皮肤干细胞在胎皮中分布的免疫组织化学研究

Histochemical studies on cutaneous stem cells in human fetal skin

目的采用免疫组织化学方法研究不同时期胚胎皮肤中的干细胞,分析皮肤干细胞的形态、分布特点及发育过程中在胎儿皮肤中的迁徙、增殖分化特征,探讨皮肤干细胞与皮肤发生发育的关系。方法不同发育时期胎儿皮肤,取材、固定、制成石蜡切片,SP法检测整合素-β1、角蛋白19(K19)、K14、K10和PCNA的表达。结果胚胎发育期可见整合素-β1阳性的细胞在基底层散在分布。随胎龄增加,整合素-β1表达减弱,表达范围减小。同时,胚胎发育的不同阶段K19均在表皮基底层强烈表达。表皮分层期后,K14阳性细胞从基底层向上延伸至亚基底层。而K10作为表皮终末分化细胞的标志,主要分布在表皮的中层和外层。此外,在毛囊发育过程中,胎皮表皮嵴的细胞相互聚集成团,形成毛囊初级原基,表达整合素-β1、K19、K14及PCNA为阳性。随着毛囊的形成、成熟,皮肤干细胞主要聚集在与表皮相延续的外根鞘、毛囊隆突部及毛母质,表达整合素-β1、K19、K14和PCNA为阳性。结论(1)皮肤的发生、发育与角蛋白的程序性改变密切相关;(2)毛囊的发生、发育受到毛乳头的诱导作用。毛囊成熟期后,皮肤干细胞主要迁移至与表皮相延续的外根鞘、毛囊隆突部及毛母质等处。此外,还发现毛乳头及其周围组织内分布着单核样细胞表达整合素-β1、K19和K14为阳性。

Objective To investigate the distribution and morphological characteristics of cutaneous stem cells and their subpopulations in the human fetal skin during various stages of embryogenesis, and to introduce an immunohistochemical method to analyze the differentiation of cutaneous stem cells into epidermis and hair follicles. Methods The expression of keratin 10, an established marker of differentiated cells,integrins β1, K14, K19 and PCNA, which were expressed by cutaneous stem cells and their subpopulations were analyzed during human skin development by using immunohistochemical methods. Results Both integrins β1 and K19 were coexpressed in the undifferentiated epidermis. A specific, developmental downregulation of β1 expression was observed in the basal layer at the period of follicular keratinization. Coinciding with the differentiation of the epidermis, differential expression of K14 was observed in the basal and spinous layers, while K10 was confined to the differentiated spinous and granular layers. At the period of interfollicular keratinization, the epidermal progenitor cells were mainly localized in the basal layer of epidermis and outer sheath,bulge and hair matrix of follicles, which were positive for integrins β1, K19, K14 and PCNA. Conclusion The cutaneous cells in the basal layer contribute to the development of epidermis and hair follicles. Additionally, cues from underlying mesenchymal may also contribute to hair follicle formation and its cycling.