Rare intercellular material transfer as a confound to interpreting inner retinal neuronal transplantation following internal limiting membrane disruption.

Intercellular cytoplasmic material transfer (MT) occurs between transplanted and developing photoreceptors and ambiguates cell origin identification in developmental, transdifferentiation, and transplantation experiments. Whether MT is a photoreceptor-specific phenomenon is unclear. Retinal ganglion cell (RGC) replacement, through transdifferentiation or transplantation, holds potential for restoring vision in optic neuropathies. During careful assessment for MT following human stem cell-derived RGC transplantation into mice, we identified RGC xenografts occasionally giving rise to labeling of donor-derived cytoplasmic, nuclear, and mitochondrial proteins within recipient Müller glia. Critically, nuclear organization is distinct between human and murine retinal neurons, which enables unequivocal discrimination of donor from host cells. MT was greatly facilitated by internal limiting membrane disruption, which also augments retinal engraftment following transplantation. Our findings demonstrate that retinal MT is not unique to photoreceptors and challenge the isolated use of species-specific immunofluorescent markers for xenotransplant identification. Assessment for MT is critical when analyzing neuronal replacement interventions.

The Mydriatic Red Eye as the Initial Presentation of Syphilis.

BACKGROUND: Syphilis is a sexually transmitted infection that has been increasing in prevalence since the early 2000s. Ocular involvement occurs in a minority of patients and must be in the differential diagnosis for patients who present with red eye and uveitis. CASE REPORT: A 29-year-old woman presented to the emergency department with a painful, mydriatic red eye. Review of systems revealed a rash as well as a recent genital lesion and, on further questioning, she admitted to a history of intravenous drug use and high-risk sexual activity. Ophthalmology was consulted and the patient was diagnosed with bilateral uveitis. Serologic testing was positive for syphilis, and she was admitted and treated with intravenous penicillin, with resolution of her uveitis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Red eye is a common ocular symptom in patients presenting to the emergency department. The differential diagnosis of the red eye is broad and can range from benign etiologies, such as conjunctivitis, to life- and sight-threatening conditions, such as endogenous endophthalmitis. Systemic diseases such as syphilis may present with primarily ocular symptoms, and ocular syphilis must be identified and managed appropriately to prevent devastating sequelae.

Analyses of transplanted human retinal ganglion cell morphology and localization in murine organotypic retinal explant culture.

Retinal ganglion cell (RGC) transplantation has the potential to restore vision in optic neuropathy, but donor neuron survival and retinal integration remain challenging. Here, we present a protocol for ex vivo human RGC transplantation on flatmounted murine organotypic retinal explants, providing a robust platform for studying donor RGC survival, dendritic stratification, topographic distribution, donor-host interactions, and pro-engraftment strategies. The protocol includes microscopy-based analyses to evaluate donor cell engraftment and can be adapted to various donor cell types or culture systems. For complete details on the use and execution of this protocol, please refer to Zhang et al. (2021a, 2021b).

Racial and socioeconomic disparities in ocular surface squamous neoplasia: a National Cancer Database analysis.

PURPOSE: A retrospective population-based study to investigate racial and socioeconomic disparities in patients diagnosed with ocular surface squamous neoplasia (OSSN). METHODS: To explore racial disparity, we selected OSSN patients with known age, insurance, gender and zip code-level income and education from the National Cancer Database (NCDB). Comparisons of clinical and socioeconomic variables stratified by race were made with the chi-square or Mann-Whitney tests. Survival outcome was examined a Cox regression model. RESULTS: Of the 2,402 identified patients from 2004 to 2015, 117 were black. Unadjusted differences were found between groups in regard to age, histology, insurance, income, and education. Black patients in comparison to white patients were younger (mean age: 62 years vs. 70 years; p < .001), represented a higher proportion of Medicaid use (10.3% vs. 3.2%; p < .001) or uninsured (10.3% vs. 2.7%; p < .001), and were more likely to reside in areas of low educational attainment (32.5% vs. 16.1% of whites; p < .001). Multivariate analysis found significantly higher risk of death in patients who were male (HR: 1.66, 95% CI 1.37-2.01) or black (HR: 1.57, 95% CI 1.03-2.38). CONCLUSION: Disparities in socioeconomic factors were observed in black patients with OSSN. OSSN occurred earlier in blacks, who were also socioeconomically disadvantaged and faced higher risk of death.

Retinal Ganglion Cell Transplantation: Approaches for Overcoming Challenges to Functional Integration.

As part of the central nervous system, mammalian retinal ganglion cells (RGCs) lack significant regenerative capacity. Glaucoma causes progressive and irreversible vision loss by damaging RGCs and their axons, which compose the optic nerve. To functionally restore vision, lost RGCs must be replaced. Despite tremendous advancements in experimental models of optic neuropathy that have elucidated pathways to induce endogenous RGC neuroprotection and axon regeneration, obstacles to achieving functional visual recovery through exogenous RGC transplantation remain. Key challenges include poor graft survival, low donor neuron localization to the host retina, and inadequate dendritogenesis and synaptogenesis with afferent amacrine and bipolar cells. In this review, we summarize the current state of experimental RGC transplantation, and we propose a set of standard approaches to quantifying and reporting experimental outcomes in order to guide a collective effort to advance the field toward functional RGC replacement and optic nerve regeneration.

The internal limiting membrane: Roles in retinal development and implications for emerging ocular therapies.

Basement membranes help to establish, maintain, and separate their associated tissues. They also provide growth and signaling substrates for nearby resident cells. The internal limiting membrane (ILM) is the basement membrane at the ocular vitreoretinal interface. While the ILM is essential for normal retinal development, it is dispensable in adulthood. Moreover, the ILM may constitute a significant barrier to emerging ocular therapeutics, such as viral gene therapy or stem cell transplantation. Here we take a neurodevelopmental perspective in examining how retinal neurons, glia, and vasculature interact with individual extracellular matrix constituents at the ILM. In addition, we review evidence that the ILM may impede novel ocular therapies and discuss approaches for achieving retinal parenchymal targeting of gene vectors and cell transplants delivered into the vitreous cavity by manipulating interactions with the ILM.

Role of the Internal Limiting Membrane in Structural Engraftment and Topographic Spacing of Transplanted Human Stem Cell-Derived Retinal Ganglion Cells.

Retinal ganglion cell (RGC) replacement holds potential for restoring vision lost to optic neuropathy. Transplanted RGCs must undergo neuroretinal integration to receive afferent visual signals for processing and efferent transmission. To date, retinal integration following RGC transplantation has been limited. We sought to overcome key barriers to transplanted human stem cell-derived RGC integration. Following co-culture ex vivo on organotypic mouse retinal explants, human RGCs cluster and extend bundled neurites that remain superficial to the neuroretina, hindering afferent synaptogenesis. To enhance integration, we increased the cellular permeability of the internal limiting membrane (ILM). Extracellular matrix digestion using proteolytic enzymes achieved ILM disruption while minimizing retinal toxicity and preserving glial reactivity. ILM disruption is associated with dispersion rather than clustering of co-cultured RGC bodies and neurites, and increased parenchymal neurite ingrowth. The ILM represents a significant obstacle to transplanted RGC connectivity and its circumvention may be necessary for functional RGC replacement.