Micronized acellular dermal matrix combined with platelet rich plasma in the treatment of atrophic acne scars: A self‐controlled split face study

Micronized acellular dermal matrix (mADM) can induce tissue regeneration and repair, and filling.


| INTRODUC TI ON
Atrophic acne scars are the common type of acne scars.They are mainly classified into boxcar scars, rolling scars, and ice pick scars. 1 Different treatments have been used to treat atrophic acne scars.
Each of these treatments has a different mechanism and each type of scar show a better response to a treatment modality than others. 2ythema, pain, pigmentation, long recovery time, and other adverse reactions have been reported in different treatments. 3ellular Dermal Matrix (ADM) is a new kind of regenerating material.It is categorized according to their origin into xenograft or allograft.ADM is produced by removing the epidermal layer, cellular, and any antigenic component that can cause rejection and infection.
The remaining component is the reticular structure of dermal extracellular matrix (ECM).This media allows the host cell to grow inward and promote tissues to repair.These results suggest that ADM can induce tissue regeneration, repair, and filling. 4Micronized Acellular Dermal Matrix (mADM) is the preparation of ADM by physical cutting and grinding methods.Compared with the ordinary ADM, mADM could be easily used as injection for filling treatment, making it easier to operate, lighter trauma and more likely to be accepted by patients.mADM is used currently in facial rejuvenation and soft tissue filling.
As the atrophy in acne scars results mainly from reduction of collagen deposition caused by insufficient repair response in the process of scar formation, which is seen mainly in moderate to severe acne, it can be speculated that the regenerative scaffold material mADM can be used as dermal matrix with the effect of inducing tissue regeneration, repair and filling.This study will assess the mADM efficacy and safety in the treatment of atrophic acne scar.

| Study design
This study was designed as a self-controlled and split-face study.
Patients who met the inclusion criteria were treated in one side using mADM (Type D, national machinery note: 20173463366, JIANGSU UNITRUMP BIOMEDICAL TECHNOLOGY CO., LTD.) and platelet rich plasma (PRP) in the treatment group.On the other side PRP alone was used as a control group.The treatment site is the temporal and cheek regions on both sides.The Acne Scar Assessment Scale (ASAS), Acne Scar Weight Rating Scale (ECCA) were used to evaluate the effect before and 3 months after treatment.The adverse reactions at 1 week, 1 month and 3 months after treatment and the self-satisfaction survey score at 3 months after treatment were recorded to evaluate the treatment effect, adverse reactions, and patients' satisfaction.

| Preoperative preparation
The face of each patient was cleansed and dried.Photographs under same lighting conditions for the front, the left, and right sides at 45-degrees were taken with a DSLR camera and a VISIA skin detector for archiving.ANTERA 3D photographic analyzer was used to record the scar sites (temporal and cheek) on both sides of the face.

| PRP preparation
Heparin sodium was used to draw 20 mL of the patient's own venous blood and centrifuged at 3000R/min for 15 min at room temperature.After centrifugation, the platelet-poor layer and platelet-rich plasma layer were extracted with a sterile syringe and reserved for future use.All the above steps were aseptic.
The treatment group: A 1 mL syringe was used to prepare a subcutaneous tunnel for the treated area of acne atrophic scar.0.5 g of mADM microparticles (diameter 0.25 mm) were loaded into a 5 mL spiral-mouth syringe connected in a three-way tube with 2 mL of PRP added to another 5 mL spiral-mouth syringe.The material is then injected by a 26 G spiral-mouth injection needle through a 1 mL syringe to fill the atrophic site.
The control group: Using the same 1 mL syringe for preparation of subcutaneous tunnel, PRP only was used to fill the atrophic scars through a 1 mL syringe connected to a 26 G spiral injection needle.
The filling sites of the two groups were subcutaneous tissue and dermis.The injection process was slow, and the needle was withdrawn while injecting.Squeezing the injection sites was avoided.
The end point injection of the treatment is to make the atrophic scar area slightly higher than normal skin.

| Postoperative care
Immediately after the treatment, we used a gauze to press and ice to avoid swelling and bruising.The filling area was kept dry and avoided to contact water for 3 days after treatment.No kneading or vigorous exercise was allowed in the filling part of the face within 1 week after treatment.
Follow up was done at 1 week, 1 month, and 3 months after treatment to check whether there were any complications.

| The curative effect evaluation methods
SLR camera photos and VISIA images were collected before and 3 months after treatment under the same photographic conditions.Two aesthetic dermatologists who did not participate in this clinical study evaluated the efficacy according to the ASAS, ECCA, and 4grade scar improvement scale. 5,6(Tables S1, S2 & S3).

| Patient satisfaction and safety evaluation
Three months after treatment, satisfaction survey was conducted for all subjects, and the degree of scar improvement was scored.0 is no improvement, not satisfied, 1 is slight improvement, not satisfied; 2, moderate improvement, relatively satisfactory; 3, significant improvement, and satisfaction; 4 is close to complete improvement, very satisfactory.

| Statistical analysis
This clinical study used SPSS 23.0 statistical software for statistical analysis, measurement data were expressed as (X ± s).This study was a self-controlled test, and paired sample t-test was used for comparison between the two groups.Numerical data were represented by frequency and constituent ratio.Chi-square test or Fisher exact test was used for comparison between groups.Nonparametric rank sum test was used for comparison of rank data between groups.p < 0.05 indicates statistical significance.

| Demographic characteristics of subjects
The study included 20 patients with atrophic acne scars.Four patients (two men and two women) dropout due to personal reasons, The remaining 16 patients' ages ranged from 21 to 36, with a mean age 28.75 ± 3.94 years, 13 (81.3%)men and three women (18.8%), and a total of 48 scars, The scar's duration mean was 8.88 ± 2.94 years, three cases (18.8%) were rolling scars, six cases (37.5%) were boxcar scars, and seven cases (43.8%) had both types.Thirteen patients had a history of treatment with fractional CO 2 laser more than 6 months ago and one patient with radiofrequency (Table 1).

| ASAS scores analysis
The ASAS scores of the treatment group and the control group before treatment were 4.12 ± 0.61 and 4.04 ± 0.69 respectively.
There was no significant difference in ASAS score between the two groups before treatment (p > 0.05).After 3 months of treatment, the scores of the treatment group, and control group were 2.50 ± 0.51 and 3.62 ± 0.77 respectively.The differences between both groups after treatment was statistically significant (p < 0.001) (Table 2; Figure 1).mADM combined with PRP demonstrated a good effect on both Utype scar and M-type scar.(Table 2; Figure 2).

| Grading scar improvement scale scoring method
There were significant differences between the control group and the treatment group by 4-grade scar improvement scale score, z = −4.999,p<0.05.The degree of improvement was better in the treatment group than in the control group (Table 2) (Figures S1 and S2).

| Analysis of satisfaction survey
Three months after treatment, the degree of scar improvement was evaluated.The satisfaction scores of treatment group and control group were 3.56 ± 0.51 and 1.31 ± 0.6, respectively, Satisfaction of the treatment group was significantly higher than that of the control group (t = 13.175,p < 0.001) (Table 2).

| Evaluation of safety
The treatment group (24 scar sites) was followed up 1 week later.
Six bruises, two indurations were noted.Follow-up was performed 1 month later, and the bruises disappear.There was still one induration, Follow-up was performed 3 months later, and it disappeared.
The control group (24 scar sites) was followed up 1 week later, four bruises were recorded.One month later, the bruises disappeared.
No adverse reactions such as bruising, infection, induration and vascular embolism were observed in the other cases in both groups.

| DISCUSS ION
ADM is a new type of tissue regenerating material.It is produced from the ECM, which has a weak immune triggering effect after removal of the cells that could trigger strong immune response. 7Therefore, immune responses are rarely seen.ADM is mainly composed of fibershaped structures, containing a variety of collagen types (typeI, III, IV), chondroitin sulfate, elastin, hyaluronidase, chondroitin sulfate, fiber binding protein, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), transforming growth factorβ (TGFβ), Neuregulin, epidermal growth factor (EGF), and bone morphogenic protein-4 (BMP-4).Type I collagen is the basic skeleton of ADM, and it gives the tissue strength and flexibility. 8,9anning electron microscopy shows that ADM has a porous threedimensional network structure.Its structure allows cells to accumulate rapidly, thereby promoting collagen binding and the formation of new blood vessels.ADM is used to fill the facial subcutaneous soft tissues and dermis, which can cause the surrounding soft tissues to grow into the 3D reticular frame of the ADM.[12] The occurrence of atrophic scar in acne is mainly caused by the reduction of collagen deposition due to insufficient repair response in the process of scar formation.Therefore, ADM working as a 3D mesh scaffold material could induce tissue regeneration, repair and filling effect.Using mADM with its granular form can be used as injection, making it is easy to operate and faster to recover.
In this clinical trial, we used acupuncture method to prepare a subcutaneous tunnel at the bottom of the scar and injected the mADM.
This method helps to cut the fibrous tracts that are tethering the scar to the underlying structure and causing some degree of tissue damage that stimulates wound repair mechanism, promoting the synthesis and remodeling of new collagen. 13The mADM used in this clinical study was a microgranular acellular dermal matrix that can be injected and implanted and has been approved by the China Food and Drug Administration (CFDA).Its particle size is ≤0.25 mm (250 μm).The needle used was 26 g needle, so it can help to reduce pain, bleeding and swelling during the procedure and make it easier to inject and fill the fine facial acne concave scar.
In this clinical study, 16 patients with boxcar and rolling scars (48 scar sites in total) were enrolled in a self-control, split face study.
One side of the face was injected with mADM combined with PRP as the treatment group, and the other side of the face was injected with PRP as a control group.There were significant differences between the two groups before and after treatment using ASAS and ECCA weight scores, suggesting that the therapeutic effect of mADM combined with PRP was better than that of PRP alone.
The most common adverse effects noted in mADM combined with PRP were pain and swelling at site of injection, which was obvious within 2-3 days after the procedure.Bruising and induration were also noted.The bruises subsided spontaneously in approximately 7-14 days after the procedure, and the induration subsided spontaneously in about 1-3 months.No postoperative vascular embolism was observed mainly because the mADM size of 0.25 mm (250 μm), which is much larger than that of capillaries (7 μm), arterioles and venules (30 μm) made the possibility of vascular embolism a rare event.
In conclusion, atrophic acne scars can be effectively treated with mADM utilizing PRP as a solvent, showing esthetically satisfactory objective and subjective outcomes with a low risk of complications.
This study highlighted a favorable outcome in treating boxcar and rolling scars through immediate filling effect and gradual tissue regeneration on a long run with no downtime making mADM a feasible option in treating atrophic acne scars.
Patients were recruited from the Dermatology Hospital, Southern Medical University between January 2021 and December 2021, with the diagnosis of atrophic acne scars (boxcar scars and rolling scars).The inclusion criteria included patients aged 18-50 years, with lesions located on the cheek and temporal region, and stable scar time of half a year.Exclusion criteria included receiving other treatments for atrophic scars within 3 months before treatment, presence of active infection at the proposed site of injection, allergy to lidocaine and collagen, poor compliance, pregnant, and breast-feeding women, and patients with immune dysfunction and defects.Informed consent was obtained from each patient.This research was approved by Dermatology Hospital ethical committee, Southern Medical University.The clinical trial registered number was ChiCTR2200061288.

F I G U R E 1
ASAS score (mean ± st) change of mADM+ PRP (treatment) group and PRP (control) group in patients of atrophic acne scars from baseline to 3 months.p < 0.001.ASAS, acne scar assessment scale; mADM, micronized acellular dermal matrix; PRP, platelet rich plasma.F I G U R E 2 ECCA weight score (mean ± st) change of mADM+ PRP (treatment) group and PRP (control) group in patients of atrophic acne scars from baseline to 3 months.p < 0.001.ECCA, acne scar weight rating scale; mADM, micronized acellular dermal matrix; PRP, platelet rich plasma.| 2391 PARK et al.
Demographics of included patients.
weight score of the treatment group, and the control group decreased to 14.17 ± 10.18 and 31.88 ± 13.25, respectively.The treatment group decreased significantly compared with the control group (p < 0.001).The ECCA weight scores of different scar types [boxcar scars (U type, rolling scar M type)] were further compared.Under two treatment modalities, ECCA weight score decreased after treatment, the differences were statistically significant (p < 0.05).
Results of the study.
TA B L E 2 a p-value<0.05 is considered significant.