双层人工皮对猪急性皮肤缺损创面的疗效评价及作用机制

Efficacy of dermal scaffold for promoting repair of acute full-thickness skin defects in pigs

目的探讨双层人工皮对猪急性皮肤缺损创面的治疗效果及可能的作用机制。方法于6只藏猪背部正中线两侧分别由前向后切取3个5 cm×5 cm全层皮肤缺损创面。右侧3个创面为实验组,左侧3个创面为对照组。实验组创面移植Lando?双层人工皮肤,对照组创面应用凡士林纱布。两组创面均于伤后2周移植自体刃厚皮(实验组移植前揭下硅胶膜)。观察伤后3 d、2、10周的创面大体情况及创面收缩率。于各时相点切取创面中央组织标本,采用免疫组化法检测α-平滑肌肌动蛋白(α-SMA)、转化生长因子β1(TGF-β1)的表达水平,用RT-PCR法检测基质金属蛋白酶-1(MMP-1)及其组织抑制物(TIMP-1)m RNA的表达水平。结果两组伤后3 d各检测指标结果比较差异无统计学意义。实验组伤后2周肉芽组织鲜红、平整,创缘规则;伤后10周皮片收缩不明显。对照组伤后2周肉芽组织较为表浅,创缘不规则;伤后10周皮片收缩明显。伤后2周、10周实验组创面收缩率分别为(30.5±3.4)%、(39.2±2.8)%,均显著低于对照组[(51.8±2.6)%,t=-29.840,P=0.000;(60.7±2.2)%,t=-50.213,P=0.000]。伤后2周实验组组织α-SMA、TGF-β1AOD(average optical density)值均显著高于对照组(t=15.921,P=0.000;t=29.995,P=0.000),伤后10周实验组组织α-SMA、TGF-β1AOD值均显著低于对照组(t=-41.823,P=0.000;t=-99.777,P=0.000)。伤后2周实验组组织MMP-1 m RNA的表达低于对照组(t=-45.412,P=0.000),伤后10周则显著高于对照组(t=78.769,P=0.000)。伤后2、10周实验组组织TIMP-1 m RNA的表达均低于对照组(t=-27.064,P=0.000;t=-40.535,P=0.000)。结论创面应用Lando?真皮支架能够促进创面肉芽组织生长,可能与TGF-β1表达增强、MMP-1表达减弱有关;支架能够减轻创面收缩和愈合后的瘢痕增生及其挛缩,与创面愈合后α-SMA、TGF-β1、TIMP-1表达减弱及MMP-1表达增强有关。

Objective To investigate the efficacy of Lando？dermal scaffold for promoting repair of acute full-thickness skin defects in pigs and explore the possible mechanism. Methods Three 5 cm×5 cm full-thickness skin defects were created on the left dorsal skin（control group） and another 3 on the right dorsal skin（treatment group） of each of 6 Tibetan pigs. The wounds in the treatment group were covered with a bilayer artificial skin（Lando） and the control wounds with vaseline gauze. In both groups, autogenous split-thickness skin were grafted to the wounds 2 weeks later（with the silicone rubber membrane removed before grafting in the treatment group）. At 3 days and 2 and 10 weeks after the injury, the wounds were assessed for general condition and contraction, and tissue samples were collected from the wounds to examine the expressions of α-smooth muscle actin（α-SMA） and transforming growth factor-β1（TGF-β1） using immunohistochemistry and the expressions of MMP-1 and TIMP-1 m RNA using RT-PCR. Results At 3 days after the injury, the wounds in the 2 groups showed no significant differences in the results of any examinations. At 2 weeks after the injury, the wounds in the treatment group showed rich and more smooth granulation tissues with more regular wound edges compared with the control wounds. At 2 and 10 weeks after the injury, the wound contraction rates in the treatment group were（30.5 ± 3.4）% and（39.2 ± 2.8）%, respectively, significantly lower than the rates of（51.8±2.6）%（t=-29.840, P=0.000） and（60.7±2.2）%（t=-50.213, P=0.000） in the control group. At 2 weeks, the wound tissues in the treatment group expressed significantly higher levels of α-SMA（t=15.921, P=0.000） and TGF-β1（t=29.995,P=0.000） than the control wounds, but at 10 weeks, the expressions of α-SMA（t=-41.823, P=0.000） and TGF-β1（t=-99.777, P=0.000） in the treatment group were significantly lower than those in the control group. Compared with those in the control group, the expression of MMP-1 m RNA in the treatment group was significantly lower at 2 weeks（t=-45.412, P=0.000） but significantly higher at 10 weeks（t=78.769, P=0.000）, and the expression of TIMP-1 m RNA in the treatment group was significantly lower both at 2 weeks（t=-27.064, P=0.000） and at 10 weeks（t=-40.535, P=0.000）. Conclusions Lando？dermal scaffold can promote granulation tissue growth possibly in relation with increased TGF-β1 and decreased MMP-1 expression in the wounds. This scaffold material also reduces wound contraction and lessens scar hyperplasia and contracture after wound healing, probably as a result of decreased α-SMA, TGF-β1, and TIMP-1 and increased MMP-1 expressions.