损伤皮肤修复和伤口愈合过程中的干细胞:问题与前景

Stem cells in the skin regeneration and wound healing: problem and perspective

背景:当前皮肤慢性伤口的治疗方法是有限的,成体干细胞具有治疗许多皮肤疾病潜在功能。目的:综述干细胞在损伤皮肤修复和伤口愈合方面的作用。方法:第一作者用计算机检索中国期刊全文数据库(CNKI:2000至2010年)和Medline数据库(2000至2010年),检索词分别为"表皮干细胞;毛囊干细胞;干细胞;移植;表皮干细胞;真皮干细胞;"和"Epidermal stem cells;hair follicle stem cells;stem cells;Transplantation;Epidermal stem cells;Dermal stem cells",共计489篇论文,语言分别设定为中文和英文。最终纳入30篇文献。结果与结论:表皮干细胞和其他成体干细胞作为细胞治疗应用于治愈伤口和其他皮肤疾病。表皮干细胞是皮肤发生、修复、重塑的关键性源泉,机体内表皮干细胞多处于静息状态,只有当皮肤受损或在体外培养的情况下,该细胞分裂、增殖才明显加快。表皮干细胞主要通过不对称分裂来维持表皮的稳定,具体表现为1个亚细胞群的不对称分裂,其每次分裂产生的2个子细胞,其中1个具有干细胞自身的特性,而另1个子细胞分化为短暂扩充细胞,后者经过3-5次分裂后形成有丝分裂后细胞,其不断变迁为基底层上的终末分化细胞,最后以皮屑的形式从表皮脱落。此外,在创伤修复的过程中甚至在生理条件下,是否由于表皮因素的影响而发生细胞凋亡、迁移和分化,目前仍未知。因此,干细胞在损伤皮肤修复和伤口愈合方面的作用仍有很多问题尚待解决。

BACKGROUND： Present treatments for chronic skin wounds have certain limitations, and adult stem cells play a potential part in cutaneous repair and regeneration. OBJECTIVE： To review effects of stem cells in skin regeneration and wound healing. METHODS： The first author retrieved CNKI and Medline databases by computer for relevant articles published from 2000 to 2010. The keywords were ＂epidermal stem cells, hair follicle stem cells, stem cells, transplantation, dermal stem cells＂ in Chinese and in English, respectively. Then totally 489 papers were obtained after initial survey, and according to the inclusion criteria, 30 articles were selected for review. RESULTS AND CONCLUSION： Epidermal stem cells and other adult stem cells have been applied to treat wounds and other skin diseases. Epidermal stem cells are the crucial cell source of skin development, repair and remodeling. Epidermal stem cells are always in a resting state in vivo. Unless, skin injure or culture in vitro, cell division and proliferation will be significantly fastened. The stability of the epidermis mainly depends on the asymmetric division of a subpopulation, in which two daughter cells are produced, including one with characteristics of stem cells, and the other differentiated into transient amplifying cells that will be differentiated into post mitotic cells after a series of cell divisions（3-5 times）. Afterwards, those post mitotic cells are developed into terminal differentiation cells on the basal layer, finally detach from the epidermis as dander. In addition, it is unclear whether epidermal factors are related to apoptosis, migration and differentiation in the process of wound repair and even under physiological conditions. Therefore, application of stem cells in wound healing requires a further discussion.