Retinal Stem Cells Research Articles

Examining perfluorohexane sulfonate (PFHxS) impacts on sensorimotor and circadian rhythm development.

Perfluorohexane sulfonate (PFHxS) is a ubiquitous perfluoroalkyl substance known for its environmental persistence and potential toxicity. This study investigated PFHxS's impact on zebrafish embryos, focusing on sensorimotor behavior, circadian rhythm disruption, and underlying molecular mechanisms. Under 24 hr dark incubations, PFHxS exposure induced concentration-dependent hyperactivity within larval photomotor response, characterized by the distinctive "O-bend" response, strong light-phase hyperactive movement and seizure-like movements. It appears that PFHxS-treated embryos cannot sense light cues in a normal manner. Similar hyperactivity was seen for acoustic startle response assay, suggesting that the response is not merely visual, but sensorimotor. LC-MS studies confirmed detectable uptake of PFHxS into embryos. We then conducted mRNA-sequencing across multiple time points (48 and 120 hpf) and concentrations (0.00025, 0.0025 and 25 µM). Data at the 25 µM (2-120 hpf) exposure showed disrupted pathways associated with DNA and cell cycle. Interestingly, data at 0.00025 µM - an environmentally relevant concentration- at 48 hpf showed disruption of MAPK and other signaling pathways. Immunohistochemistry of eyes showed reduced retinal stem cell proliferation, consistent with observed DNA replication pathway disruptions. To assess if these impacts were driven by circadian rhythm development, we manipulated light/dark cycles during PFHxS incubation; this manipulation altered behavioral patterns, implicating circadian rhythm modulation as a target of PFHxS. Since circadian rhythm is modulated by the pineal gland, we ablated the gland using metronidazole; this ablation partially rescued hyperactivity, indicating the gland's role in driving the phenotype. Collectively, these findings underscore proclivity of PFHxS to cause neurodevelopmental toxicity, necessitating further mechanistic exploration and environmental health assessments.

The Endogenous Expression of BMI1 in Adult Human Eyes.

BMI1, also known as B lymphoma Mo-MLV insertion region 1, is a protein in the Polycomb group that is implicated in various cellular processes, including stem cell self-renewal and the regulation of cellular senescence. BMI1 plays a role in the regulation of retinal progenitor cells and the renewal of adult neuronal cells. However, the presence, location, and quantification of BMI1 in the adult human eye have never previously been reported. In this study, we collected 45 frozen globes from eye banks, and ocular tissues were dissected. Protein was quantified by utilizing a custom electrochemiluminescence (ECL) assay developed to quantify the BMI1 protein. BMI1 was found in all ocular tissues at the following levels: the retina (1483.6 ± 191.7 pg/mL) and the RPE (296.4 ± 78.1 pg/mL). BMI1 expression was noted ubiquitously in the GCL (ganglion cell layer), the INL (inner nuclear layer), the ONL (outer nuclear layer), and the RPE (retinal pigment epithelium) via immunofluorescence, with higher levels in the inner than in the outer retinal layers and the RPE. These data confirm that BMI1 is expressed in the human retina. Further studies will illuminate the role that BMI1 plays in ocular cells. BMI1 levels are lower in aged retinas, possibly reflecting changes in retinal somatic and stem cell maintenance and disease susceptibility.

The role of Atoh7/Notch signaling in the differentiation of retinal stem cells into retinal ganglion cells and its potential application in glaucoma treatment

Background: One of the main causes of blindness in persons over 60 is glaucoma, yet there are presently no viable therapies available. The differentiation to retinal ganglion cell (RGC) is a key step in the stem cell-based ocular regeneration therapy that have become a new hotspot in this field. This study aimed to investigate the differentiation pathway of Retinal stem cells (RSCs) and their potential for future application in glaucoma treatment. Methods: Gas pressurization was employed to simulate intraocular pressure (IOP) conditions in vitro, utilizing polyimide membranes as the culture chamber. RSCs were derived from mice and underwent a series of transfection and detection procedures. The expression levels of mRNA and protein were quantified using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting, respectively. Cell apoptosis and proportion were assessed through flow cytometry analysis. Immunofluorescence staining was performed to identify cell morphology, growth status, and relative markers. In vivo validation was conducted on glaucoma mouse models, highlighting the regulatory system involving Atoh7/Notch for RSC differentiation. Results: At 40 mmHg, Atoh7 facilitates RGC differentiation through the regulation of Notch expression. Activation of Atoh7/Notch signaling in glaucomatous retina enhances RSC viability and differentiation. Subsequent transplantation of RSCs significantly improves visual acuity in glaucoma animal models, accompanied by increased expression and number of positive cells for RGC markers, as well as activation of Atho7/Notch signaling. Conclusion: The present study elucidates the alterations and impacts of IOP in glaucoma, while also highlighting the potential utility of Atoh7/Notch as a promising avenue for comprehending the underlying mechanisms governing retinal ganglion cell differentiation.

Mycb and Mych stimulate Müller glial cell reprogramming and proliferation in the uninjured and injured zebrafish retina.

In the injured zebrafish retina, Müller glial cells (MG) reprogram to adopt retinal stem cell properties and regenerate damaged neurons. The strongest zebrafish reprogramming factors might be good candidates for stimulating a similar regenerative response by mammalian MG. Myc proteins are potent reprogramming factors that can stimulate cellular plasticity in differentiated cells; however, their role in MG reprogramming and retina regeneration remains poorly explored. Here, we report that retinal injury stimulates mycb and mych expression and that, although both Mycb and Mych stimulate MG reprogramming and proliferation, only Mych enhances retinal neuron apoptosis. RNA-sequencing analysis of wild-type, mychmut and mycbmut fish revealed that Mycb and Mych regulate ∼40% and ∼16%, respectively, of the genes contributing to the regeneration-associated transcriptome of MG. Of these genes, those that are induced are biased towards regulation of ribosome biogenesis, protein synthesis, DNA synthesis, and cell division, which are the top cellular processes affected by retinal injury, suggesting that Mycb and Mych are potent MG reprogramming factors. Consistent with this, forced expression of either of these proteins is sufficient to stimulate MG proliferation in the uninjured retina.

Small extracellular vesicles of organoid-derived human retinal stem cells remodel Müller cell fate via miRNA: A novel remedy for retinal degeneration

Remodeling retinal Müller glial fate, including gliosis inhibition and pro-reprogramming, represents a crucial avenue for treating degenerative retinal diseases. Stem cell transplantation exerts effects on modulating retinal Müller glial fate. However, the optimized stem cell products and the underlying therapeutic mechanisms need to be investigated. In the present study, we found that retinal progenitor cells from human embryonic stem cell-derived retinal organoids (hERO-RPCs) transferred extracellular vesicles (EVs) into Müller cells following subretinal transplantation into RCS rats. Small EVs from hERO-RPCs (hERO-RPC-sEVs) were collected and were found to delay photoreceptor degeneration and protect retinal function in RCS rats. hERO-RPC-sEVs were taken up by Müller cells both in vivo and in vitro, and inhibited gliosis while promoting early dedifferentiation of Müller cells. We further explored the miRNA profiles of hERO-RPC-sEVs, which suggested a functional signature associated with neuroprotection and development, as well as the regulation of stem cell and glial fate. Mechanistically, hERO-RPC-sEVs might regulate the fate of Müller cells by miRNA-mediated nuclear factor I transcription factors B (NFIB) downregulation. Collectively, our findings offer novel mechanistic insights into stem cell therapy and promote the development of EV-centered therapeutic strategies.

Neuron image segmentation based on convolution and BN fusion and multi-input feature fusion

The segmentation of neuronal morphology in electron microscopy images is crucial for the analysis and understanding of neuronal function. However, most of the existing segmentation methods are not suitable for challenging datasets where the neuronal structure is contaminated by noise or has interrupted parts. In this paper, we propose a segmentation method based on deep learning to determine the location information of neurons and reduce the influence of image noise in the data. Specifically, we adapt our neuron dataset based on UNet by using convolution with BN fusion and multi-input feature fusion. The method is named REDAFNet. The model simplifies the model structure and enhances the generalization ability by fusing the convolution layer and BN layer. The noise interference in the data was reduced by multi-input feature fusion, and the ability to understand and express the data was enhanced. The method takes a neuron image as input and its pixel segmentation map as output. Experimental results show that the segmentation accuracy of the proposed method is 91.96%, 93.86% and 80.25% on the ISBI2012 dataset, U-RISC retinal neuron dataset and N2DH-GOWT1 stem cell dataset, respectively. Compared with the existing segmentation methods, the proposed method can extract more complete feature information and achieve more accurate segmentation.

Platelet-Activating Factor Receptor (PAFR) Regulates Retinal Progenitor/Stem Cells Profile in Ciliary Epithelium Cells.

The retina is a central nervous tissue essential to visual perception and highly susceptible to environmental damage. Lower vertebrate retinas activate intrinsic regeneration mechanisms in response to retinal injury regulated by a specialized population of progenitor cells. The mammalian retina does not have populations of progenitor/stem cells available to activate regeneration, but contains a subpopulation of differentiated cells that can be reprogrammed into retinal stem cells, the ciliary epithelium (CE) cells. Despite the regenerative potential, stem cells derived from CE exhibit limited reprogramming capacity probably associated with the expression of intrinsic regulatory mechanisms. Platelet-activating factor (PAF) is a lipid mediator widely expressed in many cells and plays an important role in stem cell proliferation and differentiation. During mammalian development, PAF receptor signaling showed important effects on retinal progenitors' cell cycle regulation and neuronal differentiation that need to be further investigated. In this study, our findings suggested a dynamic role for PAF receptor signaling in CE cells, impacting stem cell characteristics and neurosphere formation. We showed that PAF receptors and PAF-related enzymes are downregulated in retinal progenitor/stem cells derived from PE cells. Blocking PAFR activity using antagonists increased the expression of specific progenitor markers, revealing potential implications for retinal tissue development and maintenance.

Awakening adult neural stem cells: NOX signalling as a positive regulator of the quiescence-to-proliferation transition in the Xenopus retina.

A growing wealth of data suggest that reactive oxygen species (ROS) signalling might be crucial in conferring embryonic or adult stem cells their specific properties. However, how stem cells control ROS production and scavenging, and how ROS in turn contribute to stemness, remain poorly understood. Using the Xenopus retina as a model system, we first investigated the redox status of retinal stem cells (RSCs). We discovered that they exhibit higher ROS levels compared with progenitors and retinal neurons, and express a set of specific redox genes. We next addressed the question of ROS functional involvement in these cells. Using pharmacological or genetic tools, we demonstrate that inhibition of NADPH oxidase-dependent ROS production increases the proportion of quiescent RSCs. Surprisingly, this is accompanied by an apparent acceleration of the mean division speed within the remaining proliferating pool. Our data further unveil that such impact on RSC cell cycling is achieved by modulation of the Wnt/Hedgehog signalling balance. Altogether, we highlight that RSCs exhibit distinctive redox characteristics and exploit NADPH oxidase signalling to limit quiescence and fine-tune their proliferation rate.

Trim9 regulates the directional differentiation of retinal Müller cells to retinal ganglion cells.

Glaucoma is a leading cause of irreversible blindness, and effective therapies to reverse the visual system damage caused by glaucoma are still lacking. Recently, the stem cell therapy enable the repair and regeneration of the damaged retinal neurons, but challenges regarding the source of stem cells remain. This study aims to investigate a protocol that allows the dedifferentiation of Müller cells into retinal stem cells, following by directed differentiation into retinal ganglion cells with high efficiency, and to provide a new method of cellular acquisition for retinal stem cells. Epidermal cell growth factor and fibroblast growth factor 2 were used to induce the dedifferentiation of rat retinal Müller cells into retinal neural stem cells. Retinal stem cells derived from Müller cells were infected with a Trim9 overexpression lentiviral vector (PGC-FU-Trim9-GFP), and the efficiency of viral infection was assessed by fluorescence microscopy and flow cytometry. Retinoic acid and brain-derived neurotrophic factor treatments were used to induce the differentiation of the retinal stem cells into neurons and glial cells with or without the overexpression of Trim9. The expressions of each cellular marker (GLAST, GS, rhodopsin, PKC, HPC-1, Calbindin, Thy1.1, Brn-3b, Nestin, Pax6) were detected by immunofluorescence, PCR/real-time RT-PCR or Western blotting. Rat retinal Müller cells expressed neural stem cells markers (Nestin and Pax6) with the treatment of epidermal cell growth factor and fibroblast growth factor 2. The Thy1.1 positive cell rate of retinal stem cells overexpressing Trim9 was significantly increased, indicating their directional differentiation into retinal ganglion cells after treatment with retinoic acid and brain-derived neurotrophic factor. In this study, rat retinal Müller cells are dedifferentiated into retinal stem cells successfully, and Trim9 promotes the directional differentiation from retinal stem cells to retinal ganglion cells effectively.

Design of a Subretinal Injection Robot Based on the RCM Mechanism.

This study presents an investigation focusing on the advancement of a robot designed for subretinal injections in the context of macular degeneration treatment. The technique of subretinal injection surgery stands as the most efficacious approach for the successful transplantation of stem cells into the retinal pigment epithelium layer. This particular procedure holds immense significance in advancing research and implementing therapeutic strategies involving retinal stem cell transplantation. The execution of artificial subretinal surgery poses considerable challenges which can be effectively addressed through the utilization of subretinal injection surgery robots. The development process involved a comprehensive modeling phase, integrating computer-aided design (CAD) and finite element analysis (FEA) techniques. These simulations facilitated iterative enhancements of the mechanical aspects pertaining to the robotic arm. Furthermore, MATLAB was employed to simulate and visualize the robot's workspace, and independent verification was conducted to ascertain the range of motion for each degree of freedom.

TRIM9 promotes Müller cell-derived retinal stem cells to differentiate into retinal ganglion cells by regulating Atoh7.

Glaucoma is a multifactorial, irreversible blinding eye disease characterized by a large number of retinal ganglion cell (RGC) deaths. Müller cell-derived retinal stem cells (RSCs) can be induced to differentiate into RGCs under certain conditions. This study aimed to explore the regulatory effect and mechanism of TRIM9 on the differentiation of Müller cell-derived stem cells into RGCs. First, episcleral vein cauterization was used to induce high intraocular pressure (IOP) rat model. Next, Müller cells were isolated from rat retina, identified and induced to dedifferentiate into RSCs. Finally, RSCs were intervened with lentivirus PGC-FU-TRIM9-GFP transfection or siRNA Atoh7 and induced to redifferentiate into RGCs. In vivo, TRIM9 was highly expressed and Müller cells proliferated abnormally in the high IOP rat model. In vitro, S-100, GFAP, vimentin, and GS were positively expressed in Müller cells isolated from rat retina, and the purity of cells was 97.17%. Under the stimulation of cytokines, the proliferative capacity of the cells and the expression of Nestin and Ki67 gradually increased with the prolongation of culture time. Furthermore, RSCs transfected with the lentiviral vector PGC-FU-TRIM9-GFP displayed a striking morphological feature of long neurites. Additionally, there was a remarkable increase in the fluorescence intensity of Brn-3b and Thy1.1, accompanied by elevated mRNA and protein expression levels of Brn-3b, Thy1.1, and Atoh7. After knocking down Atoh7, the effect of TRIM9 on the above indicators was reversed. TRIM9 might promote the differentiation of Müller cells into RGCs by regulating the expression of Atoh7.

Unravelling the link between embryogenesis and adult stem cell potential in the ciliary marginal zone: A comparative study between mammals and teleost fish

The discovery and study of adult stem cells have revolutionized regenerative medicine by offering new opportunities for treating various medical conditions. Anamniote stem cells, which retain their full proliferative capacity and full differentiation range throughout their lifetime, harbour a greater potential compared to mammalian adult stem cells, which only exhibit limited stem cell potential. Therefore, understanding the mechanisms underlying these differences is of significant interest. In this review, we examine the similarities and differences of adult retinal stem cells in anamniotes and mammals, from their embryonic stages in the optic vesicle to their residence in the postembryonic retinal stem cell niche, the ciliary marginal zone located in the retinal periphery. In anamniotes, developing precursors of retinal stem cells are exposed to various environmental cues during their migration in the complex morphogenetic remodelling of the optic vesicle to the optic cup. In contrast, their mammalian counterparts in the retinal periphery are primarily instructed by neighbouring tissues once they are in place. We explore the distinct modes of optic cup morphogenesis in mammals and teleost fish and highlight molecular mechanisms governing morphogenesis and stem cells instruction. The review concludes with the molecular mechanisms of ciliary marginal zone formation and offers a perspective on the impact of comparative single cell transcriptomic studies to reveal the evolutionary similarities and differences.

Epigenetic regulation in the commitment of progenitor cells during retinal development and regeneration

Retinal development is initiated by multipotent retinal progenitor cells, which undergo several rounds of cell divisions and subsequently terminal differentiation. Retinal regeneration is usually considered as the recapitulation of retinal development, which share common mechanisms underlying the cell cycle re-entry of adult retinal stem cells and the differentiation of retinal neurons. However, how proliferative retinal progenitor cells perform a precise transition to postmitotic retinal cell types during the process of development and regeneration remains elusive. It is proposed that both the intrinsic and extrinsic programming are involved in the transcriptional regulation of the spatio-temporal fate commitment. Epigenetic modifications and the regulatory mechanisms at both DNA and chromatin levels are also postulated to play an important role in the timing of differentiation of specific retinal cells. In the present review, we have summarized recent knowledge of epigenetic regulation that underlies the commitment of retinal progenitor cells in the settings of retinal development and regeneration.

Differential Susceptibility of Fetal Retinal Pigment Epithelial Cells, hiPSC- Retinal Stem Cells, and Retinal Organoids to Zika Virus Infection.

Zika virus (ZIKV) causes microcephaly and congenital eye disease. The cellular and molecular basis of congenital ZIKV infection are not well understood. Here, we utilized a biologically relevant cell-based system of human fetal retinal pigment epithelial cells (FRPEs), hiPSC-derived retinal stem cells (iRSCs), and retinal organoids to investigate ZIKV-mediated ocular cell injury processes. Our data show that FRPEs were highly susceptible to ZIKV infection exhibiting increased apoptosis, whereas iRSCs showed reduced susceptibility. Detailed transcriptomics and proteomics analyses of infected FRPEs were performed. Nucleoside analogue drug treatment inhibited ZIKV replication. Retinal organoids were susceptible to ZIKV infection. The Asian genotype ZIKV exhibited higher infectivity, induced profound inflammatory response, and dysregulated transcription factors involved in retinal organoid differentiation. Collectively, our study shows that ZIKV affects ocular cells at different developmental stages resulting in cellular injury and death, further providing molecular insight into the pathogenesis of congenital eye disease.

The potential effects of nutrients and light on autophagy-mediated visual function and clearance of retinal aggregates.

Increasing findings indicate that a dysfunction in the autophagy machinery is common during retinal degeneration. The present article provides evidence showing that an autophagy defect in the outer retinal layers is commonly described at the onset of retinal degeneration. These findings involve a number of structures placed at the border between the inner choroid and the outer retina encompassing the choriocapillaris, the Bruch's membrane, photoreceptors and Mueller cells. At the center of these anatomical substrates are placed cells forming the retinal pigment epithelium (RPE), where autophagy seems to play most of its effects. In fact, a failure of the autophagy flux is mostly severe at the level of RPE. Among various retinal degenerative disorders, age-related macular degeneration (AMD) is mostly affected by a damage to RPE, which can be reproduced by inhibiting the autophagy machinery and it can be counteracted by the activation of the autophagy pathway. In the present manuscript evidence is provided that such a severe impairment of retinal autophagy may be counteracted by administration of a number of phytochemicals, which possess a strong stimulatory activity on autophagy. Likewise, natural light stimulation administered in the form of pulsatile specific wavelengths is capable of inducing autophagy within the retina. This dual approach to stimulate autophagy is further strengthened by the interaction of light with phytochemicals which is shown to activate the chemical properties of these natural molecules in sustaining retinal integrity. The beneficial effects of photo-biomodulation combined with phytochemicals is based on the removal of toxic lipid, sugar and protein species along with the stimulation of mitochondrial turn-over. Additional effects of autophagy stimulation under the combined effects of nutraceuticals and light pulses are discussed concerning stimulation of retinal stem cells which partly correspond to a subpopulation of RPE cells.

SOX2-positive retinal stem cells are identified in adult human pars plicata by single-cell transcriptomic analyses.

Stem cell therapy is a promising strategy to rescue visual impairment caused by retinal degeneration. Previous studies have proposed controversial theories about whether in situ retinal stem cells (RSCs) are present in adult human eye tissue. Single-cell RNA sequencing (scRNA-seq) has emerged as one of the most powerful tools to reveal the heterogeneity of tissue cells. By using scRNA-seq, we explored the cell heterogeneity of different subregions of adult human eyes, including pars plicata, pars plana, retinal pigment epithelium (RPE), iris, and neural retina (NR). We identified one subpopulation expressing SRY-box transcription factor 2 (SOX2) as RSCs, which were present in the pars plicata of the adult human eye. Further analysis showed the identified subpopulation of RSCs expressed specific markers aquaporin 1 (AQP1) and tetraspanin 12 (TSPAN12). We, therefore, isolated this subpopulation using these two markers by flow sorting and found that the isolated RSCs could proliferate and differentiate into some retinal cell types, including photoreceptors, neurons, RPE cells, microglia, astrocytes, horizontal cells, bipolar cells, and ganglion cells; whereas, AQP1- TSPAN12- cells did not have this differentiation potential. In conclusion, our results showed that SOX2-positive RSCs are present in the pars plicata and may be valuable for treating human retinal diseases due to their proliferation and differentiation potential.

Generation of Retinal Organoids from Healthy and Retinal Disease-Specific Human-Induced Pluripotent Stem Cells.

Pluripotent stem cells can generate complex tissue organoids that are useful for in vitro disease modeling studies and for developing regenerative therapies. This protocol describes a simpler, robust, and stepwise method of generating retinal organoids in a hybrid culture system consisting of adherent monolayer cultures during the first 4 weeks of retinal differentiation till the emergence of distinct, self-organized eye field primordial clusters (EFPs). Further, the doughnut-shaped, circular, and translucent neuro-retinal islands within each EFP are manually picked and cultured under suspension using non-adherent culture dishes in a retinal differentiation medium for 1-2 weeks to generate multilayered 3D optic cups (OC-1M). These immature retinal organoids contain PAX6+ and ChX10+ proliferating, multipotent retinal precursors. The precursor cells are linearly self-assembled within the organoids and appear as distinct radial striations. At 4 weeks after suspension culture, the retinal progenitors undergo post-mitotic arrest and lineage differentiation to form mature retinal organoids (OC-2M). The photoreceptor lineage committed precursors develop within the outermost layers of retinal organoids. These CRX+ and RCVRN+ photoreceptor cells morphologically mature to display inner segment-like extensions. This method can be adopted for generating retinal organoids using human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs). All steps and procedures are clearly explained and demonstrated to ensure replicability and for wider applications in basic science and translational research.

Vegf signaling between Müller glia and vascular endothelial cells is regulated by immune cells and stimulates retina regeneration

In the zebrafish retina, Müller glia (MG) can regenerate retinal neurons lost to injury or disease. Even though zebrafish MG share structure and function with those of mammals, only in zebrafish do MG function as retinal stem cells. Previous studies suggest dying neurons, microglia/macrophage, and T cells contribute to MG's regenerative response [White et al., Proc. Natl. Acad. Sci. U.S.A. 114, E3719 (2017); Hui et al., Dev. Cell 43, 659 (2017)]. Although MG end-feet abut vascular endothelial (VE) cells to form the blood-retina barrier, a role for VE cells in retina regeneration has not been explored. Here, we report that MG-derived Vegfaa and Pgfa engage Flt1 and Kdrl receptors on VE cells to regulate MG gene expression, Notch signaling, proliferation, and neuronal regeneration. Remarkably, vegfaa and pgfa expression is regulated by microglia/macrophages, while Notch signaling in MG is regulated by a Vegf-dll4 signaling system in VE cells. Thus, our studies link microglia/macrophage, MG, and VE cells in a multicomponent signaling pathway that controls MG reprogramming and proliferation.

SOX2 is essential for astrocyte maturation and its deletion leads to hyperactive behavior in mice.

Children with SOX2 deficiency develop ocular disorders and extra-ocular CNS anomalies. Animal data show that SOX2 is essential for retinal and neural stem cell development. In the CNS parenchyma, SOX2 is primarily expressed in astroglial and oligodendroglial cells. Here, we report a crucial role of astroglial SOX2 in postnatal brain development. Astroglial Sox2-deficient mice develop hyperactivity in locomotion and increased neuronal excitability in the corticostriatal circuit. Sox2 deficiency inhibits postnatal astrocyte maturation molecularly, morphologically, and electrophysiologically without affecting astroglia proliferation. Mechanistically, SOX2 directly binds to a cohort of astrocytic signature and functional genes, the expression of whichissignificantly reduced in Sox2-deficient CNS and astrocytes. Consistently, Sox2 deficiency remarkably reduces glutamate transporter expression and compromised astrocyte function of glutamate uptake.Our study provides insights into the cellular mechanisms underlying brain defects in children with SOX2 mutations and suggests a link of astrocyte SOX2 with extra-ocular abnormalities in SOX2-mutant subjects.

Pharmacological strategies in retinal dystrophies

AbstractThe therapeutic options for a patient affected by a retinal degenerative disease are discouraging. Despite several clinical trials show promising results, we still need to go a long way until the arrival to the clinics of therapies that could partially restore the retinal functionality, as optogenetics, or stem cell transplant, or, even better, that cure the disease by targeting its aetiology, as gene therapy. Until these therapies reach clinical success, targeting key factors in the degenerative process could temporarily slow its progression. Although there are many different retinal degenerative diseases, with different aetiology and clinical evolution, the degenerative process is always accompanied by common biochemical and molecular factors, it does not matter if the degeneration has a genetic cause, as it happens in inherited retinal dystrophies as retinitis pigmentosa, Leber congenital amaurosis or Stargardt disease; or if it is a multifactorial disease as age‐related macular degeneration; or if it is secondary to other pathologies, as diabetic retinopathy. The high metabolic rate of the retinal cells, their continuous exposition to high oxygen levels and light‐induced stress are key factors in the development of the degenerative process. When retinal cells start to die, activated glial cells secrete proinflammatory cytokines, chemokines and trophic factors that worsen the degenerative process. Thus, trying to reduce the oxidative stress and inflammation that are always present in the degenerating tissue seems a good approach to be tried. Moreover, considering the great number of mediators involved in the degenerative process, a widest approach combining therapies with antioxidant, anti‐inflammatory and antiapoptotic molecules, as well as neurotrophic factors could slow the progression of the disease and preserve the visual capacity for a certain time. Moreover, even when the vision has been completely lost, the neuroprotection could improve other non‐visual functions, like the control of circadian rhythms and pupil contraction and could also influence the patient's memory and mood. It is also relevant to note that this therapy can keep a healthy tissue and provide an adequate environment of healthy cells that will help to the clinical success of other techniques as cell transplant or optogenetic approaches, which could hardly be successful in a damaged tissue surrounded by dying cells.Supported by: Spanish Ministry of Science and Innovation (MICINN‐FEDER PID2019‐106230RB‐I00) Generalitat Valenciana (PROMETEO/2021/024).