although scarred skin had significantly fewer follicles than healthy skin in both grafted (P < .0001) and un-grafted sites (P = .0090), there were even significantly fewer follicles in grafted scars than un-grafted scars (P = .0095). In thickness of the sub-epidermal layer, there was no difference between grafted and un-grafted scars (P = .1900). Both kinds of scars had a significantly thicker sub-epidermal layer than healthy skin (P = .0010). Vancouver scar scale was 7.4 for grafted and 4.6 for nongrafted scars with grafted flame burn scars ranging higher than all others (5-11). There was no discomfort during the imaging, and no adverse events occurred during the study period. Our study demonstrates two clear morphologic differences between scars and healthy skin: thickness of the sub-epidermal layer and hair follicle density. Grafted burn scars were shown to contain fewer hair follicles than un-grafted scars.

Trans-oral endoscopic thyroidectomy vestibular approach (TOETVA) for the pediatric population: a multicenter, large case series

INTRODUCTION

A cervical scar has been shown to have an impact on the quality of life of children undergoing thyroid surgery. Transoral endoscopic vestibular thyroidectomy via the vestibular approach (TOETVA) offers the absence of a cutaneous incision, and has not been described to date in the pediatric population.

OBJECTIVE

To describe the first series of TOETVA in a pediatric population.

PATIENTS AND METHODS

A retrospective, multicenter study, including all patients > 18 years old who underwent TOETVA. Data was prospectively collected and included demographics, preoperative ultrasound, cytology and indications for surgery. Intraoperative parameters included length of surgery and complications, with final pathology and postoperative course also reviewed. TOETVA surgical success was defined as completion of surgery via this approach.

RESULTS

Forty-eight children were included. Of these, 43 (89.5%) were girls. The median age was 16 years (range 10-17). The most common indication for surgery was a benign thyroid nodule (n = 26, 54.1%). Eleven patients (22.9%) had papillary thyroid carcinoma on final pathology, of which 90.9% (10/11) were diagnosed pre-operatively based on FNA cytology. Hemithyroidectomy was performed in 36 patients (75%). All surgeries were completed endoscopically. The mean malignant tumor size was 1.4 ± 0.4 cm and all tumors were completely excised with clean margins. No permanent complications were documented. A single patient (2.1%) had transient RLN injury (1.6%, 1/60 nerves at risk). Transient hypocalcemia was documented in 4 of the 12 patients undergoing total thyroidectomy (33.3%). Transient mental nerve injury/chin hypoesthesia was documented in 2 patients (4.2%).

CONCLUSIONS

TOETVA appears to be a feasible and safe approach for thyroidectomy in the pediatric population in carefully selected cases, and may be discussed with patients and parents as an alternative for the trans-cervical approach.

Orofacial rehabilitation after severe orofacial and neck burn: Experience in a Brazilian burn reference centre

OBJECTIVE

To quantify the benefits of a functional oral rehabilitation program for impairment caused by full thickness orofacial and neck burns, comparing the effects of early and late intervention.

METHODS

An observational cross-sectional study was conducted in a burn reference center over a two-year period. Patients with full thickness orofacial and neck burns were divided in two groups: Group 1 was composed by 14 patients who began the rehabilitation program 3-12 months after the burn injury; Group 2 was composed by 15 patients who began the rehabilitation program more than 12 months after the burn injury. Treatment was based on current strategies of non-surgical exercises for orofacial contracture management. Outcome measurements included an oral motor clinical evaluation and the assessment of the mandibular range of movement.

RESULTS

The functional rehabilitation program was effective in reestablishing the oral motor functions (i.e deficits reduced to approximately 15% when compared to the optimal possible scores) and in restoring horizontal mouth opening dimensions, with more than 70% of the patients presenting measurements within the expected normal limits at the end of treatment. Our results did not indicate differences in performance between the group of patients in neither set of assessments, i.e. pre and post treatment (p > 0.05).

CONCLUSION

The results of this study indicate that non-invasive orofacial contracture management is effective for patients with orofacial and neck burns, including those with long term sequelae.

Reabilitação motora orofacial em queimaduras em cabeça e pescoço: uma revisão sistemática de literatura

RESUMO Objetivos Investigar estudos sobre o tratamento das queimaduras em cabeça e pescoço, nas diversas áreas da saúde envolvidas na assistência a queimados (médica, enfermagem, fonoaudiologia, fisioterapia e terapia ocupacional), avaliando a eficácia das técnicas empregadas, principalmente no que se refere à reabilitação da funcionalidade da musculatura em cabeça e pescoço. Estratégia de pesquisa Os artigos foram selecionados por meio da base de dados PubMed, utilizando os descritores “burn and face and speech-language pathology”, “burn and face and speech language”, “burn and face and rehabilitation”, “burn and face and myofunctional rehabilitation”, “burn and face and myofunctional therapy”, “nonsurgical and scar and management”, “burn and face and nonsurgical” e “burn and face and scar and management”. Critérios de seleção Foram incluídos artigos que investigaram os tratamentos das queimaduras em cabeça e pescoço, associados à reabilitação da funcionalidade da musculatura em cabeça e pescoço, utilizando exercícios musculares e/ou terapias manuais. Resultados A maioria dos tratamentos descritos apresentou efeitos benéficos para pacientes com queimaduras. Foi observada grande variabilidade da metodologia adotada para a aplicação e verificação dos efeitos dos tratamentos. Conclusão Apesar do crescente número de pesquisas, ainda não existe consenso quanto à melhor técnica terapêutica e ao real benefício de cada uma delas. Existe uma grande diversidade nos protocolos de tratamento, sendo que um número pequeno de estudos de tratamento visa a funcionalidade do sistema miofuncional orofacial. A maioria dos estudos tem, como foco, atividades motoras isoladas, que visam à mobilidade mandibular.

Adult Contractures in Burn Injury: A Burn Model System National Database Study

As the overall survival rate for burn injury has improved, increased emphasis is placed on postburn morbidity and the optimization of functional and cosmetic outcomes. One major cause of morbidity and functional deficits is that of joint contractures. The true incidence of postburn contractures and their associated risk factors remains unknown. This study examines the incidence and severity of contractures in a large, multicenter, burn population. The associated risk factors for the development of contractures are determined. Data from the National Institute on Disability and Rehabilitation Research Burn Model System database, for adult burn survivors from 1994 to 2003, were analyzed. Demographic and medical data were collected on each subject. The primary outcome measures included the presence of contractures, number of contractures per patient, and severity of contractures at each of nine locations (shoulder, elbow, hip, knee, ankle, wrist, neck, lumbar spine, and thoracic spine) at time of hospital discharge. Regression analysis was performed to determine predictors of the presence, severity, and numbers of contractures, with P < .05 used for statistical significance. Of the 1865 study patients, 620 (33%) developed at least 1 contracture at hospital discharge. Among those with at least one contracture, the mean is three (3.38) contractures per person. The shoulder was the most frequently contracted joint (23.0%), followed by the elbow (19.9%), wrist (17.3%), ankle (13.6%), and knee (13.4%). Most contractures were mild (47.2%) or moderate (32.9%) in severity. Statistically significant predictors of contracture development were male sex, black race, Hispanic ethnicity, medical problems, neuropathy, TBSA grafted, and TBSA burned. Predictors of the severity of contracture included male sex, black race, medical problems, neuropathy, TBSA grafted, and TBSA burned. Predictors of the number of contractures included male sex, medical problems, flash burn, neuropathy, TBSA burned, and TBSA grafted. Similar to a previous single-center study on postburn contractures, approximately one third of the patients with an eligible burn injury requiring autografting developed a contracture at hospital discharge. It is likely that these contractures develop despite early therapeutic interventions such as positioning and splinting; therefore, the challenge to the burn community remains, to identify new and better prevention strategies.

Pediatric Contractures in Burn Injury: A Burn Model System National Database Study

Joint contractures are a major cause of morbidity and functional deficit. The incidence of postburn contractures and their associated risk factors in the pediatric population has not yet been reported. This study examines the incidence and severity of contractures in a large, multicenter, pediatric burn population. Associated risk factors for the development of contractures are determined. Data from the National Institute on Disability and Rehabilitation Research Burn Model System database, for pediatric (younger than 18 years) burn survivors from 1994 to 2003, were analyzed. Demographic and medical data were collected on each subject. The primary outcome measures included the presence of contractures, number of contractures per patient, and severity of contractures at each of nine locations (shoulder, elbow, hip, knee, ankle, wrist, neck, lumbar, and thoracic) at time of hospital discharge. Regression analysis was performed to determine predictors of the presence, severity, and numbers of contractures, with P < .05 used for statistical significance. Of the 1031 study patients, 237 (23%) developed at least 1 contracture at hospital discharge. Among those with at least one contracture, the mean was three (3.3) contractures per person. The shoulder was the most frequently contracted joint (27.9%), followed by the elbow (17.6%), wrist (14.2%), knee (13.3%), and ankle (11.9%). Most contractures were mild (38.5%) or moderate (36.3%) in severity. The statistically significant predictors of contracture development were age and intensive care unit (ICU) length of stay. The statistically significant predictors of severity of contracture were age, ICU length of stay, presence of amputation, and black race. Predictors of the number of contractures included total age, length of stay, length of ICU stay, presence of amputation, TBSA burned, and TBSA grafted. This is the first study to report the epidemiology of postburn contractures in the pediatric population. Approximately one quarter of children with a major burn injury developed a contracture at hospital discharge, and this could potentially increase as the child grows. Contractures develop despite early therapeutic interventions such as positioning and splinting; therefore, it is essential that we identify novel and more effective prevention strategies.

Burn injury: Challenges and advances in burn wound healing, infection, pain and scarring

Severe burn injuries are the most traumatic and physically debilitating injuries affecting nearly every organ system and leading to significant morbidity and mortality. Early burn wound excision and skin grafting are common clinical practices that have significantly improved the outcomes for severe burn injured patients by reducing mortality rate and days of hospital stay. However, slow wound healing, infection, pain, and hypertrophic scarring continue to remain a major challenge in burn research and management. In the present article, we review and discuss issues in the current treatment of burn injuries; the advances and novel strategies developed in the past decade that have improved burn management; and also, pioneer ideas and studies in burn research which aims to enhance burn wound care with a focus on burn wound infection, pain management, treatments for scarring and skin tissue engineering.

Scar formation following excisional and burn injuries in a red Duroc pig model

Scar research is challenging because rodents do not naturally form excessive scars, and burn depth, size, and location cannot be controlled in human longitudinal studies. The female, red Duroc pig model has been shown to form robust scars with biological and anatomical similarities to human hypertrophic scars. To more closely mimic the mode of injury, recreate the complex chemical milieu of the burn wound environment and enhance scar development, an animal model of excessive burn-induced scarring was developed and compared with the more commonly used model, which involves excisional wounds created via dermatome. Standardized, full-thickness thermal wounds were created on the dorsum of female, red Duroc pigs. Wounds for the dermatome model were created using two different total dermatome settings: ∼1.5 mm and ≥ 1.9 mm. Results from analysis over 150 days showed that burn wounds healed at much slower rate and contracted more significantly than dermatome wounds of both settings. The burn scars were hairless, had mixed pigmentation, and displayed fourfold and twofold greater excess erythema values, respectively, compared with ∼1.5 mm and ≥ 1.9 mm deep dermatome injuries. Burn scars were less elastic, less pliable, and weaker than scars resulting from excisional injuries. Decorin and versican gene expression levels were elevated in the burn group at day 150 compared with both dermatome groups. In addition, transforming growth factor-beta 1 was significantly up-regulated in the burn group vs. the ∼1.5 mm deep dermatome group at all time points, and expression remained significantly elevated vs. both dermatome groups at day 150. Compared with scars from dermatome wounds, the burn scar model described here demonstrates greater similarity to human hypertrophic scar. Thus, this burn scar model may provide an improved platform for studying the pathophysiology of burn-related hypertrophic scarring, investigating current anti-scar therapies, and development of new strategies with greater clinical benefit.

The First Cut Is the Deepest: The History and Development of Safe Treatments for Wound Healing and Tissue Repair

As the skin is the primary barrier to infection, the importance of wound healing has been understood since ancient times. This article provides a synopsis on the symposium presentations focusing on how wounds were traditionally treated, what models and pathology endpoints exist to study wound healing, special considerations for wound healing studies, an overview of regulatory aspects of new pharmaceutical and medical device development, and the clinical relevance of such models. The clinical treatment of small and large wounds is also considered.

Systemic depletion of macrophages in the subacute phase of wound healing reduces hypertrophic scar formation

Hypertrophic scars are caused by trauma or burn injuries to the deep dermis and can cause cosmetic disfigurement and psychological issues. Studies suggest that M2-like macrophages are pro-fibrotic and contribute to hypertrophic scar formation. A previous study from our lab showed that M2 macrophages were present in developing hypertrophic scar tissues in vivo at 3-4 weeks after wounding. In this study, the effect of systemic macrophage depletion on scar formation was explored at subacute phase of wound healing. Thirty-six athymic nude mice that received human skin transplants were randomly divided into macrophage depletion group and control group. The former received intraperitoneal injections of clodronate liposomes while the controls received sterile saline injections on day 7, 10, and 13 postgrafting. Wound area, scar thickness, collagen abundance and collagen bundle structure, mast cell infiltration, myofibroblast formation, M1, and M2 macrophages together with gene expression of M1 and M2 related factors in the grafted skin were investigated at 2, 4, and 8 weeks postgrafting. The transplanted human skin from the control group developed contracted, elevated, and thickened scars while the grafted skin from the depletion group healed with significant less contraction and elevation. Significant reductions in myofibroblast number, collagen synthesis, and hypertrophic fiber morphology as well as mast cell infiltration were observed in the depletion group compared to the control group. Macrophage depletion significantly reduced M1 and M2 macrophage number in the depletion group 2 weeks postgrafting as compared to the control group. These findings suggest that systemic macrophage depletion in subacute phase of wound healing reduces scar formation, which provides evidence for the pro-fibrotic role of macrophages in fibrosis of human skin as well as insight into the potential benefits of specifically depleting M2 macrophages in vivo.

EdnrB Governs Regenerative Response of Melanocyte Stem Cells by Crosstalk with Wnt Signaling

Delineating the crosstalk between distinct signaling pathways is key to understanding the diverse and dynamic responses of adult stem cells during tissue regeneration. Here, we demonstrate that the Edn/EdnrB signaling pathway can interact with other signaling pathways to elicit distinct stem cell functions during tissue regeneration. EdnrB signaling promotes proliferation and differentiation of melanocyte stem cells (McSCs), dramatically enhancing the regeneration of hair and epidermal melanocytes. This effect is dependent upon active Wnt signaling that is initiated by Wnt ligand secretion from the hair follicle epithelial niche. Further, this Wnt-dependent EdnrB signaling can rescue the defects in melanocyte regeneration caused by Mc1R loss. This suggests that targeting Edn/EdnrB signaling in McSCs can be a therapeutic approach to promote photoprotective-melanocyte regeneration, which may be useful for those with increased risk of skin cancers due to Mc1R variants.

Biostable electrospun microfibrous scaffolds mitigate hypertrophic scar contraction in an immune-competent murine model

Burn injuries in the United States account for over one million hospital admissions per year, with treatment estimated at four billion dollars. Of severe burn patients, 30-90% will develop hypertrophic scars (HSc). In this study, we evaluate the impact of an elastomeric, randomly-oriented biostable polyurethane (PU) scaffold on HSc-related outcomes. In vitro, fibroblast-seeded PU scaffolds contracted significantly less and demonstrated fewer αSMA(+) myofibroblasts compared to fibroblast-seeded collagen lattices. In a murine HSc model, collagen coated PU (ccPU) scaffolds significantly reduced HSc contraction as compared to untreated control wounds and wounds treated with the clinical standard of care. Our data suggest that electrospun ccPU scaffolds meet the requirements to reduce HSc contraction including reduction of in vitro HSc related outcomes, diminished scar stiffness, and reduced scar contraction. While clinical dogma suggests treating severe burn patients with rapidly biodegrading skin equivalents, our data suggest that a more long-term scaffold may possess merit in reducing HSc.

STATEMENT OF SIGNIFICANCE

In severe burns treated with skin grafting, between 30% and 90% of patients develop hypertrophic scars (HSc). There are no therapies to prevent HSc, and treatments are marginally effective. This work is the first example we are aware of which studies the impact of a permanent electrospun elastomer on HSc contraction in a murine model that mimics the human condition. Collagen coated polyurethane scaffolds decrease αSMA+ myofibroblast formation in vitro, prevent stiffening of scar tissue, and mitigate HSc contraction. Unlike current standards of care, electrospun, polyurethane scaffolds do not lose architecture over time. We propose that the future bioengineering strategy of mitigating HSc contraction should consider a long-term elastomeric matrix which persists within the wound bed throughout the remodeling phase of repair.

Novel burn device for rapid, reproducible burn wound generation

INTRODUCTION

Scarring following full thickness burns leads to significant reductions in range of motion and quality of life for burn patients. To effectively study scar development and the efficacy of anti-scarring treatments in a large animal model (female red Duroc pigs), reproducible, uniform, full-thickness, burn wounds are needed to reduce variability in observed results that occur with burn depth. Prior studies have proposed that initial temperature of the burner, contact time with skin, thermal capacity of burner material, and the amount of pressure applied to the skin need to be strictly controlled to ensure reproducibility. The purpose of this study was to develop a new burner that enables temperature and pressure to be digitally controlled and monitored in real-time throughout burn wound creation and compare it to a standard burn device.

METHODS

A custom burn device was manufactured with an electrically heated burn stylus and a temperature control feedback loop via an electronic microstat. Pressure monitoring was controlled by incorporation of a digital scale into the device, which measured downward force. The standard device was comprised of a heat resistant handle with a long rod connected to the burn stylus, which was heated using a hot plate. To quantify skin surface temperature and internal stylus temperature as a function of contact time, the burners were heated to the target temperature (200±5°C) and pressed into the skin for 40s to create the thermal injuries. Time to reach target temperature and elapsed time between burns were recorded. In addition, each unit was evaluated for reproducibility within and across three independent users by generating burn wounds at contact times spanning from 5 to 40s at a constant pressure and at pressures of 1 or 3lbs with a constant contact time of 40s. Biopsies were collected for histological analysis and burn depth quantification using digital image analysis (ImageJ).

RESULTS

The custom burn device maintained both its internal temperature and the skin surface temperature near target temperature throughout contact time. In contrast, the standard burner required more than 20s of contact time to raise the skin surface temperature to target due to its quickly decreasing internal temperature. The custom burner was able to create four consecutive burns in less than half the time of the standard burner. Average burn depth scaled positively with time and pressure in both burn units. However, the distribution of burn depth within each time-pressure combination in the custom device was significantly smaller than with the standard device and independent of user.

CONCLUSIONS

The custom burn device's ability to continually heat the burn stylus and actively control pressure and temperature allowed for more rapid and reproducible burn wounds. Burns of tailored and repeatable depths, independent of user, provide a platform for the study of anti-scar and other wound healing therapies without the added variable of non-uniform starting injury.

The molecular basis of hypertrophic scars

Hypertrophic scars (HTS) are caused by dermal injuries such as trauma and burns to the deep dermis, which are red, raised, itchy and painful. They can cause cosmetic disfigurement or contractures if craniofacial areas or mobile region of the skin are affected. Abnormal wound healing with more extracellular matrix deposition than degradation will result in HTS formation. This review will introduce the physiology of wound healing, dermal HTS formation, treatment and difference with keloids in the skin, and it also review the current advance of molecular basis of HTS including the involvement of cytokines, growth factors, and macrophages via chemokine pathway, to bring insights for future prevention and treatment of HTS.

The natural behavior of mononuclear phagocytes in HTS formation

Hypertrophic scars (HTS) are caused by trauma or burn injuries to the deep dermis and are considered fibrosis in the skin. Monocytes, M1 and M2 macrophages are mononuclear phagocytes. Studies suggest that M2 macrophages are profibrotic and might contribute to HTS formation. Our lab has established a human HTS-like nude mouse model, in which the grafted human skin develops red, raised, and firm scarring, resembling HTS seen in humans. In this study, we observed the natural behavior of mononuclear phagocyte system in this nude mouse model of dermal fibrosis at multiple time points. Thirty athymic nude mice received human skin grafts and an equal number of mice received mouse skin grafts as controls. The grafted skin and blood were harvested at 1, 2, 3, 4, and 8 weeks. Wound area, thickness, collagen morphology and level, the cell number of myofibroblasts, M1- and M2-like macrophages in the grafted skin, as well as monocyte fraction in the blood were investigated at each time points. Xenografted mice developed contracted and thickened scars grossly. The xenografted skin resembled human HTS tissue based on enhanced thickness, fibrotic orientation of collagen bundles, increased collagen level, and infiltration of myofibroblasts. In the blood, monocytes dramatically decreased at 1 week postgrafting and gradually returned to normal in the following 8 weeks. In the xenografted skin, M1-like macrophages were found predominantly at 1-2 weeks postgrafting; whereas, M2-like macrophages were abundant at later time points, 3-4 weeks postgrafting coincident with the development of fibrosis in the human skin tissues. This understanding of the natural behavior of mononuclear phagocytes in vivo in our mouse model provides evidence for the role of M2-like macrophages in fibrosis of human skin and suggests that macrophage depletion in the subacute phases of wound healing might reduce or prevent HTS formation.

Race Does Not Predict Melanocyte Heterogeneous Responses to Dermal Fibroblast-Derived Mediators

Introduction

Abnormal pigmentation following cutaneous injury causes significant patient distress and represents a barrier to recovery. Wound depth and patient characteristics influence scar pigmentation. However, we know little about the pathophysiology leading to hyperpigmentation in healed shallow wounds and hypopigmentation in deep dermal wound scars. We sought to determine whether dermal fibroblast signaling influences melanocyte responses.

Methods and Materials

Epidermal melanocytes from three Caucasians and three African-Americans were genotyped for single nucleotide polymorphisms (SNPs) across the entire genome. Melanocyte genetic profiles were determined using principal component analysis. We assessed melanocyte phenotype and gene expression in response to dermal fibroblast-conditioned medium and determined potential mesenchymal mediators by proteome profiling the fibroblast-conditioned medium.

Results

Six melanocyte samples demonstrated significant variability in phenotype and gene expression at baseline and in response to fibroblast-conditioned medium. Genetic profiling for SNPs in receptors for 13 identified soluble fibroblast-secreted mediators demonstrated considerable heterogeneity, potentially explaining the variable melanocyte responses to fibroblast-conditioned medium.

Discussion

Our data suggest that melanocytes respond to dermal fibroblast-derived mediators independent of keratinocytes and raise the possibility that mesenchymal-epidermal interactions influence skin pigmentation during cutaneous scarring.

Treatment of Hypertrophic Scar in Human with Autologous Transplantation of Cultured Keratinocytes and Fibroblasts along with Fibrin Glue

Objective

Hypertrophic scar involves excessive amounts of collagen in dermal layer and may be painful. Nowadays, we can’t be sure about effectiveness of procedure for hypertrophic scar management. The application of stem cells with natural scaffold has been the best option for treatment of burn wounds and skin defect, in recent decades. Fibrin glue (FG) was among the first of the natural biomaterials applied to enhance skin deformity in burn patients. This study aimed to identify an efficient, minimally invasive and economical transplantation procedure using novel FG from human cord blood for treatment of hypertrophic scar and regulation collagen synthesis.

Materials and Methods

In this case series study, eight patients were selected with hypertrophic scar due to full-thickness burns. Human keratinocytes and fibroblasts derived from adult skin donors were isolated and cultured. They were tested for the expression of cytokeratin 14 and vimentin using immunocytochemistry. FG was prepared from pooled cord blood. Hypertrophic scars were extensively excised then grafted by simply placing the sheet of FG containing autologous fibroblast and keratinocytes. Histological analyses were performed using Hematoxylin and eosin (H&E) and Masson’s Trichrome (MT) staining of the biopsies after 8 weeks.

Results

Cultured keratinocytes showed a high level of cytokeratin 14 expression and also fibroblasts showed a high level of vimentin. Histological analyses of skin biopsies after 8 weeks of transplantation revealed re-epithelialization with reduction of hypertrophic scars in 2 patients.

Conclusion

These results suggest may be the use of FG from cord blood, which is not more efficient than previous biological transporters and increasing hypertrophic scar relapse, but could lead to decrease pain rate.

A novel immune competent murine hypertrophic scar contracture model: a tool to elucidate disease mechanism and develop new therapies

Hypertrophic scar (HSc) contraction following burn injury causes contractures. Contractures are painful and disfiguring. Current therapies are marginally effective. To study pathogenesis and develop new therapies, a murine model is needed. We have created a validated immune-competent murine HSc model. A third-degree burn was created on dorsum of C57BL/6 mice. Three days postburn, tissue was excised and grafted with ear skin. Graft contraction was analyzed and tissue harvested on different time points. Outcomes were compared with human condition to validate the model. To confirm graft survival, green fluorescent protein (GFP) mice were used, and histologic analysis was performed to differentiate between ear and back skin. Role of panniculus carnosus in contraction was analyzed. Cellularity was assessed with 4′,6-diamidino-2-phenylindole. Collagen maturation was assessed with Picro-sirius red. Mast cells were stained with Toluidine blue. Macrophages were detected with F4/80 immune. Vascularity was assessed with CD31 immune. RNA for contractile proteins was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Elastic moduli of skin and scar tissue were analyzed using a microstrain analyzer. Grafts contracted to ∼45% of their original size by day 14 and maintained their size. Grafting of GFP mouse skin onto wild-type mice, and analysis of dermal thickness and hair follicle density, confirmed graft survival. Interestingly, hair follicles disappeared after grafting and regenerated in ear skin configuration by day 30. Radiological analysis revealed that panniculus carnosus doesn't contribute to contraction. Microscopic analyses showed that grafts show increase in cellularity. Granulation tissue formed after day 3. Collagen analysis revealed increases in collagen maturation over time. CD31 stain revealed increased vascularity. Macrophages and mast cells were increased. qRT-PCR showed up-regulation of transforming growth factor beta, alpha smooth muscle actin, and rho-associated protein kinase 2 in HSc. Tensile testing revealed that human skin and scar tissues are tougher than mouse skin and scar tissues.

Glyaderm(®) dermal substitute: clinical application and long-term results in 55 patients

INTRODUCTION

Glycerol preserved acellular dermis (Glyaderm(®)) consists of collagen and elastin fibers and is the first non-profit dermal substitute derived from glycerol-preserved, human allogeneic skin. It is indicated for bi-layered skin reconstruction of full thickness wounds.

METHODS

A protocol for clinical application and optimal interval before autografting with split thickness skin graft (STSG) was developed in a pilot study. A phase III randomized, controlled, paired, intra-individual study compared full thickness defects engrafted with Glyaderm(®) and STSG versus STSG alone. Outcome measures included percentage of Glyaderm(®) take, STSG take, and scar quality assessment.

RESULTS

Pilot study (27 patients): Mean take rates equaled 91.55% for Glyaderm(®) and 96.67% for STSG. The optimal autografting interval was 6 days (±1 day). Randomized trial (28 patients): Mean Glyaderm(®) take rate was 88.17%. STSG take rates were comparable for both research groups (p=0.588). One year after wound closure, Glyaderm(®)+STSG was significantly more elastic (p=0.003) than STSG alone. Blinded observers scored Glyaderm(®) treated wounds better in terms of scar quality.

DISCUSSION

The efficacy of Glyaderm(®) as a suitable dermal substitute for full thickness wounds is attested. Currently a procedure for simultaneous application of Glyaderm(®) and STSG is adopted, allowing for further widespread use of Glyaderm(®).

Response of human skin to esthetic scarification

This study was undertaken to investigate changes in RNA expression in previously healthy adult human skin following thermal injury induced by contact with hot metal that was undertaken as part of esthetic scarification, a body modification practice. Subjects were recruited to have pre-injury skin and serial wound biopsies performed. 4 mm punch biopsies were taken prior to branding and 1 h, 1 week, and 1, 2 and 3 months after injury. RNA was extracted and quality assured prior to the use of a whole-genome based bead array platform to describe expression changes in the samples using the pre-injury skin as a comparator. Analysis of the array data was performed using k-means clustering and a hypergeometric probability distribution without replacement and corrections for multiple comparisons were done. Confirmatory q-PCR was performed. Using a k of 10, several clusters of genes were shown to co-cluster together based on Gene Ontology classification with probabilities unlikely to occur by chance alone. OF particular interest were clusters relating to cell cycle, proteinaceous extracellular matrix and keratinization. Given the consistent expression changes at 1 week following injury in the cell cycle cluster, there is an opportunity to intervene early following burn injury to influence scar development.

The molecular mechanism of hypertrophic scar

Hypertrophic scar (HTS) is a dermal form of fibroproliferative disorder which often develops after thermal or traumatic injury to the deep regions of the skin and is characterized by excessive deposition and alterations in morphology of collagen and other extracellular matrix (ECM) proteins. HTS are cosmetically disfiguring and can cause functional problems that often recur despite surgical attempts to remove or improve the scars. In this review, the roles of various fibrotic and anti-fibrotic molecules are discussed in order to improve our understanding of the molecular mechanism of the pathogenesis of HTS. These molecules include growth factors, cytokines, ECM molecules, and proteolytic enzymes. By exploring the mechanisms of this form of dermal fibrosis, we seek to provide some insight into this form of dermal fibrosis that may allow clinicians to improve treatment and prevention in the future.

Double-blind, randomized, pilot study assessing the resolution of postburn pruritus

The objective of this study was to evaluate whether Provase®, a nonprescription moisturizer with a blend of protease enzymes, would reduce postburn itching in adult burn survivors relative to a control moisturizer. This was a prospective, single-center, double-blinded, pilot study where 23 burn survivors were randomized to either the treatment group, who applied Provase, or the control group, who applied the base moisturizer used in Provase every 8 hours for 4 weeks. Twelve were randomized to the treatment and 11 to the control groups with 9 participants in each group completing the study. There was no difference between groups with respect to gender, ethnicity, causative factor, TBSA burned, or time postinjury. Participant's pruritus and scar were reevaluated on a weekly basis for 4 consecutive weeks. Relative to baseline, there was a significant reduction of itch duration in minutes at weeks 3 and 4, the number of days per week that itch was experienced at weeks 2, 3, and 4, and the number of itch episodes per day at week 2 for the treatment group. The itch TBSA reduced significantly relative to baseline for the treatment group at week 1, 2, and 3. The affective itch characteristics were significantly reduced for the treatment group for bothersome at weeks 1, 2, 3, and 4; for annoying at week 4; and for unbearable at weeks 2, 3, and 4. Although this was a pilot study and not powered for statistical differences, there were statistically significant differences for itch duration, weekly frequency, itch episodes per day, itch TBSA, and reported affective burden of itch after treatment. Further investigation is recommended with a larger sample size treated for a longer period of time where participants are stratified based on acute or chronic itch.

Hypertrophic scar

Hypertrophic scars are common complications of burn injury and other soft tissue injuries. Excessive extracellular matrix combined with inadequate remodeling of scar tissue results in an aesthetically and functionally unsatisfactory, painful, pruritic scar that can impair function. Treatment options are available to rehabilitation practitioners, but none are entirely satisfactory. An interdisciplinary clinical program is necessary for best outcomes. Challenges to be met by the rehabilitation community include research into the quantification of burn scar measurement, the effects of mechanical forces on wound healing and scar management, and the best combination of surgical, pharmacologic, and therapy interventions to maximize outcome from reconstructive procedures.

Predictors of health-care needs in discharged burn patients

Patients' health-care needs are an important issue, but have not been studied in the burn field. The aims of this study were to explore discharged burn patients' health-care needs and related factors. This cross-sectional study used convenience sampling and four questionnaires, including basic information, Mental Status Inventory, Burn Patients' Social Support and Burn Patients' Healthcare Needs for data collection. There were 93 adults, injured on average 45% of total body surface area, who completed the study. Results indicated that the level of psychosocial care needs were higher than physiological needs. The level of physiological care needs changed over time, but psychosocial needs did not change. Self-reported psychosocial needs and physiological care needs correlated with each other. The multiple regressions showed that the most important predictors of overall health-care needs were numbers of visible scarred areas, time since discharge and previous psychiatric history. The findings revealed the burn patients provided clinically useful information and supported further evaluation in the area of care needs for burn patients.

A systematic review of the quality of burn scar rating scales for clinical and research use

INTRODUCTION

Scar rating scales have the potential to contribute to better evaluation of scar properties in both research and clinical settings. Despite a large number of scars assessment scales being available, there is limited information regarding the clinimetric properties of many of these scales. The purpose of the review was to inform clinical and research practice by determining the quality and appropriateness of existing scales. This review summarises the available evidence for the clinimetric properties of reliability, validity (including responsiveness), interpretability and feasibility of existing scales.

METHODS

Electronic searches of MEDLINE, CINAHL, EMBASE and The Cochrane Library databases from 1990 onwards were used to identify English articles related to burn scar assessment scales. Scales were critically reviewed for clinimetric properties that were reported in, but not necessarily the focus of studies.

RESULTS

A total of 29 studies provided data for 18 different scar rating scales. Most scar rating scales assessed vascularity, pliability, height and thickness. Some scales contained additional items such as itch. Only the Patient and Observer Scar Assessment Scale (POSAS) received a high quality rating but only in the area of reliability for total scores and the subscale vascularity. The Vancouver Scar Scale (VSS) received indeterminate ratings for construct validity, reliability and responsiveness. Where evidence was available, all other criteria for the POSAS, VSS and the remaining 17 scales received an indeterminate rating due to methodological issues, or a low quality rating. Poorly defined hypotheses limited the ability to give a high quality rating to data pertaining to construct validity, responsiveness and interpretability. No scale had empirical testing of content validity and no scale was of sufficient quality to consider criterion validity.

CONCLUSIONS

The POSAS, with high quality reliability but indeterminate validity, was considered to be superior in performance based on existing evidence. The VSS had the most thorough review of clnimetrics although available data received indeterminate quality ratings. On the basis of the evidence, the use of total scores has not been supported, nor has the measurement of pigmentation using a categorical scale.

Pathological axes of wound repair: gastrulation revisited

Post-traumatic inflammation is formed by molecular and cellular complex mechanisms whose final goal seems to be injured tissue regeneration.

In the skin -an exterior organ of the body- mechanical or thermal injury induces the expression of different inflammatory phenotypes that resemble similar phenotypes expressed during embryo development. Particularly, molecular and cellular mechanisms involved in gastrulation return. This is a developmental phase that delineates the three embryonic germ layers: ectoderm, endoderm and mesoderm. Consequently, in the post-natal wounded skin, primitive functions related with the embryonic mesoderm, i.e. amniotic and yolk sac-derived, are expressed. Neurogenesis and hematogenesis stand out among the primitive function mechanisms involved.

Interestingly, in these phases of the inflammatory response, whose molecular and cellular mechanisms are considered as traces of the early phases of the embryonic development, the mast cell, a cell that is supposedly inflammatory, plays a key role.

The correlation that can be established between the embryonic and the inflammatory events suggests that the results obtained from the research regarding both great fields of knowledge must be interchangeable to obtain the maximum advantage.

Secondary surgery for cicatricial complications of facial injury

PURPOSE

To investigate the nature of surgical revision procedures necessitated by cicatricial complications of facial injury.

PATIENTS AND METHODS

All patients who had facial trauma in a period of approximately 5 years managed by a single surgeon were reviewed. Of these, 36 were found to have undergone secondary revision procedures arising specifically from scar-related complications.

RESULTS

The average age of patients undergoing revision surgery was 34 years; 27 of the 36 patients (75%) were men, and 9 of the 36 (25%) required multiple revision surgical visits. The most common cause of injury was motor vehicle collision; the interval between the initial trauma and the first revision surgery was most commonly 6 to 12 months. Scar-related complications were categorized on the face by anatomic subsite; they occurred most frequently on the forehead/cheeks/chin area, with the eyes/periorbital area the second most frequent location. One hundred twelve discrete surgical procedures (as per current procedural terminology) were performed on these 36 patients to address the cicatricial sequelae of their initial injuries.

CONCLUSIONS

Facial trauma can frequently entail secondary morbidity in the form of facial scar deposition, which itself can necessitate surgical repair. This represents a substantial but as yet underappreciated health care burden attendant to maxillofacial injury.

Scar and contracture: biological principles

Dysregulated wound healing and pathologic fibrosis cause abnormal scarring, leading to poor functional and aesthetic results in hand burns. Understanding the underlying biologic mechanisms involved allows the hand surgeon to better address these issues, and suggests new avenues of research to improve patient outcomes. In this article, the authors review the biology of scar and contracture by focusing on potential causes of abnormal wound healing, including depth of injury, cytokines, cells, the immune system, and extracellular matrix, and explore therapeutic measures designed to target the various biologic causes of poor scar.

Transforming growth factor-beta and angiotensin in fibrosis and burn injuries

This review considers the roles of transforming growth factor-beta (TGF-beta), the signaling Smad proteins, and angiotensin II (AT II) in conditions leading to human fibrosis. The goal is to update the burn practitioner and researcher about this important pathway and to introduce AT II as a possible synergistic signal to TGF-beta in burn scarring. Literature searches of the MEDLINE database were performed for English manuscripts combinations of TGF-beta, Smad, angiotensin, fibrosis, burn, and scar. AT II and TGF-beta both activate the Smad protein system, which leads to the expression of genes related to fibrosis. In fibrotic conditions, such as tubulointerstitial nephritis, systemic sclerosis, and myocardial infarctions, AT II acts both independently and synergistically with TGF-beta. Both AT II and TGF-beta act through a messenger system, the Smad proteins that lead to excessive extracellular matrix formation. Treatment and research implications are reviewed. The interaction between AT II and TGF-beta leading to fibrosis is well described in some human diseases. This pathway may be of importance in human burn scarring as well.

Nonlinear spectral imaging of human hypertrophic scar based on two-photon excited fluorescence and second-harmonic generation

BACKGROUND

A noninvasive method using microscopy and spectroscopy for analysing the morphology of collagen and elastin and their biochemical variations in skin tissue will enable better understanding of the pathophysiology of hypertrophic scars and facilitate improved clinical management and treatment of this disease.

OBJECTIVE

To obtain simultaneously microscopic images and spectra of collagen and elastin fibres in ex vivo skin tissues (normal skin and hypertrophic scar) using a nonlinear spectral imaging method, and to compare the morphological structure and spectral characteristics of collagen and elastin fibres in hypertrophic scar tissues with those of normal skin, to determine whether this approach has potential for in vivo assessment of the pathophysiology of human hypertrophic scars and for monitoring treatment responses as well as for tracking the process of development of hypertrophic scars in clinic.

METHODS

Ex vivo human skin specimens obtained from six patients aged from 10 to 50 years old who were undergoing skin plastic surgery were examined. Five patients had hypertrophic scar lesions and one patient had no scar lesion before we obtained his skin specimen. A total of 30 tissue section samples of 30 mum thickness were analysed by the use of a nonlinear spectral imaging system consisting of a femtosecond excitation light source, a high-throughput scanning inverted microscope, and a spectral imaging detection system. The high-contrast and high-resolution second harmonic generation (SHG) images of collagen and two-photon excited fluorescence (TPEF) images of elastin fibres in hypertrophic scar tissues and normal skin were acquired using the extracting channel tool of the system. The emission spectra were analysed using the image-guided spectral analysis method. The depth-dependent decay constant of the SHG signal and the image texture characteristics of hypertrophic scar tissue and normal skin were used to quantitatively assess the amount, distribution and orientation of their collagen and elastin components.

RESULTS

Our experiments and data analyses demonstrated apparent differences between hypertrophic scar tissue and normal skin in terms of their morphological structure and the spectral characteristics of collagen and elastin fibres. These differences can potentially be used to distinguish hypertrophic scar tissues from normal skin and to evaluate treatment responses.

CONCLUSIONS

All the measurements were performed in backscattering geometry and demonstrated that nonlinear spectral imaging has the ability to differentiate hypertrophic scar tissue from normal skin based on noninvasive SHG imaging, and TPEF imaging revealed the microstructure and spectral features of collagen and elastin fibres. With the advances in spectral imaging apparatus miniaturization, we have good reason to believe that this approach can become a valuable tool for the in vivo pathophysiology study of human skin hypertrophic scars and for assessing the treatment responses of this disfiguring disease in clinic. It can also be used to track the development of hypertrophic scars and to study wound healing processes in a noninvasive fashion without biopsy, fixation, sectioning and the use of exogenous dyes or stains.