Stem cell organisation and differentiation in the niche

人们期望干细胞有朝一日能够治愈多种人类疾病。然而，干细胞疗法的发展依赖于对这些令人着迷的细胞生物学的良好理解。干细胞在人体内占据着一种特殊的环境，被称为？利基？它控制着干细胞的行为和存活。大多数人类干细胞的位置都在人体深处，因此很难研究。位于眼睛前表面的角膜最外层有干细胞，这些干细胞生活在一个名为角膜缘的透明区域。我们最近在角膜缘发现了新的结构，我们认为这可能是干细胞的利基。我们建议使用扫描电子显微镜和共聚焦显微镜等技术来研究捐献的人类角膜中的这些结构和相关细胞，以确定干细胞的确切位置和它们的功能。我们还将研究年龄对干细胞及其生态位的影响。这一点非常重要，因为在临床上，可以对健康的角膜缘进行小范围的活组织检查，为因特定损伤或角膜最外层疾病而失明的患者准备干细胞治疗。然而，我们和其他人在不知道最佳活检位置的情况下提供了这种疗法。因此，我们的研究将改进这项手术技术。我们还必须能够改进对个别患者的治疗，这需要了解干细胞移植后会发生什么。我们建议开发一种标记干细胞并将其移植到人类角膜上的技术，使用非常小的颗粒，这些颗粒发出明亮的荧光，可以用临床仪器检测到。使用这种方法，我们还将确定干细胞在移植后在利基细胞中的组织情况，以及它们是否对该利基细胞有任何影响。我们的数据将帮助我们了解有助于视力清晰的眼睛的重要特征之一(即，角膜缘中健康、功能正常的干细胞)，这将有助于改进角膜的干细胞治疗。如果发现我们的数据提供了与其他人类干细胞利基环境的相似之处，它将支持使用易于接触的透明角膜作为开发其他干细胞疗法的模型。

There is an expectation that stem cells will one day be able to cure a wide variety of human diseases. However, development of stem cell therapies relies upon a sound understanding of the biology of these fascinating cells. Stem cells occupy a specialised environment in the body known as a ?niche? which controls stem cell behaviour and survival. Most human stem cell niches are deep in the body and so difficult to study. The outermost layer of the cornea on the front surface of the eye has stem cells which live in a transparent area called the limbus. We have recently discovered new structures in the limbus which we believe may be the stem cell niche. We propose to study these structures and the cells associated them in donated human corneas using techniques including scanning electron and confocal microscopy determine where exactly the stem cells are and how they function. We will also study the effect of age upon the stem cells and their niche. This is very important because clinically it is possible to take a small biopsy of the healthy limbus to prepare stem cell therapy for patients blinded by specific injuries or diseases of the outermost layer of the cornea. However, we and others are providing this therapy without knowing the optimal biopsy location. Our study will therefore improve this surgical technique. We must also be able to refine treatments for individual patients which requires knowledge of what happens to the stem cells after they have been transplanted. We propose to develop a technique for labelling and transplanting stem cells onto the human cornea using very small particles which fluoresce brightly and can be detected with clinical instruments. Using this methodology we will also determine how well stem cells organise themselves in the niche after transplantation and if they have any affect upon that niche. Our data will help us to understand one of the important features of the eye which contributes to clear vision (i.e. healthy, functioning stem cells in the limbus) which will help to improve stem cell therapy for the cornea. If it is found that our data provide parallels with other human stem cell niches, it would support the use of the readily accessible and transparent cornea as a model for the development of other stem cell therapies.