Victor H. Guaiquil

Dry eye disease (DED) is an ocular surface disorder characterized by tear film instability, inflammation, epithelial damage, and neurosensory abnormalities. Due to its multifactorial etiology and pathophysiology, conventional therapies that focus on lubrication and immunosuppression often fall short in addressing the neuropathic component of ocular pain experienced by a growing subset of patients. Recent developments in sensory neuroscience have highlighted the pivotal role of ion channels in mediating ocular surface homeostasis, pain signaling, and inflammation. This review examines the role of the following major ion channel families in the pathophysiology of DED and neuropathic ocular pain: transient receptor potential (TRP) channels, voltage-gated sodium (Nav) channels, and purinergic P2X receptors. The review details their anatomical distribution, molecular function, and responses to environmental stimuli such as heat, cold, osmolarity, and injury. Current treatments, such as artificial tears, anti-inflammatory drops, and systemic neuromodulators, are also reviewed in relation to their effects on ion channel modulation. Additionally, emerging therapies that directly target sensory transduction pathways are introduced. This review highlights the therapeutic potential of ion channel modulation in personalizing treatment for patients with ocular surface pain, particularly those with neuropathic features unresponsive to standard care.

Corneal regeneration has gained growing interest in recent years, largely due to the limitations of conventional treatments and the persistent shortage of donor tissue. Among the emerging strategies, extracellular vehicles (EVs), especially those derived from mesenchymal stromal cells (MSCs), have shown great promise as a cell-free therapeutic approach. These nanoscale vesicles contribute to corneal healing by modulating inflammation, supporting epithelial and stromal regeneration, and promoting nerve repair. Their therapeutic potential is largely attributed to the diverse and bioactive proteomic cargo they carry, including growth factors, cytokines, and proteins involved in extracellular matrix remodeling. This review presents a comprehensive examination of the proteomic landscape of EVs in the context of corneal regenerative medicine. We explore the biological functions of EVs in corneal epithelial repair, stromal remodeling, and neurodegeneration. In addition, we discuss advanced proteomic profiling techniques such as mass spectrometry (MS) and liquid chromatography–mass spectrometry (LC-MS/MS), which have been used to identify and characterize the protein contents of EVs. This review also compares the proteomic profiles of EVs derived from various MSC sources, including adipose tissue, bone marrow, and umbilical cord, and considers how environmental cues, such as hypoxia and inflammation, influence their protein composition. By consolidating current findings, this article aims to provide valuable insights for advancing the next generation of cell-free therapies for corneal repair and regeneration.

Corneal nerve integrity is vital for maintaining ocular surface health and visual clarity, but damage from injury or disease can lead to pain, persistent epithelial defects, and even vision loss. A deeper understanding of how corneal nerves regenerate at the molecular level is key to developing therapies that restore both anatomical structure and function. In this review, we bring together current insights into the pathways that drive corneal nerve repair after injury. We outline the major signaling pathways that promote neuronal survival, axon extension, and nerve–epithelial interactions, along with evolving research around novel modulators that could improve repair outcomes. Although advances in imaging and molecular therapies have led to significant progress in promoting nerve regrowth, functional sensory recovery often lags. This gap in recovery emphasizes the need for research approaches that align anatomical restoration with sensory function. In this review, we aim to clarify the mechanisms underlying corneal nerve regeneration (and their intersections) and identify opportunities for improving patient outcomes.

Axon guidance proteins have been found to play a regenerative role in the peripheral nervous system and the cornea. Netrin‐4 is a member of the Netrins family of axon guidance proteins implicated in diabetic retinopathy and corneal hemangiogenesis. However, its effects on corneal nerve and epithelium repair are not well understood. We performed in vitro and in vivo studies to assess the effects of Netrin‐4 in corneal wound healing. We found that Netrin‐4 induced extensive neurite growth and branching in trigeminal ganglia neurons and accelerated the scratch closure of corneal epithelial cells. In vivo, the dual action of Netrin‐4 enhanced corneal epithelium healing and nerve regeneration in mice subjected to corneal epithelium debridement. Inhibition studies demonstrate that Netrin‐4‐induced neuronal growth may be mediated by interaction with Neogenin or α6β1 Integrin receptors. In conclusion, our data demonstrate that Netrin‐4 has trophic and neuroregenerative effects in the cornea and could be a suitable therapeutic target to treat corneal injury.

Nociceptors respond to noxious stimuli and transmit pain signals to the central nervous system. In the cornea, the nociceptors located in the most external layer provide a myriad of sensation modalities. Damage to these corneal nerve fibers can induce neuropathic pain. In response, corneal nerves become sensitized to previously non-noxious stimuli. Assessing corneal pain origin is a complex ophthalmic challenge due to variations in its causes and manifestations. Current FDA-approved therapies for corneal nociceptive pain, such as acetaminophen and NSAIDs, provide only broad-acting relief with unwanted side effects, highlighting the need for precision medicine for corneal nociceptive pain. A few targeted treatments, including perfluorohexyloctane (F6H8) eye drops and Optive Plus (TRPV1 antagonist), are FDA-approved, while others are in preclinical development. Treatments that target signaling pathways related to neurotrophic factors, such as nerve growth factors and ion channels, such as the transient receptor potential (TRP) family or tropomyosin receptor kinase A, may provide a potential combinatory therapeutic approach. This review describes the roles of nociceptors in corneal pain. In addition, it evaluates molecules within nociceptor signaling pathways for their potential to serve as targets for efficient therapeutic strategies for corneal nociceptive pain aimed at modulating neurotrophic factors and nociceptive channel sensitivity.

Extracellular vesicles (EVs), a diverse group of cell-derived exocytosed particles, are pivotal in mediating intercellular communication due to their ability to selectively transfer biomolecules to specific cell types. EVs, composed of proteins, nucleic acids, and lipids, are taken up by cells to affect a variety of signaling cascades. Research in the field has primarily focused on stem cell-derived EVs, with a particular focus on mesenchymal stem cells, for their potential therapeutic benefits. Recently, tissue-specific EVs or cell type-specific extracellular vesicles (CTS-EVs), have garnered attention for their unique biogenesis and molecular composition because they enable highly targeted cell-specific communication. Various studies have outlined the roles that CTS-EVs play in the signaling for physiological function and the maintenance of homeostasis, including immune modulation, tissue regeneration, and organ development. These properties are also exploited for disease propagation, such as in cancer, neurological disorders, infectious diseases, autoimmune conditions, and more. The insights gained from analyzing CTS-EVs in different biological roles not only enhance our understanding of intercellular signaling and disease pathogenesis but also open new avenues for innovative diagnostic biomarkers and therapeutic targets for a wide spectrum of medical conditions. This review comprehensively outlines the current understanding of CTS-EV origins, function within normal physiology, and implications in diseased states.

Extracellular vesicles (EVs), a diverse group of cell-derived exocytosed particles, are pivotal in mediating intercellular communication due to their ability to selectively transfer biomolecules to specific cell types. EVs, composed of proteins, nucleic acids, and lipids, are taken up by cells to affect a variety of signaling cascades. Research in the field has primarily focused on stem-cell derived EVs, with a particular focus on mesenchymal stem cells, for their potential therapeutic benefits. Recently, tissue specific EVs or cell type specific extracellular vesicles (CTS-EVs), have garnered attention for their unique biogenesis and molecular composition because they enable highly targeted cell-specific communication. Various studies have outlined the roles that CTS-EVs play in signaling for physiological function and maintenance of homeostasis, including immune modulation, tissue regeneration, and organ development. These properties are also exploited for disease propagation, such as in cancer, neurological disorders, infectious diseases, autoimmune conditions, and more. The insights gained from analyzing CTS-EVs in different biological roles not only enhance our understanding of intercellular signaling and disease pathogenesis, but also open new avenues for innovative diagnostic biomarkers and therapeutic targets for a wide spectrum of medical conditions. This review comprehensively outlines current understanding of CTS-EV origins, function within normal physiology, and implications in diseased states.

Extracellular vesicles (EVs) have been recognized as promising candidates for developing novel therapeutics for a wide range of pathologies, including ocular disorders, due to their ability to deliver a diverse array of bioactive molecules, including proteins, lipids, and nucleic acids, to recipient cells. Recent studies have shown that EVs derived from various cell types, including mesenchymal stromal cells (MSCs), retinal pigment epithelium cells, and endothelial cells, have therapeutic potential in ocular disorders, such as corneal injury and diabetic retinopathy. EVs exert their effects through various mechanisms, including promoting cell survival, reducing inflammation, and inducing tissue regeneration. Furthermore, EVs have shown promise in promoting nerve regeneration in ocular diseases. In particular, EVs derived from MSCs have been demonstrated to promote axonal regeneration and functional recovery in various animal models of optic nerve injury and glaucoma. EVs contain various neurotrophic factors and cytokines that can enhance neuronal survival and regeneration, promote angiogenesis, and modulate inflammation in the retina and optic nerve. Additionally, in experimental models, the application of EVs as a delivery platform for therapeutic molecules has revealed great promise in the treatment of ocular disorders. However, the clinical translation of EV-based therapies faces several challenges, and further preclinical and clinical studies are needed to fully explore the therapeutic potential of EVs in ocular disorders and to address the challenges for their successful clinical translation. In this review, we will provide an overview of different types of EVs and their cargo, as well as the techniques used for their isolation and characterization. We will then review the preclinical and clinical studies that have explored the role of EVs in the treatment of ocular disorders, highlighting their therapeutic potential and the challenges that need to be addressed for their clinical translation. Finally, we will discuss the future directions of EV-based therapeutics in ocular disorders. Overall, this review aims to provide a comprehensive overview of the current state of the art of EV-based therapeutics in ophthalmic disorders, with a focus on their potential for nerve regeneration in ocular diseases.