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目的 探讨真皮干细胞即皮肤前体细胞(skin-derived precursors, SKPs)抗体外三维(three-dimensional, 3D)皮肤光损伤的作用,为皮肤光损伤的治疗提供实验依据.方法 按既往SKPs培养方法,采用悬浮培养法从新生小鼠真皮中分离、培养 SKPs.同前期构建3D皮肤方法,以I型胶原为支架,接种来自儿童包皮的原代培养的角质形成细胞(keratinocytes, KC)和成纤维细胞(fibroblasts,FBs)构建体外3D皮肤模型.然后将3D皮肤模型分为模型组、治疗组和对照组.在照射前24h,将 SKPs细胞悬液和Hanks液各25μL分别注入治疗组和对照组,模型组未做处理.然后,予以UVA和UVB混合单剂量照射三组3D皮肤.照射后继续培养,72h后收集皮肤和上清液.HE染色观察各组皮肤组织病理学改变、TUNEL染色分析细胞凋亡情况以及ELISA检测SOD、CAT、MDA等氧化应激指标的变化.结果 原代培养SKPs呈悬浮生长的圆形或椭圆形克隆样细胞球.3D皮肤经UV照射后,其表皮细胞肿胀排列紊乱、核浓缩,基底细胞部分液化变性,真皮胶原降解且FBs明显减少;凋亡细胞明显增加、凋亡指数AI值升高(P ＜0.05) ;SOD、CAT和GSH-Px表达降低(P＜0.05),而MDA水平升高(P＜0.05).但经SKPs注射后,KC整齐清晰仅轻度肿胀,核浓缩不明显,FBs轻微减少,未见细胞坏死及胶原降解;凋亡细胞显著减少、AI值下降(P ＜0.05) ;SOD,CAT和GSH-Px水平显著升高(P ＜0.05),MDA明显降低(P＜0.05).而对照组无明显改善.结论 SKPs能抗UV诱导的3D皮肤损伤,为皮肤光损伤的治疗奠定基础.“,”Objective To explore the protective effect of dermal stem cells,also called skin-derived precursors ( SKPs), on skin photodamage in three-dimensional (3D) model in vitro,and to provide an experimental evidence for the treatment of skin photodamage. Methods SKPs were isolated and cultured from the dermis of mouse neonates in a traditional way of suspension culture.3D skin models in vitro were constructed with keratinocytes ( KC) and fibroblasts ( FBs) from infant foreskin basing on type I collagen. Then, they were divided into three groups: model group, treatment group and control group. Twenty-four hours before irradiation,SKPs and Hanks were respectively injected into treatment group and control group, whereas model group remained untreated. Subsequently, 3 D skin models in three groups were exposed to a single dose of UVA + UVB,after which all groups continued to be cultured for 72 hours before the skin and the supernatant were harvested. HE staining was used to observe histopathological changes,while TUNEL staining was employed for apoptosis and ELISA analysis was conducted for SOD, CAT and MDA detection. Results SKPs in primary culture displayed round or oval-shaped floating spheres. After exposure to UV,epidermal cells of 3D skin took on swelling disorder,concentrated nuclei and partial liquefaction in basal layer,while dermal collagen were degraded and FBs significantly decreased; the apoptotic cells were increased remarkably with high apoptotic index(AI) value(P ＜0.05); the levels of SOD,CAT and GSH-Px were reduced(P ＜0.05),whereas MDA was increased ( P ＜ 0.05 ). After SKPs injection,however,KC arrangement was neat and clear and presented mild swelling with few concentrated nuclei; FBs were slightly reduced without cell necrosis and collagen degradation. Apoptotic cells were significantly decreased with low AI value (P ＜0.05),accompanied with the significant elevation of SOD,CAT and GSH-Px(P ＜0.05) ,and the remarkable decrease of MDA(P＜ 0.05 ). In contrast,little improvement had been observed in control group. Conclusion SKPs exert a beneficial effect on resistance to UV-induced 3D skin damage,which provide the basis for the treatment of skin photodamage.