Hematopoietic Stem Cells Regenerate RPE

描述(申请人提供)：视网膜色素上皮(RPE)功能障碍与多种眼部疾病有关，包括老年性黄斑变性(AMD)以及遗传性疾病，如Stargardt病和视网膜色素变性。RPE具有广泛的重要功能，可以保护视网膜的其他细胞并维持正常的视网膜生理。对于眼睛来说，RPE层的功能与组织巨噬细胞在其他器官中的功能相同。在这种能力下，RPE不断地暴露在自由基释放和其他代谢分解产物中。随着年龄的增长，累积的损害导致整体RPE功能下降，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这一层翻转或再生。几种治疗模式试图通过直接移植来取代眼睛内的RPE。到目前为止，这些模式取得的成功非常有限。RPE层的一个特点是产生各种细胞因子，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为HSC/HPC进入RPE层提供了通道。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。我们采用了三种急性损伤RPE层的模型，然后进行标记HSC/HPC移植。在每一种模型中，供体HSC/HPC都能够在损伤的RPE层中定位和整合。供体-HSC/HPC来源的细胞采用了RPE特有的立方形态，在白化受体的电子和光学显微镜下表达黑色素，PAN白细胞标志CD45的表达缺失。综上所述，这些数据表明HSC/HPC可以被招募到受损的RPE层，在那里它们分化为RPE或RPE样细胞。在这项提案中，我们试图扩展这些初步发现，并检验以下具体假设：目的1：HSC/HPC可以修复急性损伤后的RPE功能。目的：HSC/HPC在急性RPE损伤区的募集需要损伤区特异性细胞因子的表达。这些细胞因子反应的增强应该会促进HSC/HPC的修复。目的3：HSC/HPC也能在慢性损伤后再生RPE。

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.