Efficacy and safety of 1565‐nm nonablative fractional laser combined with mucopolysaccharide polysulfate cream for erythematous acne scars

To evaluate the efficacy and safety of 1565‐nm nonablative fractional laser (NAFL) combined with mucopolysaccharide polysulfate (MPS) cream in the treatment of erythematous acne scars.


| INTRODUC TI ON
As a disfiguring skin disease, acne scarring occurs in 43% of acne patients and seriously affects their appearance, quality of life, and psychological health. 1 Acne scarring develops due to excessive or incomplete repair of collagen fibers and elastic fibers during the healing process of inflammatory skin lesions; the pathogenesis may be related to genetics, infection with Propionibacterium acnes, and prolonged inflammatory response. 2,3Acne scarring can present in a variety of manifestations; it has diverse effective treatment alternatives such as lasers, chemical peels, needling, radiofrequency, platelet-rich plasma, filler therapy, and surgical treatment. 4Erythematous acne scar is a type of acne scar classified according to scar color, which is in the early stages of scar development and often suggests the presence of inflammation; it has been attributed occasionally to scar-associated erythema (SAE) in some literature; the effective treatment options include nonablative fractional laser (NAFL), intense pulsed light (IPL), potassium titanyl phosphate (KTP, also known as frequency-doubled Nd: YAG), and pulsed dye laser (PDL). 5,68][9] Based on the principle of fractional photothermolysis, the NAFL promotes collagen regeneration and microvascular destruction of vessels by selectively forming microthermal zones in the dermis.
Nevertheless, multiple session treatments are required, and results are often clinically unsatisfactory. 61][12] As a topical drug, MPS cream has been in widespread clinical practice for decades.It is often used alone or in combination with other options to treat skin diseases such as superficial phlebitis, pressure sores, postoperative edema and ecchymosis, skin contusions, and non-exudative eczema. 10,11,13,14Furthermore, it has shown some potential in preventing and treating scars. 15,16rly treatment of scars can control their further development and shorten the immature phase of scars.Combination therapy using multiple approaches with different mechanisms of action may increase the efficacy of scars.Therefore, in order to improve acne scars effectively and safely in a short time, in this study, 1565-nm NAFL and MPS cream were combined to explore the efficacy and safety of erythematous acne scarring.Both sides of the face of all subjects were treated with 1565-nm NAFL (Intense Pulsed Light and Laser System, M22 ResurFX, Lumenis Ltd).Subjects were treated in two sessions at 4-week intervals.A topical anesthetic cream containing prilocaine 2.5% and lidocaine 2.5% (Compound Lidocaine Cream, Tongfang Pharmaceutical Group Co., Ltd) was applied on the whole face under occlusion for 45-60 min before each laser treatment.Both sides of the face were processed with standardized parameters as follows: two passes for each 1565-nm NAFL treatment in all subjects were carried out by the same dermatologist, the initial pass of laser treatment was applied for the entire lesion area with the 8-mm square spot size, a density of 150-200 spots/ cm 2 , an energy of 40-50 mJ/cm 2 , and no more than 10% overlap of the spot, then the second pass was focused on acne scars with a 5-mm regular hexagonal spot size, a density of 150-200 spots/cm 2 and an energy of 70 mJ/cm 2 .A cooling medical mask was applied immediately after each laser therapy, followed by a consistent mask application for a fortnight.In addition, subjects were advised to avoid sun exposure and to use sunscreen or physical sun protection when going outside.

| ME THODS
One side of the face was randomly treated with MPS cream (Hirudoid, Mobilat Produktions GmbH), and the other side used placebo cream (Mobilat Produktions GmbH).The placebo cream was a matrix agent without MPS.The randomization was done by a simple random allocation sequence created using computer-based random number generators.The two topical creams were started after the first laser treatment and applied evenly to each side of the facial acne scars, respectively, massaging well for 2-5 min, twice daily for 8 weeks.Using the same packaging and appearance for MPS creams and placebo creams, neither the subject nor the practitioner was aware of the distribution.

| Scar assessments
Objective evaluations of acne scars improvement were conducted by using the CBS® (Multispectral dermoscope image processing workstation, CBS-2021, Wuhan Boshi Electronics Co., Ltd) and acne scars, erythematous, mucopolysaccharide polysulfate, nonablative fractional laser dermoscopy (Digital dermoscopy, FotoFinder bodystudio ATBM, FotoFinder Systems GmbH), both of which were performed by the same examiner under the same examination room, environment, and light for all subjects at baseline and after treatment.Subjects maintained the same position for each CBS® examination.The images and quantitative data on red area, red area concentration, smoothness, and pore from CBS® on both sides of the face were obtained.Regarding dermoscopy, each half of the face was divided into four quadrants and two quadrants were randomly selected using computer-based random number generators for examination at 30 times magnification.The examiner took images of one of the acne scars in each selected quadrant using equal intensity.After dermoscopic images were disordered, the quantitative acne scar area and scar redness were measured by an assessor using ImageJ software, each acne scar was measured three times, and the mean value was obtained for analysis.
The efficacy of acne scar improvement was subjectively assessed by quantitative GSS and subjects' satisfaction assessment.Two experienced dermatologists performed quantitative GSS scores based on half-face CBS® images at baseline and after treatment in a fully blinded manner.After treatment, patients assessed their degree of satisfaction with the improvement of acne scars on each side of the face using a five-point Likert scale: very satisfied (5), satisfied (4), slightly satisfied (3), dissatisfied (2), or very dissatisfied (1). 9bjects' post-laser responses including erythema and pinpoint bleeding were recorded.Other complaints such as hyperpigmentation, dryness, and secondary scars during follow-up were documented.

| Statistical analysis
Statistical analyses were performed by using SPSS version 26.0 software and GraphPad Prism version 9 software; p < 0.05 was considered statistically significant.For the quantitative data, paired Student's t-test and Wilcoxon rank sum test were performed to analyze the differences between the groups; data were expressed in mean ± SD and median (IQR).Ranked data were analyzed by using the Wilcoxon rank sum test.

| General information of the subjects
Twenty-eight subjects with erythematous acne scars, 14 females and 14 males, aged ranged from 18 to 32 years (with a mean of 23.68 ± 3.51), enrolled and completed the trial.All subjects had Fitzpatrick skin types III or IV.The median BMI was 21.20 kg/m 2 , with a range of 17.22-25.44kg/m 2 .Subjects with acne of grade 2 accounted for 85.7%.The duration of acne ranged from 0.3 to 10 years with a mean of 5.11 ± 3.45 years (Table 1).There was no significant difference in the mean quantitative GSS score at baseline on both sides of the face.

| Objective assessments of scar improvement
Compared to the baseline, a significant improvement was observed in the parameters of the red area, red area concentration, smoothness, and pore using CBS® analyses for both sides of the face after treatment (p < 0.001).Nevertheless, the side of 1565nm NAFL combined with MPS cream showed significantly better improvement in the red area, red area concentration, and smoothness (p = 0.015, p = 0.013, and p = 0.021); there was no significant difference in pore improvement between both sides of the face (Table 2; Figure 1).Dermoscopic images were quantified by ImageJ software.After treatment, the mean percentage reduction in acne scar area on the NAFL combined with MPS cream side and NAFL combined with placebo cream side was 21.52% and 10.93%, respectively, and the mean percentage reduction in acne scar redness was 6.26% and 2.87%, respectively, which showed significantly greater improvement in both scar area and scar redness on the side of 1565-nm NAFL combined with MPS cream than the other side (p = 0.005 and p = 0.041; Table 3; Figure 2).

| Physician's subjective assessment
There was no statistical difference in quantitative GSS scores between the two sides at baseline (p > 0.05).After 8-week treatment, the quantitative GSS score revealed a statistical reduction for both sides of the face (NAFL + MPS cream side: 9.4 ± 3.2 → 5.9 ± 2.9, p < 0.001; NAFL + placebo cream side: 9.2 ± 3.5 → 6.71 ± 2.9, TA B L E 1 Characteristics of the enrolled erythematous acne scars subjects.p < 0.001).However, the level of reduction was greater on the side of the face that was treated with 1565-nm NAFL combined with MPS cream (p = 0.037; Figure 3).

| Subjects' subjective assessment
The number of subjects' satisfaction evaluations indicated very satisfied or satisfied was 13 out of 28 on the 1565-nm NAFL combined with MPS cream side and 7 out of 28 on the 1565-nm NAFL combined with placebo cream side.Subjects were more satisfied with 1565-nm NAFL combined with MPS cream treatment (p = 0.048; Figure 4).

| Adverse effects
All subjects suffered from erythema with a burning sensation on both sides of the face after each 1565-nm NAFL treatment; the mean duration of the erythema was 2.84 ± 1.57 days on the NAFL combined with MPS cream side and 2.89 ± 1.76 days on the other side, with no significant difference between the two sides (p > 0.05).One subject experienced mild pinpoint bleeding on both sides of the face after the first laser treatment, which resolved spontaneously within 1 week and did not reappear after the second laser treatment.No subject reported intolerance or allergy to the cream during follow-up.

| DISCUSS ION
Acne scarring is a severe sequela of acne, which has a high incidence and affects the normal social interaction of patients.It includes atrophic scarring, hypertrophic scarring, and keloid, with atrophic scars accounting for around 75% of all cases.Local lesions tend to have a longer duration of inflammation in acne patients who are prone to scarring.Furthermore, inflammatory cell infiltration was observed in 77% of acne scars. 18Acne relapse, delay in effective medication, genetic predisposition, increased BMI, male gender, and a positive family history of severe acne have been identified as risk factors for acne scar development. 19Extensive and persistent inflammatory response of the pilosebaceous unit causes an imbalance in the expression of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs), as well as abnormal expression of transforming growth factor-β1 (TGFβ), resulting in tissue destruction and incomplete or excessive repair of dermal structures, and the process eventually leads to scar formation. 3Acne scar color can be categorized as erythematous, hyperpigmented, or hypopig- proliferation and improving epidermal barrier function.Topical heparinoids raised the levels of mRNA expression in mouse skin for proteins involved in epidermal differentiation (filaggrin and involucrin), lipid synthesis (HMGCoA and SPT1), and epidermal proliferation. 30,31In addition to the respective effects of the two treatments themselves, part of the reason for the superior efficacy of the combined therapy may be that the laser promoted drug delivery via the skin, which enhanced the penetration and absorption of MPS cream so that it could better exert its effects. 32l subjects suffered from transient facial erythema after each 1565-nm NAFL treatment.Facial erythema is a frequent side effect of NAFL therapy, and in most cases, it goes away on its own within 3 days.Additionally, NAFL normally carries minimal danger of crusting or secondary scar formation. 7Our findings revealed no statistically significant difference between the two sides in the mean erythema duration following laser treatment.On one hand, adverse events were subjectively judged by participants; however, due to the very faint color and brief duration of the erythema, the subject may not be able to appropriately measure the duration of erythema on both sides.On the other side, it could be because This study also had some limitations.First, there was a similar ethnic background among all sufferers.Second, we did not perform histopathological examinations.Thus, the histological changes of acne scars during NAFL alone or combined with MPS cream treatment remained unclear.Third, the overall number of subjects was modest, and the follow-up time was relatively short.Therefore, studies with more subjects and longer follow-up time should be conducted in the future.

| CON CLUS IONS
In conclusion, the 1565-nm NAFL shows significant benefits for erythematous acne scars, and the combined application of

An 8 -
week prospective, spilt-face, randomized controlled clinical trial was conducted in accordance with the Declaration of Helsinki.The written informed consent was signed by all subjects.Subjects were randomly assigned to receive NAFL combined with MPS cream on one side of the face, while the other side was treated with NAFL combined with placebo cream.The efficacy and safety of NAFL combined with MPS cream on acne scars were evaluated.A total of 28 Chinese subjects (14 males and 14 females) with erythematous acne scars were enrolled from June 2021 to April 2022.The size of the sample was determined based on viability considerations.Inclusion criteria were as follows: (1) age range from 18 to 45 years, (2) similar erythematous acne scars on both sides of the face newly formed within 6 months, (3) half-face quantitative global scarring grading system (GSS) score of at least 3, 17 and (4) no active acne of grade III or above (Pillsbury classification).Exclusion criteria included a history of any other treatments for facial acne scars within 6 months before inclusion, other current facial skin conditions at the sites of treatment, immunocompromised status, history of cancer, photosensitivity, and pregnant or breastfeeding status.

F I G U R E 1
Comparison of spilt-face CBS® images of four subjects with erythematous acne scars before and after treatment.(I) NAFL+ MPS cream.(II) NAFL+ Placebo cream.(A) and (C) Before treatment.(B) and (D) After 8-week treatment.(A) and (B) RGB white light imaging.(C) and (D) Imaging of an inflammation area with mixed light.NAFL, non-ablative fractional laser; MPS, mucopolysaccharide polysulfate.TA B L E 3 Spilt-face scar quantitative analysis of dermoscopic images of subjects with erythematous acne scars.
mented.Erythematous acne scar represents the early stages of scar formation and indicates the presence of inflammation.20Addressing both the redness and scars can be effective in improving the overall appearance of erythematous acne scars, which was why the combination treatment in our study, utilizing the pro-collagen regenerating effects led by NAFL and the anti-inflammatory, redness-reducing effects led by MPS cream.F I G U R E 2 Comparison of spilt-face dermoscopic images of four subjects with erythematous acne scars before and after treatment.(I) NAFL+ MPS cream.(II) NAFL+ Placebo cream.(A), (C), (E), and (G) Before treatment.(B), (D), (F), and (H) After 8-week treatment.NAFL, nonablative fractional laser; MPS, mucopolysaccharide polysulfate.NAFL can relieve acne scars by promoting collagen proliferation via the formation of controlled fractional microthermal zones.Some studies have shown the apparent efficacy of 1565-nm NAFL for the treatment of atrophic acne scars.21,22Furthermore, Gao et al.discovered that 1565-nm NAFL therapy significantly decreased the index of hemoglobin and red areas in acne vulgaris.22However, to the best of our knowledge, there has been no study on 1565-nm NAFL alone treatment for erythematous acne scars has been conducted.Our study results demonstrated that 1565-nm NAFL improved the appearance of erythematous acne scars over 8 weeks, with photographs and quantitative analysis from CBS® and dermoscopy on both sides of the face showing a significant reduction in redness and area of the scars.The therapeutic mechanism may be that the fractional microthermal columns in the dermis generated by the 1565-nm NAFL promoted collagen remodeling and simultaneously destructed part of the excess proliferating vessels.7 Therefore, the 1565-nm NAFL provided a non-specific redness-reducing effect at the same time of improving scars depth and area, ultimately achieving the goal of treating erythematous acne scars.The active ingredient of MPS cream is a heparinoid, which can permeate rapidly into the dermis and subcutaneous tissues to exert multiple effects,23 so that it has been topically used to treat vascular disorders, skin contusion, and other dermatoses.24,25Our study showed that 1565-nm NAFL combined with MPS cream had a superior efficacy than 1565-nm NAFL alone in improving erythematous acne scars after 8-week treatment, which suggested that MPS cream may be a useful adjunctive treatment for erythematous acne scars.We hypothesized that this might be related to the multiple mechanisms of MPS.First, MPS cream may reduce inflammation of acne scars.Inflammatory cell infiltration and proinflammatory cytokine mRNA expression may be inhibited by MPS cream.26Moreover, it also suppresses IL-1ß production from keratinocytes.27Second, MPS cream could repair the damaged skin tissue in acne scars by promoting dermal microcirculation, anticoagulation, and normal connective tissue regeneration action.11,13,16MPS cream can contribute to dermal microvascular stabilization and barrier integrity.28,29Finally, MPS cream might improve the appearance of acne scars by promoting epidermal F I G U R E 3 The mean quantitative GSS score change of each side evaluated from baseline to after treatment.*** p < 0.001 compared with baseline, ns p > 0.05 compared between two sides, * p < 0.05 compared between two sides.GSS, global scarring grading system; NAFL, non-ablative fractional laser; MPS, mucopolysaccharide polysulfate.F I G U R E 4 Subjects' satisfaction assessment for the improvement of acne scars using a 5-point scale (1 = very dissatisfied, 2 = dissatisfied, 3 = slightly satisfied, 4 = satisfied, and 5 = very satisfied).NAFL, non-ablative fractional laser; MPS, mucopolysaccharide polysulfate.
MPS cream only has a limited anti-inflammatory effect.One subject experienced mild pinpoint bleeding on both sides of the face after the first laser treatment, which may have been related to the excessively high laser energy.No subject reported intolerance or allergy to the cream during follow-up.This result suggested that NAFL combined with MPS cream is relatively safe in the treatment of facial acne scars.Dermoscopy is a convenient noninvasive examination device widely used in recent years, which can observe the microstructure of the epidermis and the superficial dermis through the stratum corneum.It has been widely applied in the auxiliary diagnosis and therapeutic effect judgment of a variety of skin diseases.There are several studies about dermoscopic features of acne, while few studies are on the application of dermoscopy to assess the improvement of acne scars.33Our study first employed dermoscopic quantitative data by ImageJ software to assess acne scars improvement, and the obtained results were consistent with CBS® examination and quantitative GSS scores.This reminded us that dermoscopy has the potential to be a useful tool for evaluating the dynamic efficacy of erythematous acne scars.
1565-nm NAFL and MPS cream is more effective than 1565-nm NAFL alone in the treatment of erythematous acne scars.MPS cream could be used as an adjunct to erythematous acne scars treatment with high safety.The combined application of dermoscopy and ImageJ software enables the quantitative assessment of acne scarring.
Spilt-face CBS® quantitative data analysis of subjects with erythematous acne scars before and after treatment.Note: p1, p value for comparing between the before and after treatment; p2, p value for comparing change between the two groups.