Filament coating system assists recovery of ablative fCO2 laser treatment: A split‐face clinical observation

The current nursing procedure after fractional carbon dioxide (fCO2) is complex and needs to be optimized. The present study was conducted to evaluate the assisting effect of filament coating system after fCO2 laser treatment.


| INTRODUC TI ON
Fractional carbon dioxide (fCO 2 ) laser is an excellent option for skin rejuvenation through improving skin textural irregularities. 1,2tients always suffer from some nearly (erythema, edema, crust, and pain) and long-time (hyperpigmentation) complications.It takes approximately 1 week to recover. 3 In our department, three topical ointments have been applied after fCO 2 laser for decades to accelerate wound healing and prevent inflammation and post-inflammatory hyperpigmentation: fusidic acid cream two times for 7 days, desonide cream two times for 3 days, and recombinant human epidermal growth factor (RhEGF) gel four times for 7 days.However, the nursing procedure is too complex to some patients.Therefore, more convenient methods should be demonstrated to simplify the procedure.
Filament coating system is a newly developed system.It launches virous nanofibers and forms an ultrathin membrane on the treating area.Ectoin is added to the nanofibers.It impacts on the hydration kinetics and biomechanics of human stratum corneum, and is applied as a humectant. 4The filament coating system provides a moisture environment, which is beneficial for growth factors, cytokines and chemokines, and thus stimulates cell growth and accelerates wound healing. 5Recently, the filament coating system has been clinically applied to assist recovery after some medical cosmetics, but no related studies have been demonstrated till now.Therefore, we conducted the present split-face clinical observation, in order to evaluate the efficacy, safety, and convenience of the filament coating system in assisting recovery of fCO 2 laser.

| Ethics statement
The clinical observation complied with the principles of 1975

| Included and excluded criteria
The study was performed at outpatient clinic of Department of Dermatology, The First Hospital of China Medical University from February 2022 to August 2022.Chinese individuals aged from 18 to 65 years diagnosed as photoaging or atrophic acne scar were recruited, with no sex limitation.Participant with severe systemic disease, keloid, or photosensitive disease was excluded.Pregnant or lactating woman, participant who has usage of photosensitive drugs within previous 3 months, unequal appearances on both sides of the face were also excluded.Before enrollment, all participants were informed the whole treating and observation procedure and signed the informed consent forms voluntary.Any other treatment was forbidden during the study period.

| Filament coating system
The filament coating system® (Liaoning Yanyang Medical Instrument Co., Ltd, Shenyang, China; patent number: ZL2020 22203357.3,China) system consists of a filament coating device® (YY-FMY-V01; patent number: ZL 2019 22158249.6,China) (Figure 1A) and a liquid dressing (Nano fiber simulation®; patent number: ZL 2019 21782114.0,China) (Figure 1B).The liquid dressing changed to various tiny silk-like filaments with the help of the filament coating device, and forms a membrane suddenly on the treating area (Figure 1C).

| Study design
All participants were treated with one single pass of fCO 2 laser with wavelength of 10 600 nm (UltraPulse; Lumenis Ltd., Santa Clara, CA, USA).A split face was randomly assigned by using random number table (treating side or control side).The participants were asked to wash their faces with a neutral cleanser and have a rest in a temperature and humidity-controlled room (20-25°C, 30%-50%) for 30 min before treatment.The whole face (besides eyelids, eyebrow, and lips) was incubated with 5% compound lidocaine cream (Tongfang Pharmaceutical Group Co., Ltd, Beijing, China) and wiped off 1 hour later.All participants were treated with ablative fCO 2 laser in Deep mode at an energy of 7.5-15 mJ and a density of 5%-10% over the affected area.For participants with acne scar, fCO 2 in active mode at an energy of 80-150 mJ and a density of 5% was additionally applied thereafter.The parameters varied according to the severity of the eruptions and the participants' tolerance to the treatment.Cold compresses were prescribed for 20 min immediately after fCO 2 treatment.
For control side, conventional procedure was topically applied respectively, including desonide cream (Chongqing Huabang Pharmaceutical Co. Ltd., Chongqing, China) two times for 3 days, fusidic acid cream (Bright Future Pharmaceutical Laboratories Ltd., Hong Kong, China) two times for 7 days, and recombinant human epidermal growth factor (RhEGF) gel (Guilin Pavay Gene Pharmaceutical Co. Ltd., Guilin, China) four times for 7 days.For treating side, a filament coating system was applied immediately after one application of fusidic acid cream, desonide cream, and RhEGF gel, and was removed 3 h later.The whole procedure (creams + filament coating system) was conducted once for 3 consecutive days.All participants were asked to wash their faces 48 h after the fCO 2 laser treatment.

| Efficacy evaluation
All participants were photographed by using a VISIA facial imaging device (Canfield Scientific, Inc., Parsippany, NJ, USA) and a digital camera (EOS60D, Canon, Tokyo, Japan) before and 1, 2, 4, and 7 days after fCO 2 laser treatment.At each observation time, erythema, edema, crust, and pain on treating side and control side were separately scored from 0 to 10 by two independent dermatologists based on digital photographs (0 points = no erythema/edema/ crust/pain, 10 points = maximal erythema/edema/crust/pain). 6,7A third dermatologist was asked for help if there was disagreement.
Stratum corneum hydration (SCH) and sebum of forehead and cheek on both sides were also measured three times for average by using Corneometre-sebumetre (CM825, SM810, Courage and Khazaka, Monaderm) on each observation day.

| Statistical analysis
The statistical analysis was conducted by using IBM SPSS Statistics Version 26 (IBM Corporation).Quantitative data were averaged and expressed as mean ± standard deviation.Scores of erythema, edema, crust, and pain, and values of SCH and sebum on both sides were compared by using paired t-test.p < 0.05 was considered as statistical significance.

| Basic characteristics
Thirty-one participants with average age of 31.48 ± 7.43 years (22-61 years) finished the observation.Among them, 18 participants were male (29.78 ± 5.15, 22-39 years) and 13 were female (33.85 ± 9.47, 24-61 years).Twenty participants were diagnosed as photoaging (Figure 2) and 11 were diagnosed as atrophic acne scar (Figure 3).Treatment side of 16 participants were located on left side while that of 15 participants were on right side.

| Erythema
All participants complained of erythema on both sides on Day 1 and Day 2. For participants with photoaging, the erythema score decreased from 2.950 ± 1.276 on Day 1 to 0.200 ± 0.410 on Day 7 on treating side, whereas that from 3.050 ± 1.503 on Day 1 to 0.300 ± 0.470 on Day 7 on control side.For participants with acne scar, the erythema score decreased gradually, from 3.091 ± 0.701 on Day 1 to 0.182 ± 0.405 on Day 7 on treating side, whereas that from 3.273 ± 1.009 on Day 1 to 0.273 ± 0.467 on Day 7 on control side.There were no statistical significances between the two sides at all observation times, with no preference to photoaging or acne scar (p > 0.05) (Figure 4A).

| Edema
All participants suffered from edema on both sides on Day 1 and Day 2, but not on Day 7.For participants with photoaging, the edema score decreased from 2.600 ± 0.995 on Day 1 to 0.300 ± 0.470 on Day 4 on treating side, whereas that from 2.700 ± 1.For participants with photoaging or acne scar, there were no statistical significances between the two sides at all observation times (p > 0.05) (Figure 4B).

| Crust
The crust score of all participants increased from Day 1 to Day 2, but decreased gradually thereafter.For participants with photoaging, the crust score increased from 2.900 ± 1.

| Pain
All participants complained of pain on both sides on Day 1 and Day 2. The pain score decreased gradually as time went on.For participants with photoaging, the pain score decreased from 4.000 ± 0.918 on Day 1 to 0.250 ± 0.444 on Day 7 on treating side, whereas that from 3.950 ± 0.826 on Day 1 to 0.350 ± 0.489 on Day 7 on control side.For participants with acne scar, the pain score decreased from 6.091 ± 0.701 on Day 1 to 0.091 ± 0.302 on Day 7 on treating side, whereas that from 6.272 ± 1.009 on Day 1 to 0.182 ± 0.405 on Day 7 on control side.The degrees of pain were comparable between the two sides at all observation times for both groups (p > 0.05) (Figure 4D).

| SCH and sebum
For participants with photoaging or acne scar, the SCH on forehead and cheek on both sides decreased after fCO 2 laser treatment and increased gradually since Day 2. The SCH on Day 7 were comparable with those before treatment (p > 0.05).There were no statistical significances between the two sides at all observation times, with no preference to photoaging (Figure 5A) or acne scar (Figure 5B) (p > 0.05) (Table 1).
For participants with photoaging or acne scar, the sebum on forehead and cheek on both sides increased after CO 2 laser treatment and decreased gradually since Day 1.The sebum on Day 7 were comparable with those before treatment (p > 0.05).There were no statistical significances between the two sides of both groups at all observation times (p > 0.05) (Figure 5C,D) (Table 2).

F I G U R E 2
Facial photographs of a participant with photoaging at different observation times (treatment side: right side).
In our department, fusidic acid cream, desonide cream, and RhEGF gel have been applied after fCO 2 laser treatment for decades.The nursing procedure lasted for 7 days.As a topical antibiotic, fusidic acid cream could prevent inflammation. 8As a low-potency topical corticosteroid, desonide cream could inhibit inflammation and postinflammatory hyperpigmentation. 9,10RhEGF gel is used to accelerate wound healing after fCO 2 laser. 11Therefore, the above ointments were set as control side in the present study.As for the treating side, the kinds of ointments were the same as those of control side, but the frequency was limited to once for 3 days with the help of filament coating system.The nursing procedure was simplified and shortened comparing to the control side, which provided more convenience for patients after laser treatment.
3][14] In our study, erythema, edema, crust, and pain were observed between treating side and control side without statistical significances, indicating that the side effects were related to fCO 2 laser.As the biggest organ of human beings, skin prevents water inside the stratum corneum evaporating and foreign substances outside entering, that is the function of skin barrier. 15As reported, fCO 2 therapy decreased skin hydration and increased transepidermal water loss. 16In our study, the SCH transiently decreased after fCO 2 treatment, but recovered to the baseline 1 week later.
The results were consistent with Theerawattanawit's study. 17r study showed suddenly increased sebum after fCO 2 treatment and gradually decreased thereafter.That might be caused by forbidden of washing face in the first 48 h after fCO 2 treatment.There were not statistical significances of SCH and sebum between treatment side and control side at all observation times in our study, indicating that filament coating system did not alter skin barrier function, which might be safe for the patients receiving laser treatment.Therefore, filament coating system was more suitable for wide applications with high safety.Some potential mechanisms of filament coating system might take part in the skin wound healing procedure.
First, there are many micro-wounds on the treating area after fCO 2 laser.Various dry crusts form on the micro-wounds subsequently, 18 which inhibit epidermal cells migrating to the wound surface during the healing process.Wound dressing is a material to promote wound healing by providing a desirable moist environment.
A moist circumstance facilitates keratinocyte migration and reepithelialization, 19 collagen synthesis, and autolytic debridement.It also decreases necrosis, pain, inflammation, and scar formation. 20,21reover, it allows cell-cell signaling and precise delivery of topical treatments, supports function of soluble mediators, and provides desirable environment for cell and tissue transplantation. 22,23An ideal wound dressing is excellent in stopping bleeding, preventing microbial infections, accelerating exudates absorption and wound debridement. 245][26][27] The filaments in the present study are nanofibers with diameter 0.1-0.27μm and pore rate 18.3744%, which provide a physical barrier to capture pathogenic microorganisms from the wound surface, and enhance the absorptions of some topical medicines.
Second, a vital ingredient ectoin is added in the filaments.Ectoin, with a chemical name (S)-2-methyl-1,4,5,6-tetrahydropyrimidine-4carboxylic acid, is an innovative multifunctional natural active cyclic amino acid. 28It was first extracted from a bacterium named Ectothiorhodospira halochloris that lives under high salt concentrations.It plays important roles in protecting skins against various external pressures, for example, dryness, radiation, high temperature, and osmolarity. 29Ectoin is an excellent long-term moisturizer because it could increase intermolecular spacing, enhance lipid head groups mobility in cell membranes, and improve cell surface hydration. 30It improves the impaired skin barrier function and protects the skin against some physical and chemical damages.Therefore, it is beneficial for some inflammatory skin diseases, with the advantages of excellent tolerability and safety. 28,31Ectoin prevents UV-induced Langerhans cell depletion and sunburn cell formation in humans, protects against UVA radiation-induced gene expression in keratinocytes.As a result, ectoin could be used to some dermatoses related to sunlight. 28Therefore, ectoin has been applied to some cosmetics and pharmaceutical industry recently. 29ird, the expense of filament coating system is low and could be easily accepted by patients.It costs approximately 15 dollars per application, and 45 dollars in total for one session of fCO 2 laser.Compared with the high price of cosmetic medical treatments, the system might be more economic to be accepted by the patients.

TA B L E 1
Stratum corneum hydration on forehead and cheek at different observation times.
031 on Day 1 to 0.350 ± 0.489 on Day 4 on control side.For participants with acne scar, the edema score decreased from 3.455 ± 1.036 on Day 1 to 1.091 ± 1.221 on Day 4 on treating side, whereas that from 3.364 ± 0.924 on Day 1 to 1.182 ± 1.250 on Day 4 on control side.

F I G U R E 1
Filament coating system.(A) filament coating device; (B) liquid dressing; (C) facial photograph of a participant after filament coating system treatment on left side.
165 on Day 1 to 3.550 ± 1.986 on Day 2 and decreased to 1.000 ± 1.214 on Day 4 on treating side, whereas that from 3.000 ± 1.338 on Day 1 to 3.650 ± 2.10 on Day 2 and 1.100 ± 1.294 on Day 4 on control side.All crust disappeared on Day 7 on both sides.For participants with acne scar, the crust score increased from 4.818 ± 1.471 on Day 1 to 5.727 ± 1.489 on Day 2 and decreased to 0.091 ± 0.302 on Day 7 on treating side, whereas that from 4.901 ± 1.221 on Day 1 to 5.909 ± 1.044 on Day 2 and 0.182 ± 0.603 on Day 7 on control side.For both groups, no statistical significances were seen between the two sides at all observation times (p > 0.05) (Figure 4C).

F I G U R E 3
Facial photographs of a participant with atrophic acne scar at different observation times (treatment side: right side).F I G U R E 4 Scores of erythema, edema, crust and pain on treatment side and control side 1, 2, 4, and 7 days after fCO 2 laser treatment.(A) erythema, (B) edema, (C) crust, and (D) pain.F I G U R E 5 Values of stratum corneum hydration (SCH) and sebum on treatment side and control side on forehead and cheek 1, 2, 4, and 7 days after fCO 2 laser treatment.(A-C) stratum corneum hydration of (A) SCH (photoaging), (B) SCH (acne scar), (C) sebum (photoaging), and (D) sebum (acne scar).
Declaration of Helsinki and was approved by the Medical Ethics and Human Research Committee of The First Hospital of China Medical University (grand number: [2022] 30).
Sebum on forehead and cheek at different observation times.