A Novel Rat Model with Long Range Optic Nerve Injury to Study Retinal Ganglion Cells Endogenous Regeneration

Cathepsin B promotes optic nerve axonal regeneration

This study explored the role of cathepsin B (CTSB) in optic nerve regeneration. Sprague-Dawley rats were utilized for optic nerve crush and long-range crush injury model. Gene and protein expression changes were analyzed via reverse transcription quantitative polymerase chain reaction and western blot. Primary cortical neurons and BV2 cells were cultured to assess CTSB's effects on neuronal outgrowth and microglial activity. Local CTSB administration degraded chondroitin sulfate proteoglycans (CSPGs), promoting axonal growth in-vivo. In-vitro, CTSB neutralized CSPG-mediated inhibition of neuronal growth. Quantitative proteomics revealed elevated microglial marker proteins in the regenerative environment. Activation of signal transducer and activator of transcription 3 (STAT3) and signal transducer and activator of transcription 6 (STAT6) pathways in BV2 cells increased CTSB secretion. These findings suggest that postinjury regenerative microenvironment reconstruction is associated with upregulated CTSB, which degrades CSPGs to facilitate axonal growth. Microglia-derived CTSB, regulated by STAT3/STAT6 signaling, may play a key role in this process. Modulating CTSB expression could thus be a therapeutic strategy to enhance optic nerve regeneration by modifying the injury microenvironment.

Unlocking the potential for optic nerve regeneration over long distances: a multi-therapeutic intervention

Retinal ganglion cells (RGCs) generally fail to regenerate axons, resulting in irreversible vision loss after optic nerve injury. While many studies have shown that modulating specific genes can enhance RGCs survival and promote optic nerve regeneration, inducing long-distance axon regeneration in vivo through single-gene manipulation remains challenging. Nevertheless, combined multi-gene therapies have proven effective in significantly enhancing axonal regeneration. At present, research on promoting optic nerve regeneration remains slow, with most studies unable to achieve axonal growth beyond the optic chiasm or reestablish connections with the brain. Future research priorities include directing axonal growth along correct pathways, facilitating synapse formation and myelination, and modifying the inhibitory microenvironment. These strategies are crucial not only for optic nerve regeneration but also for broader applications in central nervous system repair. In this review, we discuss multifactors therapeutic strategies for optic nerve regeneration, offering insights into advancing nerve regeneration research.

Implantation of biomimetic polydopamine nanocomposite scaffold promotes optic nerve regeneration through modulating inhibitory microenvironment

Optic nerve regeneration remains challenging worldwide due to the limited intrinsic regenerative capacity of retinal ganglion cells (RGCs) and the inhibitory microenvironment. Oxidative stress, induced by excessive reactive oxygen species (ROS) following optic nerve injury, is associated with prolonged neuroinflammation, resulting in a secondary injury of RGCs and the impairment of axon regeneration. Herein, we developed a bionic nanocomposite scaffold (GA@PDA) with immunoregulatory ability for enhanced optic nerve regeneration. The ice-templating method was employed to fabricate biopolymer-based scaffolds with a directional porous structure, mimicking the optic nerve, which effectively guided the oriented growth of neuronal cells. The incorporation of bioinspired polydopamine nanoparticles (PDA NPs) further confers excellent ROS scavenging ability, thereby modulating the phenotype transformation of microglia/macrophages from pro-inflammatory M1 to anti-inflammatory M2. In a rat optic nerve crush model, the implantation of GA@PDA scaffold enhanced survival of RGCs and promoted axonal regeneration. Our study offers novel insights and holds promising potential for the advancement of engineered biomaterials in facilitating optic nerve regeneration.

Whole-eye transplantation: Current challenges and future perspectives

Whole-eye transplantation emerges as a frontier in ophthalmology, promising a transformative approach to irreversible blindness. Despite advancements, formidable challenges persist. Preservation of donor eye viability post-enucleation necessitates meticulous surgical techniques to optimize retinal integrity and ganglion cell survival. Overcoming the inhibitory milieu of the central nervous system for successful optic nerve regeneration remains elusive, prompting the exploration of neurotrophic support and immunomodulatory interventions. Immunological tolerance, paramount for graft acceptance, confronts the distinctive immunogenicity of ocular tissues, driving research into targeted immunosuppression strategies. Ethical and legal considerations underscore the necessity for stringent standards and ethical frameworks. Interdisciplinary collaboration and ongoing research endeavors are imperative to navigate these complexities. Biomaterials, stem cell therapies, and precision immunomodulation represent promising avenues in this pursuit. Ultimately, the aim of this review is to critically assess the current landscape of whole-eye transplantation, elucidating the challenges and advancements while delineating future directions for research and clinical practice. Through concerted efforts, whole-eye transplantation stands to revolutionize ophthalmic care, offering hope for restored vision and enhanced quality of life for those afflicted with blindness.