BIOMIMETIC TISSUES--ORAL MUCOSACONJUNCTIVA, AND SKIN

将皮肤移植到口腔中通常用于前庭 扩展程序，修复创伤引起的缺陷，以及 修复切除后的口腔粘膜缺损 恶性肿瘤 然而，移植到口腔中的皮肤 其原有的结构和功能，经常和患者的头发有关 从嫁接的皮肤上生长和出汗。 理想情况下，口腔粘膜 组织将用于这种移植物，但这受到缺乏 足够的供体组织 就像口腔中的组织一样， 结膜是衬在眼睛和眼睑上的粘膜组织。 它 由非角化复层鳞状上皮组成， 类似于颊粘膜。 有两种情况会产生扩散 结膜瘢痕，导致疼痛性视力丧失：眼部 瘢痕性类天疱疮和眼表碱烧伤。 那里 目前还没有令人满意的治疗方法。 它将 如果口腔粘膜和结膜两者都可以 被生物工程替代品所取代。问题出现在试图 为不断更新的组织构建替代品， 如口腔粘膜和结膜的上皮细胞。 所有持续 更新的上皮组织含有干细胞， 未分化的细胞能够自我更新，并负责 维持分化细胞群，这构成了 上皮组织结构 在复层鳞状上皮中， 细胞驻留在增殖基底细胞区室中， 人们普遍认为，它们的分裂频率低于其他物种， 增殖细胞群的数量， 损伤后的上皮细胞因此，当生物工程 上皮组织，我们包括适当的上皮干细胞， 在制作组织的初始阶段。 不幸的是，到目前为止， 分离上皮干细胞是有问题的。 此前，使用 氚标记的胸苷，我们能够标记一个亚群， 在小鼠皮肤和口腔粘膜中的循环基底细胞，我们称之为标签， 保留细胞（LRCs），表现出干细胞的许多特征， 细胞 这种标记方法在过去十年中一直被用于 在其他几种上皮细胞中识别干细胞，包括四肢， the eye. 最近，我们发明了一种方法， 干细胞数量从2%增加到50%以上， 这些选择的细胞显示出生长和再增殖的潜力 预期是表皮干细胞。 在这项研究中，我们建议使用我们的 一种从口腔粘膜中筛选干细胞的新富集方法， 角膜缘上皮，以确定这些细胞显示克隆形成 干细胞在体外的特性，它们可以用于生物工程 组织作为长期替代品，并确定是否干 细胞对内在或外在因素作出反应， 特定的组织连接。

Grafting skin into the oral cavity is commonly used for vestibular extension procedures, repair of trauma induced defects, and to reconstruct large oral mucosal defects resulting from excision of malignant tumors. However, skin grafted into the oral cavity maintains its original structure and function, and often patients experience hair growth and sweating from the grafted skins. Ideally, oral mucosal tissues would be used for such grafts, but this is limited by a lack of sufficient donor tissue. Like the tissues in the oral cavity, the conjunctiva is a mucosal tissue that lines the eye and the eyelids. It is comprised of a non-keratinizing stratified squamous epithelium, similar to the buccal mucosa. Two conditions produce diffuse conjunctival scarring, which result in painful visual loss: ocular cicatricial pemphigoid and alkali burns of the ocular surface. There is currently no satisfactory treatment for either condition. It would highly desirable if both the oral mucosa and the conjunctiva could be replaced with bioengineered substitutes. The problem arises when trying to build replacements for tissues that are continuously renewing, such as the epithelia of the oral mucosa and conjunctiva. All continuously renewing epithelial tissues contain stem cells, which are the undifferentiated cells capable of self-renewal and responsible for the maintenance of the differentiating cell population, which makes up the epithelial tissue architecture. In stratified squamous epithelia, stem cells reside in the proliferative basal cell compartment, and it has been generally accepted that they divide less frequently than the rest of the proliferative cell population and that they repopulate the epithelia after damage. Thus, it is critical when bioengineering epithelial tissues that we include the appropriate epithelial stem cells in the initial phase of making the tissues. Unfortunately, to date, isolating epithelial stem cells has been problematic. Previously, using tritiated thymidine, we were able to label a subpopulation of slowly- cycling basal cells in mouse skin and oral mucosa that we called label- retaining cells (LRCs), which showed many of the characteristics of stem cells. This tagging method has been used for the last decade to identify stem cells in several other epithelia, including the limbs of the eye. Recently, we have devised a method that enriches the epidermal stem cell population from 2 percent to over 50 percent, and further that these selected cells show the growth and repopulation potential expected for epidermal stem cells. In this study, we propose to use our novel enrichment method to select stem cells from oral mucosal and limbal epithelia, to determine that these cells show the clonogenic properties of stem cells in vitro, and they can be used to bioengineer tissues for use as long term replacements, and to determine whether stem cells respond to intrinsic or extrinsic factors when maintaining specific tissue junctions.