Stem Cells for Corneal Engineering

在美国，人口老龄化和屈光手术的普及威胁着用于移植的角膜供应的充分性。在世界范围内，角膜捐赠已经不足，导致600万至800万人患有角膜失明。在实验室培育并按需提供的人造角膜最终将有助于缓解这一公共卫生问题。该项目的长期目标是利用培养的人类干细胞开发可用于移植的等量角膜。最初，该项目将重点关注角膜基质，即占角膜质量90%的结缔组织。我们最近从人角膜基质中发现了一群具有成体干细胞特性的细胞。与角化细胞不同，人角膜基质干细胞（hCSSC）可以在培养中多次传代，但在体内和体外仍保留成为角化细胞的能力。我们推测人角膜基质干细胞在体内和体外均参与角膜损伤反应，并能再生透明基质组织。这一假设将被验证(1)，通过证明hCSSC流入病理人类角膜，并通过记录hCSSC在体内引入正常和愈合的小鼠角膜的命运。(2)用hCSSC治疗出现类似角膜疤痕和注射转化生长因子β瘢痕的Lumican null小鼠，观察这些细胞恢复角膜透明的能力。(3)将hCSSC体外生成的组织等量物植入小鼠角膜，研究间质组织对透明度的分子和结构要求。这些目标的成功实现将阐明新发现的成体基质干细胞的生物学作用，并为基质超微结构和角膜透明度在体内的维持提供新的信息。该实验还将开发角膜瘢痕细胞治疗和可直接用于板层的生物工程组织制造的基本技术

DESCRIPTION: Aging of the population and popularity of refractive surgery threaten adequacy of the cornea supply used for transplantation in the USA. World-wide, cornea donations already fall short, leaving 6-8 million individuals suffering corneal blindness. Engineered corneas, grown in the laboratory and available on demand, will ultimately help alleviate this public health problem. The long-term goal of this project is to develop corneal equivalents for transplantation using cultured human stem cells. Initially the project will focus on the corneal stroma, the connective tissue that makes up 90% of the corneal mass. We have recently discovered a population of cells from human corneal stroma with properties of adult stem cells. Unlike keratocytes, the human corneal stromal stem cells (hCSSC) can be passaged numerous times in culture but still retain the ability to become keratocytes in vivo and in vitro. We hypothesize that the human corneal stromal stem cells participate in response to corneal injury and can regenerate transparent stromal tissue both in vivo and in vitro. This hypothesis will be tested (1) by demonstrating the influx of hCSSC into pathological human corneas and by documenting the fate of hCSSC introduced into normal and healing mouse corneas in vivo. (2) Lumican null mice which develop opacity similar to corneal scars and corneas scarred by injection of transforming growth factor beta will be treated with hCSSC to investigate observed ability of these cells to restore corneal transparency. (3) Tissue equivalents produced in vitro by hCSSC will be implanted into mouse cornea to investigate the molecular and structural requirements for transparency in stromal tissue. Successful accomplishment of these aims will elucidate biological roles of the newly discovered adult stromal stem cells and provide novel information about how the stromal ultrastructure and corneal transparency are maintained in vivo. The experiments will also develop essential technologies for cell-based therapy for corneal scars and for fabrication of bioengineered tissue which could be used directly for lamellar keratoplasty or serve as the basis of a fully bioengineered cornea.