An oxygen gradient across the retina plays a crucial role in its development and function. The inner retina resides in a hypoxic environment (2% O2) adjacent to the vitreous cavity. Oxygenation levels rapidly increase towards the outer retina (18% O2) at the choroid. In addition to retinal stratification, oxygen levels are critical for the health of retinal ganglion cells (RGCs), which relay visual information from the retina to the brain. Human stem cell derived retinal organoids are being engineered to mimic the structure and function of human retina for applications such as disease modeling, development of therapeutics, and cell replacement therapies. However, rapid degeneration of the retinal ganglion cell layers are a common limitation of human retinal organoid platforms. We report the design of a novel retinal organoid chip (ROC) that maintains a physiologically relevant oxygen gradient and allows the maturation of inner and outer retinal cell phenotypes for human retinal organoids. Our PDMS-free ROC holds 55 individual retinal organoids that were manually seeded, cultured for extended periods (over 150 days), imaged in situ, and retrieved. ROC was designed from first principles of liquid and gas mass transport, and fabricated from biologically- and chemically inert materials using rapid prototyping techniques such as micromachining, laser cutting, 3D printing and bonding. After computational and experimental validation of oxygen gradients, human induced pluripotent stem cell derived retinal organoids were transferred into the ROC, differentiated, cultured and imaged within the chip. ROCs that maintained active perfusion and stable oxygen gradients were successful in inducing higher viability of RGCs within retinal organoids than static controls, or ROC without oxygen gradients. Our physiologically relevant and higher-throughput retinal organoid culture system is well suited for applications in studying developmental perturbations to primate retinogenesis, including those driven by inherited traits, fetal environmental exposure to toxic agents, or acquired by genetic mutations, such as retinoblastoma.

中文翻译：

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视网膜类器官芯片：设计拟态氧梯度，以优化人类视网膜类器官的长期培养。


视网膜上的氧梯度在其发育和功能中起着至关重要的作用。视网膜内层位于玻璃体腔附近的缺氧环境 （2% O2） 中。氧合水平向脉络膜处的外视网膜 （18% O2） 迅速增加。除了视网膜分层外，氧气水平对视网膜神经节细胞 （RGC） 的健康也至关重要，RGC 将视觉信息从视网膜传递到大脑。人类干细胞衍生的视网膜类器官正在被改造成模拟人类视网膜的结构和功能，用于疾病建模、治疗开发和细胞替代疗法等应用。然而，视网膜神经节细胞层的快速退化是人类视网膜类器官平台的常见限制。我们报道了一种新型视网膜类器官芯片 （ROC） 的设计，该芯片可维持生理相关的氧梯度，并允许人类视网膜类器官的内部和外部视网膜细胞表型成熟。我们的无 PDMS ROC 包含 55 个单独的视网膜类器官，这些类器官是手动接种、长时间培养（超过 150 天）、原位成像和检索的。ROC 是根据液体和气体质量传递的第一原理设计的，并使用快速原型制作技术（如微加工、激光切割、3D 打印和粘合）由生物和化学惰性材料制成。在氧梯度的计算和实验验证后，将人诱导的多能干细胞衍生的视网膜类器官转移到 ROC 中，在芯片内进行分化、培养和成像。 与静态对照或没有氧梯度的 ROC 相比，保持主动灌注和稳定氧梯度的 ROCs 成功地在视网膜类器官中诱导更高的 RGC 活力。我们的生理相关和高通量视网膜类器官培养系统非常适合研究灵长类动物视网膜发生的发育扰动的应用，包括由遗传性状驱动的扰动、胎儿环境暴露于有毒物质或通过基因突变（如视网膜母细胞瘤）获得。