Elucidating the Molecular Underpinnings of Endogenous RPE Regeneration

摘要：导致视网膜色素上皮(RPE)退化的疾病是主要的 在世界范围内导致失明的原因，目前还没有可以取代RPE或恢复失明视力的治疗方法。与年龄相关的 黄斑变性(AMD)就是这样一种疾病，是世界上第三大致盲原因。 虽然有一些有效的治疗渗出性(湿)AMD的方法，但约90%的AMD病例是萎缩性(干性)和 这些目前是无法治疗的。干细胞来源的RPE移植已经成为一种可能 治疗地理萎缩和临床试验正在进行中。然而，人们对他的命运知之甚少 移植的RPE以及能否提高其存活率和整合能力。一个引人入胜的选择 治疗AMD和其他RPE疾病的方法是开发专注于刺激内源性的治疗方法 RPE再生。要做到这一点，我们必须首先对机制有更深入的了解。 潜在的RPE再生。在哺乳动物中，RPE的再生极其有限，在某些情况下，RPE 细胞在损伤后过度增殖，例如在增生性玻璃体视网膜病变期间，其中增殖的RPE细胞 侵入视网膜下间隙，导致失明。最近，一个静止的人类RPE干细胞亚群 鉴定出在体外可被诱导增殖并分化为RPE或间充质细胞的细胞 类型，这表明人的RPE包含一群可以被诱导再生的细胞。 尽管有这些研究，但对RPE细胞如何对损伤做出反应以引发 再生反应，而不是病态反应。事实上，还没有研究表明 在任何模型系统中，在严重的RPE损伤之后，功能性RPE单层。这种技术的发展 模型是深入了解RPE背后的分子机制的关键第一步 再生。这一知识差距是制定有效战略以恢复RPE损失的主要障碍 疾病或伤害，这是我们提案的重点。我们开发了一种转基因斑马鱼模型来研究RPE 研究表明，斑马鱼的RPE在严重损伤后会再生。我们进一步 证明1)RPE再生涉及一个强大的增殖反应，在这个过程中，增殖的细胞 转移到损伤部位并分化为RPE，II)再生细胞的来源可能是未受损伤的 外周RPE，III)使用这个系统，我们可以识别再生的分子基础 反应，以及iv)先天免疫系统在RPE再生中起着关键作用。在这方面的实验 建议建立在这些强大的初步数据的基础上，以测试RPE再生受 损伤激活的常驻RPE细胞群，在损伤后增殖并再生丢失的RPE组织。 了解损伤反应的RPE细胞如何在体内增殖，以及在 损伤反应具有确定刺激或重新激活人类这一能力的策略的重要前景 这将是治疗AMD和其他影响RPE的疾病的变革性药物。

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.