Elucidating the Molecular Underpinnings of Endogenous RPE Regeneration

摘要：导致视网膜色素上皮细胞（RPE）变性的疾病是导致视网膜色素上皮细胞（RPE）变性的主要原因之一。 视网膜色素上皮是全球范围内的致盲原因，目前还没有可以替代视网膜色素上皮或恢复视力的治疗方法。年龄相关 黄斑变性（AMD）就是这样一种疾病，并且是世界上第三大致盲原因。 虽然对于渗出性（湿性）AMD存在一些有效的治疗，但约90%的AMD病例是萎缩性（干性）， 目前无法治愈。干细胞衍生的RPE移植已经成为治疗视网膜病变的一种可能。 治疗地图状萎缩和临床试验正在进行中。然而，人们对这一事件的命运知之甚少。 移植的RPE以及它们的存活和整合是否可以改善。一个有趣的替代方案 治疗AMD和其他RPE疾病的方法是开发专注于刺激内源性 RPE再生。要做到这一点，我们必须首先深入了解这些机制 潜在的RPE再生。在哺乳动物中，RPE再生极其有限，并且在某些情况下，RPE 细胞在损伤后过度增殖，例如在增殖性玻璃体视网膜病变期间，其中增殖性RPE细胞 侵入视网膜下腔导致失明最近，一个静止的人RPE干细胞亚群， 细胞在体外可被诱导增殖并分化为RPE或间充质细胞 这表明人类RPE含有一群可以被诱导再生的细胞。 尽管有这些研究，但人们对RPE细胞对损伤的反应过程知之甚少， 再生的而不是病理性的反应事实上，没有研究表明再生的一个 在任何模型系统中严重RPE损伤后的功能性RPE单层。发展这种 模型是深入了解RPE分子机制的关键第一步 再生这种知识差距是制定有效战略以恢复失去的RPE的主要障碍， 疾病或伤害，这是我们建议的重点。我们建立了一个转基因斑马鱼模型来研究RPE 损伤和再生，并证明斑马鱼RPE在严重损伤后再生。我们进一步 证明i）RPE再生涉及强烈的增殖反应，在此期间增殖细胞 移动到损伤部位并分化成RPE，ii）再生细胞的来源可能未受损伤 iii）使用该系统，我们可以识别再生性视网膜色素上皮细胞的分子基础。 iv）先天免疫系统在RPE再生中起关键作用。在这方面的实验 一项基于这些强有力的初步数据的建议，以检验RPE再生受 损伤激活的常驻RPE细胞群，其在损伤时增殖并再生丢失的RPE组织。 了解损伤反应性RPE细胞如何在体内增殖以及在增殖过程中激活的信号/途径 损伤反应对于确定刺激或重新激活人类这种能力的策略具有重要的希望。 这将是治疗AMD和其他影响RPE的疾病的变革。

SUMMARY: Diseases resulting in degeneration of the retinal pigment epithelium (RPE) are among the leading causes of blindness worldwide and no therapy exists that can replace RPE or restore lost vision. Age-related macular degeneration (AMD) is one such disease and is the third leading cause of blindness in the world. While there are some effective treatments for exudative (wet) AMD, ~90% of AMD cases are atrophic (dry) and these are currently untreatable. Transplantation of stem-cell derived RPE has emerged as a possibility for treating geographic atrophy and clinical trials are underway. However, little is known about the fate of transplanted RPE and whether their survival and integration can be improved. An intriguing alternative approach to treating AMD and other RPE diseases is to develop therapies focused on stimulating endogenous RPE regeneration. For this to be possible, we must first gain a deeper understanding of the mechanisms underlying RPE regeneration. In mammals, RPE regeneration is extremely limited and in some contexts RPE cells overproliferate after injury, such as during proliferative vitreoretinopathy, where proliferative RPE cells invade the subretinal space and lead to blindness. Recently, a subpopulation of quiescent human RPE stem cells was identified that can be induced to proliferate in vitro and differentiate into RPE or mesenchymal cell types, suggesting that the human RPE contains a population of cells that could be induced to regenerate. Despite these studies, little is known about the process by which RPE cells respond to injury to elicit a regenerative, rather than pathological, response. Indeed, no studies have demonstrated regeneration of a functional RPE monolayer following severe RPE damage in any model system. The development of such a model is a critical first step to acquiring a deeper understanding of the molecular mechanisms underlying RPE regeneration. This knowledge gap is a major barrier to developing effective strategies to restore RPE lost to disease or injury and is the focus of our proposal. We developed a transgenic zebrafish model to study RPE injury and regeneration and demonstrate that the zebrafish RPE regenerates after severe injury. We further demonstrate i) that RPE regeneration involves a robust proliferative response during which proliferative cells move to the injury site and differentiate into RPE, ii) that the source of regenerated cells is likely uninjured peripheral RPE, iii) using this system, we can identify the molecular underpinnings of the regenerative response, and iv) the innate immune system plays a critical role in RPE regeneration. Experiments in this proposal build off of these strong preliminary data to test the hypothesis that RPE regeneration is effected by a population of injury-activated resident RPE cells that proliferate upon injury and regenerate lost RPE tissue. Understanding how injury-responsive RPE cells proliferate in vivo and the signals/pathways active during the injury response holds significant promise to identify strategies to stimulate or reactivate this ability in the human eye, which would be transformational for treating AMD and other diseases that affect the RPE.