The Stem Cell Niche and Lens Fibrotic Disease

干细胞生态位和晶状体纤维化疾病

• 批准号: 7639113
• 负责人: Janice Lynn Walker
• 金额: $ 22.82万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7639113
• 关键词: Antigens; Automobile Driving; Behavior; Biological Models; Biological Preservation; Blocking Antibodies; Bromodeoxyuridine; Cadherins; Calcium; Cataract; Cataract Extraction; Cell Lineage; Cell Proliferation; Cell physiology; Cell surface; Cells; Complement; Confocal Microscopy; Cytometry; Development; Disease; Epiblast; Epithelial Cells; Etiology; Fibrosis; Goals; Immunofluorescence Immunologic; Injury; Integrins; Label; Lead; Lens Diseases; Lens Opacities; Location; Magnetism; Maintenance; Mediating; Mesenchymal; Modeling; Muscle satellite cell; Myofibroblast; Phenotype; Regulation; Resolution; Role; Skeletal Muscle; Smooth Muscle; Smooth Muscle Actin Staining Method; Sorting - Cell Movement; Source; Stem cells; System; Techniques; Therapeutic; Time; Vision; capsule; cell behavior; cell motility; lens; lens capsule; lens induction; migration; precursor cell; prevent; public health relevance; research study; response; response to injury; skeletal; src-Family Kinases; stem; stem cell niche; stem cell population; wound

DESCRIPTION (provided by applicant): The stem cell niche regulates stem cell function through mechanisms not well understood. We have developed an "ex vivo" culture model system, which allows us the unique ability to study stem/progenitor cell behavior response to injury within their native microenvironment. This system was established as a model for the fibrotic lens disease, Posterior Capsule Opacification, which involves collective migration of lens epithelial cells onto the posterior capsule and the emergence of mesenchymal cells. The etiology of this disease is unknown. Recently, a small subpopulation of myo D/G8 antigen positive epiblast-skeletal muscle stem cells has been identified in the lens. In our "ex vivo" model we have identified a these G8 positive (G8pos) epiblast- skeletal muscle stem cells within a niche nestled among the lens epithelial cells of the equatorial zone (EQ), that remain tightly adherent to the lens capsule after our mock cataract surgery. Upon injury in our "ex vivo" model we detect G8 antigen positive epiblast-skeletal muscle stem/progenitor cells moving from their native microenvironment within the EQ zone to the leading edge of the collectively migrating lens epithelial cells. G8pos skeletal muscle stem/progenitor cells may provide the source of 1-smooth muscle actin positive myofibroblasts detected in lens fibrotic diseases. We hypothesize that disruption of the G8pos epiblast- skeletal muscle stem cell niche, such that could occur during lens injury and cataract surgery, causes the aberrant regulation and emergence of mesenchymal cell precursors that 1) drive the collective migration of the lens epithelial cells for wound closure and 2) transdifferentiate into myofibroblasts causing fibrosis. Our "ex vivo" culture model provides the unique opportunity to ask fundamental questions regarding how reciprocal interactions are regulated within the stem cell niche, such as between niche stem/progenitor cells and their surrounding lens cells, and between the cells in the niche and their matrix microenvironment, all in response to wounding. Elucidation of such mechanisms could not only broaden our understanding of the behavior of a subset of stem/progenitor cells in response to injury-induced changes to their niche but also lead to the development of anti-fibrotic therapeutics to preserve vision. The major goals of this proposal are to 1) Examine the hypothesis that G8pos cells found outside the niche following injury to the lens are derived from amplification of the G8pos epiblast-skeletal muscle stem cell population and/or by recruitment of lens epithelial cells to the G8 lineage. 2) Examine the hypothesis that cadherin-mediated cell-cell and integrin-mediated cell- matrix interactions are critical determinants essential to maintain the normal G8 stem cell niche and are altered upon injury for emergence of G8pos mesenchymal precursor cells. 3) Examine the hypothesis that alterations in the G8pos epiblast skeletal muscle stem cell niche causes the aberrant regulation and emergence of mesenchymal precursors that drive collective migration of lens epithelial cells and ultimately transdifferentiate into myofibroblast. PUBLIC HEALTH RELEVANCE: Lens fibrotic disease causes lens opacities leading to the formation of cataracts which block vision. The exact etiology of lens fibrotic disease is unknown and the long term goals of this project are to understand the role of a subpopulation of G8pos skeletal muscle stem cells, which are located in the lens and emerge from their stem cell niche upon injury, in the induction of lens fibrotic disease. Elucidation of such mechanisms could not only broaden our understanding of stem cell behavior in response to injury-induced changes to their niche but also lead to the development of anti-fibrotic therapeutics to preserve vision.

描述（由申请人提供）：干细胞龛通过尚不清楚的机制调节干细胞功能。我们已经开发了一种“离体”培养模型系统，这使我们能够研究干/祖细胞在其天然微环境中对损伤的行为反应。该系统被建立为纤维化透镜疾病，后囊膜混浊的模型，其涉及透镜上皮细胞集体迁移到后囊膜上和间充质细胞的出现。这种疾病的病因不明。最近，在透镜中发现了一小部分肌球蛋白D/G8抗原阳性的外胚层-骨骼肌干细胞。在我们的“离体”模型中，我们已经鉴定了位于赤道区（EQ）的透镜上皮细胞之间的小生境内的这些G8阳性（G8 pos）外胚层-骨骼肌干细胞，其在我们的模拟白内障手术后保持紧密粘附于透镜囊。在我们的“离体”模型中损伤后，我们检测到G8抗原阳性的外胚层-骨骼肌干细胞/祖细胞从EQ区内它们的天然微环境移动到集体迁移的透镜上皮细胞的前缘。G8 pos骨骼肌干/祖细胞可能提供在透镜纤维化疾病中检测到的1-平滑肌肌动蛋白阳性肌成纤维细胞的来源。我们假设，G8 pos外胚层-骨骼肌干细胞小生境的破坏，例如可能发生在透镜损伤和白内障手术期间，导致间充质细胞前体的异常调节和出现，其1）驱动透镜上皮细胞的集体迁移以用于伤口闭合和2）转分化成肌成纤维细胞，从而导致纤维化。我们的“离体”培养模型提供了独特的机会来询问关于干细胞龛内如何调节相互作用的基本问题，例如龛干/祖细胞与其周围透镜细胞之间，以及龛中的细胞与其基质微环境之间，所有这些都是对创伤的响应。阐明这些机制不仅可以拓宽我们对干/祖细胞亚群响应损伤诱导的其生态位变化的行为的理解，而且还可以导致抗纤维化治疗的发展，以保护视力。该提议的主要目的是1）检验以下假设：在透镜损伤后在小生境外发现的G8 pos细胞来源于G8 pos外胚层-骨骼肌干细胞群的扩增和/或通过透镜上皮细胞向G8谱系的募集。2)检查以下假设：钙粘蛋白介导的细胞-细胞和整合素介导的细胞-基质相互作用是维持正常G8干细胞生态位所必需的关键决定因素，并且在损伤后发生改变以出现G8 pos间充质前体细胞。3)检查G8 pos外胚层骨骼肌干细胞龛的改变导致间充质前体的异常调节和出现的假设，所述间充质前体驱动透镜上皮细胞的集体迁移并最终转分化成肌成纤维细胞。公共卫生相关性：透镜纤维变性疾病导致透镜混浊，进而形成白内障，阻碍视力。透镜纤维化疾病的确切病因尚不清楚，本项目的长期目标是了解G8 pos骨骼肌干细胞亚群在诱导透镜纤维化疾病中的作用，G8 pos骨骼肌干细胞位于透镜中，并在损伤后从其干细胞龛中出现。阐明这些机制不仅可以拓宽我们对干细胞行为的理解，以应对损伤引起的干细胞生态位变化，而且还可以促进保护视力的抗纤维化治疗方法的开发。