FETAL SKIN BIOLOGY

我们之前对正常人和变态人发育的研究 皮肤已经记录了各种表达的变化 分化特异的标记与细胞的形态相一致 组织。这项工作提供了一幅连贯的皮肤图像 发展以及确定的发展事件和发展时期，这些事件和发展时期 被认为是建立正常成人模板的关键 皮肤。我们现在更加重视对理解的研究。 影响这些变化的细胞相互作用的种类 描述并将阐述细胞-细胞和组织相互作用的作用 在调节皮肤的新生发生和分化方面。这些种类 相互作用的最好例证是表皮的形成 附件，因此本提案的重点是形成 毛脂状结构。我们使用的是一个非常有特色的系统 可以直接在活体(新鲜组织)和实验中进行研究 体外培养(细胞培养、器官培养、移植)。我们已经开发了 悬浮器官培养，可重复地支持形成和 表皮附属物的持续发育(见初步数据和 附录)长达60天，并维持并允许生长 表皮和真皮看起来很正常。我们不知道 任何其他具有这种潜力的人类皮肤培养系统。这 将使用文化系统来确定对 诱导、启动、生长、分化和维持 人皮肤发育中的表皮附属物，并测定 上皮(角质形成细胞)和间充质细胞在血管内皮细胞中的作用 互动。我们将重点介绍生长因子(NGF、 EGF、POGF、转化生长因子-8)及其受体(其中一些特异性 影响上皮细胞，其他为间充质细胞所特有 细胞)、基质成分(1、111、V和VI型胶原；纤维连接蛋白 和胶原酶)、其他相关分子(如米诺地尔)和神经 毛囊发育中的纤维。来自受感染患者的皮肤 X连锁少汗性外胚层发育不良，一种遗传性疾病， 附件的发育和出生后的异常形成是 这些疾病的特征，将进行研究，以确定 任何被确定为重要的增长因素等 附属物的个体发育在成体组织中异常表达。

Our previous studies of the development of both normal and abnormal human skin have documented changes in the expression of various differentiation-specific markers coordinate with the morphology of the tissue. This work has provided a coherent picture of cutaneous development and identified events and periods of development which are presumed to be critical in establishing the template of the normal, adult skin. We are now placing more emphasis in our studies on understanding the kinds of cellular interactions that occur to effect the changes described and will address the role of cell-cell and tissue interactions in modulating niorphogenesis and differentiation of the skin. These kinds of interactions are best exemplified in the formation of epidermal appendages, hence the focus of this proposal on the formation of pilosebaceous structures. We are using a very well characterized system that can be studied directly in vivo (fresh tissue) and experimentally in vitro (cell culture, organ culture, grafting). We have developed the suspension organ culture which supports, reproducibly, the formation and continued development of epidermal appendages (see preliminary data and appendix) for as long as 60 days and maintains, and permits growth, of epidermis and dermis in an apparently normal manner. We are unaware of any other human skin culture system which has this potential. This culture system will be used to identify the requirements for the induction, initiation, growth, differentiation and maintenance of epidermal appendages in developing human skin, and to determine the presumptive roles of epithelial (keratinocytes) and mesenchymal cells in the interaction. We will focus on parts played by growth factors (NGF, EGF, POGF, TGF-8) and their receptors (some of which specifically influence epithelial cells, others which are specific for mesenchymal cells), matrix components (collagen types 1, 111, V and VI; fibronectin and collagenase), other relevant molecules (e.g., minoxidil) and nerve fibers in hair follicle development. Skin from patients affected with X-linked hypohidrotic ectodermal dysplasia, a genetic disorder in which development and postnatal abnormalities of appendage formation are the hallmark of the diseases, will be studied in order to determine whether any of the growth factors, etc. identified to be important in the ontogeny of appendages are abnormally expressed in the adult tissue.