Assembling Retinal Organoids with Microglia
Summary
Microglia are unique resident immune cells in the retina, playing crucial roles in various retinal degenerative diseases. Generating a co-culture model of retinal organoids with microglia can facilitate a better understanding of the pathogenesis and development progress of retinal diseases.
Abstract
Due to the limited accessibility of the human retina, retinal organoids (ROs) are the best model for studying human retinal disease, which could reveal the mechanism of retinal development and the occurrence of retinal disease. Microglia (MG) are unique resident macrophages in the retina and central nervous system (CNS), serving crucial immunity functions. However, retinal organoids lack microglia since their differentiation origin is the yolk sac. The specific pathogenesis of microglia in these retinal diseases remains unclear; therefore, the establishment of a microglia-incorporated retinal organoid model turns out to be necessary. Here, we successfully constructed a co-cultured model of retinal organoids with microglia derived from human stem cells. In this article, we differentiated microglia and then co-cultured to retinal organoids in the early stage. As the incorporation of immune cells, this model provides an optimized platform for retinal disease modeling and drug screening to facilitate in-depth research on the pathogenesis and treatment of retinal and CNS-related diseases.
Introduction
As the limited source of the human retina, the differentiation of human stem cells into three-dimensional (3D) retinal organoids represents a promising in vitro model for simulating the retina1. It contains different cell types in the retina, including photoreceptors, retinal ganglion cells, bipolar cells, Müller cells, horizontal cells, and astrocytes2. This model enables the emulation and study of both retinal development mechanisms and the pathogenesis of retinal diseases. However, due to the directional differentiation method, retinal organoids were derived from the neuroectoderm3, lacking many other cell types originating from different germ layers, such as microglia from the yolk sac and perivascular cells from the mesoderm4,5,6.
At present, many retinal diseases, such as retinitis pigmentosa7, glaucoma8, and retinoblastoma9, have been proven to be closely related to microglia within the retina. However, due to the lack of proper research models, specific mechanisms illustrating the relationship between microglia and these diseases still remain unclear. While mice have served as a favorable model for studying retinal diseases, recent studies have highlighted significant differences between mouse and human microglia in terms of lifespan, proliferation rate, and the absence of human homologous genes10,11. These findings suggested that conclusions drawn from mouse models may not be entirely reliable, emphasizing the importance of constructing human retinal organoids containing microglia.
Over the past few decades, various methods for the 3D differentiation of retinal organoids have been developed12,13. To facilitate the co-culture operation of microglia within retinal organoids, we have selected a differentiation method involving a transition from adherent to suspension culture. This approach successfully enables microglia to be incorporated into the retinal organoids, maintaining them for at least 60 days14.
Protocol
Representative Results
Discussion
Due to the restricted availability of the human retina, our current comprehension of retinal inflammatory responses almost comes from animal models. To overcome this limitation, retinal organoids were differentiated. The development of retinal organoid models has been an active area of research, aiming to recapitulate the complexity of the human retina for disease modeling and therapeutic development. Several studies have reported successfully generating retinal organoids from human pluripotent stem cells<sup class="xref…
Divulgaciones
The authors have nothing to disclose.
Acknowledgements
This study is supported by the National Natural Science Foundation of China (82101145) and the Beijing Natural Science Foundation (Z200014).
Materials
| Acctuase | Stemcell Technologies | 07920 | |
| Advanced DMEM/F12 | Thermo | 12634-010 | |
| Anti-CRX(M02) | abnova | H00001406-M02 | Antibody; dilution as per the manufacturer's instructions |
| Anti-IBA1 | Abcam | ab5076 | Antibody; dilution as per the manufacturer's instructions |
| B27 | Life Technologies | 17105-041 | |
| Dispase (1U/mL) | Stemcell Technologies | 07923 | |
| DMEM basic | Gibco | 10566-016 | |
| DMEM/F12 | Gibco | 10565-042 | |
| DPBS | Gibco | C141905005BT | |
| EDTA | Thermo | 15575020 | |
| F12 | Gibco | 11765-054 | |
| FBS | Biological Industry | 04-002-1A | |
| Gelatin | Sigma | G7041-100G | Solid |
| Glutamax | Gibco | 35050-061 | |
| H9 cell line | WiCell Research Institute | ||
| IL-3 | RD Systems | 203-IL-050 | |
| IL-34 | PeproTech | 200-34-50UG | |
| KSR | Gibco | 10828028 | |
| Matrix | Corning | 356231 | |
| M-CSF | RD Systems | 216-MC-500 | |
| MEM Non-essential Amino Acid Solution | Sigma | M7145 | |
| N2 | Life Technologies | 17502-048 | |
| Neurobasal | Gibco | 21103-049 | |
| Pen/strep | Gibco | 15140-122 | |
| Stem cell medium | Stemcell Technologies | 5990 | |
| Taurine | Sigma | T-8691-25G | |
| X-ViVO | LONZA | 04-418Q | |
| Y27632 | Selleck | S1049 | |
| β-mercaptoethanol | Life Technologies | 21985-023 |
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