Altering CO2 Laser Pulse Energy Settings Did Not Influence Differential Gene Transcription in Normal Skin in a Red Duroc Pig Model

OBJECTIVES

Fractional ablative CO2 lasers are used clinically to treat cutaneous burn scars with reported varying degrees of effectiveness. It was hypothesized that different laser pulse energy settings may lead to differential gene transcription in a porcine model.

METHODS

Uninjured skin from red Duroc pigs was treated with a fractional ablative CO2 laser set to 70, 100, or 120 mJ across the abdomen (n = 4 areas per treatment). Punch biopsies of both treated and untreated sites were taken before treatment (baseline), at 30 min, and at each hour for 6 h and stored in All-Protect tissue reagent. The biopsies were then used to isolate RNA, which was subsequently used in qRT-PCR for eight genes associated with wound healing and the extracellular matrix: CCL2, IL6, FGF2, TIMP1, TIMP3, COL1A2, MMP2, and DCN. RPL13a was used as a housekeeping gene to normalize the eight genes of interest. One-way ANOVA tests were used to assess for differences among laser pulse energies and two-way ANOVA tests were used to assess the differences between treated and untreated areas.

RESULTS

While six of the eight genes were upregulated after treatment (p < 0.05), there were no significant differences in gene expression between the different laser pulse energies for any of the eight genes.

CONCLUSION

While laser treatment is correlated with a positive and significant upregulation for six of the eight genes 4 h after intervention, the pulse energy settings of the laser did not lead to a statistically significant difference in gene transcription among the treatment areas. Different laser pulse energies may not be required to induce similar cellular responses in a clinical setting.

Safety and Effectiveness of Laser or Intense Pulsed Light Treatment for Early Surgical Scar: A Systematic Review and Meta-analysis

OBJECTIVE

We aimed to investigate the safety and efficacy of laser or intense pulsed light therapy for early treatment of surgical scar.

METHODS

A literature search was conducted for relevant prospective, randomized controlled trials published in PubMed, Embase, Web of Science, Cochrane Library, CNKI, WanFang Database, and VTTMS between January 2006 and January 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist was used to extract literature data. The risk of bias was assessed by RevMan. Safety was assessed based on the presence of serious adverse reactions (blisters, infections, burns above the second degree), while effectiveness was assessed using the Vancouver Score Scale.

RESULTS

1512 related articles were preliminarily retrieved, including 1211 English articles and 301 Chinese articles. According to the inclusion criteria and exclusion criteria, 12 articles were selected for this analysis. In total, 475 patients were included (laser group, 238; control group, 236). All studies confirmed that the laser group was superior to the control group. In the subgroup analysis of 7 articles, the standardized mean difference was 1.99 (P = 0.0001).

CONCLUSIONS

This meta-analysis demonstrates that laser or intense pulsed light therapy is a safe and effective approach for early surgical scar treatment, resulting in improved scar appearance and minimal adverse reactions.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Prevention and Treatment of Burn Scar Contracture: A Practical Review

Burn contracture affects close to one-third of all burn patients, leading to significant functional impairment and costs. Effective prevention and treatment strategies are necessary to decrease morbidity and unnecessary costs. This scoping review aimed to summarize prevention and treatment strategies used for management of burn scar contractures published in the literature since 2000. A comprehensive PubMed review was performed in October 2022 to identify methods of burn contracture prevention and treatments. Non-English, duplicate, and unavailable articles were excluded. Data were extracted including publication year, techniques, and outcomes. A total of 327 publications met criteria for inclusion. Most articles were published in 2011 (n = 22). Treatment strategies were discussed in 82.9% of studies, prevention in 16.5%, and both in 0.6%. The most common areas discussed included the upper extremity (n = 127) and neck (n = 102). Flaps were the most frequently used method (n = 208), followed by autografts (n = 89). Most preventative therapies were still in early stages of development. Burn contracture management requires a highly individualized approach with many available reconstructive techniques available. Further research is needed to improve prevention techniques and decrease morbidity and cost to patients.

Fractional carbon dioxide laser alone and as an assisted drug delivery for treatment of alopecia areata: a clinical, dermoscopic and immunohistochemical study

Alopecia areata (AA) is a common cause of hair loss with no available universally successful treatment. Thus, new innovative treatments are urgently needed. This research aimed to evaluate the effectiveness of fractional carbon dioxide laser (FCL) alone or combined with triamcinolone acetonide (TA) solution, platelet-rich plasma (PRP), or vitamin D3 solution in treating AA. Sixty-four AA patients with 185 lesions were recruited and divided into four treatment groups. All patients received FCL either alone (group A, n = 19) or followed by topical TA (group B, n = 16) or PRP (group C, n = 15), or vitamin D3 solution (group D, n = 14). The response was assessed using Alopecia Areata Severity Index (AASI), MacDonald Hull and Norris grading, and trichoscopy. Histopathological features and immunohistochemical decorin expression were studied. All groups showed significant improvement in AASI compared to the baseline, with insignificant differences between them. Post-treatment, trichoscopic features of disease activity significantly decreased in all groups. Compared to control biopsies, both anagen follicles and decorin expression were significantly decreased in all pretreatment specimens. After treatment, all groups showed significantly increased anagen follicles and decorin expression compared to the baseline. Accordingly, FCL is an effective treatment for AA alone or combined with TA, PRP, or vitamin D3 solution. In AA, Decorin expression was downregulated, while enhanced expression following successful treatment occurred. This suggests the role of decorin in AA pathogenesis. However, further research is still recommended to clarify the exact role of decorin in AA pathogenesis and to investigate the therapeutic benefits of decorin-based therapy.

Long-Term Outcomes in Burn Patients

Better understanding of long-term outcomes after burn injury is essential for the burn clinician. Contractures are present in almost half of patients at discharge. Although less common, neuropathy and heterotopic ossification may be missed or go unaddressed. Close attention to psychological distress and to challenges with community reentry is essential. Obviously long-term problems with skin issues occur but other issues must be attended to maximize health and quality of life after injury. Facilitating access to community resources and providing long-term medical follow-up should be the standard of care.

Model to Inhibit Contraction in Third-Degree Burns Employing Split-Thickness Skin Graft and Administered Bone Marrow-Derived Stem Cells

Third-degree burns typically result in pronounced scarring and contraction in superficial and deep tissues. Established techniques such as debridement and grafting provide benefit in the acute phase of burn therapy, nevertheless, scar and contraction remain a challenge in deep burns management. Our ambition is to evaluate the effectiveness of novel cell-based therapies, which can be implemented into the standard of care debridement and grafting procedures. Twenty-seven third-degree burn wounds were created on the dorsal area of Red Duroc pig. After 72 h, burns are surgically debrided using a Weck knife. Split-thickness skin grafts (STSGs) were then taken after debridement and placed on burn scars combined with bone marrow stem cells (BM-MSCs). Biopsy samples were taken on days 17, 21, and 45 posttreatment for evaluation. Histological analysis revealed that untreated control scars at 17 days are more raised than burns treated with STSGs alone and/or STSGs with BM-MSCs. Wounds treated with skin grafts plus BM-MSCs appeared thinner and longer, indicative of reduced contraction. qPCR revealed some elevation of α-SMA expression at day 21 and Collagen Iα2 in cells derived from wounds treated with skin grafts alone compared to wounds treated with STSGs + BM-MSCs. We observed a reduction level of TGFβ-1 expression at days 17, 21, and 45 in cells derived from wounds treated compared to controls. These results, where the combined use of stem cells and skin grafts stimulate healing and reduce contraction following third-degree burn injury, have a potential as a novel therapy in the clinic.

A Review of Laser Therapies for the Treatment of Scarring and Vascular Anomalies

Significance: Laser use has become part of the gold standard of treatment as an effective adjuvant in multimodal therapy for pathologic scarring caused by burns, trauma, acne, and surgery, as well as vascular anomalies. Understanding indications and applications for laser therapy is essential for physicians to improve patient outcomes. Recent Advances: Since the 1980s, the medical use of lasers has continuously evolved with improvements in technology. Novel lasers and fractionated technologies are currently being studied in the hopes to improve treatment efficacy, while reducing complications. Recent advancements include acne treatment with novel picosecond lasers, new hypertrophic scar therapies with simultaneous laser and intense pulsed light use, and novel systems such as lasers with intralesional optical fiber delivery devices. In addition, optimizing the timing of laser therapy and its use in multimodal treatments continue to advance the field of photothermolysis. Critical Issues: Selecting the correct laser for a given indication is the fundamental decision when choosing a laser balancing effective treatment with minimal complications. This article covers the principles of laser therapy, the preferred lasers used for the treatment of scarring and vascular anomalies, and discusses the current evidence behind these laser choices. Future Directions: To optimize laser therapy, larger randomized control trials and split scar studies are needed. Continued advancement through better randomized controlled studies will help to improve patient outcomes on a broader scale.

Non-ablative laser treatment improves lip volume, texture, and color

Lips undergo several changes with age, decreased volume, elasticity, turgor, and collagen content. Q-switched Nd:YAG laser are known to increase the production of procollagen and elastin and can promote the generation of collagen, which visibly improves facial imperfections. We aimed to determine the efficacy of a 1064 nm Q-switched Nd:YAG fractional laser on improving lip definition, color, and volume. 32 female patients were treated every 2-3 weeks for a total of 3-5 treatments. Improvement was measured in a follow-up visit a month after the final treatment (29.9 ± 1.4 days) by patients' self-satisfaction questionnaire and physicians blinded evaluations (Likert scale). Patients achieved meaningful aesthetic improvement in in lip color (94% of patients), volume (72%), texture (91%), and overall lip appearance (82%). Furthermore, 91% were satisfied with treatment results and 100% from the overall experience. There were no associated side effects, and the associated pain level (on a 0-10 scale) was rated as 0 in 84% of individuals and 16% as 1. Therefore, laser treatment using a 1064 nm Q-switched Nd:YAG fractional laser on lips is a safe, noninvasive treatment that increases the color and volume of lips, with results that are maintained for at least one month following treatments.

Advantages and Disadvantages of Using Small and Large Animals in Burn Research: Proceedings of the 2021 Research Special Interest Group

Multiple animal species and approaches have been used for modeling different aspects of burn care, with some strategies considered more appropriate or translatable than others. On April 15, 2021, the Research Special Interest Group of the American Burn Association held a virtual session as part of the agenda for the annual meeting. The session was set up as a pro/con debate on the use of small versus large animals for application to four important aspects of burn pathophysiology: burn healing/conversion; scarring; inhalation injury; and sepsis. For each of these topics, 2 experienced investigators (one each for small and large animal models) described the advantages and disadvantages of using these preclinical models. The use of swine as a large animal model was a common theme due to anatomic similarities with human skin. The exception to this was a well-defined ovine model of inhalation injury; both of these species have larger airways which allow for incorporation of clinical tools such as bronchoscopes. However, these models are expensive and demanding from labor and resource standpoints. Various strategies have been implemented to make the more inexpensive rodent models appropriate for answering specific questions of interest in burns. Moreover, modelling burn-sepsis in large animals has proven difficult. It was agreed that the use of both small and large animal models have merit for answering basic questions about the responses to burn injury. Expert opinion and the ensuing lively conversations are summarized herein, which we hope will help inform experimental design of future research.

A Systematic Review Comparing Animal and Human Scarring Models

Introduction

A reproducible, standardised model for cutaneous scar tissue to assess therapeutics is crucial to the progress of the field. A systematic review was performed to critically evaluate scarring models in both animal and human research.

Method

All studies in which cutaneous scars are modelling in animals or humans were included. Models that were focused on the wound healing process or those in humans with scars from an existing injury were excluded. Ovid Medline^® was searched on 25 February 2019 to perform two near identical searches; one aimed at animals and the other aimed at humans. Two reviewers independently screened the titles and abstracts for study selection. Full texts of potentially suitable studies were then obtained for analysis.

Results

The animal kingdom search yielded 818 results, of which 71 were included in the review. Animals utilised included rabbits, mice, pigs, dogs and primates. Methods used for creating scar tissue included sharp excision, dermatome injury, thermal injury and injection of fibrotic substances. The search for scar assessment in humans yielded 287 results, of which 9 met the inclusion criteria. In all human studies, sharp incision was used to create scar tissue. Some studies focused on patients before or after elective surgery, including bilateral breast reduction, knee replacement or midline sternotomy.

Discussion

The rabbit ear scar model was the most popular tool for scar research, although pigs produce scar tissue which most closely resembles that of humans. Immunodeficient mouse models allow for in vivo engraftment and study of human scar tissue, however, there are limitations relating to the systemic response to these xenografts. Factors that determine the use of animals include cost of housing requirements, genetic traceability, and ethical concerns. In humans, surgical patients are often studied for scarring responses and outcomes, but reproducibility and patient factors that impact healing can limit interpretation. Human tissue use in vitro may serve as a good basis to rapidly screen and assess treatments prior to clinical use, with the advantage of reduced cost and setup requirements.

Molecular Features of Hypertrophic Scars After Thermal Injury: Is There a Biologic Basis for Laser Therapy?

Significance: Hypertrophic scars (HTS) and keloids are common after thermal injuries and other trauma to deep regions of dermis of the skin. These abnormal scars can cause contractures and the thick masses of scar tissue that result in functional and cosmetic impairment. Management of these dermal fibrotic conditions includes a wide range of medical and surgical treatments, which can be time consuming, only partially effective, and often uncomfortable for patients. Recent Advances: The molecular pathophysiology of HTS has become more understood over the past two decades, where thermal injury to the reticular dermis results in an inflammatory response, fibrogenic growth factor release, and the formation of a dermal scar with increased collagen and proteoglycan composition in an abnormal morphology. Lasers are becoming a widely used form of treatment for these types of scars; however, the evidence for the beneficial effects of laser treatments and the understanding of their mechanism of action are still evolving. Critical Issues: Paradoxically, laser delivery of thermal energy to the skin is suggested to improve scar remodeling and wound healing, yet HTS is a well-recognized complication of excessive thermal energy delivered by laser treatments. This review aims to examine the current evidence for the use of lasers for HTS, and to investigate the molecular mechanisms where re-injury of a burn scar from laser treatment could result in overall improvements in scar quality. Future Directions: Improved design of clinical trials for the treatment of scarring in the future will evolve from new methodology and models of HTS in animals and humans.

595-nm pulsed dye laser combined with fractional CO2 laser reduces hypertrophic scar through down-regulating TGFβ1 and PCNA

595-nm pulsed dye laser and fractional CO2 laser have been demonstrated effective to treat hypertrophic scar. The underlying mechanism may involve transforming growth factor-beta1 (TGFβ1) and proliferating cell nuclear antigen (PCNA), but remains to be clarified. Our study was performed to investigate how 595-nm pulsed dye laser combined with fractional CO2 laser treats hypertrophic scars in a rabbit model through regulating the expression of TGFβ1 and PCNA. Twenty-four New Zealand white rabbits were randomly divided into control group, pulsed dye laser group, fractional CO2 laser group, and pulsed dye laser + fractional CO2 laser (combination) group. Surgical wounds were made and allowed to grow into hypertrophic scars at day 28. Next, 595-nm pulsed dye laser (fluence: 15 J/cm2; square: 7 mm; pulse duration: 10 ms) was used in pulsed dye laser and combination group, while fractional CO2 laser (combo mode, deep energy: 12.5 mJ; super energy: 90 mJ) in fractional CO2 laser and combination groups, once every 4 weeks for 3 times. The appearance and thickness of hypertrophic scar samples were measured with hematoxylin-eosin and Van Gieson's straining. The expressions of TGFβ1 and PCNA were evaluated by immunohistochemical and western blot analysis. A significant improvement was noted in the thickness, size, hardness, and histopathology of hypertrophic scar samples after laser treatment, especially in combination group. Scar Elevation Index (SEI), fiber density (NA), and collagen fiber content (AA) decreased most significantly in combination group (2.10 ± 0.14; 2506 ± 383.00; 22.98 ± 2.80%) compared to 595-nm pulsed dye laser group (3.35 ± 0.28; 4857 ± 209.40; 42.83 ± 1.71%) and fractional CO2 laser group (2.60 ± 0.25; 3995 ± 224.20; 38.33 ± 3.01%) (P < 0.001). Furthermore, TGFβ1 and PCNA expressions were more suppressed in combination group (8.78 ± 1.03; 7.81 ± 1.51) than in 595-nm pulsed dye laser (14.91 ± 1.68; 15.73 ± 2.53) and fractional CO2 laser alone group (15.96 ± 1.56; 16.13 ± 1.72) (P < 0.001). The combination of 595-nm pulsed dye laser with fractional CO2 laser can improve the morphology and histology of hypertrophic scars in a rabbit model through inhibiting the expression of TGFβ1 and PCNA protein. Our findings can pave the way for new clinical treatment strategies for hypertrophic scars.

Efficacy of combined treatment with intense pulsed light and fractional erbium:YAG Laser in scar prevention: A randomized split wound trial

Various methods have been used for scar prevention; however, the optimal method remains unclear. We investigated the efficacy of combinational intense pulsed light (IPL)/fractional erbium-doped yttrium aluminum garnet (Er:YAG) laser treatment in early wound healing. This was a prospective, randomized, controlled split wound trial. Scars were divided into three sites: the combined IPL/fractional Er:YAG treatment, fractional Er:YAG laser treatment, and untreated control sites. Treatment was conducted in three sessions: at removal of stitches and after 4 and 8 weeks. Treatment efficacy was evaluated using the Patient Observer Scar Assessment Scale (POSAS) and Vancouver Scar Scale (VSS) scores. The erythema index (EI) and melanin index (MI) were measured. In the total POSAS score, the IPL/fractional Er:YAG site showed steady and significant improvement, in contrast to the other sites. At week 8, the combined treatment sites had better POSAS scores than the fractional Er:YAG laser alone sites (p = 0.001) and the control sites (p = 0.000). The effect of combinational treatment was maintained until the follow-up period by comparing the Er:YAG (p = 0.015) and control sites (p = 0.007). In terms of VSS scores, the IPL/fractional Er:YAG combined treatment sites had consistent improvement at week 8 (p = 0.005) and week 20 (p = 0.02) compared to that at week 4, while the other sites showed no such improvement. In conclusion, the combination of IPL and Er:YAG showed more favorable effects on scar prevention than Er:YAG or no treatment. IPL/Er:YAG therapy could be an effective and safe strategy in the early wound healing process for reducing scar formation.

Treatment of Wound Healing with Sequential Therapy to Accelerate Recovery and Inhibit Scar Hyperplasia: A Case Report

Study Design/Patients and Methods

A 19-year-old male was reported to have a postoperative facial trauma suture as a result of being involved in a car accident. Red light-emitting diode (LED) therapy (20 min, 96 J/cm², 633 nm), Botulinum Toxin Type A 36 IU injection, BroadBand Light and Er:YAG laser at various stages of wound healing were applied as the sequential therapy.

Results

Since the correction was promptly apparent and acceptable, the treatment proved secure and efficacious for repairing wound healing.

Conclusion

Clinically sequential therapy has demonstrated marked improvement in our case. Scar sequential therapy may offer a new strategy for wound healing recovery.

Recent Advances in Experimental Burn Models

Simple Summary

Human burns are diverse and the most difficult injuries to study in clinical settings. Numerous experimental burn models designed to study and compare different aspects of burns and their consequences and treatment are steadily progressing. This review summarizes the latest advances in experimental burn research as a guide to aid in the future design of studies.

Abstract

Experimental burn models are essential tools for simulating human burn injuries and exploring the consequences of burns or new treatment strategies. Unlike clinical studies, experimental models allow a direct comparison of different aspects of burns under controlled conditions and thereby provide relevant information on the molecular mechanisms of tissue damage and wound healing, as well as potential therapeutic targets. While most comparative burn studies are performed in animal models, a few human or humanized models have been successfully employed to study local events at the injury site. However, the consensus between animal and human studies regarding the cellular and molecular nature of systemic inflammatory response syndrome (SIRS), scarring, and neovascularization is limited. The many interspecies differences prohibit the outcomes of animal model studies from being fully translated into the human system. Thus, the development of more targeted, individualized treatments for burn injuries remains a major challenge in this field. This review focuses on the latest progress in experimental burn models achieved since 2016, and summarizes the outcomes regarding potential methodological improvements, assessments of molecular responses to injury, and therapeutic advances.

Combination Treatment of Intra/Perilesional Botulinum Toxin-A Injection and Ablative Fractional Laser for Better Clinical Outcomes of Hypertrophic Fibrotic Thyroidectomy Scars Following Fractional Ablative Laser Resurfacing

BACKGROUND

Recent reports have shown that intralesional botulinum toxin type-A (BTX-A) works on scar cosmesis.

OBJECTIVE

To evaluate the clinical efficacy of combination treatment of laser and BTX-A injection and compare the effects of conventional intralesional injection and intra- and perilesional BTX-A injection on fibrotic thyroidectomy scars.

METHODS

Patients with fibrotic thyroidectomy scars showing insufficient responses to previous ablative fractional laser (AFL) treatment were enrolled. Combination treatment with AFL and BTX-A injection was performed. Patients who received intra/perilesional BTX-A injections were classified into group A. Group B was patients in whom the injection was performed only intralesionally. The improvement was assessed based on the Vancouver Scar Scale (VSS).

RESULTS

A total of 24 patients was included. Statistically significant improvement in pliability and total VSS score after the combination treatment were observed in overall patient group. Subgroup analysis demonstrated that pliability, height, and total VSS improved significantly in group A. In group B, only pliability significantly improved.

CONCLUSION

BTX-A injection combined with AFL can provide better relief for the previously treated fibrotic thyroidectomy scars. Injection of BTX-A not only into the scar itself, but also into perilesional muscles that can exert tension on the scar site may provide additional benefit in flattening scar height.

Early Treatment Effects of Nonablative Fractional Lasers (NAFL) on Hypertrophic Scars in an Animal Model

BACKGROUND AND OBJECTIVES

Recently, there have been several attempts to apply the laser therapy to hypertrophic scars (HTS). In particular, the fractional laser is in the spotlight for its usefulness in rapid wound healing and dermal remodeling. However, most previous studies have focused on the ablative fractional laser (AFL), and there are no studies on the mechanism of the nonablative fractional laser (NAFL) effect in HTS treatment. In this study, we aimed to evaluate the changes in histology and molecular chemistry to provide scientific evidence for the early treatment of HTS with NAFL.

STUDY DESIGN/MATERIALS AND METHODS

A total of 40 hypertrophic burn scars were made on the abdomens of two female pigs. After epithelialization, the HTS were randomly subdivided into four groups-control, AFL, NAFL (low energy), and NAFL (high energy). Laser treatment was initiated 1 week after the crust fell and the epithelium became covered, and it was repeated for six sessions over an interval of 2 weeks. Five excisional biopsies were obtained for histologic analysis and biomarker assessment.

RESULTS

Histologically, dermal remodeling with thin coil-shaped collagen fibers was observed in the NAFL groups. It also showed a significant increase of matrix metalloproteinase-2 (MMP-2) and Decorin at 16 weeks in an enzyme-linked immunosorbent assay. The reverse-transcription polymerase chain reaction analysis showed a tendency that high-pulse energy of NAFL led to higher messenger RNA expression than did the low-energy group.

CONCLUSION

The NAFL-treated groups showed characteristic collagen re-arrangement and a significant increase in MMP-2 and Decorin. These molecular changes suggest that MMP-2 and Decorin play a significant role in dermal remodeling. Early NAFL treatment for HTS could be supported with both histological and molecular evidence. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

Moist exposed burn therapy in recovery of patients with immature, red hypertrophic scars successfully treated with a pulsed dye laser in combination with a fractional CO2 laser

BACKGROUND

The efficacy of pulsed dye laser combined (PDL) and UltraPulse fractional CO₂ in treatment of hypertrophic scars is well documented. The present study investigates the efficacy of moist exposed burn ointment (MEBO)/moist exposed burn therapy (MEBT) in postlaser wound management.

METHODS

Sixty-one patients with immature, red hypertrophic scars were enrolled in this clinical trial. Patients were randomly divided into two groups: (a) the MEBO treatment group (n = 30) and (b) the control group (n = 31) treated with chlortetracycline hydrochloride ointment. Demographic data such as age, gender, and cause of scars were recorded. A visual analogue score (VAS) was collected to measure pain at 1, 6, 24, 72 hours, and 7 days post-treatment. The Vancouver Scar Scale (VSS) was used to determine the response of the scars before and 3 months after the treatment. The wound healing time and pigmentation scores were also recorded.

RESULTS

No significant differences were found in age, gender, and etiology of the scars in the two groups. The VAS scores in MEBO group were significantly lower than the control group within the first 3 days after treatment. The wound healing time of the MEBO group was significantly shorter than the control group. For both groups, VSS scores were significantly decreased and the scar markedly improved. However, the VSS scores were significantly lower in the MEBO group compared with the control group 3 months after treatment and pigmentation formation was dramatically lower in MEBO group compared with the control.

CONCLUSION

MEBT/MEBO treatment reduced the post-treatment pain, shortened the wound healing duration, promoted the overall scar condition, and reduced the incidence of pigmentation.

Strategies to prevent hypertrophic scar formation: a review of therapeutic interventions based on molecular evidence

Once scar tissues mature, it is impossible for the surrounding tissue to regenerate normal dermal tissue. Therefore, it is essential to understand the fundamental mechanisms and establish effective strategies to inhibit aberrant scar formation. Hypertrophic scar formation is considered a result of the imbalance between extracellular matrix synthesis and degradation during wound healing. However, the underlying mechanisms of hypertrophic scar development are poorly understood. The purpose of this review was to outline the management in the early stage after wound healing to prevent hypertrophic scar formation, focusing on strategies excluding therapeutic agents of internal use. Treatment aimed at molecular targets, including cytokines, will be future options to prevent and treat hypertrophic scars. More basic studies and clinical trials, including combination therapy, are required to investigate the mechanisms and prevent hypertrophic scar formation.

Fractional CO2 laser ablation of porcine burn scars after grafting: Is deeper better?

INTRODUCTION

Fractional CO₂ lasers have been used in clinical settings to improve scarring following burn injury. Though used with increasing frequency, the appropriate laser settings are not well defined and overall efficacy of this therapy has not been definitively established. As it has been proposed that for thick hypertrophic scars proportionally greater fluence and thus deeper ablation into the scar tissue would be most effective, the goal of this study was to examine the role of ablation depth on scar outcomes in a highly-controlled porcine model for burn scars-after grafting.

METHODS

Properties of laser ablated wells were quantified on ex vivo pig skin as a function of laser energy (20, 70 or 150mJ). Full-thickness burn wounds were created on the dorsum of red Duroc pigs with the eschar excised and grafted with a split-thickness autograft meshed and expanded 1.5:1. After four weeks of healing, sites were treated with either 20, 70, or 150mJ pulse energy from a fractional CO₂ laser at 5% density or left untreated as a control. Sites were treated every four weeks with three total sessions. Scar area, pigmentation, erythema, roughness, histology, and biomechanics were evaluated prior to each laser treatment at day 28, 56, and 83, as well as four weeks after the final laser treatment, day 112. Additional biopsies were collected at day 112 for gene expression analysis.

RESULTS

The depth of the laser ablated wells increased with increasing pulse energy while the width of the wells was smaller in the 20mJ group and not significantly different in the 70 and 150mJ groups. Scar properties (area, color, biomechanics) were not significantly altered by laser therapy at any of the laser energies tested versus controls. Average scar roughness was improved by laser therapy in a dose dependent manner with scars treated with 150mJ of energy having the smoothest surface; however, these changes were not statistically significant. Assessment of matrix metalloproteinase 9 gene expression showed a slight upregulation in scars treated with 70 or 150mJ versus control scars and scars treated with 20mJ pulse energy.

CONCLUSION

The current study demonstrated that the properties of the ablative well (depth and width) are not linearly correlated with laser pulse energy, with only a small increase in well depth at energies between 70 and 150mJ. Overall, the study suggests that there is little difference in outcomes as a function of laser energy. Fractional CO₂ laser therapy did not result in any statistically significant benefit to scar properties assessed by quantitative, objective measures, thus highlighting the need for additional clinical investigation of laser therapy efficacy with non-treated controls and objective measures of outcome.