The efficacy of adipose stem cell-derived exosomes in hair regeneration based on a preclinical and clinical study.

BACKGROUND: Androgenetic alopecia (AGA) is a prevalent hair loss disorder with psychological repercussions. Traditional treatments have limitations, leading to the exploration of regenerative therapies such as exosomes derived from adipose tissue stem cells (ASC-Exosomes). METHODS: First, using human hair follicle (HF) dermal papilla cells (hDPCs) treated with ASC-Exosomes, ALP, VCAN, ß-catenin, and LEF-1 levels with RT-PCR and p-GSK3ß, GSK3ß, ß-catenin, ALP, and ß-actin levels with western blot analysis were assessed. Hair shaft elongation test and assay for ALP, Ki-67, and ß-catenin were done using human HF organ culture. Patients with AGA had ASC-Exosomes treatment and were evaluated for hair counts, photographic assessments, subjective satisfaction, and safety profiles. RESULTS: ASC-Exosomes impact hDPCs, increasing proliferation and the upregulation of hair growth-related genes, including ALP, VCAN, ß-catenin, and LEF-1. The Wnt/ß-catenin pathway was activated, indicating their role in promoting hair growth. ASC-Exosomes also promoted hair shaft elongation and ALP activity, suggesting a potential for hair regeneration. Thirty participants with AGA enrolled and treated over 24 weeks. The subjects experienced a significant increase in total hair density, improved global photographic assessments, and reported higher subjective satisfaction without severe adverse reactions. CONCLUSION: This research contributes to the growing body of evidence supporting the use of exosomes in hair loss treatment, offering a safe and effective alternative for individuals with AGA.

Parallelized Particle Swarm Optimization on FPGA for Realtime Ballistic Target Tracking.

This paper addresses the problem of tracking a high-speed ballistic target in real time. Particle swarm optimization (PSO) can be a solution to overcome the motion of the ballistic target and the nonlinearity of the measurement model. However, in general, particle swarm optimization requires a great deal of computation time, so it is difficult to apply to realtime systems. In this paper, we propose a parallelized particle swarm optimization technique using field-programmable gate array (FPGA) to be accelerated for realtime ballistic target tracking. The realtime performance of the proposed method has been tested and analyzed on a well-known heterogeneous processing system with a field-programmable gate array. The proposed parallelized particle swarm optimization was successfully conducted on the heterogeneous processing system and produced similar tracking results. Also, compared to conventional particle swarm optimization, which is based on the only central processing unit, the computation time is significantly reduced by up to 3.89×.

Efficacy of combined treatment with human adipose tissue stem cell-derived exosome-containing solution and microneedling for facial skin aging: A 12-week prospective, randomized, split-face study.

BACKGROUND: Studies have reported promising results of mesenchymal stem cell therapies for skin aging. However, in the use of mesenchymal stem cells, some drawbacks including rarely possible tumorigenicity and low engraftment rates have limited their widespread clinical use. Adipose tissue stem cell-derived exosomes (ASCEs) are emerging as effective cell-free therapeutic agents. AIMS: It was evaluated the clinical efficacy of combining the application of human ASCE-containing solution (HACS) with microneedling to treat facial skin aging. METHODS: A 12-week, prospective, randomized, split-face, comparative study was conducted. Twenty-eight individuals underwent three treatment sessions separated by 3-week intervals and were followed up for 6 weeks after the last session. At each treatment session, HACS and microneedling were administered to one side of the face, and normal saline solution and microneedling were administered to the other side as a control. RESULTS: The Global Aesthetic Improvement Scale score was significantly higher on the HACS-treated side than on the control side at the final follow-up visit (p = 0.005). Objective measurements obtained by different devices including PRIMOS Premium, Cutometer MPA 580, Corneometer CM 825, and Mark-Vu confirmed greater clinical improvements in skin wrinkles, elasticity, hydration, and pigmentation on the HACS-treated side than on the control side. The results of the histopathological evaluation were consistent with the clinical findings. No serious adverse events were observed. CONCLUSIONS: These findings demonstrate that combined treatment using HACS and microneedling is effective and safe for treating facial skin aging.

Exosomes derived from human adipose tissue-derived mesenchymal stem cells for the treatment of dupilumab-related facial redness in patients with atopic dermatitis: A report of two cases.

BACKGROUND: Atopic dermatitis is a chronic, pruritic, and inflammatory dermatosis that affects approximately 20% of children and 10% of adults worldwide. Dupilumab facial redness is gaining attention as additional cases are coming to light in the medical literature. OBJECTIVES AND METHODS: Exosomes are nano-sized vesicles that are constantly released by almost all cells. They can travel between cells and transport their cargo (lipids, proteins, and nucleic acids), making them a possible cell-free therapeutic option for various diseases. Herein, we investigated whether topical application of human adipose tissue-derived mesenchymal stem cell-derived exosomes could reduce dupilumab facial redness in patients with severe atopic dermatitis. RESULTS: Two patients with atopic dermatitis and refractory dupilumab facial redness were successfully treated with electroporation-assisted topical application of human adipose tissue-derived mesenchymal stem cell-derived exosomes. Six repeated sessions of treatment, with an interval of 1 week between each session, led to marked improvement in erythematous facial lesions. CONCLUSIONS: We suggest that human adipose tissue-derived mesenchymal stem cell-derived exosomes may serve as an effective agent in the management of dupilumab facial redness. However, further controlled studies with a larger number of patients are necessary to confirm the efficacy and safety of this agent, as well as the optimal treatment protocol.

Tightening and Reduction of Unwanted Submental Fat Using Triple-Layer High-Intensity Focused Ultrasound: Clinical and 3-Dimensional Imaging Analysis.

BACKGROUND: Unwanted submental fat (SMF) is aesthetically unappealing, but methods of reduction are either invasive or lack evidence of their use. OBJECTIVE: The authors sought to evaluate the safety and efficacy of a novel triple-layer high-intensity focused ultrasound (HIFU) regimen for SMF reduction. METHODS: Forty Korean subjects with moderate/severe SMF were evaluated after receiving a session of triple-layer HIFU treatments (using 3.0-, 4.5-, and 6.0-mm focusing transducers). The objective evaluation based on the 5-point Clinician-Reported Submental Fat Rating Scale (CR-SMFRS) and patients' satisfaction based on the 7-point Subject Self-Rating Scale (SSRS) were determined 8 weeks after treatment. Three-dimensional image analysis was also performed. RESULTS: At the follow-up visit, the proportion of treatment responders defined as subjects with ≥1-point improvement in CR-SMFRS was 62.5%, and the proportion of patients satisfied with appearance of their face and chin (score ≥4 on the SSRS) was 67.5% of the total patients. The results of 3-dimensional analysis were consistent with clinical observations. Only mild and transient side effects were observed for some patients with no serious adverse effects. CONCLUSION: The triple-layer HIFU regimen including the novel 6.0-mm transducer has benefits for tightening and rejuvenation of the area with unwanted SMF, showing reasonable safety profiles.

Combination Treatment with Human Adipose Tissue Stem Cell-derived Exosomes and Fractional CO2 Laser for Acne Scars: A 12-week Prospective, Double-blind, Randomized, Split-face Study.

A variety of applications of human adipose tissue stem cell-derived exosomes have been suggested as novel cell-free therapeutic strategies in the regenerative and aesthetic medical fields. This study evaluated the clinical efficacy and safety of adipose tissue stem cell-derived exosomes as an adjuvant therapy after application of fractional CO2 laser for acne scars. A 12-week prospective, double-blind, randomized, split-face trial was performed. A total of 25 patients received 3 consecutive treatment sessions of fractional CO2 laser to the whole face, with a follow-up evaluation. Post-laser treatment regimens were applied; for each patient, one side of the face was treated with adipose tissue stem cell-derived exosomes gel and the other side was treated with control gel. Adipose tissue stem cell-derived exosomes-treated sides had achieved a significantly greater improvement than the control sides at the final follow-up visit (percentage reduction in échelle d'évaluation clinique des cicatrices d'acné scores: 32.5 vs 19.9%, p < 0.01). Treatment-related erythema was milder, and post-treatment downtime was shorter on the applications of human adipose tissue stem cell-derived exosomes-treated side. In conclusion, the combined use of this novel material with resurfacing devices would provide synergistic effects on both the efficacy and safety of atrophic acne scar treatments.

Mesenchymal Stem/Stromal Cell-Derived Exosomes for Immunomodulatory Therapeutics and Skin Regeneration.

Exosomes are nano-sized vesicles that serve as mediators for cell-to-cell communication. With their unique nucleic acids, proteins, and lipids cargo compositions that reflect the characteristics of producer cells, exosomes can be utilized as cell-free therapeutics. Among exosomes derived from various cellular origins, mesenchymal stem cell-derived exosomes (MSC-exosomes) have gained great attention due to their immunomodulatory and regenerative functions. Indeed, many studies have shown anti-inflammatory, anti-aging and wound healing effects of MSC-exosomes in various in vitro and in vivo models. In addition, recent advances in the field of exosome biology have enabled development of specific guidelines and quality control methods, which will ultimately lead to clinical application of exosomes. This review highlights recent studies that investigate therapeutic potential of MSC-exosomes and relevant mode of actions for skin diseases, as well as quality control measures required for development of exosome-derived therapeutics.

Toxicological evaluation of exosomes derived from human adipose tissue-derived mesenchymal stem/stromal cells.

Several studies report that the therapeutic mechanism of action of mesenchymal stem/stromal cells (MSCs) is mainly mediated by paracrine factors that are released from MSCs such as exosomes. Exosomes are nano-sized extracellular vesicles that are transferred to target cells for cell-to-cell communication. Although MSC-derived exosomes (MSC-exosomes) are suggested as novel cell-free therapeutics for various human diseases, evaluation studies for the safety and toxicity of MSC-exosomes are limited. The purpose of our study was to evaluate the toxicological profile, including skin sensitization, photosensitization, eye and skin irritation, and acute oral toxicity using exosomes derived from human adipose tissue-derived MSCs (ASC-exosomes) in accordance with the OECD guidelines and the principles of Good Laboratory Practice. The ASC-exosomes were classified as a potential non-sensitizer in the skin sensitization test, UN GHS no category in the eye irritation test, and as a skin non-irritant in the skin irritation test, and did not induce any toxicity in the phototoxicity test or in acute oral toxicity testing. Our findings are the first to suggest that ASC-exosomes are safe for use as a topical treatment, with no adverse effects in toxicological testing, and have potential application as a therapeutic agent, cosmetic ingredient, or for other biological uses.

Exosomes from Human Adipose Tissue-Derived Mesenchymal Stem Cells Promote Epidermal Barrier Repair by Inducing de Novo Synthesis of Ceramides in Atopic Dermatitis.

Atopic dermatitis (AD) is a multifactorial, heterogeneous disease associated with epidermal barrier disruption and intense systemic inflammation. Previously, we showed that exosomes derived from human adipose tissue-derived mesenchymal stem cells (ASC-exosomes) attenuate AD-like symptoms by reducing multiple inflammatory cytokine levels. Here, we investigated ASC-exosomes' effects on skin barrier restoration by analyzing protein and lipid contents. We found that subcutaneous injection of ASC-exosomes in an oxazolone-induced dermatitis model remarkably reduced trans-epidermal water loss, while enhancing stratum corneum (SC) hydration and markedly decreasing the levels of inflammatory cytokines such as IL-4, IL-5, IL-13, TNF-α, IFN-γ, IL-17, and TSLP, all in a dose-dependent manner. Interestingly, ASC-exosomes induced the production of ceramides and dihydroceramides. Electron microscopic analysis revealed enhanced epidermal lamellar bodies and formation of lamellar layer at the interface of the SC and stratum granulosum with ASC-exosomes treatment. Deep RNA sequencing analysis of skin lesions demonstrated that ASC-exosomes restores the expression of genes involved in skin barrier, lipid metabolism, cell cycle, and inflammatory response in the diseased area. Collectively, our results suggest that ASC-exosomes effectively restore epidermal barrier functions in AD by facilitating the de novo synthesis of ceramides, resulting in a promising cell-free therapeutic option for treating AD.

Combined treatment of recalcitrant papulopustular rosacea involving pulsed dye laser and fractional microneedling radiofrequency with low-dose isotretinoin.

BACKGROUND: While a considerable number of cases with papulopustular rosacea (PPR) are resistant to conventional medications, therapeutic regimens are not currently established. Pulsed dye laser (PDL) and fractional microneedling radiofrequency (FMR) have previously demonstrated satisfactory results for anti-angiogenesis, anti-inflammation, and dermal remodeling. AIMS: To evaluate the efficacy and safety of novel combination regimen with low-dose oral isotretinoin, PDL, and FMR in the treatment of recalcitrant PPR. PATIENTS AND METHODS: A retrospective study was undertaken for recalcitrant PPR patients to evaluate the clinical course of novel combination regimen. Twenty-five PPR patients who had failed in previous first-line therapies were enrolled. They were treated with three sessions of PDL and FMR consecutively at 4-week intervals, maintaining daily oral administration of 10 mg isotretinoin for 8 weeks. Objective assessments, erythema index measurement, and patients' subjective satisfaction were evaluated at each visit and 16 weeks after the final treatment. RESULTS: At the final follow-up visit, the number of papules and pustules decreased by 71%, and erythema index by 54% compared with baseline (P < 0.05 for both). Physician's global assessment based on rosacea severity score and patients' subjective assessments paralleled with these results. No serious side effect was observed during whole study periods. CONCLUSION: This novel combination regimen demonstrated satisfactory efficacy with reasonable safety profiles for the treatment of recalcitrant PPR.

A Novel Combined Light-Based Treatment of Acne Vulgaris With 1,450-nm Diode Laser and 450-nm Blue Light.

BACKGROUND: Nonablative 1,450-nm diode laser (DL) and visible blue light (BL) have been effectively used for acne with superior safety profiles. OBJECTIVE: To evaluate synergistic effects of sequential DL and BL application for acne. METHODS: A 20-week, randomized split-face study was conducted to compare clinical courses between 2 facial sides either receiving sequential application of DL and BL or BL alone in 24 patients with mild to moderate facial acne vulgaris. Patients were scheduled to receive 3 consecutive sessions at 4-week intervals. Objective assessments, including revised Leeds grades, lesion counts, and sebum output measurements, and patients' subjective satisfaction were investigated. RESULTS: Both combination and BL sides demonstrated steady improvement of inflammatory acne lesions with 62.3% and 35.2% decreases at the 12-week follow-up visit compared with baseline respectively. For noninflammatory lesions and seborrhea, only combination regimen demonstrated improvement. Patients' subjective assessments paralleled objective findings. For safety profiles, no severe adverse effect was observed on both sides, and mild symptoms resolved spontaneously within a day. CONCLUSION: The combination regimen demonstrated synergistic efficacies for acne and seborrhea, with satisfactory safety profiles. Therefore, a few sessions of these light-based applications would be a viable option for acne treatments.

Clinical Evaluations of a Novel Thread Lifting Regimen Using Barbed Polyglyconate Suture for Facial Rejuvenation: Analysis Using a 3-Dimensional Imaging System.

BACKGROUND: Thread lifting with absorbable sutures has recently gained prominence for rejuvenating ptotic and sagging soft tissues in aging face. A barbed, delayed absorbable polyglyconate monofilament shows significantly high tensile loads with superior flexibility and elasticity. OBJECTIVE: To evaluate the safety and efficacy of novel thread lifting regimen with barbed polyglyconate suture for counteracting the descent and laxity of the aging face. METHODS: A retrospective chart review was conducted for 25 Korean patients with mild to moderate facial skin laxity receiving thread lifting procedures using barbed polyglyconate suture. Dermatologists' objective assessments using a 5-point Global Aesthetic Improvement Scale (GAIS), 3D imaging system, and subjective satisfaction were recorded at baseline and 4 months after treatments. RESULTS: In most patients (84%), GAIS scores were more than score 3 ("improved"), with 40% of score 4 ("much improved") and 24% of score 5 ("excellent") at the follow-up point. Subjective assessments paralleled these patterns. Three-dimensional analysis quantitatively showed volume migration of low face upward, clinically interpreted as facial lifting. No serious adverse effect was observed. CONCLUSION: This novel thread lifting procedure using barbed polyglyconate suture is a safe and effective method for tightening and lifting for aging face with mild to moderate face sagging.

Combined treatment of melasma involving low-fluence Q-switched Nd:YAG laser and fractional microneedling radiofrequency.

Background: While low fluence Q-switched Nd:YAG laser (QSNY) demonstrates moderate efficacy in the melasma treatment for darker skin types, this single regimen still remains challenges. Fractional microneedling radiofrequency (FMR) is known to enhance dermal microenvironment, possibly offsetting pathogenic factors of melasma aggravation. Objectives: To compare the effectiveness and safety of combination therapy using low-fluence QSNY and FRM with QSNY monotherapy in Asian melasma patients Methods: A retrospective study was undertaken for melasma patients to compare clinical data between 56 patients receiving combination regimen and 58 patients with QSNY only. For the 10 sessions at 1-week intervals, combination group was consecutively treated with QSNY and FRM, while QS toning group with QSNY alone. Two blinded dermatologists evaluated the efficacy based on modified Melasma Area and Severity Index (mMASI) and the physician's global assessment (PGA) at baseline and 3 months after the final treatment. Treatment-related side effects and disease course was recorded in detail. Results: Combination group demonstrated better efficacy compared with QS toning only group. Both median degrees of mMASI decrease (2.9 vs. 1.8) and proportions of PGA achieving better than 'good' grades (68% vs. 54%) showed superior efficacies of combination group. No significant difference was observed for treatment-related side effects between two groups, while the prevalence of mottle hypopigmentation and rebound hyperpigmentation was higher in QSNY only group. Conclusion: A novel dual mode of low-fluence QSNY and FRM represents a safe and effective treatment for melasma in Asian melasma patients.

Expression of inflammatory and fibrogenetic markers in acne hypertrophic scar formation: focusing on role of TGF-ß and IGF-1R.

Acne vulgaris is a universal skin disease and it may leave a scar when the original skin lesion disappears. These scars can cause cosmetic problems and psychological burden, leading to poor quality of life of patients. Acne scars are classified into atrophic scars and hypertrophic scars. As most of the acne scars are atrophic, many studies have been conducted focusing on the treatment of atrophic lesions. This study was conducted to investigate the underlying pathogenesis of acne hypertrophic scars by identifying roles of fibrogenetic and inflammatory markers. Skin biopsy samples were obtained from hypertrophic scars of face and back and from adjacent normal tissues as control group. Some samples from back were immature hypertrophic scars and the other samples were in mature stages. Immunohistochemistry staining and quantitative PCR were performed for fibrogenetic and inflammatory markers. Both in mature and immature hypertrophic scars, vimentin and α-SMA were increased. Production of TGF-ß3 protein as well as transcription of TGF-ß3 was also significantly elevated. In contrast, expression of TGF-ß1 showed no increase. Instead, expression levels of SMAD2 and SMAD4 were increased. Elevations of CD45RO, TNF-α and IL-4 and reduction of IL-10 were observed. In immature hypertrophic scars, IGF-1R and insulin-degrading enzyme expression were increased. Increased apoptosis was observed in immature stages of hypertrophic scars but not in mature stages. Elevations of TGF-ß3, SMAD2 and SMAD4 in hypertrophic scars and increase of IGF-1R in immature stages may give some clues for acne hypertrophic scar formation.

Comparison of novel dual mode vs conventional single pass of a 1450-nm diode laser in the treatment of acne vulgaris for Korean patients: A 20-week prospective, randomized, split-face study.

BACKGROUND: Although a 1450-nm diode laser has been shown to be effective for acne, the conventional high-energy stamp-only regimen is often associated with pain and hyperpigmentation, especially for dark-skinned individuals. AIMS: To evaluate whether the novel dual regimen has clinical advantages for acne treatments compared with conventional regimen in Asian patients. PATIENTS AND METHODS: Twenty-four Korean patients with facial acne were treated with a 1450-nm diode laser through a 20-week, randomized, split-face study. The patients were treated with three consecutive sessions at 4-week intervals. One half of the face received a dual regimen consisting of low-fluence stamping mode (5-6 J/cm2 ) for inflammatory acne lesions only, followed by 4-5 passes of moving mode for the full face. The other side received a single-pass treatment of conventional high-fluence stamp mode (14-15 J/cm2 ). Evaluations for acne, sebum secretion measurements, and safety profiles were performed. RESULTS: At the final 12-week follow-up evaluations, the dual-mode side demonstrated better improvements in both inflammatory and noninflammatory lesion counts, acne severity assessments, and reduction in sebum secretion compared with stamp-only side. Subjective satisfaction for the improvement for acne, seborrhea, and texture correlated well with objective assessments. In addition, degrees of pain and treatment-related side effects were remarkably decreased in the novel dual mode. CONCLUSION: This novel dual regimen of the 1450-nm laser demonstrated improved efficacies for acne and seborrhea with satisfactory safety profiles. Therefore, this regimen would be a viable option for acne treatments either as monotherapy or as combination therapy.

Epidemiological and clinical features of rosacea in Korea: A multicenter cross-sectional study.

Rosacea is a common chronic inflammatory skin condition. Although several epidemiological and etiologic studies with large sample sizes have been conducted on Caucasians, such data regarding Asian populations are lacking. A total of 580 patients diagnosed with rosacea were enrolled from October 2014 to February 2015 at 14 general hospitals. Questionnaires, including the standard classification and grading system, were used for evaluation. The average age of the patients was 47.9 years. While 83.8% of patients revealed a single subtype, 16.2% of patients revealed mixed subtypes showing two or more subtypes simultaneously. Erythematotelangiectatic rosacea (ETR) was the most prevalent subtype. ETR combined with papulopustular rosacea showed the highest proportion in the mixed subtype group. Mild severity was revealed in 71.9% of patients. The most common aggravating factor was emotional changes (51.7%), followed by stress (48.4%). Approximately half of the patients (47.4%) showed relatively low awareness of rosacea. By identifying the epidemiological and etiologic features in Korea, we can suggest valuable clinical avenues for research, education and awareness among rosacea patients.

Combined treatment for skin laxity of the aging face with monopolar radiofrequency and intense focused ultrasound in Korean subjects.

BACKGROUND: Although various minimal invasive approaches are available for aging skin laxity, they alone may not lead to notably satisfactory results. OBJECTIVE: To evaluate the effectiveness and safety of combination regimen with monopolar radiofrequency (MRF) and intense-focused ultrasound (IFUS) in facial lifting and tightening. METHODS: Twenty-two Korean participants with aging face received a sequential single session of MRF and IFUS treatment. Objective and subjective assessments for improvement were performed at the 20-week post-treatment. Safety profiles were also recorded, and skin biopsies were taken at baseline and follow-up visit. RESULTS: Based on the objective assessment for the overall facial skin tightening and laxity, 19 patients (90%) demonstrated "moderate" or better improvements (more than 25%) compared with baseline. Specifically, improvements of skin laxity and sagging, and droopy jaw line were more noticeable compared with that of superficial skin texture (P < 0.05). Subjective satisfactions were generally consistent with objective findings, and no serious adverse effect was observed. Histologic evaluation showed increased dermal collagen fibers throughout the dermis after treatments (P < 0.05). CONCLUSION: Combination treatment of MRF and IFUS has cumulative benefits for skin lifting and tightening with satisfactory safety profiles in Asian subjects.

Combination of platelet rich plasma in fractional carbon dioxide laser treatment increased clinical efficacy of for acne scar by enhancement of collagen production and modulation of laser-induced inflammation.

BACKGROUND: Platelet-rich plasma (PRP) which contains large amounts of growth factors has been tried to enhance therapeutic efficacy of laser treatment for acne scar with unknown underlying mechanism. OBJECTIVES: The present study was conducted to investigate the molecular mechanism of increased clinical efficacy of PRP when combined with fractional laser treatment for treating acne scars. METHODS: Subjects with mild to moderate acne scars were treated with two sessions of fractional CO2 laser therapy given with and without co-administration of PRP. Skin biopsy specimens were obtained at baseline, 1, 3, 7, and 28 days for investigation of molecular profiles associated with skin changes produced by laser plus PRP treatment. RESULTS: The PRP treatment increased clinical efficacy with decreased severity of adverse effects such as erythema, swelling and oozing. Productions of TGFß1 and TGFß3 proteins were more highly elevated on the PRP-treated side of the face compared to the control side at day 28. Furthermore, PRP-treated side showed significant increase of c-myc, TIMP, and HGF expression. Experimental fibroblast culture model was also used. PRP administration after laser irradiation increased expressions of p-Akt, TGFß1, TGFß3, ß-catenin, collagen 1, and collagen 3 in both dose-dependent and time dependent manners in fibroblast. Moreover, we acquired clinical and histological data through randomized control clinical trial. CONCLUSION: Taken together with human study results combined with the data from cell experiments we suggest that PRP treatment increased fibrogenetic molecules induced by fractional CO2 laser, which have association with clinical effect. Lasers Surg. Med. 50:302-310, 2018. © 2017 Wiley Periodicals, Inc.

Histologic analyses on the response of the skin to 1,927-nm fractional thulium fiber laser treatment.

BACKGROUND: The histologic responses to varied parameters of 1,927-nm fractional thulium fiber laser treatment have not yet been sufficiently elucidated. OBJECTIVE: This study sought to evaluate histologic changes immediately after 1,927-nm fractional thulium fiber laser session at various parameters. METHODS: The dorsal skin of Yucatan mini-pig was treated with 1,927-nm fractional thulium fiber laser at varied parameters, with or without skin drying. The immediate histologic changes were evaluated to determine the effects of varying laser parameters on the width and the depth of treated zones. RESULTS: The increase in the level of pulse energy widened the area of epidermal changes in the low power level, but increased the dermal penetration depth in the high power level. As the pulse energy level increased, the increase in the power level under the given pulse energy level more evidently made dermal penetration deeper and the treatment area smaller. Skin drying did not show significant effects on epidermal changes, but evidently increased the depth of dermal denaturation under both high and low levels of pulse energy. CONCLUSION: These results may provide important information to establish treatment parameters of the 1,927-nm fractional thulium fiber laser for various skin conditions.