Search Results (146)

Adult optic nerve axon regeneration has traditionally been framed as a problem of limited intrinsic growth capacity in central nervous system neurons. However, growing evidence suggests that intrinsic factors alone cannot account for regenerative failure: restrictive extrinsic environmental factors largely govern optic nerve regeneration, dictating the intrinsic capacity axons can express. In this review, we frame the extrinsic optic nerve environment as a dynamic regenerative niche, in which vascular, immune, glial, matrix, and metabolic compartments are spatially co-localized and temporally coordinated rather than acting as independent barriers. These compartments follow a shared trajectory, broadly protective in the acute phase, then inhibitory once the underlying response fails to resolve, while also actively driving one another, such as reactive astrocytes promoting the matrix remodeling that subsequently restricts axon regrowth. Consequently, the niche’s overall permissiveness for regeneration reflects the aggregate and interdependent state of these compartments rather than the action of any single barrier. This review integrates current evidence on extrinsic barriers, intervention opportunities, and disease-specific variability relevant to RGC axon regeneration after injury. These interventions must incorporate the spatial, temporal, and metabolic factors that shape the goal of functional recovery and vision restoration. Full article

Progranulin (PGRN) is a secreted protein composed of 7.5 granulin domains. The protein is implicated in various functions, including cell survival, inflammation, lysosomal homeostasis, tumorigenesis, and aging. Haploinsufficiency and complete loss of PGRN function cause the neurodegenerative disorders frontotemporal lobar degeneration and neuronal ceroid lipofuscinosis type 11, respectively. In the nervous system, administration of exogenous PGRN has been shown to promote the survival of various nerve cell types under different pathological conditions and to stimulate neurite outgrowth in vitro and axonal regeneration in vivo. In the retina, PGRN dysfunction results in photoreceptor and retinal ganglion cell (RGC) loss, whereas PGRN administration promotes photoreceptor cell survival. In the present study, we analyzed whether a sustained intravitreal administration of PGRN promotes the survival of axotomized RGCs and the regrowth of the lesioned axons. To this end, we generated a PGRN-overexpressing clonal neural stem cell line and injected the cells into the vitreous cavity of a mouse optic nerve crush model. The progression of the lesion-induced degeneration of RGCs was studied at different time points after the nerve crush. The regeneration of the injured RGC axons into the distal optic nerve stump was analyzed one month after nerve lesioning. We found that the intravitreally administered PGRN slowed the degeneration of the injured RGCs for up to four months, the latest post-lesion interval analyzed. Furthermore, PGRN stimulated the regeneration of some RGC axons over long distances into the distal optic nerve stumps. Taken together, our results identify PGRN as a novel neurotrophic factor for retinal ganglion cells. Full article

The retina is a complex sensory neural tissue composed of six major types of neurons and one type of glial cell. The cell fate specification of retinal cells is tightly governed by intrinsic factors and extrinsic microenvironmental cues. Among the key regulators directing retinal cell fate differentiation is a group of bHLH family transcription factors (TFs). Our previous work demonstrated that the bHLH TF Ngn3 exhibits robust potential to induce retinogenesis in both distantly related fibroblasts in vitro and late retinal progenitor cells (RPCs) in vivo. However, the underlying molecular mechanisms remain largely elusive. In this study, we combined immunohistological examination and RNA-seq and ATAC-seq analyses to investigate the cellular and molecular mechanisms governing Ngn3-driven retinogenesis in late RPCs. Our results revealed that Ngn3 overexpression promotes premature cell cycle exit in late RPCs and remodels their transcriptomic and epigenomic landscape towards a state favoring rod photoreceptor and RGC differentiation. Furthermore, cross-comparison with Ngn3-overexpressing fibroblasts in vitro revealed cell-type-specific mechanisms underlying Ngn3-mediated neuronal fate reprogramming. These findings advance our understanding of Ngn family-mediated retinal cell fate regulation and provide a mechanistic framework for optimizing Ngn3-based retinal regeneration strategies for the treatment of retinal degeneration diseases. Full article

Background/Objectives: Vascular inflammation and impaired endothelial regeneration contribute to chronic degenerative disorders, including ocular neovascularization and retinal degeneration. Nutritional bioactives that modulate molecular pathways governing angiogenesis and tissue remodeling represent promising adjunct strategies for vascular health. This study investigated whether cocoa powder (CP) regulates hypoxia-driven molecular signaling and attenuates vascular inflammation and degeneration. Methods: The vascular-modulatory effects of CP were examined in human umbilical vein endothelial cells (HUVECs) and in murine models of alkali-induced corneal neovascularization and N-methyl-N-nitrosourea (MNU)-induced retinal degeneration. Hypoxia-inducible factor-1α (HIF-1α) signaling and downstream angiogenic targets were assessed by Western blotting and quantitative PCR. Endothelial migration, tube formation, and transwell assays were performed to evaluate angiogenic responses. In vivo, oral CP (50 or 200 mg/kg) was administered, and vascular growth, inflammatory and remodeling markers, and retinal structural integrity were analyzed by histology, immunofluorescence, and protein expression. Results: At non-cytotoxic concentrations (0.1–1.0 μg/mL), CP suppressed hypoxia-induced HIF-1α protein stabilization without altering HIF-1α mRNA levels and reduced expression of VEGFA, EPO, and GLUT1. CP significantly inhibited VEGF-A-induced endothelial migration, network formation, and chemotactic invasion. In alkali-injured corneas, CP reduced the neovascularized area and downregulated VEGF, MMP2, MMP9, α-smooth muscle actin, and Ninj1, indicating attenuation of vascular inflammation and fibrotic remodeling. In the MNU model, CP preserved outer nuclear layer thickness, reduced glial activation (GFAP), maintained rhodopsin expression, and decreased MMP9 induction. Conclusions: CP functions as a nutritional modulator of hypoxia-responsive and inflammatory pathways, suppressing pathological angiogenesis while supporting structural preservation in degenerative vascular conditions. These findings highlight the translational potential of dietary polyphenol-rich interventions in regulating vascular inflammation and regeneration. Full article

The zebrafish (Danio rerio) is a widely used model for studying retinal regeneration. In adults, light-induced retinal damage (LIRD) serves as an environmental phototoxic stressor that induces photoreceptor degeneration and regenerative responses, whereas larval models remain comparatively underexplored. In this study, we validate a larval LIRD paradigm as a versatile system for studying acute phototoxic injury and early regeneration-associated transcriptomic responses. Using high-throughput RNA sequencing, we profiled retinal transcriptional changes 48 h post-LIRD and complemented these findings with targeted pharmacological modulation of redox signaling. Larval LIRD induced robust activation of canonical apoptotic and regeneration-associated pathways, recapitulating key features of adult LIRD models while engaging previously underexplored gene-regulatory networks. Among these, pathways related to oxidative stress responses, antioxidant enzymes, and oxygen metabolism were prominently regulated. Functional attenuation of oxidative stress using the N-acetylcysteine reduced phototoxic injury-induced apoptosis and proliferation, while inflammatory markers remained largely unaffected. Conversely, subtoxic intra-retinal hydrogen peroxide exposure was sufficient to induce proliferative markers without eliciting apoptosis response. At the signaling level, modulation of oxidative stress influenced components of growth-associated signaling pathways activated during early injury response. Together, these findings support a role for oxidative stress as a key component of early injury-associated signaling in larval retinal regeneration. This study integrates histological, transcriptomic, and pharmacological analyses to interrogate early regenerative programs and provides a comprehensive transcriptomic resource for exploring redox-associated mechanisms in retinal injury and repair. Full article

Background: The principal glial cells of the retina, Müller glia, play a central role in retinal regeneration in teleost fish and have recently attracted attention as potential sources of neuronal regeneration in mammals. Objectives: In this study, we examined whether SV40-immortalized rat Müller glia could be directed toward neuronal differentiation using a non-genetic approach with defined culture conditions. Methods: Comprehensive transcriptomic profiling by RNA sequencing indicated that changes in culture medium alone could induce transcriptional reprogramming toward a neuronal lineage. Results: Specifically, expression of Müller glia-related genes decreased, while a subset of photoreceptor-related transcription factors and specific genes showed altered expression, suggesting early-stage induction toward a photoreceptor-like fate. This finding suggests that even immortalized cells may exhibit activation of neuronal genes through non-genetic culture interventions. Gene set enrichment analysis further revealed upregulation of pathways related to the synaptic vesicle cycle, metabolic activation, oxidative stress defense, and lysosomal function, consistent with initiation of neuronal differentiation. Conversely, pathways associated with cell cycle regulation and stemness signaling were downregulated, reflecting a transition from a proliferative to a differentiation-prone state. Collectively, these results provide preliminary molecular markers for early neuronal induction and potential targets for chemical screening. Conclusions: Importantly, this strategy enables neuronal-like differentiation of Müller glia without genetic manipulation, offering a safe and cost-effective platform. Overall, our findings may support the development of in vitro models for retinal neuroregeneration and facilitate research toward regenerative therapies for retinal disorders. Full article

Mitochondrial lipid metabolism is an emerging regulator of neuronal regeneration, yet its role remains poorly defined. We investigated the function of phosphatidylserine decarboxylase (PSD), a mitochondrial enzyme that converts phosphatidylserine to phosphatidylethanolamine (PE), in retinal ganglion cell (RGC) regeneration. Using human glaucomatous degenerating optic nerves, we found PE was aberrantly accumulated with an elevated PSD expression and activity. In contrast, transcriptomes of regenerating RGCs present downregulated PSD, implicating PSD as a potential negative regulator of axonal growth. Using AAV2-mediated gene modulation, we evaluated how PSD knockdown (PSDKD) and PSD overexpression (PSDOE) alter RGC neurite outgrowth in vitro while evaluating effects on mitochondrial morphology, membrane fluidity by C-Laurdan staining, and lipidomes by LC-MS analysis. PSDOE did not support RGC neurite outgrowth, fragmented mitochondria, and increased polyunsaturated triacylglycerols. PSDKD significantly enhanced RGC neurite outgrowth and increased somal membrane fluidity accompanied by decreased cholesterol and saturated triacylglycerols. Notably, Doxorubicin, which attenuates PSD activity, increased neurite growth in PSDOE RGCs, supporting PSD’s activity as a negative role for growth. Using the optic nerve crush degenerative model in C57BL/6 mice, we confirm PSDKD RGCs have higher growth competency in vivo. These findings indicate PSDKD positions RGCs in a more growth-permissive state. Full article

Optic nerve (ON) injury by trauma induces progressive retinal ganglion cell (RGC) death and axonal loss, which leads to irreversible visual impairment and even blindness. Recently, we discovered that cellular senescence is involved in RGC survival regulation post-ON injury, and senolytic (dasatinib and quercetin) treatments can promote RGC survival and electroretinography activity. Here, we aimed to further evaluate the effects of dasatinib and quercetin on RGC dendrites and axons in mice with an ON crush injury. Longitudinal in vivo imaging analysis demonstrated that the RGC dendritic shrinkage was significantly reduced in mice with both individual and combined treatment of dasatinib and quercetin as compared to the vehicle treatment group. Similarly, dasatinib and quercetin treatments significantly promoted axonal regeneration post-ON injury as compared to the vehicle-treated mice. RNA sequencing analysis showed that the differentially expressed genes were enriched in the response to glucocorticoid, calcium ion binding, and cerebral cortex development. Sybr green PCR and immunofluorescence analyses validated that the axonal extension-related gene, meteorin (Metrn), was significantly upregulated in the dasatinib-only and combined dasatinib and quercetin treatments. In summary, this study revealed that dasatinib and quercetin alleviated RGC dendritic shrinkage and promoted axonal regeneration in mice after ON injury, probably mediated through meteorin, suggesting the dendrite repair and axonal regeneration potentials of dasatinib and quercetin for traumatic optic neuropathy treatment. Full article

As the central hub of retinal metabolism, mitochondria are vital for sustaining the integrity of the inner blood-retinal barrier (iBRB), which is fundamental to retinal homeostasis. Mitochondrial dysfunction accelerates severe iBRB disruption, a process which is increasingly implicated in a cascade of mitochondrial pathologies including mitochondrial DNA destabilization, oxidative stress, calcium homeostasis disruption, mitochondrial autophagy deficiency, and dysregulated dynamic regulation. This review establishes the iBRB as a crossroads for metabolic, redox, and inflammatory signaling. By analyzing evidence from diabetic retinopathy and retinal vein occlusion models, we clarify how mitochondrial decline translates local energy deficiency into chronic barrier dysfunction. We posit that restoring mitochondrial function is indispensable for vascular resilience and regeneration, a conclusion drawn from integrating molecular, cellular, and translational findings. To advance mitochondrial discoveries into clinical practice, subsequent studies must prioritize achieving spatiotemporally controlled, cell-type-specific interventions with robust in vivo efficacy, thereby successfully translating mitochondrial science into clinical vascular medicine. Full article

11-cis-retinal, the indispensable chromophore of photoreceptor opsins, is fundamental for light detection and the initiation of visual signal transduction. Its synthesis and regeneration through the visual cycle are critical not only for phototransduction but also for maintaining retinal homeostasis. Disruption of key enzymes, such as retinal pigment epithelium (RPE)65 and retinol dehydrogenases, results in toxic retinoid accumulation, oxidative stress, and progressive photoreceptor degeneration. These pathological mechanisms contribute to inherited and acquired retinal diseases, including Stargardt disease type 1, age-related macular degeneration, Leber congenital amaurosis, retinitis pigmentosa, and fundus albipunctatus. Recent therapeutic advances, ranging from gene replacement therapy with RPE65 (voretigene neparvovec, Luxturna^®) to small-molecule modulators and antioxidant strategies, underscore the translational potential of targeting chromophore metabolism. This review outlines molecular processes underlying chromophore synthesis and regeneration, elucidates how disruptions in these processes contribute to inherited and acquired retinal pathologies, and evaluates existing and emerging therapeutic strategies that target chromophore metabolism. We highlight ongoing challenges and critical knowledge gaps to guide future investigations on basic science, translational research, and clinical practice. This review provides a comprehensive overview of the molecular mechanisms, current therapeutic approaches, and outstanding challenges, with a focus on future intervention directions. Full article

Visual impairment impacts nearly half a billion people globally. Corrective glasses, artificial lens replacement, and medical management have markedly improved the management of diseases inherent to the eye, such as refractive errors, cataracts, and glaucoma. However, therapeutic strategies for retinopathies, optic nerve damage, and distal optic pathways remain limited. The complex optic apparatus comprises multiple neural structures that transmit information from the retina to the diencephalon to the cortex. Over the last few decades, innovations have emerged to address the loss of function at each step of this pathway. Given the retina’s lack of regenerative potential, novel treatment options have focused on replacing lost retinal cell types through cellular replacement with stem cells, restoring lost gene function with genetic engineering, and imparting new light sensation capabilities with optogenetics. Additionally, retinal neuroprosthetics have shown efficacy in restoring functional vision, and neuroprosthetic devices targeting the optic nerve, thalamus, and cortex are in early stages of development. Non-invasive neuromodulation has also shown some promise in modulating the visual cortex. Recently, the first in-human whole-eye transplant was performed. While functional vision was not restored, the feasibility of such a transplant with viable tissue graft at one year was demonstrated. Subsequent studies are now focused on guidance cues for axonal regeneration past the graft site to reach the lateral geniculate nucleus. Although the methods discussed above have shown promise individually, improvements in vision have been modest at best. Achieving the goal of restoration of functional vision will clearly require further development of cellular therapies, genetic engineering, transplantation, and neuromodulation. A concerted multidisciplinary effort involving scientists, engineers, ophthalmologists, neurosurgeons, and reconstructive surgeons will be necessary to restore vision for patients with vision loss from these challenging pathologies. In this expert review article, we describe the current literature in visual neurorestoration with respect to cellular therapeutics, genetic therapies, optogenetics, neuroprosthetics, non-invasive neuromodulation, and whole-eye transplant. Full article

Cell-based therapeutics are redefining interventions for vision loss by enabling tissue replacement, regeneration, and neuroprotection. This review surveys contemporary cellular strategies in ophthalmology through the lenses of therapeutic effectiveness, translational readiness, and governance. We profile principal sources—embryonic and induced pluripotent stem cells, mesenchymal stromal cells, retinal pigment epithelium, retinal progenitor and limbal stem cells—and enabling platforms including extracellular vesicles, encapsulated cell technology and biomaterial scaffolds. We synthesize clinical evidence across age-related macular degeneration, inherited retinal dystrophies, and corneal injury/limbal stem-cell deficiency, and highlight emerging applications for glaucoma and diabetic retinopathy. Delivery routes (subretinal, intravitreal, anterior segment) and graft formats (single cells, sheets/patches, organoids) are compared using standardized structural and functional endpoints. Persistent barriers include GMP-compliant derivation and release testing; differentiation fidelity, maturation, and potency; genomic stability and tumorigenicity risk; graft survival, synaptic integration, and immune rejection despite ocular immune privilege; the scarcity of validated biomarkers and harmonized outcome measures and ethical, regulatory, and health-economic constraints. Promising trajectories span off-the-shelf allogeneic products, patient-specific iPSC-derived grafts, organoid and 3D-bioprinted tissues, gene-plus-cell combinations, and cell-free extracellular-vesicle therapeutics. Overall, cell-based therapies remain investigational. With adequately powered trials, methodological harmonization, long-term surveillance, scalable xeno-free manufacturing, and equitable access frameworks, they may eventually become standards of care; at present, approvals are limited to specific products/indications and regions, and no cell therapy is the standard of care for retinal disease. Full article

In the last years, the zebrafish model has become a primary model system for vertebrate tissue regeneration, particularly for neurodegeneration and metabolic disease. Zebrafish (Danio rerio) are small freshwater teleosts valued for disease modelling, which are widely used in genetic laboratories, as a key model for studying neurodegenerative, metabolic, cardiac and dystrophic diseases, supporting the goal of identifying new therapeutic targets and approaches. Zebrafish can proliferate and produce/regenerate neurons. In response to retinal injury, zebrafish can regenerate multiple classes of retinal neurons and particularly, Müller glia-derived progenitor cells (MGPCs) can regenerate all types of neurons and restore visual function upon injury. The Jak/Stat-pathway of zebrafish retina represents one of the cell-signalling pathways involved in reprogramming Müller glia into MGPCs. In this era characterized by a revolution in experimental models and the future of omics, zebrafish might represent a suitable animal model for studying retinal degeneration and regeneration. In this context, the review is not meant to be entirely comprehensive of the zebrafish field, but it will highlight the usefulness of this model in discovering some mechanisms underlying retinal repair and regeneration. Full article

Background/Objectives: Inflammatory processes, both acute and chronic, encompass a wide range of autoimmune, metabolic, and neurodegenerative conditions. Conventional treatments, primarily anti-inflammatories and immunosuppressants, provide partial relief but are often hampered by adverse effects and limited durability. Mesenchymal stem cells (MSCs) have emerged as a powerful new treatment due to their immunomodulatory and anti-inflammatory properties, primarily mediated through their secretome, which is a complex mixture of bioactive factors. Secretome-based therapeutic strategies show strong potential for controlling inflammation, mitigating oxidative stress, and supporting tissue regeneration and repair. However, the therapeutic efficacy of MSCs’ secretome is subject to modification by concurrent anti-inflammatory drug regimens used in clinical settings. Methods: To evaluate the effect of combinatorial treatment strategies on the secretome of the MSCs, we employed an in vitro retinal inflammation model to investigate whether the exposure of the MSCs to five representative anti-inflammatory drugs (ketorolac, diclofenac, α-lipoic acid, N-acetyl-L-cysteine, and nicotinamide) impacts the functionality of the resulting secretome. Specifically, we evaluated the effect of the above-mentioned drugs on the anti-inflammatory properties of the secretome in relation to the secreted levels of two main MSC secretome factors—the Brain-Derived Neurotrophic Factor (BDNF) and the Vascular Endothelial Growth Factor (VEGF)—and on the secretome’s pro-metabolic activity. Results: Our findings provide evidence that the presence of any of the tested drugs during MSC secretome production does not compromise its anti-inflammatory activity; BDNF and VEGF levels remain stable, and the secretome retains a high degree of its pro-metabolic effect. Conclusions: These results underscore the robustness and clinical resilience of MSC-based therapies, even when administered alongside pharmacological agents. This work advances the translational viability of MSC therapies for inflammatory diseases and supports the development of safe, combinatorial treatment strategies. Full article

Background/Objectives: Glucagon-like peptide-1 (GLP-1) is an endogenous hormone with receptors widely expressed across multiple organs. GLP-1 receptor agonists (GLP-1RAs), primarily used for diabetes management, have demonstrated anti-inflammatory and antioxidant properties beyond glucose regulation. This study explores the protective effect of semaglutide, a GLP-1RA, in reducing oxidative stress and promoting wound healing in human dermal fibroblasts. Additionally, it assesses whether semaglutide offers the direct protection of retinal endothelial cells under oxidative stress. Methods: Human dermal fibroblasts and retinal endothelial cells were treated with semaglutide at concentrations ranging from 0 to 45 pg/mL for 24 h under oxidative stress induced by hydrogen peroxide (H₂O₂). Cell viability and ATP levels were measured via MTT and ATP assays. Apoptosis was evaluated using propidium iodide staining. Intracellular reactive oxygen species (ROS) and mitochondrial superoxide were assessed through confocal microscopy with specific fluorescent probes. Wound healing was tested using scratch assays, with closure monitored over time and quantified with ImageJ (version 1.51). Gene expression levels of antioxidants, extracellular matrix components, inflammatory cytokines, and MMPs (MMP3, MMP9) were determined via real-time PCR. Results: Semaglutide significantly improved cell viability and ATP production under oxidative stress (p < 0.001), while reducing apoptosis and intracellular ROS levels. It notably accelerated fibroblast wound closure, achieving near-complete restoration. Gene analysis revealed increased expression of antioxidant and ECM-related genes, along with decreased pro-inflammatory cytokines and MMPs, indicating reduced inflammation and enhanced tissue remodeling. Conclusions: Semaglutide offers robust antioxidative and cytoprotective effects in dermal fibroblasts and retinal endothelial cells, promoting wound healing. These findings highlight its therapeutic potential for diabetic foot ulcers and diabetic retinopathy, supporting further in vivo investigation. Full article