Hematopoietic Stem Cells Regenerate RPE

描述（由申请人提供）：视网膜色素上皮（RPE）的功能障碍与多种眼部疾病有关，包括年龄相关性黄斑变性（AMD）以及遗传性疾病，如Stargardt病和色素性视网膜炎。RPE具有多种重要功能，用于保护视网膜的其他细胞并维持适当的视网膜生理学。对于眼睛，RPE层的功能与其他器官中的组织巨噬细胞一样。在这种能力下，RPE不断暴露于自由基释放和其他代谢分解产物。随着年龄的增长，累积的损伤会降低整体RPE功能，这似乎是AMD建立和发展的关键步骤。RPE通常被认为是终末分化的细胞，很少或没有证据表明该层翻转或再生。几种治疗模型试图通过直接移植来替代眼内的RPE。迄今为止，这些模式取得的成功非常有限。RPE层的一个标志是产生多种细胞因子，如MCP-1和SDF-1。SDF-1是造血干/祖细胞（HSC/HPC）的主要募集因子之一。脉络膜的充足血液供应提供HSC/HPC进入RPE层。基于这些数据，我们测试了HSC/HPC是否有助于RPE层的修复和再生。我们使用了三种模型的急性损伤的RPE层，然后标记的HSC/HPC移植。在每个模型中，供体HSC/HPC能够归巢并整合在损伤的RPE层内。供体-HSC/HPC衍生的细胞采用RPE的特征性立方体形态，在白化病受体中通过电子和光学显微镜表达黑色素，并且全白细胞标记物CD 45的表达丧失。总的来说，这些数据表明HSC/HPC可以被募集到受损的RPE层，在那里它们分化成RPE或RPE样细胞。在这个建议中，我们试图扩展这些初步的研究结果，并测试以下具体的假设：目的1：HSC/HPC可以修复急性损伤后的RPE功能。目的2：HSC/HPC向急性RPE损伤区域的募集需要损伤区域的特异性细胞因子表达。这些细胞因子反应的增强应改善HSC/HPC修复。目的3：HSC/HPC对慢性损伤的RPE也有再生作用。

DESCRIPTION (provided by applicant): Dysfunction of the retinal pigmented epithelium (RPE) has been linked to a variety of ocular disorders including age-related macular degeneration (AMD) as well as hereditary disorders such as Stargardt's disease and Retinitis Pigmentosa. The RPE has a wide variety of crucial functions that serve to protect the other cells of the retina and maintain proper retinal physiology. For the Eye the RPE layer Functions as tissue macrophages do in other organs. In this capacity the RPE are constantly exposed to free radical release and other metabolic breakdown products. With age the accumulated damage serves to decrease overall RPE function, which appears to be a critical step in the establishment and progression of AMD. RPE are generally considered to be terminally differentiated cells with little or no evidence that the layer turns over or regenerates. Several therapeutic models attempt to replace RPE within the eye by direct transplant. These models have so far yielded very limited success. One hallmark of the RPE layer is the production of a variety of cytokines such as MCP-1 and SDF-1. SDF-1 is one of the primary recruitment Factors for the hematopoietic stem and progenitor cells (HSC/HPC). The ample blood supply of the choroid provides HSC/HPC access to the RPE layer. Based on these data we tested whether HSC/HPC can contribute to repair and regeneration of the RPE layer. We used three models of acute injury to the RPE layer followed by tagged HSC/HPC transplantation. In each model donor HSC/HPC were able to home to and integrate within the injured RPE layer. The donor-HSC/HPC derived cells adopted the characteristic cuboidal morphology of RPE, expressed melanin by electron and light microscopy in albino recipients, and the loss of expression of the pan leukocyte marker CD45. Collectively, the data suggests that HSC/HPC can be recruited to an injured RPE layer where they differentiate into RPE or RPE-like cells. In this proposal we seek to extend these initial findings and test the following specific hypotheses: Aim 1: HSC/HPC can repair RPE function following an acute injury. Aim 2: Recruitment of HSC/HPC to areas of acute RPE injury requires specific cytokine expression by the injured area. Enhancement of these cytokine responses should improve HSC/HPC repair. Aim 3: HSC/HPC can also regenerate the RPE in response to chronic injury.