Nanoscale Structural Characterisations of Ocular Tissues Derived from Human iPS Cells

组成我们身体的细胞具有特定的功能，并适应于它们所在的特定组织。成熟细胞通常被称为分化细胞，因为它们已经适应了它们的生物学作用。很长一段时间以来，人们都认为，一旦一个细胞“选择了它的路径”并分化成一种特定类型的细胞，它就开始了一段不可逆转的旅程。然而，2012年，分别来自剑桥大学和京都大学的约翰·戈登爵士（Sir John gordon）和山中伸弥（Shinya Yamanaka）教授因他们的研究获得了诺贝尔奖。他们的研究表明，分化的成年细胞可以通过基因重新编程，变得分化程度较低，并能够形成许多不同的细胞类型。这种细胞被称为诱导多能干细胞，通常简称为iPS细胞。我们提出的这项新研究源于我们与日本合作者的发现，即人类iPS细胞（hipsc）可以在实验室中培养，以模仿出生前人眼细胞发育的方式生长。眼睛的组成组织具有相互关联的发育途径，覆盖眼睛表面的角膜和结膜上皮，眼睛内的晶状体和产生眼泪的泪腺都是从同一类型的细胞进化而来的。hiPSCs已经生成了薄的角膜和结膜上皮薄片，其中一些角膜薄片已被用于恢复视力丧失患者的视力。新的研究现在开始展示hiPSCs如何用于形成泪腺和晶状体的3D类器官（器官或其特定方面的微型化版本）。它们是关键的眼部组织，分别帮助合成泪膜和将光线聚焦到视网膜上。然而，这些类器官如何准确地模仿自然组织还有待充分认识。我们现在计划使用高规格电子显微镜和高强度x射线束（包括使用世界上最强大的实验x射线源，日本的SPring8同步加速器）进行一系列实验，以全面了解由hiPSCs产生的泪腺和晶状体的3D类器官。视力丧失对一个人的生活有着毁灭性的影响。社会成本也很严重，伦敦经济学院的研究人员估计，英国每年因视力丧失而造成的经济成本为252亿英镑，预计到2050年将上升到335亿英镑。健康的泪腺和晶状体对正确的视力至关重要。泪腺功能失调会导致严重的干眼综合征，影响全世界数千万人，如果不及时治疗，可能导致角膜溃疡和失明。此外，白内障（混浊的晶状体）是导致视力下降的唯一主要原因，尤其是在老年人中。我们的研究有可能对未来产生真正的影响，因为由人类细胞形成的特征良好的3D泪腺样和晶状体样器官代表了一种极好的资源，作为动物实验的替代方案，科学家可以设计和测试新的药物来治疗/预防泪腺和晶状体威胁视力的疾病。此外，hipsc衍生的类器官，当更充分地了解和进一步研究时，有可能用于移植手术。在近期或中期，由于可植入的人工晶状体的可用性，类器官移植的研究可能会针对泪腺而不是晶状体病理的治疗。正确表征hipsc衍生的晶状体样器官的直接价值预计在于它们用于研究抑制或逆转晶状体蛋白聚集和老年白内障发展的药物。

The cells that comprise our body have specific functions and are adapted to suit the particular tissue in which they exist. Mature cells are generally known as differentiated cells because they have become tailored to their biological role. For a long time, it was accepted that once a cell had "chosen its path" and differentiated into a particular type of cell, it had embarked on an irreversible journey. However, in 2012 Professors Sir John Gurdon and Shinya Yamanaka, of Cambridge and Kyoto Universities, respectively, were awarded the Nobel Prize for their research, which showed that differentiated adult cells could be genetically reprogrammed to become less differentiated and capable of forming many different cell types. Such cells are called induced pluripotent stem cells, commonly abbreviated to iPS cells. The new research we propose originates with the discovery, made with our collaborators in Japan, that human iPS cells (hiPSCs) can be cultivated in the laboratory to grow in a manner that mimics the way cells in the human eye develop before birth.Component tissues of the eye have interrelated developmental pathways, with the corneal and conjunctival epithelia that cover the eye's surface, the lens within the eye and the tear-producing lacrimal gland all evolving from the same cell type. Thin flat sheets of corneal and conjunctival epithelia have been generated from hiPSCs, and some of the corneal sheets have been used to restore sight in patients with vision loss. New research is now starting to show how hiPSCs can be used to form 3D organoids (miniaturised versions of an organ or selected aspects of it) of lacrimal gland and lens. These are key ocular tissues, which, respectively, help synthesise the tear film and focus light onto the retina. How accurately these organoids mimic the natural tissue, however, is yet to be fully appreciated. We now plan a series of experiments using high-specification electron microscopes and high-intensity x-ray beams (including use of the world's most powerful experimental x-ray source, the SPring8 synchrotron in Japan) to obtain a comprehensive understanding of 3D organoids of lacrimal glands and lenses generated from hiPSCs.Vision loss has a devastating impact on an individual's life. The societal cost, too, is severe, with researchers at The London School of Economics estimating that the economic cost to the UK of sight loss stands at £25.2 billion each year, predicted to rise to £33.5 billion by 2050. Healthy lacrimal glands and lenses are essential for correct vision. Dysfunctional lacrimal glands cause severe dry eye syndrome, which affects tens of millions of people worldwide and can result in corneal ulceration and blindness if left untreated. Cataracts (cloudy lenses), moreover, are the single major reason for sight loss, especially in the elderly. Our research has the potential to have real future impact because well-characterised 3D lacrimal gland-like and lens-like organoids formed from cells of a human origin represent an excellent resource, as an alternative to experiments on animals, for scientists to devise and test new medications to treat/prevent sight-threatening diseases of the lacrimal gland and lens. In addition, the hiPSC-derived organoids, when more fully understood and further investigated, have the potential to be used in transplant surgery. In the near/mid-term future, research into organoid transplantation will likely be directed towards the treatment of lacrimal gland, rather than lens, pathology because of the availability of implantable synthetic lenses. The immediate value of properly characterised hiPSC-derived lens-like organoids is predicted to lie in their use to investigate medications to inhibit or reverse lens protein aggregation and the development of cataract in old age.