Mesenchymal Stem Cells and Exosomes: A Novel Therapeutic Approach for Corneal Diseases

Mesenchymal vs. epithelial extracellular vesicles in corneal epithelial repair, apoptosis, and immunomodulation: An in vitro study

Corneal injuries often lead to epithelial damage, apoptosis, and inflammation which impact visual function. Effective epithelial healing is critical for optimal vision and functioning of the cornea. Mesenchymal stem/stromal cells (MSCs)-derived extracellular vesicles (EVs) present promising avenues for cell-free therapy, however, evaluation of their specific roles in corneal epithelial injury requires further investigations with due consideration to the endogenous human corneal epithelial cell-derived EVs (HCEC-EVs). This study aims to isolate and characterize the EVs from a commonly available human corneal epithelial cell line (HCE-2 [50. B1], ATCC) and evaluate their corneal epithelial repair, anti-apoptotic, and immunomodulatory potential in comparison with human bone marrow mesenchymal stem cell-derived EVs (BM-MSC-EVs) in vitro. Both the BM-MSC- and HCEC-EVs exhibited similar morphology with a diameter <150 nm. However, the yield of EVs from HCECs was higher than that of BM-MSCs. Nanoparticle tracking analysis revealed an average EV size of ∼120 nm, while western blotting confirmed the presence of CD63, CD81, and TSG101, whereas Calnexin could not be detected in the BM-MSC- and HCEC-EVs. The corneal epithelial repair was monitored through in vitro wound healing assay, whereas apoptosis was studied through flow cytometry-based Propidium iodide staining in H2O2-treated cells. IL-1β-stimulated HCECs were treated with BM-MSC- and HCEC-EVs for 24 h and expression of pro- (IL-6 and TNF-α) and anti-inflammatory (IL-10 and TGF-β) cytokines was evaluated through ELISA. Our results, limited to in vitro investigations, suggest that compared with HCEC-EVs, BM-MSC-EVs showed: i) accelerated corneal epithelial healing, ii) enhanced anti-apoptotic potential, and iii) improved anti-inflammatory properties, in cultured HCECs.

Innovative Bioscaffolds in Stem Cell and Regenerative Therapies for Corneal Pathologies

Corneal diseases, which can result in substantial visual impairment and loss of vision, are an important worldwide health issue. The aim of this review was to investigate the novel application of bioscaffolds in stem cell and regenerative treatments for the treatment of corneal disorders. The current literature reports that organic and artificial substances create bioscaffolds that imitate the inherent structure of the cornea, facilitating the attachment, growth, and specialization of stem cells. Sophisticated methods such as electrospinning, 3D bioprinting, and surface modification have been reported to enhance the characteristics of the scaffold. These bioscaffolds have been shown to greatly improve the survival of stem cells and facilitate the regrowth of corneal tissue in both laboratory and live animal experiments. In addition, the incorporation of growth factors and bioactive compounds within the scaffolds can promote a favorable milieu for corneal regeneration. To summarize, the advancement of these groundbreaking bioscaffolds presents a hopeful treatment strategy for the regeneration of the cornea, which has the potential to enhance the results for individuals suffering from corneal disorders. This study highlights the possibility of utilizing the fields of biomaterials science and stem cell treatment to tackle medical demands that have not yet been satisfied in the field of ophthalmology.

Serum-derived extracellular vesicles for the treatment of severe ocular surface disease

PURPOSE

Autologous serum is widely used for the treatment of severe ocular surface disease with mixed efficacy. Extracellular vesicles (EVs) are small membrane bound structures present in all body fluids, including serum. This study compared the proteomic, metabolomic, and inflammatory cytokine composition of serum-derived EVs (SDEVs) to that of the soluble free protein fraction and the subsequent capacity of SDEVs to induce corneal epithelial cell migration and inflammation.

METHODS

SDEVs were isolated from human serum using size exclusion chromatography. SDEVs were analyzed using nanoparticle tracking analysis, transmission electron microscopy, and western blotting. The effects of SDEVs on corneal epithelial cell migration were tested using a standard scratch assay. Inflammatory cytokines in SDEVs and the free protein fraction were quantified using a microarray. A mutli-omics approach was further used to define SDEV cargo. The ability of SDEVs to modulate inflammation in corneal epithelial cells was quantified using ELISAs.

RESULTS

Western blot and TEM confirmed the presence of SDEVs. Proinflammatory cytokines, along with complement proteins and TGF-β, were decreased in SDEVs compared to serum. Metabolites present in SDEVs were mostly involved in amino acid biosynthesis, the TCA cycle and oxidative phosphorylation. SDEVs exhibited pro-migratory effects similar to serum however, SDEVs did not induce secretion of IL-6 or IL-8.

CONCLUSIONS

SDEVs exhibit reduced levels of pro-inflammatory cytokines while retaining the beneficial wound healing properties of serum. Unlike serum, SDEVs do not induce inflammation. SDEVs may represent an alternative option for patients with severe ocular surface disease where traditional autologous serum has failed.

The role of the JAK/STAT3 signaling pathway in acquired corneal diseases

Acquired corneal diseases such as dry eye disease (DED), keratitis and corneal alkali burns are significant contributors to vision impairment worldwide, and more effective and innovative therapies are urgently needed. The Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway plays an indispensable role in cell metabolism, inflammation and the immune response. Studies have shown that regulators of this pathway are extensively expressed in the cornea, inducing significant activation of JAK/STAT3 signaling in specific acquired corneal diseases. The activation of JAK/STAT3 signaling contributes to various pathophysiological processes in the cornea, including inflammation, neovascularization, fibrosis, and wound healing. In the context of DED, the hypertonic environment activates JAK/STAT3 signaling to stimulate corneal inflammation. Inflammation and injury progression in infectious keratitis can also be modulated by JAK/STAT3 signaling. Furthermore, JAK/STAT3 signaling is involved in every stage of corneal repair after alkali burns, including acute inflammation, angiogenesis and fibrosis. Treatments modulating JAK/STAT3 signaling have shown promising results in attenuating corneal damage, indicating its potential as a novel therapeutic target. Thus, this review emphasizes the multiple roles of the JAK/STAT3 signaling pathway in common acquired corneal disorders and summarizes the current achievements of JAK/STAT3-targeting therapy to provide new insights into future applications.

Immunological Regulation of Gut-Tropic Immune Cells by Extracellular Vesicles

The remarkable diversity of lymphocytes, essential components of the immune system, serves as an ingenious mechanism for maximizing the efficient utilization of limited host defense resources. While cell adhesion molecules, notably in gut-tropic T cells, play a central role in this mechanism, the counterbalancing molecular details have remained elusive. Conversely, we've uncovered the molecular pathways enabling extracellular vesicles secreted by lymphocytes to reach the gut's mucosal tissues, facilitating immunological regulation. This discovery sheds light on immune fine-tuning, offering insights into immune regulation mechanisms.

Current Advances in Regenerative Strategies for Dry Eye Diseases: A Comprehensive Review

Dry eye disease (DED) is an emerging health issue affecting millions of individuals annually. Ocular surface disorders, such as DED, are characterized by inflammation triggered by various factors. This condition can lead to tear deficiencies, resulting in the desiccation of the ocular surface, corneal ulceration/perforation, increased susceptibility to infections, and a higher risk of severe visual impairment and blindness. Currently, the clinical management of DED primarily relies on supportive and palliative measures, including the frequent and lifelong use of different lubricating agents. While some advancements like punctal plugs, non-steroidal anti-inflammatory drugs, and salivary gland autografts have been attempted, they have shown limited effectiveness. Recently, there have been promising developments in the treatment of DED, including biomaterials such as nano-systems, hydrogels, and contact lenses for drug delivery, cell-based therapies, biological approaches, and tissue-based regenerative therapy. This article specifically explores the different strategies reported so far for treating DED. The aim is to discuss their potential as long-term cures for DED while also considering the factors that limit their feasibility and effectiveness. These advancements offer hope for more effective and sustainable treatment options in the future.