Nathan Hubbard, Shahna Shahul Hameed, Tasneem Sharma

Determining the Therapeutic Effect of Human Neuritin 1 on the Restoration of Degenerated Retinal Ganglion Cells from Glaucoma Patients

Introduction

Determining the therapeutic effect of human neuritin 1 on the restoration of degenerated retinal ganglion cells from glaucoma patients. Explore Neuritin 1's therapeutic potential for restoring degenerated retinal ganglion cells in glaucoma patients. This study demonstrates NRN1's efficacy, offering hope for vision recovery in glaucoma.

Abstract

Background and Hypothesis: Glaucoma is a group of optic neuropathies that affects approximately 76 million people worldwide. The main risk factor is elevated intraocular pressure (IOP) which predominantly affects retinal ganglion cells (RGC), resulting in cell death and permanent vision loss. Current therapeutics for glaucoma involve reducing IOP and halting progression of disease, but no current treatments can revive degenerated RGCs. Our project aims to evaluate the therapeutic effect of human Neuritin 1 (NRN1) in regenerating and protecting RGC loss in glaucoma. By administering NRN1 to the RGCs in culture, we hope to elucidate the efficacy in helping glaucomatous RGCs recover from cell death. Project Methods: Immunofluorescence (IF), gene expression, and karyotyping experiments were performed on iPSCs to confirm they were successfully reprogrammed from donor keratocytes. The iPSCs were differentiated to retinal organoids (RO) to generate RGCs in vitro. After around 30 days of differentiation, the ROs were dissociated to isolate RGCs. The RGCs were seeded at one end of three different in vitro collagen scaffolds. The first received no NRN1 treatment, the second received NRN1 at the cell body, and the third received NRN1 at the opposite end. IF was done on RGC-seeded scaffolds with RBPMS and NEFL antibodies to confirm RGC marker expression and neurite growth. Results: The iPSCs were successfully reprogrammed from donor keratocytes. We successfully generated RGCs from both non-glaucomatous and glaucomatous donor iPSCs. The RGCs effectively integrated within the collagen scaffolds. After NRN1 treatment, non-glaucomatous and glaucomatous RGCs demonstrated differential expression of RGC specific markers. Conclusions and Potential Impact: Our study demonstrates that NRN1 exhibits a therapeutic effect on glaucomatous RGCs. This study lays the foundation that NRN1 could potentially restore vision in glaucoma patients. Additionally, iPSC-derived RGCs can successfully be obtained from human donor eyes and cultured for future research for testing therapeutics.

Review

This study addresses a critical unmet need in glaucoma treatment by exploring novel strategies for the regeneration and protection of retinal ganglion cells (RGCs). The authors propose human Neuritin 1 (NRN1) as a potential therapeutic agent, aiming to revive degenerated RGCs—a goal beyond the scope of current therapies. A significant strength of this work lies in the development and utilization of an advanced in vitro model, employing iPSC-derived RGCs from both non-glaucomatous and glaucomatous human donors. This patient-specific approach offers a highly relevant platform for disease modeling and therapeutic screening, providing a robust foundation for evaluating NRN1's efficacy. The methodology demonstrates a comprehensive approach to model generation, from confirming iPSC reprogramming via immunofluorescence, gene expression, and karyotyping, to differentiating them into RGCs within retinal organoids. The subsequent culture of these RGCs on collagen scaffolds, with varying NRN1 administration sites, is particularly insightful, suggesting an exploration into the compound's localized effects on RGC bodies versus neurites. While the abstract confirms successful iPSC derivation, RGC generation, and integration into scaffolds, the pivotal result stating "non-glaucomatous and glaucomatous RGCs demonstrated differential expression of RGC specific markers" following NRN1 treatment is intriguing. This finding represents the core evidence for a therapeutic effect, though the specific nature and implications of this differential expression (e.g., upregulation of survival factors, neurotrophic support, or regeneration markers) remain to be elaborated in the full manuscript. In conclusion, this preliminary work presents compelling evidence for the potential therapeutic utility of NRN1 in managing glaucoma. The successful establishment of iPSC-derived RGCs from human donors provides an invaluable tool for future research, drug development, and personalized medicine in ophthalmology. While the abstract's claim of a "therapeutic effect" is supported by observed differential marker expression, a more detailed quantification and characterization of these changes, alongside functional assessments such as neurite outgrowth, cell survival rates, or electrophysiological activity, will be crucial to fully substantiate the exciting potential to "restore vision in glaucoma patients." Nevertheless, these initial findings are highly promising and lay a strong groundwork for advancing NRN1 as a regenerative therapeutic.

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