Target specification and therapeutic potential of extracellular vesicles for regulating corneal angiogenesis, lymphangiogenesis, and nerve repair.

Extracellular vesicles, including exosomes, are small extracellular vesicles that range in size from 30 nm to 10 μm in diameter and have specific membrane markers. They are naturally secreted and are present in various bodily fluids, including blood, urine, and saliva, and through the variety of their internal cargo, they contribute to both normal physiological and pathological processes. These processes include immune modulation, neuronal synapse formation, cell differentiation, cancer metastasis, angiogenesis, lymphangiogenesis, progression of infectious disease, and neurodegenerative disorders like Alzheimer's and Parkinson's disease.

Cell Type-Specific Extracellular Vesicles and Their Impact on Health and Disease.

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.

Extracellular-Vesicle-Based Therapeutics in Neuro-Ophthalmic Disorders.

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.

Bone marrow mesenchymal stromal cells in a 3D system produce higher concentration of extracellular vesicles (EVs) with increased complexity and enhanced neuronal growth properties.

Purpose: Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have been demonstrated to possess great potential in preclinical models. An efficient biomanufacturing platform is necessary for scale up production for clinical therapeutic applications. The aim of this study is to investigate the potential differences in neuro-regenerative properties of MSC-derived EVs generated in 2D versus 3D culture systems.

Benzalkonium chloride, a common ophthalmic preservative, compromises rat corneal cold sensitive nerve activity.

Purpose: Corneal nerves comprise the densest sensory network in the body. Dysfunction of the corneal cold sensitive neurons (CSN) is implicated in ophthalmic disorders, including Dry Eye Disease, the most common ocular surface disorder. The preservative Benzalkonium chloride (BAK) and the mydriatic agent Phenylephrine hydrochloride (PHE) are considered to be inactive at the level of the CSNs.

Expression of axon guidance ligands and their receptors in the cornea and trigeminal ganglia and their recovery after corneal epithelium injury.

Axon guidance proteins are essential for axonal pathfinding during development. In adulthood, they have been described as pleiotropic proteins with multiple roles in different organs and tissues. While most studies on the roles of these proteins in the cornea have been performed on the Semaphorin family members, with few reports on Netrins or Ephrins, their function in corneal epithelium wound healing and functional nerve regeneration is largely unknown.

The Limbal Niche and Regenerative Strategies.

The protective function and transparency provided by the corneal epithelium are dependent on and maintained by the regenerative capacity of limbal epithelial stem cells (LESCs). These LESCs are supported by the limbal niche, a specialized microenvironment consisting of cellular and non-cellular components. Disruption of the limbal niche, primarily from injuries or inflammatory processes, can negatively impact the regenerative ability of LESCs.

Hydrogels derived from acellular porcine corneal stroma enhance corneal wound healing.

Acellular cornea derived hydrogels provide significant advantages in preserving native corneal stromal keratocyte cells and endothelial cells. However, for clinical application, hydrogel physical properties need to be improved, and their role in corneal epithelial wound healing requires further investigation. In this study, an acellular porcine corneal stroma (APCS) hydrogel (APCS-gel) was successfully prepared from 20 mg/ml APCS, demonstrated optimal light transmittance and gelation kinetic properties and retained critical corneal ECM of collagens and growth factors.

Vinaxanthone inhibits Semaphorin3A induced axonal growth cone collapse in embryonic neurons but fails to block its growth promoting effects on adult neurons.

Semaphorin3A is considered a classical repellent molecule for developing neurons and a potent inhibitor of regeneration after nervous system trauma. Vinaxanthone and other Sema3A inhibitors are currently being tested as possible therapeutics to promote nervous system regeneration from injury. Our previous study on Sema3A demonstrated a switch in Sema3A's function toward induction of nerve regeneration in adult murine corneas and in culture of adult peripheral neurons.

Silk films with nanotopography and extracellular proteins enhance corneal epithelial wound healing.

Corneal wound healing depends on extracellular matrix (ECM) and topographical cues that modulate migration and proliferation of regenerating cells. In our study, silk films with either flat or nanotopography patterned parallel ridge widths of 2000, 1000, 800 nm surfaces were combined with ECMs which include collagen type I (collagen I), fibronectin, laminin, and Poly-D-Lysine to accelerate corneal wound healing. Silk films with 800 nm ridge width provided better cell spreading and wound recovery than other size topographies.

The Effect of Micro- and Nanoscale Surface Topographies on Silk on Human Corneal Limbal Epithelial Cell Differentiation.

We previously reported that micro- and nano-scale topographic pitch created on silk films mimic features of the corneal basement membrane by providing biophysical cues to direct corneal epithelial cell adherence and migration. However, the effect of these topographical features on corneal limbal epithelial cell differentiation has not been explored. We hypothesize in the current study that various topographical pitch created on silk may affect corneal epithelial stem cell differentiation and alter the expression of genes involved in cell differentiation and self-renewal.

Semaphorin3A induces nerve regeneration in the adult cornea-a switch from its repulsive role in development.

The peripheral sensory nerves that innervate the cornea can be easily damaged by trauma, surgery, infection or diabetes. Several growth factors and axon guidance molecules, such as Semaphorin3A (Sema3A) are upregulated upon cornea injury. Nerves can regenerate after injury but do not recover their original density and patterning.

Micro- and Nanoscale Topographies on Silk Regulate Gene Expression of Human Corneal Epithelial Cells.

Purpose: Corneal basement membrane has topographical features that provide biophysical cues to direct cell adherence, migration, and proliferation. In this study, we hypothesize that varying topographic pitch created on silk films can alter epithelial cell morphology, adhesion, and the genetic expression involved in cytoskeletal dynamics-related pathways.

Methods: Silicon wafers with parallel ridge widths of 2000, 1000, and 800 nm were produced and used to pattern silk films via soft lithography.

Silk-Derived Protein Enhances Corneal Epithelial Migration, Adhesion, and Proliferation.

Purpose: The corneal surface is vulnerable to a myriad of traumatic insults including mechanical, chemical, and thermal injuries. The resulting trauma may render the naturally occurring regenerative properties of the cornea incapable of restoring a healthy epithelial surface, and may result in the loss of corneal transparency and vision. Healing of the corneal epithelium requires a complex cascade of biological processes that work to restore the tissue after injury.

Acute corneal epithelial debridement unmasks the corneal stromal nerve responses to ocular stimulation in rats: implications for abnormal sensations of the eye.

It is widely accepted that the mechanisms for transducing sensory information reside in the nerve terminals. Occasionally, however, studies have appeared demonstrating that similar mechanisms may exist in the axon to which these terminals are connected. We examined this issue in the cornea, where nerve terminals in the epithelial cell layers are easily accessible for debridement, leaving the underlying stromal (axonal) nerves undisturbed.

VEGF-B selectively regenerates injured peripheral neurons and restores sensory and trophic functions.

VEGF-B primarily provides neuroprotection and improves survival in CNS-derived neurons. However, its actions on the peripheral nervous system have been less characterized. We examined whether VEGF-B mediates peripheral nerve repair.

Retinal angiogenesis suppression through small molecule activation of p53.

Neovascular age-related macular degeneration is a leading cause of irreversible vision loss in the Western world. Cytokine-targeted therapies (such as anti-vascular endothelial growth factor) are effective in treating pathologic ocular angiogenesis, but have not led to a durable effect and often require indefinite treatment. Here, we show that Nutlin-3, a small molecule antagonist of the E3 ubiquitin protein ligase MDM2, inhibited angiogenesis in several model systems.

A murine model for retinopathy of prematurity identifies endothelial cell proliferation as a potential mechanism for plus disease.

Purpose: To characterize the features and possible mechanism of plus disease in the mouse oxygen-induced retinopathy (OIR) model for retinopathy of prematurity.

Methods: Wild-type and Adam (A Disintegrin And Metalloproteinase) knockout mice were exposed to 75% oxygen from postnatal day 7 to 12 (P7 to P12) (hyperoxia), then returned to normal air (relative hypoxia). Live fundus imaging and fluorescein angiography at P17 were compared to immunofluorescence analysis of flat-mounted retinas.

Vascular endothelial growth factor promotes anatomical and functional recovery of injured peripheral nerves in the avascular cornea.

Peripheral nerve injury is a major neurological disorder that can cause severe motor and sensory dysfunction. Neurogenic effects of vascular endothelial growth factor (VEGF) have been found in the central nervous system, and we examined whether VEGF could promote anatomical and functional recovery of peripheral nerves after injury using an avascular corneal nerve injury model. We found that VEGF enhanced neurite elongation in isolated trigeminal ganglion neurons in a dose-dependent manner.

CD11c(hi) dendritic cells regulate the re-establishment of vascular quiescence and stabilization after immune stimulation of lymph nodes.

Lymph node expansion during immune responses is accompanied by rapid vascular expansion. The re-establishment of quiescence and stabilization of the newly expanded vasculature and the regulatory mechanisms involved have not been well studied. We show that although initiation of vascular expansion in immune-stimulated nodes is associated with upregulated endothelial cell proliferation, increased high endothelial venule trafficking efficiency and VCAM-1 expression, and disrupted perivascular fibroblastic reticular cell organization, the re-establishment of vascular quiescence and stabilization postexpansion is characterized by reversal of these phenomena.

ADAM8 is a negative regulator of retinal neovascularization and of the growth of heterotopically injected tumor cells in mice.

ADAM8 is a member of the "a disintegrin and metalloproteinase" (ADAM) family of membrane-anchored metalloproteinases. ADAM8-deficient mice have no evident spontaneous developmental or pathological defects, and little is currently known about the role of ADAM8 in disease. Here, we investigated the contribution of ADAM8 to pathological neovascularization in mice using an oxygen-induced retinopathy (OIR) model and heterotopical injection of tumor cells.

Vitamin C inhibits hypoxia-induced damage and apoptotic signaling pathways in cardiomyocytes and ischemic hearts.

Reactive oxygen species play a central role in myocardial ischemic injury and are a target for therapeutic intervention. Vitamin C is an essential antioxidant yet difficult to deliver in pharmacologic concentration to the myocardium. We found that adult rat cardiomyocytes accumulate vitamin C by transporting dehydroascorbic acid (DHA), the oxidized form of vitamin C, but do not transport ascorbic acid.

Recycling of vitamin C by a bystander effect.

Human cells transport dehydroascorbic acid through facilitative glucose transporters, in apparent contradiction with evidence indicating that vitamin C is present in human blood only as ascorbic acid. On the other hand, activated host defense cells undergoing the oxidative burst show increased vitamin C accumulation. We analyzed the role of the oxidative burst and the glucose transporters on vitamin C recycling in an in vitro system consisting of activated host-defense cells co-cultured with human cell lines and primary cells.