Visualizing functional retinal integration of transplanted retinal ganglion cells

项目摘要 功能性视网膜神经节细胞（RGC）替代可以使数千万人恢复视力。 因青光眼和其他视神经病变而失明的人。技术的建立 从多能干细胞分化RGC和实现长距离 视神经内的内源性轴突再生支持RGC替代的前景 治疗然而，临床翻译需要在功能上的显著改进， 将移植的RGC整合到宿主视网膜神经回路中。为了能够研究 通过移植神经元的突触发生，我们建议开发和验证一种创新的， 多功能、灵敏的实验工具，利用小麦胚芽的跨突触转运 融合到Cre重组酶的凝集素（WGA）蛋白，以能够表达Cre依赖的 在突触整合供体神经元中的报告基因。标签经久耐用，便于下游 应用，如单细胞分离和转录组分析，以及双向，以允许 突触前或突触后移植物-宿主神经元伴侣的标记。在此，我们建议 建立人多能细胞系以与高效重组体结合使用 AAV载体来报告移植的RGC的功能性视网膜。由于表达了 由于荧光报告基因在基因组重组时是自动的，因此该工具将有助于实时 体内功能性神经元整合的检测。我们提出一个短波长（蓝色） 用于突触发生的荧光报告物，其将与另外的红色和绿色兼容 荧光显微镜和检眼镜检查。我们将描述 表达，并使用以下组合验证该突触发生报告工具的特异性： 高分辨率共聚焦显微镜，突触机制的免疫标记，以及单细胞 视网膜电生理学此外，我们还将研究 使用定制的自适应光学扫描激光器在体内移植人RGCs 检眼镜该仪器在xy平面内提供亚细胞分辨率， 通过z-叠加与视网膜的深度辨别。术后活体眼纵向成像 因此，移植将使供体RGC树突靶向的相关性成为可能。 报告功能性突触发生的内丛状层。我们将描述 导致供体RGC的视网膜整合的结构事件。这项工作将提供 未来实验的基础，包括操纵主机微环境， 提高植入效率、整合RGC的体内光学电生理学和鲁棒性 使用细胞特异性报告小鼠分析RGC与各种常驻视网膜细胞的相互作用。

PROJECT SUMMARY Functional retinal ganglion cell (RGC) replacement could restore vision to tens of millions of people who are blind from glaucoma and other optic neuropathies. Establishment of techniques for RGC differentiation from pluripotent stem cells and the achievement of long-distance endogenous axon regeneration within the optic nerve support the promise of RGC replacement therapies. However, clinical translation requires significant improvements in the functional integration of transplanted RGCs into the host retinal neurocircuitry. To enable the study of synaptogenesis by transplanted neurons, we propose developing and validating an innovative, versatile, sensitive, experimental tool that leverages transsynaptic transport of wheat germ agglutinin (WGA) protein fused to Cre recombinase to enable expression of a Cre-dependent reporter in synaptically integrated donor neurons. The label is durable, facilitating downstream applications such as single cell isolation and transcriptomic analysis, and bidirectional to allow the labeling of either pre- or post-synaptic graft-host neuronal partners. Here, we propose to establish human pluripotent cell lines to be used in conjunction with highly efficient recombinant AAV vectors to report the functional retinal of transplanted RGCs. Since expression of the fluorescent reporter is automatic upon genomic recombination, the tool will facilitate real-time detection of functional neuronal integration in vivo. We propose a short wavelength (blue) fluorescent reporter for synaptogenesis, which will be compatible with additional red and green fluorescence for multicolor microscopy and ophthalmoscopy. We will characterize the kinetics of expression and validate the specificity of this synaptogenesis reporter tool using a combination of high-resolution confocal microscopy, immunolabeling of synaptic machinery, and single-cell electrophysiology within retinal flatmounts. Further, we will study the functional integration of transplanted human RGCs in vivo using a custom-built multicolor adaptive optics scanning laser ophthalmoscope. The instrumentation provides subcellular resolution within in the xy plane and depth discrimination with the retina through z-stacking. Longitudinal imaging of living eyes post- transplantation will therefore enable the correlation of donor RGC dendrites targeting of the inner plexiform layer with reporting of functional synaptogenesis. We will characterize the structural events leading to retinal integration of donor RGCs. This work will provide a foundation for future experimentation that includes manipulation of the host microenvironment to improve engraftment efficiency, in vivo optical electrophysiology of integrated RGCs, and robust analyses of RGC interactions with various resident retinal cells using cell-specific reporter mice.