Retinal Pigment Epithelium Regeneration by Induced Pluripotent Stem Cells; Therapeutic and Modelling Approaches on Retinal Degenerative Diseases

2021 ◽  
Vol 16 ◽  
Author(s):  
Shadi Setayeshi ◽  
Seyed Ahmad Rasoulinejad
Keyword(s):  
Retinal Pigment Epithelium ◽  
Disease Modeling ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Degenerative Diseases ◽  
Rpe Cells ◽  
Age Related ◽  
Retinal Degenerative Diseases ◽  
Epithelium Regeneration ◽  
Induced Pluripotent

Abstract: Retinal Degenerative Diseases [RDDs] are irreversible ocular damages categorized as retinopathies. RDDs affects about 0.05% of individuals worldwide. The degenerations of RPE cells are involved in inherited and age-related RDDs. After the invention of induced Pluripotent Stem Cell [iPSC] by Yamanaka, a promising window has been opened to regenerative medicine and disease modeling. Retinal pigment epithelium [RPE] degeneration related-RDDs are also affected by iPSCs. IPSC-derived RPE cells created a novel method for treating the RPE degeneration related-RDDs and retinal diseases modeling regarding finding a new therapeutic approach or drug development. There are various studies based on iPSC-derived RPE cells reporting the investigation of the role of a specific mutation, protein, signaling pathway, etc., responsible for a type of RDD. Furthermore, iPSC-based RPE therapy is expanded to include some clinical trials. Despite the incredible growth rate in iPSC-based studies in RPE-related diseases, there are some challenges, i.e., teratoma formation potential of iPSCs, the highly-cost procedure of iPSC-based regeneration of RPEs, lack of a universal protocol or cellular product applicable in all patients, etc. This article reviews the iPSC-based RPE generation and their therapeutic applications, studies on RPE-related molecular and cellular pathophysiologic features of RDD in the iPSC-based models, future perspectives, and the challenges ahead.

Transplantable and functional retinal pigment epithelium derived from non-colony-type monolayer of human induced pluripotent stem cells

2020 ◽  
Author(s):  
Xiaoling Guo ◽  
Deliang Zhu ◽  
Ruiling Lian ◽  
Qiaolang Zeng ◽  
Sanjana Mathew ◽  
...  
Keyword(s):  
Stem Cells ◽  
Retinal Pigment Epithelium ◽  
Pluripotent Stem Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Degenerative Diseases ◽  
Rpe Cells ◽  
Colony Type ◽  
Cell Spheroids ◽  
Induced Pluripotent

Abstract Background Retinal pigment epithelium (RPE) cells derived from human induced pluripotent stem cells (hiPSCs) exhibit great promise in treating retinal degenerative diseases. To develop transplantable and functional hiPSC-RPE cells, here, we used a novel differentiation protocol based on a non-colony-type monolayer (NCM) culture and injectable spheroids. Methods The derived hiPSC-RPE cells were identified using reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence assay, Western blotting, and flow cytometry assay. The functions of transplantable hiPSC-RPE cells in vitro and in vivo were also analyzed by fluorescein leakage test, transepithelial electrical resistance (TEER) assay, atomic force microscopy observation, POS phagocytosis assay, frozen tissue sections, live/dead assay, SA-β-Gal activity assay, and immunocytochemistry. Results The derived hiPSC-RPE cells positively expressed biomarkers of RPE cells but not iPSCs, such as CRALBP (97.4%), EMMPRIN (93.8%), Oct4 (2.1%), and Sox2 (2.0%). hiPSC-RPE cells displayed RPE-like characteristics including barrier function, phagocytic activity, and polarized membrane. hiPSC-RPE cell spheroids positively expressed Nestin and exhibited reduced SA-β-Gal staining. Injectable hiPSC-RPE cell spheroids could form monolayers on decellularized corneal matrixes (DCM). After subretinal transplantation for one month, hiPSC-RPE cell spheroids could survive and maintain segmental sheet growth in RPE-degenerated chinchilla rabbits. Conclusion This study realized that NCM dissociated hiPSCs were effectively differentiated into transplantable and functional RPE through the sequential addition of defined factors but not involving exogenous genes. This study may lay the foundation for the clinical transplantation of hiPSC-RPE cell spheroids as therapy for RPE degenerative diseases in the future.

scholarly journals Autophagy activated via GRP78 to alleviate endoplasmic reticulum stress for cell survival in blue light-mediated damage of A2E-laden RPEs

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jingyang Feng ◽  
Yuhong Chen ◽  
Bing Lu ◽  
Xiangjun Sun ◽  
Hong Zhu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Signaling Pathway ◽  
Blue Light ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Degenerative Diseases ◽  
Caspase 12 ◽  
Age Related ◽  
Retinal Degenerative Diseases

Abstract Background Retinal pigment epithelium cells (RPEs) are critical for maintaining retinal homeostasis. Accumulation of age-related lipofuscin, N-retinylidene-N-retinylethanolamine (A2E), makes RPEs vulnerable to blue light-mediated damage, which represents an initial cause of some retinal degenerative diseases. This study investigated the activation of autophagy and the signaling pathway involved in glucose-related protein 78 (GRP78) induced autophagy in blue light-mediated damage of A2E-laden RPEs. In addition, we explored whether autophagy could play a protective role by alleviating endoplasmic reticulum (ER) stress to promote RPEs survival. Methods RPEs were incubated with 25 μM A2E for 2 h and exposed to blue light for 20 min. The expression of ER stress-related apoptotic proteins, CHOP and caspase-12, as well as autophagy marker LC3 were measured by western blot analysis. Autophagosomes were observed by both transmission electron microscopy and immunofluorescence assays. GRP78 interference performed by short hairpin RNA (shRNA) was used to identify the signaling pathway involved in GRP78 induced autophagy. Cell death was assessed using TUNEL analysis. Results Treatment with A2E and blue light markedly increased the expression of ER stress-related apoptotic molecules CHOP and caspase-12. The activation of autophagy was recognized by observing autophagosomes at ultrastructural level. Additionally, punctate distributions of LC3 immunofluorescence and enhanced conversions of LC3-I to LC3-II were found in A2E and blue light-treated RPEs. Moreover, GRP78 interference reduced AMPK phosphorylation and promoted mTOR activity, thereby downregulating autophagy. In addition, the inhibition of autophagy made RPEs vulnerable to A2E and blue light damage. In contrast, the autophagy inducer rapamycin alleviated ER stress to promote RPEs survival. Conclusions GRP78 activates autophagy via AMPK/mTOR in blue light-mediated damage of A2E-laden RPEs in vitro. Autophagy may be a vital endogenous cytoprotective process to alleviate stress for RPEs survival in retinal degenerative diseases.

scholarly journals Spheroid transplantable and functional retinal pigment epithelium derived from non-colony dissociated human induced pluripotent stem cells

2020 ◽  
Author(s):  
Xiaoling Guo ◽  
Deliang Zhu ◽  
Ruiling Lian ◽  
Qiaolang Zeng ◽  
Sanjana Mathew ◽  
...  
Keyword(s):  
Stem Cells ◽  
Retinal Pigment Epithelium ◽  
Induced Pluripotent Stem Cells ◽  
Pluripotent Stem Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Great Promise ◽  
Rpe Cells ◽  
Cell Spheroids ◽  
Induced Pluripotent

Abstract Background: Retinal pigment epithelium (RPE) cells derived from human induced pluripotent stem cells (hiPSCs) exhibit great promise in treating retinal degenerative diseases. Here, we would explore the feasibility of non-colony dissociated hiPSCs to differentiate into functional RPE cells (hiPSC-RPE), and offer an alternative transplantation method based on cell spheroids.Methods: hiPSC-RPE cells were identified using reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence assay, Western blotting, and flow cytometry assay. The functions of hiPSC-RPE cells in vitro and in vivo were assessed by fluorescein leakage test, transepithelial electrical resistance (TEER) assay, atomic force microscopy observation, POS phagocytosis assay, frozen tissue sections, live/dead assay, SA-β-Gal staining, and immunocytochemistry.Results: hiPSC-RPE cells positively expressed biomarkers of RPE cells but not iPSCs, such as CRALBP (97.4%), EMMPRIN (93.8%), Oct4 (2.1%), and Sox2 (2.0%). hiPSC-RPE cells displayed RPE-like characteristics including barrier function, phagocytic activity, and polarized membrane. The cells derived from hiPSC-RPE spheroids positively expressed Nestin and exhibited reduced SA-β-Gal staining. hiPSC-RPE cell spheroids could form monolayer on decellularized corneal matrixes (DCM). After one month of subretinal transplantation, hiPSC-RPE cell spheroids could survive and maintain segmental sheet growth in sodium iodate (NaIO3) induced RPE-degenerated chinchilla rabbits. Conclusion: This study suggested that non-colony dissociated hiPSCs were effectively differentiated into functional RPE cells, and hiPSC-RPE cell spheroids maintained segmental sheet growth in the subretinal of RPE degenerate chinchilla rabbits in vivo, which may lay the foundation for cell spheroid transplantation as an alternative method for RPE degenerative disease therapy in the future.

scholarly journals Suppressor of Cytokine Signaling 2 Regulates Retinal Pigment Epithelium Metabolism by Enhancing Autophagy

2021 ◽  
Vol 15 ◽  
Author(s):  
Xi-Yuan Liu ◽  
Rui Lu ◽  
Jing Chen ◽  
Jie Wang ◽  
Hong-Mei Qian ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Metabolic Regulation ◽  
Glycogen Synthase ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Cytokine Signaling ◽  
Suppressor Of Cytokine Signaling ◽  
Rpe Cells ◽  
Age Related

Retinal pigment epithelium (RPE) serves critical functions in maintaining retinal homeostasis. An important function of RPE is to degrade the photoreceptor outer segment fragments daily to maintain photoreceptor function and longevity throughout life. An impairment of RPE functions such as metabolic regulation leads to the development of age-related macular degeneration (AMD) and inherited retinal degenerative diseases. As substrate recognition subunit of a ubiquitin ligase complex, suppressor of cytokine signaling 2 (SOCS2) specifically binds to the substrates for ubiquitination and negatively regulates growth hormone signaling. Herein, we explore the role of SOCS2 in the metabolic regulation of autophagy in the RPE cells. SOCS2 knockout mice exhibited the irregular morphological deposits between the RPE and Bruch’s membrane. Both in vivo and in vitro experiments showed that RPE cells lacking SOCS2 displayed impaired autophagy, which could be recovered by re-expressing SOCS2. SOCS2 recognizes the ubiquitylated proteins and participates in the formation of autolysosome by binding with autophagy receptors and lysosome-associated membrane protein2 (LAMP-2), thereby regulating the phosphorylation of glycogen synthase kinase 3β (GSK3β) and mammalian target of rapamycin (mTOR) during the autophagy process. Our results imply that SOCS2 participates in ubiquitin-autophagy-lysosomal pathway and enhances autophagy by regulating GSK3β and mTOR. This study provides a potential therapeutic target for AMD.

scholarly journals Avoiding the Pitfalls of siRNA Delivery to the Retinal Pigment Epithelium with Physiologically Relevant Cell Models

Pharmaceutics ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 667
Author(s):  
Eva Ramsay ◽  
Manuela Raviña ◽  
Sanjay Sarkhel ◽  
Sarah Hehir ◽  
Neil R. Cameron ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Cell Model ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Sirna Delivery ◽  
Target Cells ◽  
Cell Models ◽  
Rpe Cells ◽  
Age Related

Inflammation is involved in the pathogenesis of several age-related ocular diseases, such as macular degeneration (AMD), diabetic retinopathy, and glaucoma. The delivery of anti-inflammatory siRNA to the retinal pigment epithelium (RPE) may become a promising therapeutic option for the treatment of inflammation, if the efficient delivery of siRNA to target cells is accomplished. Unfortunately, so far, the siRNA delivery system selection performed in dividing RPE cells in vitro has been a poor predictor of the in vivo efficacy. Our study evaluates the silencing efficiency of polyplexes, lipoplexes, and lipidoid-siRNA complexes in dividing RPE cells as well as in physiologically relevant RPE cell models. We find that RPE cell differentiation alters their endocytic activity and causes a decrease in the uptake of siRNA complexes. In addition, we determine that melanosomal sequestration is another significant and previously unexplored barrier to gene silencing in pigmented cells. In summary, this study highlights the importance of choosing a physiologically relevant RPE cell model for the selection of siRNA delivery systems. Such cell models are expected to enable the identification of carriers with a high probability of success in vivo, and thus propel the development of siRNA therapeutics for ocular disease.

scholarly journals Development-related mitochondrial properties of retinal pigment epithelium cells derived from hEROs

2021 ◽  
Vol 14 (8) ◽  
pp. 1138-1150
Author(s):  
Hao-Jue Xu ◽  
◽  
Ting Zou ◽  
Zheng-Qin Yin ◽  
◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Embryonic Stem ◽  
Age Related Macular Degeneration ◽  
Level Energy ◽  
Rpe Cells ◽  
Age Related ◽  
High Level

AIM: To explore the temporal mitochondrial characteristics of retinal pigment epithelium (RPE) cells obtained from human embryonic stem cells (hESC)-derived retinal organoids (hEROs-RPE), to verify the optimal period for using hEROs-RPE as donor cells from the aspect of mitochondria and to optimize RPE cell-based therapeutic strategies for age-related macular degeneration (AMD). METHODS: RPE cells were obtained from hEROs and from spontaneous differentiation (SD-RPE). The mitochondrial characteristics were analyzed every 20d from day 60 to 160. Mitochondrial quantity was measured by MitoTracker Green staining. Transmission electron microscopy (TEM) was adopted to assess the morphological features of the mitochondria, including their distribution, length, and cristae. Mitochondrial membrane potentials (MMPs) were determined by JC-1 staining and evaluated by flow cytometry, reactive oxygen species (ROS) levels were evaluated by flow cytometry, and adenosine triphosphate (ATP) levels were measured by a luminometer. Differences between two groups were analyzed by the independent-samples t-test, and comparisons among multiple groups were made using one-way ANOVA or Kruskal-Wallis H test when equal variance was not assumed. RESULTS: hEROs-RPE and SD-RPE cells from day 60 to 160 were successfully differentiated from hESCs and expressed RPE markers (Pax6, MITF, Bestrophin-1, RPE65, Cralbp). RPE features, including a cobblestone-like morphology with tight junctions (ZO-1), pigments and microvilli, were also observed in both hEROs-RPE and SD-RPE cells. The mitochondrial quantities of hEROs-RPE and SD-RPE cells both peaked at day 80. However, the cristae of hEROs-RPE mitochondria were less mature and abundant than those of SD-RPE mitochondria at day 80, with hEROs-RPE mitochondria becoming mature at day 100. Both hEROs-RPE and SD-RPE cells showed low ROS levels from day 100 to 140 and maintained a normal MMP during this period. However, hEROs-RPE mitochondria maintained a longer time to produce high levels of ATP (from day 120 to 140) than SD-RPE cells (only day 120). CONCLUSION: hEROs-RPE mitochondria develop more slowly and maintain a longer time to supply high-level energy than SD-RPE mitochondria. From the mitochondrial perspective, hEROs-RPE cells from day 100 to 140 are an optimal cell source for treating AMD.

scholarly journals Transcriptomic and proteomic retinal pigment epithelium signatures of age-related macular degeneration.

2021 ◽  
Author(s):  
Anne Senabouth ◽  
Maciej Daniszewski ◽  
Grace Lidgerwood ◽  
Helena Liang ◽  
Damian Hernandez ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Macular Degeneration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Disease Status ◽  
Geographic Atrophy ◽  
Age Related Macular Degeneration ◽  
Rpe Cells ◽  
Age Related ◽  
Mitochondrial Functions

Induced pluripotent stem cells generated from patients with geographic atrophy as well as healthy individuals were differentiated to retinal pigment epithelium (RPE) cells. By integrating transcriptional profiles of 127,659 RPE cells generated from 43 individuals with geographic atrophy and 36 controls with genotype data, we identified 439 expression Quantitative Trait (eQTL) loci in cis that were associated with disease status and specific to subpopulations of RPE cells. We identified loci linked to two genes with known associations with geographic atrophy - PILRB and PRPH2, in addition to 43 genes with significant genotype x disease interactions that are candidates for novel genetic associations for geographic atrophy. On a transcriptome-only level, we identified molecular pathways significantly upregulated in geographic atrophy-RPE including in extracellular cellular matrix reorganisation, neurodegeneration, and mitochondrial functions. We subsequently implemented a large-scale proteomics analysis, confirming modification in proteins associated with these pathways. We also identified six significant protein (p) QTL that regulate protein expression in the RPE cells and in geographic atrophy - two of which share variants with cis-eQTL. Transcriptome-wide association analysis identified genes at loci previously associated with age-related macular degeneration. Further analysis conditional on disease status, implicated statistically significant RPE-specific eQTL. This study uncovers important differences in RPE homeostasis associated with geographic atrophy.

scholarly journals mTOR activity is essential for retinal pigment epithelium regeneration in zebrafish

2021 ◽  
Author(s):  
Jeff Gross ◽  
Fangfang Lu ◽  
Lyndsay Leach
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Mtor Pathway ◽  
Age Related Macular Degeneration ◽  
Model Systems ◽  
Rpe Cells ◽  
Genetic Ablation ◽  
Age Related ◽  
Mtor Activity

The retinal pigment epithelium (RPE) plays numerous critical roles in maintaining vision and this is underscored by the prevalence of degenerative blinding diseases like age-related macular degeneration (AMD), in which visual impairment is caused by progressive loss of RPE cells. In contrast to mammals, zebrafish possess the ability to intrinsically regenerate a functional RPE layer after severe injury. The molecular underpinnings of this regenerative process remain largely unknown yet hold tremendous potential for developing treatment strategies to stimulate endogenous regeneration in the human eye.  In this study, we demonstrate that the mTOR pathway is activated in RPE cells post-genetic ablation. Pharmacological and genetic inhibition of mTOR activity impaired RPE regeneration, while mTOR activation enhanced RPE recovery post-injury, demonstrating that mTOR activity is necessary and sufficient for RPE regeneration in zebrafish. RNA-seq of RPE isolated from mTOR-inhibited larvae identified a number of genes and pathways dependent on mTOR activity at early and late stages of regeneration; amongst these were components of the immune system, which is emerging as a key regulator of regenerative responses across various tissue and model systems.  Our results identify crosstalk between macrophages/microglia and the RPE, wherein mTOR activity in the RPE is required for recruitment of macrophages/microglia to the injury site. In turn, these macrophages/microglia reinforce mTOR activity in regenerating RPE cells. Interestingly, the function of macrophages/microglia in maintaining mTOR activity in the RPE appeared to be inflammation-independent. Taken together, these data identify mTOR activity as a key regulator of RPE regeneration and link the mTOR pathway to immune responses in facilitating RPE regeneration.

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