Search Results (316)

Thymosin beta-4 (TB4) and the related compound commonly referred to as TB-500 are widely discussed in tissue healing and musculoskeletal medicine, but the scope and nature of the supporting literature remain unclear. We conducted a scoping review to map the evidence on TB4 and TB-500 in tissue healing, regeneration, and musculoskeletal repair. PubMed, Europe PMC, and ClinicalTrials.gov were searched through March 2026. English-language in vitro, animal, human, and registered clinical trial sources directly evaluating TB4, TB-500, or included derivatives in repair-related contexts were eligible. Of 1772 records identified, 80 studies were included. The evidence base was weighted toward mixed and in vitro designs, and most studies evaluated TB4 rather than TB-500. The most common tissue categories were wound/skin/soft tissue, vascular/endothelial, ocular/cornea, and bone. Direct musculoskeletal tissue categories such as tendon, ligament, muscle, cartilage, and spine/intervertebral disc were comparatively sparse. Human evidence was concentrated in ocular/cornea and wound/skin/soft tissue settings, whereas direct TB-500 evidence was limited to a single included study. Overall, the mapped literature supports the popular interest in several repair-related pathways but remains unevenly distributed and largely preclinical, with limited human evidence directly relevant to musculoskeletal applications. Full article

Traditional 3D bioprinting of corneal constructs relies on planar slicing, which often results in a significant stairstep effect and the loss of anatomical curvature. Curvilinear layering has emerged as a promising alternative to address these limitations. The presented methodology, based on non-planar layer integration, ensures a smoother surface finish. The model’s surface is identified via vertex normals and reconstructed using the Poisson method. Finally, surface parametrization is applied to generate spatially curved trajectories. To validate the algorithm, corneal constructs were printed using a planar and the proposed non-planar approach. Quantitative evaluation of micro-Computed Tomography data revealed that the non-planar approach achieved significantly higher morphological fidelity, successfully replicating the intended parabolic profile of the human cornea. Furthermore, the non-planar constructs demonstrated adequate functional performance, characterized by high optical transparency. Thereby, the feasibility of printing non-planar layers using the proposed novel approach is successfully demonstrated. Furthermore, the comparative analysis confirms the method’s potential for corneal biofabrication when compared to traditional planar methods. Full article

Purpose: Preclinical studies report low-intensity ultraviolet C (UVC) light to be safe and effective in treating murine bacterial keratitis, however, limbal impacts of UVC have yet to be investigated directly. This study evaluated the depth and density of UVC-induced DNA damage in the porcine and human limbus following UVC exposures of varying supratherapeutic dose. Methods: The corneoscleral junction (limbus) of full-thickness porcine corneas was exposed to supratherapeutic doses of UVC light (265 nm, 1.93 mW/cm²) for 5, 10, 15, 30, or 60 min (exposure groups) or remained unexposed for the same durations (control groups), with a sample size of 6 per group. In parallel, human corneal tissue was exposed to UVC for 1 or 5 min and processed identically. Following exposure, all tissues were frozen, dissected, and analysed using immunohistochemistry to detect cyclobutane pyrimidine dimers (CPDs) as markers of DNA damage. CPD distribution, depth, and density were subsequently evaluated. Results: CPDs were localised predominantly in the superficial corneal epithelial layers, irrespective of the UVC dose. The mean ± SD thickness of the corneal epithelium in the UVC-exposed groups was 38.9 ± 18.9 µm, and the average depth of CPD formation was 13.3 ± 8.43 µm. The proportions of cells affected by CPDs within the corneal epithelium (mean ± SD) were 47.8 ± 25.6%, 58.5 ± 16.2%, 39.9 ± 26.4%, 41.3 ± 27.3%, and 38.9 ± 28.3% for exposure durations of 5, 10, 15, 30, and 60 min, respectively (p > 0.05). Human cornea showed similarly limited penetration, with no difference in CPD proportions between the 1 and 5 min UVC exposures (p = 0.70). Conclusions: UVC-induced DNA damage in both species was confined to the superficial cellular layers of the cornea, with no detectable damage observed in deeper tissues, including those where limbal stem cells reside, even after supratherapeutic doses of up to one hour of exposure. Full article

For testing ocular irritation, 3D corneal models mimicking the corneal epithelium are considered reliable eye irritation tests and are detailed in regulatory guideline OECD Test Guideline (TG) 492. The aim of the present study was to develop and validate a Reconstructed human Cornea-like Epithelium (RhCE) in vitro irritation test method for ophthalmic medical devices according to OECD TG 492. Immortalized Human Primary Corneal Epithelium Cells (IM-HCEpiCs) were cultured on microporous inserts and exposed to an Air–Liquid Interface (ALI). Morphology was examined using standard (immuno-) histological techniques. Viability was quantified with MTT assay. Barrier integrity and function were monitored by trans-epithelial electrical resistance (TEER) and determination of IC₅₀ using MTT assay. Reproducibility was evaluated by calculating the inter-batch coefficient of variation (CV %) of the absorbance values of negative control-treated RhCE model replicates by MTT assay. Technical proficiency was verified using reference chemicals. Irritancy of ophthalmic medical devices was assessed. IM-HCEpiCs developed an epithelium-like barrier under the ALI. TEER increased after ALI introduction, and the obtained IC₅₀ value showed concordance with the guideline’s reference ranges. The developed RhCE test method demonstrated technical proficiency and correctly identified medical devices as non-irritants. A novel RhCE model was developed and validated according to OECD TG 492. Full article

The scope of the present study is to conduct a comprehensive review of the anatomy, function, major pathological conditions and clinical significance of ocular lymphatic vessels. In recent years, it has become evident that ocular lymphatics play a major role in the pathogenesis and progression of ocular disorders. Therefore, we delved into this emerging field and described newly proposed mechanisms that may explain the involvement of ocular lymphatics in healthy and pathological states. Lymphatics are present in a plethora of ocular tissues primarily under pathological conditions, including limbal stroma, optic nerve, ocular muscles, lacrimal glands and sclera. The conjunctiva contains an extensive lymphatic network, whereas the cornea and retina are typically devoid of lymphatic vessels under physiological conditions. Inflammatory conditions can give birth to nascent lymphatic vessel sprouting. Growing evidence emphasizes the role of ocular lymphatics in glaucoma pathogenesis, suggesting a previously unknown aqueous humor drainage pathway mediated by lymphatic contribution. This review is based mainly on evidence from animal and experimental models, as human clinical data remain limited; therefore, caution is warranted when translating these findings into clinical practice. By gaining insight into the mechanisms and the clinical significance of eye lymphatics, this review aims to address novel insights for future research and treatment of eye diseases, as well as to highlight a misconception that has persisted for decades in ophthalmology. Full article

Background: Corneal organoids derived from pluripotent stem cells have emerged as powerful tools for studying corneal development, disease modeling, and regenerative medicine applications. While previous protocols have successfully generated corneal tissue structures, there remains a need for three-dimensional models that recapitulate the complex cellular architecture and diversity of native human cornea. Methods: We developed a modified spontaneous three-dimensional corneal organoid model using human embryonic stem cells (hESCs) through an adapted Self-formed Ectoderm Autonomous Multi-zone (SEAM) protocol. hESCs were cultured as spheroids in ultra-low-binding plates under normoxic conditions and differentiated over 7–8 weeks. Organoids were characterized using immunofluorescence staining for corneal-specific markers and single-cell RNA sequencing to assess cellular composition and gene expression patterns. Results: Approximately 20% of organoids developed transparent regions characteristic of corneal tissue by day 30 of differentiation. Immunofluorescence analysis revealed spatially organized expression of corneal markers, including ZO-1 and E-cadherin in the outermost epithelial layers, P63α-positive putative limbal stem cells at the epithelial–stromal interface, vimentin-positive stromal cells in the interior, and laminin-1 deposition that suggests Bowman’s membrane formation. The organoids expressed cornea-specific keratins (K3, K12, and K15) and the master regulator PAX6 in appropriate cellular compartments. Single-cell RNA sequencing identified 18 distinct cell clusters, including three corneal epithelium subclusters with differential expression of MUC16, KRT12, and ΔNp63α, two stromal populations with distinct inflammatory profiles, and a corneal endothelium cluster. Transcriptomic analysis confirmed expression of key corneal genes, including AQP3, CDH1, multiple keratins, mucins, and extracellular matrix components (HAS2, CD34, CD44, COL8A1, and KERA). Conclusions: This three-dimensional spheroid-based putative corneal organoid model successfully recapitulates the multilayered architecture and cellular diversity of human cornea, including stratified epithelium, putative limbal stem cells, stroma, and endothelium in spatially appropriate arrangements. The model demonstrates molecular signatures consistent with native corneal tissue and provides a valuable platform for studying corneal development, disease mechanisms, and potential therapeutic applications. Future optimization to improve organoid formation efficiency and functional maturation will enhance the utility of this system for both basic research and translational medicine. Full article

Corneal defects are a major cause of vision loss and require rapid, biocompatible, and effective sealing methods to restore ocular integrity and prevent infection. Current clinical adhesives, such as cyanoacrylate and fibrin glue, are limited by problems such as poor biocompatibility and inadequate stability. This study presents the design and evaluation of a fast-curable polymer bioadhesive hydrogel, a corneal glue formulated for efficient sealing of corneal defects. Hydrogels were synthesized from natural and synthetic polymers, including polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl cellulose (CMC), optimized for rapid gelation (~45 s), robust adhesion (~15 kPa), and mechanical strength (tensile strength ~0.35 MPa and storage modulus G′ indicating strong elastic behavior). Physicochemical and rheological properties, including swelling behavior and optical transparency (>90% transmittance across 400–700 nm), were characterized, including gelation time, swelling behavior, and mechanical strength. In vitro biocompatibility was assessed using human corneal epithelial cells to evaluate cytotoxicity and cell adhesion. Ex vivo studies on human cadaveric corneas with full-thickness defects measured adhesive strength and sealing efficacy through burst pressure (~38 mmHg) and leakage tests, with comparisons to commercial fibrin and cyanoacrylate adhesives. The optimized corneal glue exhibited fast curing, robust adhesion, high water retention with minimal swelling, favorable viscoelastic properties, and excellent cytocompatibility effectively sealing corneal defects in ex vivo models. These results highlight its potential as a promising fast-curable bioadhesive for corneal wound repair and ocular surface restoration. 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

Corneal fibrosis, clinically referred to as corneal scarring, disrupts the normal architecture and transparency of the cornea and remains a major cause of visual impairment worldwide. Although corneal transplantation can restore vision, its effectiveness is constrained by limited accessibility, donor tissue shortages, and the risk of allograft rejection. Treatments with human corneal stromal stem cells (hCSSCs) have demonstrated scarless healing in preclinical models of acute corneal injury. Here, we report that hCSSCs also modulated pre-existing corneal opacities. We established a reproducible in vivo model of chronic corneal opacity. Given that scar severity varies among corneas even after identical injuries, we developed a non-invasive, image-based method to quantify opacity volume longitudinally in individual corneas. Using this approach, we evaluated the scar-reducing potential of three hCSSC batches previously shown to inhibit acute scarring. Following cell treatment, the pre-existing opacity volumes gradually decreased. In vitro, hCSSCs exposed to pro-inflammatory stimulus exhibited increased metalloproteinase (MMP) activity relative to tissue inhibitor of metalloproteinase (TIMP), as indicated by an elevated MMP2/TIMP2 ratio. This shift may promote matrix remodeling and scar resolution. Overall, our findings provide proof-of-concept for hCSSC-based therapy as a strategy to reduce established corneal scarring and restore corneal transparency. Full article

Background/Objectives: Corneal endothelial cells (CEnCs) exist on the inner surface of the cornea and regulate its hydration. The immune system cannot penetrate CEnCs easily because the cornea is avascular and anterior chamber-associated immune deviation suppresses the immune reaction. Nevertheless, inflammatory cells can infiltrate through the corneal stroma and anterior chambers, and corneal endothelial inflammation can occur. In this cross-sectional study, we investigated the association between the neutrophil-to-lymphocyte ratio (NLR) and human corneal endothelial cells (CEnCs). Methods: A total of 307 eyes from 307 subjects who underwent specular microscopy were included. Corneal endothelial cell density (CECD), hexagonality (HEX), central corneal thickness (CCT), coefficient of variation (CV), and cell area were measured preoperatively using specular microscopy. Whole blood samples were obtained to measure the complete blood cell count. The NLR was calculated, and its relationship with CEnCs was evaluated. Results: In all subjects, CV was positively correlated with the percentage (%) of neutrophils (r = 0.120, p = 0.037) and absolute neutrophil count (r = 0.131, p = 0.022) and negatively correlated with the % of lymphocytes (r = −0.131, p = 0.022). HEX was correlated with the % of neutrophils (r = −0.156, p = 0.006), % of lymphocytes (r = 0.141, p = 0.014), % of basophils (r = 0.142, p = 0.013), the NLR (r = −0.129, p = 0.024), and the mean corpuscular volume (r = 0.121, p = 0.035). Conclusions: CV and HEX, which indicate the stability of CEnCs, are associated with NLR in the peripheral blood, suggesting that systemic inflammation and immunity may implicate in the pathology of CEnCs. Full article

Neoplasia of the cornea is overall rare, with corneal squamous-cell carcinoma (c-SCC) being most commonly reported in all species. C-SCC pathogenesis has been related to UV exposure in humans and horses, and to papillomavirus infection in humans. In dogs, brachycephalic conformation and chronic keratitis were associated with c-SCC. Corneal vascular tumors have also been exceptionally reported in humans, and rarely in animals. In dogs, they have been suggested to be UV-related. Except for equine c-SCCs, most studies on corneal neoplasms are case reports. The present study aimed to review the literature on epithelial and vascular corneal tumors in dogs, cats, and horses, adding new cases from our archives. Pubmed and Web of Science were searched (1980–2025) using the following keywords: cornea, neoplasia, carcinoma, hemangioma, hemangiosarcoma, dog, cat, and horse. Additionally, 94 new cases of corneal neoplasia were retrieved: 47 dogs (40 epithelial and seven vascular); 29 cats (14 epithelial and 15 vascular) and 18 horses. Signalment, clinical history, and histopathological characteristics were analyzed and compared with the literature. The combined results supported a strong association between brachycephalic dogs and c-SCC occurrence and highlighted the frequent coexistence in the feline species of symblepharon and corneal perforation, with corneal tumors. Full article

Vittaforma corneae (V. corneae)-associated microsporidial keratoconjunctivitis (MKC) is increasingly recognized as an emerging infection affecting healthy individuals. However, the molecular links between environmental reservoirs and human diseases remain poorly understood. In this study, we examined the potential relationship between environmental factors and human MKC following 2 outbreaks in Nagasaki, Japan, involving 16 patients by integrating clinical, molecular, and environmental analyses. We collected ocular samples from affected patients and 16 soil and 11 water samples from related geographic areas. These samples were analyzed using nested PCR and DNA sequencing, targeting the V. corneae microsporidian ribosomal genes. Our molecular comparisons revealed a high degree of sequence similarity between clinical and environmental soil isolates, suggesting a potential soil-associated reservoir for the infection. Outbreaks of MKC occurred following periods characterized by high temperatures, high humidity, and increased rainfall. While we cannot definitively establish causality, these findings support the hypothesis that environmental exposure may contribute to microsporidial ocular infections. Temporary visual impairment among affected athletes disrupted their training and raised concerns among sports teams regarding environmentally driven ocular infections. Overall, our findings reveal a clear molecular and ecological pathway for MKC transmission in a non-endemic country. They underscore the importance of environmental surveillance in sports fields and other high-contact environments. Full article

Background: Cultivated oral mucosal epithelial transplantation (COMET/CAOMECS) is an autologous, immunosuppression-sparing option for ocular surface reconstruction in limbal stem cell deficiency (LSCD). After two decades, indications, platforms and outcome definitions vary, and COMET’s position relative to limbal-derived epithelium remains uncertain. Methods: We conducted a PRISMA-ScR scoping review of human clinical studies (PubMed, 2000–30 December 2025) with hand-searching and regulatory sources. Eligible reports included COMET/CAOMECS series and comparative cohorts (CLET/ACLET, SLET, KLAL/CLAL). The primary outcome was anatomical success (stable epithelialised cornea without recurrent persistent epithelial defect, progressive conjunctivalisation or uncontrolled neovascularisation at last assessment). Given heterogeneity in definitions and analytic frames (fixed-time vs. Kaplan–Meier [KM]), results were synthesised narratively by indication and platform. Results: Twenty-five reports (893 eyes; 821 patients) were included. Aetiologies were predominantly burns and SJS/TEN. Across amniotic membrane-based mixed-aetiology series, 12-month anatomical success clustered around 55–70%. Aggregated descriptively across COMET eyes, 211/467 (45%) had a stable surface at last follow-up. Epithelialisation was generally rapid in quiet AM-based reconstructions and slower with severe adnexal disease or carrier-free platforms. Mean BCVA improved from 1.8 ± 0.7 to 1.4 ± 0.7 logMAR (471 eyes); ≥2-line gains occurred in 308/471 (65.4%). A matched comparison suggested better 12-month survival, less neovascularisation and better BCVA with substrate-free versus AM-carried COMET; a biomaterial-/feeder-free platform reconstructed most eyes but failed more often with four-quadrant symblepharon. Observational comparative cohorts suggested higher surface survival and average visual gain with limbal-derived epithelium, at the cost of systemic immunosuppression. Conclusions: In appropriately selected bilateral LSCD, COMET offers immunosuppression-sparing reconstruction with moderate, durable surface stability and clinically meaningful visual gains when performed on a quiet, optimised surface. Platform refinements—particularly substrate-free constructs—and prospective, indication-defined comparative studies with harmonised outcomes are needed to define COMET’s role relative to limbal-derived epithelium. Full article

The cornea is essential for proper ocular function, yet its histological structure varies considerably among animal species. Of particular importance are the palisades of Vogt in the limbal region, as they serve as a niche for limbal epithelial stem cells involved in corneal epithelial regeneration. This study was conducted on 73 eyeballs collected from 18 species of non-human primates originating from the Wrocław Zoological Garden (Poland). Eyeballs were fixed, processed, and embedded in paraffin. Four-micrometer sections were stained with Mayer’s H&E and PAS. Microscopically, the cornea showed either a four-layered pattern (anterior corneal epithelium, corneal stroma, Descemet’s membrane, posterior corneal epithelium) or a five-layered pattern when Bowman’s layer was present. A four-layered cornea occurred in the ring-tailed lemur, gray mouse lemur, Guianan squirrel monkey, Angolan colobus, and L’Hoest’s monkey, while the remaining species showed a five-layered structure with Bowman’s layer. The anterior corneal epithelium varied between species in thickness and number of cell layers (central region: 2–3 to 10–15 layers; 11.81 ± 0.43 µm to 44.23 ± 0.69 µm; peripheral region: 4–5 to 9–11 layers; 8.63 ± 2.57 µm to 42.45 ± 8.61 µm). Bowman’s layer ranged from 1.18 ± 0.01 µm to 3.22 ± 0.05 µm. The corneal stroma thickness differed markedly (237.96 ± 9.64 µm to 1438.29 ± 16.38 µm), as did Descemet’s membrane (4.92 ± 0.20 µm to 43.45 ± 0.49 µm), along with PAS reaction intensity. In the limbus, palisades of Vogt ranged from weakly to clearly developed; well-defined crypt-like structures were observed in the red-bellied lemur, red ruffed lemur, black-and-white ruffed lemur, Guianan squirrel monkey, L’Hoest’s monkey, Celebes crested macaque, and yellow baboon. The limbal epithelium also varied in thickness (5–6 to 15–17 cell layers). These results confirm distinct species-specific differences in corneal and limbal morphology that may reflect ecological conditions and functional adaptation. The presented data provides a comparative reference for veterinary ophthalmology and for studies on corneal epithelial regeneration involving limbal stem cells. Full article

Eyeblink conditioning (EBC), a form of Pavlovian learning that relies on cerebellar circuits, offers a translationally relevant assay of adaptive learning and cerebellar integrity. In delay EBC, a conditioned stimulus (CS), such as a tone, overlaps with and co-terminates with the unconditioned stimulus (US), typically a brief air puff to the cornea. Trace EBC introduces a stimulus-free interval between CS offset and US onset, engaging additional brain structures such as the hippocampus. Acquisition of conditioned responses (CRs), their timing, and resistance to extinction have all been linked to cerebellar function. While EBC is a well-established paradigm in the experimental analysis of behavior and neuroscience, human studies applying it to ADHD populations remain limited and show inconsistent findings. One potential explanation for this variability lies in procedural differences across studies, particularly in the temporal structure of conditioning trials. A key parameter in Pavlovian learning is the ratio of the inter-US interval (C; time between USs) to the CS–US interval (T; time between CS onset and US onset). Known as the C/T ratio, this value indexes the informational value of the CS in predicting the US and has been shown to influence acquisition speed and response strength. Despite its theoretical importance, the C/T ratio is rarely reported or standardized in human EBC studies involving ADHD. The present review aims to characterize procedural features—especially C/T ratios—used in EBC research with ADHD populations or models, with a focus on how such parameters may shape performance and interpretability in studies probing cerebellar function. Full article