创面愈合过程中创缘表皮干细胞的再分布

目的：研究皮肤干细胞在全层皮肤创面愈合过程中的分布与增殖分化特征,以及该特征在创面愈合过程中的作用。方法：20只Wistar大鼠背部各制备4个面积为2．54cm^2的全层皮肤缺损创面,将创面随机分为2组,即银锌霜治疗组（40个创面）,空白对照组（40个创面）。分别于伤后3天、1周、2周和3周以组织学检查动态观察各组治疗效果,并以β1整合素、角蛋白19（K19）免疫组化法检测表皮干细胞在创面愈合过程中的分布情况。结果：两组创面愈合率在银锌霜组为80％（32／40）,对照组为60％（24／40）。两组创面肉芽组织于各时相点均未见β1整合素、K19阳性细胞出现,但于创缘表皮的棘层或颗粒层出现了散在的β1整合素和K19同时染色阳性细胞,且越接近创面这些阳性细胞更加密集,组织学上与基底层的阳性细胞无直接联系。其数量随着创面的缩小渐渐增加,直至创面愈合。创面上皮化后,这些阳性细胞逐渐减少,并随着愈合创面表皮脚的出现而消失;而感染创面的阳性细胞数量明显少于未感染创面。结论：表皮干细胞能动的参与创面的修复,创缘表皮干细胞再分布的主要功能可能是促进创面再上皮化。

Redistribution of epidermal stem cells in wound edge in the process of re-epithelialization

OBJECTIVE: To study the redistribution of epidermal stem cells in regenerating wound tissues, and to elucidate the role of epidermal stem cells during wound repair. METHODS: 80 circular full-thickness wounds were produced on both sides of the back in 20 male Wistar rats (4 wounds in each animal). Then the 80 wounds were randomly divided into 2 groups: group A (treated with sulfadiazine silver- sulfadiazine zinc cream, n = 40) and group B (without any treatment, n = 40). The infection and healing process of the wounds were observed with naked eyes. Five mice were killed one time 3, 7, 14, and 21 days after the wounding. Two wounds with surrounding normal skin tissues were collected from each mouse. Routine histological examination was conducted with HE staining. Beta(1) integrin and keratin19 (K19), markers of epidermal stem cells, were employed to determine the distribution of epidermal stem cells with streptavidin-peroxidase (SP) immunohistochemical method. RESULTS: The healing rate of wounds was 80% (32/40) in group A, and 60% (24/40) in group B. No beta(1) integrin and K19 positive cells was found in the granulation tissue of all wounds in these 2 groups at any time point during the healing process. However, a few beta1 integrin and K19 positive cells, bearing no anatomic relation with the epidermal stem cells in the basal layer, were found scattering in the stratum spinosum and stratum granulosum of the epidermis on the wound edges. The closer to the wound the more concentrated the beta(1) integrin and keratin19 positive cells. Their numbers increased gradually along with the shrinking of the wound surface until the wound completely healed. The numbers of the beta(1) integrin and keratin19 positive cells decreased gradually after epithelialization. The numbers of the beta(1) integrin and keratin19 positive cells were obviously lower in the infected wounds than in the uninfected wounds. CONCLUSION: Epidermal stem cells participated in the healing of wound. The function of redistribution of epidermal stem cells in wound edges seems to promote the re-epithelialization of granulating wounds.