Early Treatment Effects of Nonablative Fractional Lasers (NAFL) on Hypertrophic Scars in an Animal Model

Abstract

Background and Objectives Recently, there have been several attempts to apply the laser therapy to hypertrophic scars (HTS). In particular, the fractional laser is in the spotlight for its usefulness in rapid wound healing and dermal remodeling. However, most previous studies have focused on the ablative fractional laser (AFL), and there are no studies on the mechanism of the nonablative fractional laser (NAFL) effect in HTS treatment. In this study, we aimed to evaluate the changes in histology and molecular chemistry to provide scientific evidence for the early treatment of HTS with NAFL. Study Design/Materials and Methods A total of 40 hypertrophic burn scars were made on the abdomens of two female pigs. After epithelialization, the HTS were randomly subdivided into four groups—control, AFL, NAFL (low energy), and NAFL (high energy). Laser treatment was initiated 1 week after the crust fell and the epithelium became covered, and it was repeated for six sessions over an interval of 2 weeks. Five excisional biopsies were obtained for histologic analysis and biomarker assessment. Results Histologically, dermal remodeling with thin coil‐shaped collagen fibers was observed in the NAFL groups. It also showed a significant increase of matrix metalloproteinase‐2 (MMP‐2) and Decorin at 16 weeks in an enzyme‐linked immunosorbent assay. The reverse‐transcription polymerase chain reaction analysis showed a tendency that high‐pulse energy of NAFL led to higher messenger RNA expression than did the low‐energy group. Conclusion The NAFL‐treated groups showed characteristic collagen re‐arrangement and a significant increase in MMP‐2 and Decorin. These molecular changes suggest that MMP‐2 and Decorin play a significant role in dermal remodeling. Early NAFL treatment for HTS could be supported with both histological and molecular evidence. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

Laser Therapy Changes the Expression of Matrix Metalloproteinases in Bleomycin-Induced Skin Fibrosis

“…Using fractional lasers for scars has several advantages (rev. in [ 25 ]). Heating the dermis to 50–70 °C, irradiation with a laser produces ~3 mm deep microscopic skin lesions, initiating rapid wound healing in the affected area.…”

“…In a recent paper, Chung et al [ 25 ] reported that the AFL and NAFL treatment of pigs significantly changed the expression of Mmp2 and Mmp9. In ELISA experiments, the authors showed that the level of Mmp2 significantly increased after low- and high-energy NAFL treatment compared to the sham control and AFL treatment.…”

Laser Therapy Changes the Expression of Matrix Metalloproteinases in Bleomycin-Induced Skin Fibrosis

“…In turn, the differences between the sham control and AFL, according to the authors, were insignificant. In qPCR experiments, Chung et al [11] did not see significant differences between groups treated with AFL and any group treated with NAFL. Contrarily, the expression of Mmp2 in ALF-treated animals significantly exceeded one in sham control.…”

“…In our study (Figure 3), we show significant suppression of Mmp2 at the early stages of post-therapeutic recovery. Respectively, the following increase in the expression of Mmp2 would explain the absence of statistical differences in Chung's qPCR experiments [11] and the accumulation of secreted Mmp2 detectable by ELISA. The same hypothesis can explain higher levels of Mmp2 in animals treated with low and high-energy NAFL.…”

“…Chung et al [11] reported that the treatment of pigs with ablative and non-ablative fractional lasers (AFL and NAFL, respectively) significantly changed the expression of Mmp2 and Mmp9. In ELISA experiments, the authors showed that the level of Mmp2 significantly increased after low-and high-energy NAFL compared to sham control and AFL.…”