Inflammatory responses, matrix remodeling, and re-epithelialization after fractional CO2 laser treatment of scars

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.

Laser therapy for treating cleft lip or/and palate scarring-a systematic review and meta-analysis

This review aims to assess the efficacy and safety of laser therapy in managing scars resulting from cleft lip and/or palate (CL/P) repair surgeries, as well as to determine the optimal timing for intervention. A systematic search was conducted across four databases using a predefined search strategy. Studies included were randomized controlled trials, non-randomized studies, and case series focusing on laser therapy for CL/P scars. Data extraction and analysis were performed using Revman Software. A total of two randomized controlled trials, four non-randomized studies, and three case series were included in the analysis. The fractional CO2 laser was the most commonly utilized type of laser. Following laser therapy, there was a significant decrease in Vancouver Scar Scale (VSS) scores by 4.05 (95% CI, 2.10-5.99). Meta-analysis revealed that laser treatment groups exhibited a significantly lower mean VSS score (1.3; 95% CI, 0.02-2.67) compared to control groups. Moreover, initiating laser therapy intervention at one month postoperatively resulted in a significantly lower VSS score compared to initiation at three months postoperatively (difference of 1.70; 95% CI, 1.33-2.08). No severe complications were reported. Laser therapy demonstrates effectiveness and safety in improving CL/P scars, with earlier intervention yielding greater benefits.

Picosecond Nd:YAG versus Fractional CO2 Lasers in Management of Postburn Scars

Background

The picosecond laser was primarily designed to enhance tattoo removal. Because it has a new innovative mechanism for energy delivery, it has been modified to be used in other conditions such as skin resurfacing, which was usually treated with fractional CO2 laser. Comparing both technologies in managing postburn scars has not been widely addressed.

Methods

The current prospective comparative randomized intrapatient study was done on 15 patients who presented with unsightly postburn scarring. As a split study, one-half of the affected areas were treated using the picosecond Nd: YAG laser. The other areas were treated with a fractional CO2 laser. After three treatment sessions, the results were analyzed both objectively and subjectively.

Results

The assessment by the image analysis system (Antera camera) showed improvement in all the parameters in both groups. The melanin relative variation decreased from 11.65 ± 2.86, 15.85 ± 5.63 to 10.60 ± 1.96, 12.56 ± 3.98, respectively in picosecond laser sites and fractional CO2 sites. The percentage change in overall opinion decreased in in favor of the fractional CO2 laser sites, which is a statistically significant improvement. Instead, color scores revealed a greater reduction in the picosecond sites in comparison with the fractional CO2 sites, as it decreased from 7.67 ± 1.76, 7.73 ± 1.83 to 2.87 ± 1.06, 6 ± 1.2, respectively.

Conclusions

When compared with fractional CO2 lasers, picosecond Nd:YAG shows comparable improvements in scars' erythema, texture, and height, with some superiority in the management of hyperpigmented scars.

Ablative fractional CO2 laser treatment promotes wound healing phenotype in skin macrophages

OBJECTIVES

Ablative fractional laser (AFL) treatment is a well-established method for reducing signs of skin photoaging. However, the biological mechanisms underlying AFL-induced healing responses and skin rejuvenation remain largely unknown. It is known that macrophages play an important role in orchestrating healing, normalization, and remodeling processes in skin. Macrophage phenotypes are characterized by inflammatory markers, including arginase-1 (Arg1), major histocompatibility class II molecules (MHC II), and CD206. This study aims to explore AFL's effect on macrophage phenotype by evaluating changes in inflammatory markers and the potential concurrent accumulation of Arg1 in the skin.

METHODS

Mice (n = 9) received a single AFL treatment on the left side of the back skin (100 mJ/microbeam, 5% density) while the right side of the back remained untreated as control. Treated and untreated skin from each mouse were collected Day 5 posttreatment for flow cytometry and histology analysis. Flow cytometry evaluated the immune infiltration of macrophages and the expression of macrophage inflammatory markers (Arg1, MHC II, and CD206). In addition, Arg1 presence in the skin was evaluated through antibody staining of histology samples and quantification was performed using QuPath image analysis software.

RESULTS

Following AFL, the number of macrophages increased 11-fold (p = 0.0053). Phenotype analysis of AFL-treated skin revealed an increase in the percentage of macrophages positive for Arg1 (p < 0.0001) and a decrease in the percentage of macrophages positive for MHC II (p < 0.0001) compared to untreated skin. No significant differences were observed in percentage of CD206-positive macrophages (p = 0.8952). Visualization of AFL-treated skin demonstrated a distinct pattern of Arg1 accumulation that correlated with the microscopic treatment zones (MTZ). Quantification of the percentage of Arg1-positive area in epidermis and dermis showed a significant increase from 3.5% ± 1.2% to 5.2% ± 1.7 (p = 0.0232) and an increase from 2.2% ± 1.2% to 9.6% ± 3.3 (p < 0.0001) in whole skin samples.

CONCLUSION

AFL treatment polarizes macrophages toward a wound healing phenotype and induces Arg1 accumulation in the MTZ. We propose that the polarized wound healing macrophages are a major source for the increased Arg1 levels observed in the skin following treatment.

The role of laser and energy-assisted drug delivery in the treatment of alopecia

It has been recently established that laser treatment can be combined with topical or intralesional medications to enhance the delivery of drugs and improve overall results in a variety of different dermatological disorders. The aim of this review is to evaluate the use of laser and energy-assisted drug delivery (LEADD) for the treatment of alopecia with a specific focus on ablative fractional lasers (AFL), non-ablative fractional lasers (NAFL), and radiofrequency microneedling (RFMN). A comprehensive PubMed search was performed in December 2022 for "laser-assisted drug delivery" as well as "laser" and "alopecia." The evidence regarding LEADD for alopecia treatment is limited to two specific alopecia subtypes: alopecia areata (AA) and androgenetic alopecia (AGA)/pattern hair loss (PHL). LEADD with minoxidil and platelet-rich plasma (PRP) were evaluated for efficacy in both treatments of AA and AGA. LEADD with topical corticosteroids and intralesional methotrexate were studied for the treatment of AA, while LEADD with growth factors and stem cells were studied for the treatment of AGA. Multiple RCTs evaluated LEADD for topical corticosteroids with ablative fractional lasers for the treatment of AA. There is evidence in the literature that supports the use of topical minoxidil in combination with all devices for the treatment of AGA/PHL. All the reviewed studies show a positive treatment effect with LADD; however, some trials did not find LEADD to be superior to monotherapy or microneedling-assisted drug delivery. LEADD is a rapidly emerging treatment modality for the treatment of AGA and AA.

Impact of skin hydration on patterns of microthermal injury produced by fractional CO2 laser

OBJECTIVES

The impact of skin hydration on patterns of thermal injury produced by ablative fractional lasers (AFLs) is insufficiently examined under standardized conditions. Using skin with three different hydration levels, this study assessed the effect of hydration status on microchannel dimensions generated by a fractional CO2 laser.

METHODS

A hydration model (hyperhydrated-, dehydrated- and control) was established in ex vivo porcine skin, validated by changes in surface conductance and sample mass. After, samples underwent AFL exposure using a CO2 laser (10,600 nm) at two examined pulse energies (10 and 30 mJ/mb, fixed 10% density, six repetitions per group). Histological assessment of distinct microchannels (n = 60) determined three standardized endpoints in H&E sections: (1) depth of microthermal treatment zones (MTZs), (2) depth of microscopic ablation zones (MAZs), and (3) coagulation zone (CZ) thickness. As a supplemental in vivo assessment, the same laser settings were applied to hyperhydrated- (7-h occlusion) and normohydrated forearm skin (no pretreatment) of a human volunteer. Blinded measurement of MAZ depth (n = 30) was performed using noninvasive optical coherence tomography (OCT).

RESULTS

Modest differences in microchannel dimensions were shown between hyperhydrated, dehydrated and control skin at both high and low pulse energy. Compared to controls, hyperhydration led to median reductions in MTZ and MAZ depth ranging from 5% to 8% (control vs. hyperhydrated at 30 mJ/mb; 848 vs. 797 µm (p < 0.003) (MAZ); 928 vs. 856 µm (p < 0.003) (MTZ)), while 14%-16% reductions were shown in dehydrated skin (control vs. dehydrated at 30 mJ/mb; MAZ: 848 vs. 727 µm (p < 0.003); MTZ: 928 vs. 782 µm (p < 0.003)). The impact of skin hydration on CZ thickness was in contrast limited. Corresponding with ex vivo findings, hyperhydration was similarly associated with lower ablative depth in vivo skin. Thus, median MAZ depth in hydrated skin was 10% and 14% lower than in control areas at 10 and 30 mJ/mb pulse energy, respectively (10 mJ: 210 vs. 180 µm (p < 0.001); 30 mJ: 335 vs. 300 µm (p < 0.001)).

CONCLUSION

Skin hydration status can exert a minimal impact on patterns of microthermal injury produced by fractional CO2 lasers, although the clinical implication in the context of laser therapy requires further study.

Laser Therapy for Vulvar Lichen Sclerosus, a Systematic Review

Lichen sclerosus (LS) is a chronic inflammatory disease that mainly affects the anogenital area, with a higher incidence in post-menopausal women. In the long term, it can lead to loss of vulvar architecture or progress to squamous cell carcinoma. The evidence-based treatment involves high-potency topical corticosteroids in long regimens. However, second-line treatments are not well-established, including laser therapy. This current study aims to assess the level of evidence supporting this therapy. We conducted a search for primary-level studies published before April 2023 through MEDLINE/PubMed, Embase, Web of Science, Scopus, and CENTRAL, with no restrictions on the publication language or date. The methodological quality and risk of bias of the included studies were evaluated using the updated Cochrane Collaboration's tool for assessing risk of bias (RoB-2). Six studies (177 patients) met our eligibility criteria. Laser therapy was compared to topical corticosteroid treatment in five out of six studies. No significant histological differences were found, except for an increase in collagen production in the laser group. A greater reduction in itching, pain, and dyspareunia at 1 and 3 months of treatment in the laser group, as well as in the Skindex-29 at 6 months, was reported. Patient satisfaction was significantly higher among those who received laser therapy. Tolerability was excellent. No significant differences were observed in any of the previous aspects in the study compared to the placebo. In conclusion, there is not enough evidence to recommend laser therapy as a standalone treatment.

Laser Micropatterning Promotes Rete Ridge Formation and Enhanced Engineered Skin Strength without Increased Inflammation

Rete ridges play multiple important roles in native skin tissue function, including enhancing skin strength, but they are largely absent from engineered tissue models and skin substitutes. Laser micropatterning of fibroblast-containing dermal templates prior to seeding of keratinocytes was shown to facilitate rete ridge development in engineered skin (ES) both in vitro and in vivo. However, it is unknown whether rete ridge development results exclusively from the microarchitectural features formed by ablative processing or whether laser treatment causes an inflammatory response that contributes to rete ridge formation. In this study, laser-micropatterned and non-laser- treated ES grafts were developed and assessed during culture and for four weeks post grafting onto full-thickness wounds in immunodeficient mice. Decreases in inflammatory cytokine secretion were initially observed in vitro in laser-treated grafts compared to non-treated controls, although cytokine levels were similar in both groups five days after laser treatment. Post grafting, rete ridge-containing ES showed a significant increase in vascularization at week 2, and in collagen deposition and biomechanics at weeks 2 and 4, compared with controls. No differences in inflammatory cytokine expression after grafting were observed between groups. The results suggest that laser micropatterning of ES to create rete ridges improves the mechanical properties of healed skin grafts without increasing inflammation.

Efficacy and Safety of Fractional CO2 Laser Combined with Halometasone Cream for Treatment of Moderate-to-Severe Chronic Hand Eczema: A Prospective, Single-Center, Parallel-Group, Open-Label Randomized Trial

INTRODUCTION

The purpose of this study was to assess the efficacy and safety of fractional CO₂ laser combined with halometasone cream in patients with moderate-to-severe chronic hand eczema (CHE).

METHODS

A prospective, single-center, parallel-group, open-label randomized trial including 67 patients with moderate-to-severe CHE was carried out. Patients were randomly assigned to group A (n = 33, fractional CO₂ laser once every 4 weeks 1-2 times and halometasone cream twice daily for 8 weeks) or group B (n = 34, halometasone cream alone twice daily for 8 weeks). The primary endpoint was the proportion of patients achieving treatment success at week 12 in each group. Secondary endpoints included differences between groups in the change of hand eczema severity index (HECSI), patient global assessment (PaGA), dermatology life quality index (DLQI), and quality of life in hand eczema questionnaire (QOLHEQ) from baseline to week 12. Relapse rate and adverse effects were also recorded.

RESULTS

A total of 29 patients in each group completed the trial. At week 12, the treatment success rate was 62.1% (18/29) in group A and 27.6% (8/29) in group B (p = 0.009). At week 12, HECSI, PaGA, DLQI, and QOLHEQ all decreased compared with baseline in both groups (p < 0.05). HECSI, DLQI, and QOLHEQ decreased more in group A than group B (p = 0.014, 0.010, and 0.014, respectively), but there was no significant difference in change of PaGA between the two groups (1.0 versus 3.0, p = 0.419). Among patients achieving treatment success, 11.1% (2/18) patients in group A and 50.0% (4/8) patients in group B relapsed at week 24 (p = 0.011). Skin pigmentation was the most common adverse effect.

CONCLUSIONS

For patients with moderate-to-severe CHE, fractional CO₂ laser combined with halometasone cream is more effective than halometasone cream alone, with few adverse effects.

TRIAL REGISTRATION NUMBER

ChiCTR2100051948.

Fractional CO 2 Laser versus Fractional CO 2 Laser Plus Betamethasone/Calcipotriol Ointment in the Treatment of Nail Psoriasis

BACKGROUND

Nail psoriasis has a major negative impact on the physical and psychological aspects of the patient's life. Treatment is often unsatisfactory because of the difficult penetration of the drug into the nail.

OBJECTIVE

To compare the efficacy of fractional CO 2 laser monotherapy versus combined fractional CO 2 laser and calcipotriol/betamethasone ointment preparation in treatment of nail psoriasis.

PATIENTS AND METHODS

Thirty patients with nail psoriasis with at least 2 affected fingernails were recruited for this study. Target NAPSI (tNAPSI) score was calculated at the start of the study and at 3 months after the last laser session. One affected fingernail of each patient received 6 sessions of fractional CO 2 laser with 4-week intervals. Another affected fingernail of each patient received topical betamethasone/calcipotriol ointment once daily in addition to the 6 fractional CO 2 laser sessions.

RESULTS

In the monotherapy group, there was significant improvement in the nail matrix score, nail bed score, and tNAPSI score. In the combined therapy group, there was significant improvement in nail bed score and tNAPSI score, but nail matrix score showed no statistically significant improvement. Overall, there was no statistically significant difference between the 2 studied groups.

CONCLUSION

Fractional CO 2 laser can be an effective and promising new treatment for nail psoriasis.

Early Fractional Ablative Laser for Skin Cancer Excision Scars: A Randomized Split-Scar Study

BACKGROUND

Fractional ablative laser resurfacing has been shown to improve the final cosmetic appearance of surgical scars, but optimal timing is unknown.

OBJECTIVE

To compare surgical scars treated with fractional carbon dioxide (CO 2 ) laser performed on Day 0 and Day 14.

METHODS

Prospective, randomized, split-scar, physician-blinded study of 30 surgical scars on the limbs. Scars halves received fractional CO 2 laser on either Day 0 or Day 14. Scar assessment at 6 months evaluated patient preference, physician modified Manchester Scar Scale (MMSS) score, and quantitative scar analysis on histology (fractal dimension [F D ] and lacunarity [L] analysis).

RESULTS

There was no significant difference in patient assessment (54% preferred Day 0 side, 46% preferred Day 14 side, p = .58) or physician assessment (mean MMSS 8.4 for Day 0 vs 8.7 for Day 14, p = .28). Fractal dimensions were similar for both interventions (mean 1.778 for Day 0 vs 1.781 for Day 14, p = .80). Lacunarity was similar for both interventions (mean 0.368 for Day 0 vs 0.345 for Day 14, p = .44).

LIMITATIONS

Single-center study with wounds limited to limbs of skin Phototype I-II subjects; 4 of whom were lost to follow-up.

CONCLUSION

Intraoperative CO 2 laser is noninferior to Day 14 laser resurfacing for surgical scar treatment.

In Vitro, Ex Vivo, and In Vivo Approaches for Investigation of Skin Scarring: Human and Animal Models

Significance: The cutaneous repair process naturally results in different types of scarring that are classified as normal or pathological. Affected individuals are often affected from an esthetic, physical (functional), and psychosocial perspective. The distinct nature of scarring in humans, particularly the formation of pathological scars, makes the study of skin scarring a challenge for researchers in this area. Several established experimental models exist for studying scar formation. However, the increasing development and validation of newly emerging models have made it possible to carry out studies focused on different variables that influence this unique process. Recent Advances: Experimental models such as in vitro, ex vivo, and in vivo models have obtained different degrees of success in the reproduction of the scar formation in its native milieu and true environment. These models also differ in their ability to elucidate the molecular, cellular, and structural mechanisms involved in scarring, as well as for testing new agents and approaches for therapies. The models reviewed here, including cells derived from human skin and in vivo animal models, have contributed to the advancement of skin scarring research. Critical Issues and Future Directions: The absence of experimental models that faithfully reproduce the typical characteristics of the different types of human skin scars makes the improvement of validated models and the establishment of new ones a critical unmet need. The fields of wound healing research combined with tissue engineering have offered newer alternatives for experimental studies with the potential to provide clinically useful knowledge about scar formation.

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.

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.

Neutrophils and their extracellular traps impair ablative fractional carbon dioxide laser-induced dermal remolding in mice

OBJECTIVES

Ablative fractional CO₂ laser (AFL) therapy is an effective intervention to induce dermal remodeling. AFL treatment of the skin triggers the recruitment of immune cells, with neutrophils dominating the early phase. However, the role of recruited neutrophils in AFL-induced microinjuries and their subsequent dermal remodeling capacity remains elusive.

MATERIALS AND METHODS

A mouse model of AFL-induced dermal remodeling was established. RNA sequencing was used to identify the prominent features of AFL-treated tissues. Histological analysis, including H&E and Masson staining, ultrastructure observation by transmission microscopy, immunofluorescence, and quantitative real-time polymerase chain reaction were used for dermal remodeling analysis. Moreover, AFL-treated mice were intraperitoneally injected with anti-mouse Ly6G antibodies to deplete neutrophils. Neutrophil extracellular traps (NETs) were explored using immunofluorescence, transmission microscopy, and in vitro coculture experiments.

RESULTS

Dermal remodeling, characterized by an increased number of CD31-positve vessels and elevated messenger RNA (mRNA) expression of genes encoding transforming growth factor-β (TGF-β), collagen I, and collagen III, was observed at 15 days after AFL treatment. In the AFL-induced inflammation phase, RNA sequencing identified neutrophil chemotaxis, and degranulation genes were significantly enriched. Histology and immunofluorescence staining of human and mouse tissues harvested at Day 1 after AFL treatment revealed significant neutrophil infiltration surrounding thermal-induced microinjuries. Neutrophil depletion decreased the expression of stress-related genes such as S100A8 and S100A9 in the early phase following AFL treatment. Importantly, neutrophil depletion enhanced dermal remodeling at Day 15, as reflected by enrichment of the extracellular matrix and collagen biosynthesis genes based on RNA sequencing. Moreover, increased collagen I, collagen III, and TGF-β mRNA expression, increased cell proliferation, and vascularity were observed. Interestingly, NETs, which could be induced by AFL-treated fibroblasts in vitro, were identified in both human and mouse tissues on Day 1 after AFL treatment.

CONCLUSIONS

AFL-treated human and mouse skin recruited a large number of neutrophils. The neutrophil surge impaired dermal remodeling in mice. The microenvironment and fibroblast functional modulation mediated by neutrophil degranulation and NET formation were determined to be the underlying mechanisms. Our results indicate that modification of infiltrated neutrophil activity might be a potential therapeutic target for AFL-induced dermal remodeling.

Efficacy and safety of a dual-scan protocol for carbon dioxide laser in the treatment of split-thickness skin graft contraction in a red Duroc pig model

BACKGROUND

Fractional CO₂ laser plays an important role in scar management post split-thickness skin graft by loosening the graft contracture and restoring the smoothness of the surface. However, the optimal treatment protocol remains unknown. This study applied a dual-scan protocol to achieve both releasing and ablation of contracted skin graft. We comprehensively describe this treatment method and compare the efficacy and safety between this dual-scan method and the conventional mono-scan mode.

METHODS

A hypercontracted scar model after split-thickness skin grafting in red Duroc pigs was established. All scars meeting the inclusion criteria were randomly divided into four groups: high fluence-low density (HF-LD), low fluence-high density (LF-HD), combined group and control group. The energy per unit area was similar in the HF-LD and LF-HD groups. Two laser interventions were performed at a 6-week interval. The efficacy of the treatment was evaluated by objective measures of scar area, release rate, elasticity, thickness and flatness, while the safety was evaluated based on adverse reactions and melanin index. Collagen structure was observed histologically. The animals were followed up for a maximum of 126 days after modeling.

RESULTS

A total of 28 contracted scars were included, 7 in each group. At 18 weeks postoperatively, the HF-LD and the combined groups showed significantly increased scar release rate (p = 0.000) and elasticity (p = 0.036) and decreased type I/III collagen ratio (p = 0.002) compared with the control and LF-HD groups. In terms of flatness, the combined group was significantly better than the HF-LD group for elevations <1 mm (p = 0.019). No significant skin side effects, pigmentation or scar thickness changes were observed at 18 weeks.

CONCLUSIONS

Dual-scan protocol could achieve superficial ablation and deep release of contracted split-thickness skin graft in a single treatment, with similar contraction release and texture improvement compared to a single deep scan. Its main advantage is to restore a smoother scar appearance. Adequate laser penetration was necessary for the release of contracted scars.

Efficacy of Fractional Carbon Dioxide Laser (FCO2) with Intralesional 5-Fluorouracil (5-FU) in the Treatment of Keloids

Context:

Managing keloids remains a challenge in clinical practice. Many therapeutic options are available, but none is universally accepted or without recurrence. Therefore, an effort is required to choose the treatment with maximal outcomes.

Aims:

To evaluate the effectiveness of combining fractional carbon dioxide (FCO₂) laser and intralesional 5-fluorouracil (5-FU) for the treatment of keloids.

Materials and Methods:

In this prospective open-label study, 24 patients received FCO₂ laser treatment, started at baseline, for a total of six sittings. The patients also received 1 mL/cm²/keloid of 5-FU (50 mg/mL) intralesionally, following irradiation, at identical time points. The primary outcome evaluated was the clinical response concerning height, pliability, vascularity, and pigmentation, using the Vancouver Score Scale (VSS). Adverse reactions and recurrences were recorded as secondary outcomes.

Results:

A significant reduction was observed in the VSS in terms of pliability and height after three treatment sessions. The mean VSS reduction was 65%, from 8.45 ± SD 0.93 at baseline to 3 ± SD 1.8 one month after the last treatment (P < 0.05). Most patients (79.1%; n = 19) showed a satisfactory response to treatment, with 57.8% (n = 11) achieving an excellent result. Adverse reactions included post-inflammatory hyperpigmentation in four patients and ulceration in two. Recurrences were reported in 21% of the patients who responded well.

Conclusions:

Combination therapy with FCO₂ laser and intralesional 5-FU showed a promising effect in the treatment of resistant keloids, with an acceptable safety profile and low recurrence rate.

Laser Immunotherapy: A Potential Treatment Modality for Keratinocyte Carcinoma

Simple Summary

In light of expanding incidences of keratinocyte carcinoma (KC) with many patients developing multiple tumors, the demand for new treatment modalities is high. With the approval of cemplimab for locally advanced and metastasizing basal cell carcinoma and squamous cell carcinoma, KC is now included as an indication for systemic immunotherapy. At present, however, systemic KC therapy remains limited by the severe side effects associated with treatment. Immunotherapy might be more broadly applied if locally administered. Localized to the skin, KCs are easily accessible to topical drugs and physical interventions such as laser. There is an increasing appreciation of lasers’ potential to activate an immune response. Further enhancement of the laser-based immune activation might be obtained by combining laser and immunotherapeutic agents, known as laser immunotherapy. In search of new treatment modalities for KC and aiming to broaden the field of KC immunotherapy, this review discusses the current literature on immune activation following both laser monotherapy and laser immunotherapy.

Abstract

The role of the immune system in cancer growth is well recognized and the development of immunotherapy represents a breakthrough in cancer treatment. Recently, the use of systemic immunotherapy was extended to keratinocyte carcinoma (KC), specifically locally advanced and metastasizing basal and squamous cell carcinoma. However, since most KC lesions are non-aggressive, systemic treatment with associated side effects is rarely justified. Conversely, topical immunotherapy with imiquimod remains restricted to premalignant and superficial lesions. Use of laser in the treatment of KC has evolved from physical tumor destruction and laser-assisted drug delivery to laser-mediated immune modulation. Evidence indicates that laser monotherapy can lead to immune cell infiltration, tumor reduction and resistance to tumor re-inoculation. Combining laser with immunotherapeutic agents, termed laser immunotherapy (LIT), may further potentiate immune activation and tumor response. Studies on LIT show not only direct anti-tumor effects but systemic adaptive immunity, illustrated by the prevention of tumor recurrence and regression in distant untreated tumors. These findings imply a therapeutic potential for both local and metastatic disease. This work provides rationales for immune-based treatment of KC and presents the current status of KC immunotherapy. Aiming to expand the field of KC immunotherapy, the review discusses the literature on immune activation following laser monotherapy and LIT.

Phase-Adapted Rehabilitation for Acute Coronavirus Disease-19 Patients and Patient With Long-term Sequelae of Coronavirus Disease-19

ABSTRACT

Since the beginning of the COVID-19 pandemic in early 2020, many papers have highlighted the need for the rehabilitation of patients with SARS-CoV-2 infection. Most papers refer to the need for respiratory rehabilitation in the acute phase; however, the fact that the infection also affects other organ systems has to be considered in rehabilitation interventions. Long-term symptoms in many cases severely limit activity and participation and alter quality of life, leading to rehabilitation needs. This article proposes a phase-adapted model of linking the acute, postacute, and long-term symptoms of COVID-19 with the well-established matrix of acute, postacute, and long-term rehabilitation services. A review of currently available recommendations for phase-adapted rehabilitation strategies, including the relevance of prehabilitation within this context, is provided.

Low-fluence and low-density CO2 laser: histological analysis of collagen fiber changes in skin and its clinical repercussions in photorejuvenation

This study refers to clinical and histologic analysis of effects on photorejuvenation after one single treatment of fractional CO2 laser with low fluence and low density. To analyze histologically the quantitative variation of collagen fibers type I and III, elastic fibers, and epidermal thickness on D84, besides clinical evaluation of amount, length, thickness, and depth of periocular wrinkles during the same period. This is an open, prospective, interventional study. There were 40 healthy female with age between 35 and 65 years. Twenty-six participants were randomly selected for D0 and D84 biopsy. A single session of fractional CO2 laser was done in the hole face, using a 800-µm tip, 5% density, and 10 mJ fluence with a single pass. On D0, D42, and D84, a clinical comparative analysis of amount, length, depth, and thickness of periocular wrinkles has been done. On histological analysis, a comparative quantitative evaluation of collagen fibers type I and III, elastic fibers, and epidermal thickness has been done on D0 and D84. The results of this study denoted a significant clinical improvement of amount (- 32.17%; p < 0.0001), thickness (- 33%; p < 0.0001), lenght (- 35.84%; p < 0.0001), and depth of periocular wrinkles (- 32.46%; p < 0.0001). A significant increase in the amount of collagen fibers type III was observed on D84 (+ 60.67%; p = 0.0013). Collagen fibers type I and elastic fibers did not have the same result, with a nonsignificant increase (+ 8.31%; p = 0.3820) and a decrease (- 12.4%; p = 0.0585) respectively. Epidermal thickness has a tendency to significant variation (p = 0.05553). The results demonstrate that fractional CO2 laser with low fluence and low density is a safe and efficient option for photorejuvenation of the face.

[Effect of CO₂ fractional laser on the early control of scar post-secondary repair in patients with a cleft lip]

OBJECTIVE

To observe and compare the clinical efficacy of CO₂ fractional laser in the early control of scar post-secondary repair in patients with a cleft lip.

METHODS

In the treatment group, 43 patients with secondary repair of cleft lip were treated via CO₂ fractional laser. The control group covered 70 patients post-cheiloplasty. The effect in the two groups after six months was compared. The duration from the beginning of the laser treatment to surgery and patient gender were analyzed to determine if they affected the efficacy of the laser treatment for scars.

RESULTS

1) The curative effect in the treatment group was better than that in the control group (P<0.000 1), the total effectiveness rate was 90.7% in the treatment group. 2) No significant statistical difference in efficacy was observed between men and women (P=0.487). Moreover, no significant statistical difference in efficacy (P=0.055) was observed among patients one year after surgery, within the duration of <3 months, and within the duration of ≥3 months.

CONCLUSIONS

CO₂ fractional laser had a definite effect on the treatment of scar post-secondary repair in patients with a cleft lip. No significant correlation was observed between treatment effect and patient gender, and no difference was noted among patients one year after surgery. In the beginning of the laser treatment, no difference was observed between the durations of <3 months and ≥3 months after the reconstruction, Therefore, early intervention of scars a year after secondary repair of a cleft lip can achieve good results.

3D Mesh Releasing Method: A Retrospective Analysis of Fractional CO2 Treatment on Contracture Scars

BACKGROUND AND OBJECTIVES

There has been reports on fractional CO₂ laser successfully improving contracture scars that impair the function of a joint. It seems that certain contracture problems could be solved by laser instead of surgery. However, the clinical application could be difficult when the efficacy of the method remains unknown. The purpose of this study is to report the releasing capacity of the fractional CO₂ laser on contracture scars based on a defined treatment method.

STUDY DESIGN/MATERIALS AND METHODS

We conducted a retrospective study in patients with limited function in joints caused by contracture scars. Fractional CO₂ laser and our "3D mesh releasing" protocol were applied. The primary outcome was the improvement measured in range of motion (ROM) of the relevant joint before all intervention and 6 months after the last treatment.

RESULT

From November 2016 to January 2018, 11 joints of 10 cases were treated by the fractional CO₂ laser. Patients went through 2.27 (standard deviation [SD] 1.42, 1-5) sessions. The average progress of ROM before and 6 months after all treatments was 19.13° (SD 10.25, P < 0.02). In six cases, we recorded that there was an 8.53° (SD 5.81, P < 0.02) of increase in ROM immediately after the laser session, and the average improvement reached up to 13.58° (SD 8.15, P < 0.02) after 2-3 months during the next follow-up.

CONCLUSION

The fractional CO₂ laser could achieve functional improvement in contracture scars and it maintained its effect for at least 6 months. The "3D Mesh Releasing" protocol would help to standardize the treatment procedure. This modality has minimal-invasiveness and potentially could become a supplement to the current treatment choices for mild contracture scars. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Mitigation of Postsurgical Scars Using Lasers: A Review

Background:

Most postsurgical scars are considered esthetically and functionally acceptable. Currently, there is no definite consensus treatment for postsurgical scarring. The purpose of this review is to shed some light on the value of scar mitigation and the efficacy of different lasers employed on postsurgical wounds.

Methods:

A systematic literature review and computational analysis were conducted to identify relevant clinical articles that pertained to the use of lasers for mitigating postsurgical scars. Articles included the National Institutes of Health–National Center for Biotechnology Information–PubMed search and sources cited from relevant studies after 1995. Trials that attributed pre- and posttreatment scores of scar severity based on a verified scar evaluation scale (eg, Patient and Observer Scar Assessment Scale, Vancouver Scar Scale, Global Assessment Scale) were chosen. Clinical assessments varied for each study. To adequately assess the efficacy of the modalities, the final scaled scar appearance scores were realigned and normalized to a standard scale for unbiased comparison.

Results:

After filtering through a total of 124 studies, 14 relevant studies were isolated and thus included in the review. Studied lasers were as follows: Pulsed dye laser (PDL), carbon dioxide, diode, potassium titanyl phosphate (KTP), and erbium glass (Er-Glass) lasers.

Conclusion:

Treatment with lasers in the postsurgical wound healing phase is safe, effective, and advised in mitigation of pathologic scar formation.

Laser management of hypertrophic burn scars: a comprehensive review

Hypertrophic scars often develop following burn-related injuries. These scars can be cosmetically unappealing, but associated symptoms of pruritus, pain and restricted range of motion can impair a person’s quality of life. Laser and light therapies offer a minimally invasive, low-risk approach to treatment, with a short postoperative recovery period. As laser technology developed, studies have shown decreased scar thickness, neuropathic pain and need for surgical excision, as well as improved scar pigmentation, erythema, pliability, texture, height and pruritus. In this review, we present the evolution of laser therapy for hypertrophic burn scars, how different types of lasers work, indications, perioperative considerations and guidelines for practice management.

Fractional CO2 laser micropatterning of cell-seeded electrospun collagen scaffolds enables rete ridge formation in 3D engineered skin

Rete ridges are interdigitations of the epidermis and dermis of the skin that play multiple roles in homeostasis, including enhancing adhesion via increased contact area and acting as niches for epidermal stem cells. These structures, however, are generally absent from engineered skin (ES). To develop ES with rete ridges, human fibroblast-seeded dermal templates were treated with a fractional CO₂ laser, creating consistently spaced wells at the surface. Constructs with and without laser treatment were seeded with keratinocytes, cultured for 10 days, and grafted onto athymic mice for four weeks. Rete-ridge like structures were observed in the laser-patterned (ridged) samples at the time of grafting and were maintained in vivo. Ridged grafts displayed improved barrier function over non-lasered (flat) grafts at the time of grafting and 4 weeks post-grafting. Presence of ridges in vivo corresponded with increased keratinocyte proliferation, epidermal area, and basement membrane length. These results suggest that this method can be utilized to develop engineered skin grafts with rete ridges, that the ridge pattern is stable for at least 4 weeks post-grafting, and that the presence of these ridges enhances epidermal proliferation and establishment of barrier function. STATEMENT OF SIGNIFICANCE: Rete ridges play a role in epidermal homeostasis, enhance epidermal-dermal adhesion and act as niches for epidermal stem cells. Despite their role in skin function, these structures are not directly engineered into synthetic skin. A new method to rapidly and reproducibly generate rete ridges in engineered skin was developed using fractional CO₂ laser ablation. The resulting engineered rete ridges aided in the establishment of epidermal barrier function, basement membrane protein deposition and epidermal regeneration. This new model of engineered skin with rete ridges could be utilized as an in vitro system to study epidermal stem cells, a testbed for pharmaceutical evaluation or translated for clinical use in full-thickness wound repair.

When Wounds Are Good for You: The Regenerative Capacity of Fractional Resurfacing and Potential Utility in Chronic Wound Prevention

Significance: Fractional resurfacing involves producing arrays of microinjuries on the skin, by thermal or mechanical means, to trigger tissue regeneration. Originally developed for cosmetic enhancement, fractional resurfacing induces a broad array of improvements in the structural and functional qualities of the treated skin and is especially effective at returning defective skin to a more normal state. In addition to fascinating questions about the nature of this remarkable regenerative capacity, there may be potential utility in ulcer prevention by halting or even reversing the progressive decline in overall skin quality that usually precedes chronic wound development. Recent Advances: Photoaging and scarring are the two skin defects most commonly treated by fractional resurfacing, and the treatment produces profound and long-lasting improvements in skin quality, both clinically and at the cellular/histologic level. Chronic wounds usually occur in skin that is compromised by various pathologic factors, and many of the defects found in this ulcer-prone skin are similar to those that have seen improvements after fractional resurfacing. Critical Issues: The mechanisms responsible for the regenerative capacity of fractional resurfacing are mostly unknown, as is how ulcer-prone skin, which is usually afflicted by stressors external to the skin tissue itself, would respond to fractional resurfacing. Future Directions: Better understanding of the cellular and molecular mechanisms underlying the unique healing response to fractional resurfacing could reveal fundamental information about adult tissue regeneration, lead to improvements in current applications, as well as new therapies in other pathologic conditions.

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.

Overview on the Evolution of Laser Welding of Vascular and Nervous Tissues

Laser welding presents a core position in the health sector. This process has had an outstanding impact on the surgical procedures from many medical areas, such as on vascular and nervous surgeries. The aim of the present research is to present an overview on the evolution of laser welding of vascular and nervous tissues. These surgeries present many advantages, such as an absence of foreign-body reactions and aneurysms and good tensile strengths. However, despite the sutureless nature of the process, complementary sutures have been applied to support the procedure success. An important concern in vascular and nervous laser welding is the thermal damage. The development of temperature-controlled feedback systems has reduced this concern with a very precise control of the laser parameters. The bonding strength of vascular and nerve laser welds can be enhanced with the application of solder solutions, bonding materials, and laser-activated dyes. Alternative techniques to laser welding, such as photochemical tissue bonding and electrosurgical high-frequency technologies, have also been tested for vascular and nervous repairs.

Beneath the Surface: A Review of Laser Remodeling of Hypertrophic Scars and Burns

Significance: Hypertrophic scars, keloids, and burn injuries of the skin have a significant impact on patients' lives and impact the health care system tremendously. Treating skin wounds and lesions can be challenging, with a variety of choices available for treatment. Scar and burn managements range from invasive, surgical options such as scar excision to less invasive, nonsurgical alternatives such as laser therapy or topical drug application. Recent Advances: Laser treatment has become increasingly popular, with a growing body of research supporting its use for scars and burns. Numerous methods are available for the treatment of these skin diseases, including different nonsurgical laser therapies. Critical Issues: To date, the optimal treatment method for scars, keloids, and burn injuries of the skin has not yet been established, although it is an area of increasing clinical concern. Future Directions: This review provides an updated summary of the treatment of scars and burn wounds of the skin using different laser treatments, including the most recent technologies. It addresses their indications, mechanisms of action, differences, efficacies, and complications.

[The role of CO2-laser in scarring management]

AIM

To assess the role of CO2-laser in treatment of various scars and to determine the indications for its application.

PATIENTS AND METHODS

It has been carried out a prospective analysis of treatment of 218 patients with scars of different duration, locations and anatomic areas with the use of CO2-laser for the period 2011-2017. POSAS scale and sonography were used for analysis.

RESULTS

1. Laser therapy is not effective for scarring-related functional defects (contractures, ectropion, microstomia), when surgery is indicated. 2. The outcomes of treatment (both surgical and laser) depend on the time of existence of the scars rather their cause and anatomical region. 3. Laser therapy is not effective enough for formed scars existing over 12 months. 4. Laser therapy is effective for immature scars, especially indicated for cicatricial deformation when the aesthetics cannot be repaired with traditional surgery.

CONCLUSION

Application of CO2-laser in scars treatment with regard to its real efficiency determines the effectiveness of therapy.

Treatment Strategies for Hypopigmentation in the Context of Burn Hypertrophic Scars

Dyspigmentation in burn scars can contribute to the development of psychosocial complications after injury and can be detrimental to social reintegration and quality of life for burn survivors. Although treatments for skin lightening to treat hyperpigmentation have been well reviewed in the literature, skin-darkening strategies to treat hypopigmentation have not. The following potential treatment options in the context of burn hypertrophic scar will be discussed: use of the melanocyte-keratinocyte transplantation procedure, use of ectopic synthetic analogues of alpha-melanocyte stimulating hormone to initiate melanogenesis, and use of FK506 to induce melanogenesis. A proposed future direction of research in laser-assisted drug delivery of inducers of local melanin production, with the hope of developing a targeted, effective approach to dyspigmentation in hypertrophic scar is also discussed.

Comparative evaluations of hypertrophic scar formation in in vivo models

BACKGROUND AND OBJECTIVE

Hypertrophic scar (HTS) results from a connective tissue reaction to trauma, inflammation, surgery, or burn on skin. In spite of various techniques for wound generation, the degree of scar in animal models after healing is still unpredictable and less reproducible. The objective of the current study was to identify the appropriate method to create the maximal HTS tissue in a reliable manner by comparing three different methods in vivo.

MATERIALS AND METHODS

A 27 ICR mice were tested for the in vivo evaluations. Three different methods were applied to develop wounds on the back of each mice for quantitative evaluations on collagen formation: Group 1 (thermal burn), Group 2 (chemical burn), and Group 3 (physical punch). After injury, each lesion was photographed to examine physical variations in the wound areas. Histological analysis was conducted on days 0, 7, and 28 to assess the extent of the injury in the tissue and to quantitatively compare the amount of collagen formation after wound healing.

RESULTS

Compared with Groups 1 and 3, Group 2 demonstrated the largest wound area that gradually decreased with healing time. However, the minimal axial damage (along tissue depth) occurred to Group 2 at day 0 (183.7 ± 28.9, 38.1 ± 9.2, and 296.0 ± 81.7 µm for Groups 1, 2, and 3, respectively). After 28 days, all the groups showed the complete healing and accompanied a significant increase in the number of fibroblast and collagen generation with well-oriented and denser collagen fibers, in comparison with normal skin. Group 2 yielded twice thicker skin (both epidermis and dermis) than the other groups (970.8 ± 108.8 µm for Group 2 vs. 381.5 ± 30.8 µm for Group 1 and 442.9 ± 56.3 µm for Group 3; P < 0.001).

CONCLUSION

The proposed chemical burn can be the optimal method to create collagenous scar tissue in the mouse model. Further in vivo investigations with rat models will be performed to validate the current technique for laser scar treatment in terms of reliability and immunohistochemical responses. Lasers Surg. Med. 9999:XX-XX, 2017. © 2017 Wiley Periodicals, Inc.