不同能量密度非剥脱点阵激光早期防治兔耳增生性瘢痕的疗效观察

Efficacy of non-ablative fractional laser at different energy and density in the early treatment of hyperplastic scars in a rabbit ear model： a clinical observation

目的 初步探讨早期防治兔耳增生性瘢痕形成的最佳激光能量密度及其可能的治疗机制。方法12只健康新西兰大耳白兔，在10只兔耳部进行增生性瘢痕造模，成功形成61处增生性瘢痕，随机分为2组（1周组30处和3周组3l处）。这两组兔耳瘢痕又分别随机分为A组（密度100PPA、能量10mJ激光）、B组（100PPA、50mJ激光）、C组（169PPA、10mJ激光）、D组（169PPA、50mJ激光）、E组（不接受激光处理）。除去3周组E组外，余均为每组6处瘢痕。2只大耳白兔未行瘢痕造模，作为F组（空白对照组）。免疫组化观察干预后1周兔耳皮肤组织中MMP-13表达情况，干预后3周兔耳皮肤组织行HE、Masson染色，观察瘢痕结构，计算瘢痕增生指数。各组瘢痕增生指数的比较采用Kruskal-Wallis H检验，MMP-13平均吸光度的比较采用单因素方差分析。结果 HE染色显示，A、B、C、D各组真皮层厚度较F组（正常皮肤组织）增厚，胶原纤维数量增加，但较E组（未处理瘢痕组）真皮厚度明显变薄，胶原纤维数量减少，排列相对有秩。A、B、C、D组问真皮层厚度未见明显差异。6组间瘢痕增生指数差异有统计学意义（H=22．757，P〈0．05）。两两多重比较显示，B、C、D组瘢痕增生指数（2．597±0．344、2．850±0．282、2．658±0．134）均显著低于E组（3．460±0．583，均P〈0．05）。Masson染色显示，A、B、C、D各组真皮层厚度较E组明显变薄，胶原纤维排列不规则，但A、B、C、D各组间真皮层厚度及胶原纤维数量未见明显差别。免疫组化显示，在相同激光密度条件下，高能量（50mJ）组的MMP-13表达水平明显高于低能量（10mJ）组（P〈0．05）；而相同激光能量条件下，A组MMP-13水平显著高于C组（P〈0．01），但B组与D组间差异无统计学意义（P〉0．05）。结论 非剥脱点阵激光对于早期增生性瘢痕的干预有效。相同密度下，50mJ能量激光干预效果优于10mJ能量激光，推测高能量激光能更好刺激细胞外基质的重组以及上调MMP-13的表达，从而早期防治增生性瘢痕。

Objective To preliminarily optimize the energy and density of laser radiation for the early treatment of hyperplastic scars in a rabbit ear model, and to explore possible therapeutic mechanisms. Methods Sixty-one hyperplastic scars were successfully established on the ears of 10 healthy New Zealand white rabbits with large ears, and randomly divided into 2 groups： 1-week group （30 scars） and 3-week group （31 scars）. These 2 groups were separately divided into 5 subgroups： group A treated with laser at a density of 100 PPA and an energy of 10 rnJ, group B with laser at a density of 100 PPA and an energy of 50 mJ, group C with laser at a density of 169 PPA and an energy of 10 mJ, group D with laser at a density of 169 PPA and an energy of 50 mJ, and group E receiving no treatment. There were 6 scars in each group, except the group E in the 3-week group. Two healthy New Zealand white rabbits with large ears were not subjected to modeling, and served as group F （blank control group）. Immunohistochemical study wasperformed to determine the expression of matrix metalloproteinase （MMP）-13 in the skin tissues from the rabbit ears 1 week after the treatment. Three weeks after the treatment, the skin tissues from the rabbit ears were subjected to hematoxylin-eosin （HE） staining and Masson staining. Then, the structure of scars was observed, and scar elevation index was calculated. Statistical analysis was carried out by Kruskal-Wallis H test for the comparison of scar elevation index, and by one-way analysis of variance （ANOVA） for the comparison of the average absorbance value of MMP-13. Results As HE staining revealed, the groups A, B, C and D all showed thicker dermis and increased number of collagen fibers compared with the group F （normal skin tissues）, but showed thinner dermis, decreased number and more ordered arrangement of collagen fibers compared with the group E （untreated scar tissues）. No obvious difference was observed in the thickness of the dermis among the groups A, B, C and D. The scar elevation index significantly differed among the 6 groups （H = 22.757, P 〈 0.05）. Multiple comparisons showed that the scar elevation index was significantly lower in the groups B, C and D （2.597 ± 0.344, 2.850 ± 0.282, 2.658 ± 0.134, respectively） than in the group E （3.460±0.583, all P 〈 0.05）. As Masson staining revealed, the groups A, B, C and D all showed thinner dermis and more irregular arrangement of collagen fibers compared with the group E. However, no obvious differences were observed in the dermal thickness or number of collagen fibers among the groups A, B, C and D. Immunohistochemical study showed that the expression of MMP-13 was siguificandy higher in the high-energy （50 mJ） laser groups than in the low-energy （10 mJ） laser groups （P 〈 0.05） at the same laser density. With the same laser energy, the expression of MMP-13 was significantly higher in the group A than in the group C （P 〈 0.01 ）, but there was no significant difference between the group B and D （P 〉 0.05）. Conclusions Non-ablative fractional laser is effective for the treatment of early-stage hyperplastic scars. At the same laser density, 50-mJ laser was superior to l0-mJ laser for the treatment of hyperplastic scars, likely because high-energy laser can stimulate the recombination of extracellular matrices and up-regulated MMP-13 expression to a greater extent.