Human corneal stromal stem cells express anti-fibrotic microRNA-29a and 381-5p - A robust cell selection tool for stem cell therapy of corneal scarring

Effects of exosomes derived from activated corneal stromal keratocytes on the inflammation, proliferation, neuroprotection and epithelial-mesenchymal transition in retinal pigment epithelium cells

AIMS

This study investigated the effects of activated keratocyte-derived exosomes (aKExo) on retinal pigment epithelial (RPE) cells in-vitro, focusing on cell viability, inflammatory cytokine expression, and neuroprotective properties.

MATERIALS AND METHODS

Keratocytes were cultured, and exosomes were extracted and characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), flow cytometry, and dynamic light scattering (DLS). RPE cells, isolated from a human donor, were confirmed via RPE65 expression. aKExo effects on RPE cells were assessed using MTT assay at concentrations from 10-1 (35 μg/mL) to 10-5 (3.5 × 10-3 μg/mL). The optimal aKExo concentration (10-5) enhanced cell viability and exhibited the highest proliferative potential compared to the control group, making it the optimal dose for subsequent experiments including gene expression analysis, and ELISA.

KEY FINDINGS

aKExo downregulated IL-6 mRNA (0.70 ± 0.06, p = 0.0009) and marginally reduced TGF-β mRNA (0.75 ± 0.16, p = 0.0575). ELISA confirmed a reduction in IL-6 (31.33 ± 5.77 pg/mL vs. 50.22 ± 13.47 pg/mL, p = 0.0894) and TGF-β (8.91 ± 0.16 pg/mL vs. 11.39 ± 1.49 pg/mL, p = 0.0460). No significant changes were observed for IL-1β expression or other epithelial-mesenchymal transition (EMT)-related genes (α-SMA, ZEB-1, β-catenin). Neuroprotective genes NGF (4.34 ± 1.05, p = 0.0053) and CD90 (1.55 ± 0.25, p = 0.0184) were significantly upregulated, while VEGF-A was elevated (1.65 ± 0.15, p = 0.0018).

SIGNIFICANCE

These findings highlight aKExo's immunomodulatory, neuroprotective, and anti-EMT effects, suggesting potential therapeutic applications for retinal disorders, while noting that VEGF-A upregulation requires further investigation.

LNP-encapsulated miRNA29b for corneal repair: A novel approach to combat fibrosis

Severe corneal injuries often result in corneal scarring, leading to visual impairment and corneal blindness. Currently, there is a lack of effective anti-corneal fibrosis drugs in clinical practice. MicroRNA-based therapies hold significant potential in combating fibrosis. However, the barrier function of the cornea and the fluid environment of the ocular surface reduce drug permeability and bioavailability, presenting significant challenges for local drug application. This study employs microfluidic technology to encapsulate miRNA29b in lipid nanoparticles (LNP) to create an LNP-miRNA29b delivery system (LNP-mir29b) for treating corneal mechanical injuries. In vitro experiments show that LNP-mir29b significantly inhibits the expression of α-smooth muscle actin (α-SMA) in an induced corneal stromal cell fibrosis model. In vivo experiments using rabbit corneal mechanical injury models indicate that LNP-mir29b effectively reduces fibrosis in the corneal stroma, promotes organized rearrangement of stromal collagen fibers, and decreases the expression of fibrosis-related genes, including Col1A2, Col3A1, Fn, and α-SMA. Additionally, LNP-mir29b accelerates the migration of corneal epithelial cells, promotes wound healing of the epithelium, restores the structural integrity of the corneal epithelium. The LNP system proposed in this study offers a novel approach with anti-fibrotic functionality, providing a new strategy for reducing scarring during the corneal injury repair process.

Advances in Regenerative Medicine, Cell Therapy, and 3D Bioprinting for Corneal, Oculoplastic, and Orbital Surgery

Advances in regenerative medicine, cell therapy, and 3D bioprinting are reshaping the landscape of ocular surgery, offering innovative approaches to address complex conditions affecting the cornea, ocular adnexal structures, and the orbit. These technologies hold the potential to enhance treatment precision, improve functional outcomes, and address limitations in traditional surgical and therapeutic interventions.The cornea, as the eye's primary refractive and protective barrier, is particularly well-suited for regenerative approaches due to its avascular and immune-privileged nature. Cell-based therapies, including limbal stem cell transplantation as well as stromal keratocyte and corneal endothelial cell regeneration, are being investigated for their potential to restore corneal clarity and function in conditions such as limbal stem cell deficiency, keratoconus, and endothelial dysfunction. Simultaneously, 3D bioprinting technologies are enabling the development of biomimetic corneal constructs, potentially addressing the global shortage of donor tissues and facilitating personalized surgical solutions.In oculoplastic and orbital surgery, regenerative strategies and cell therapies are emerging as possible alternatives to conventional approaches for conditions such as eyelid defects, meibomian gland dysfunction, and Graves' orbitopathy. Stem cell-based therapies and bioengineered scaffolds are showing potential in restoring lacrimal glands' function as well as reconstructing complex ocular adnexal and orbital structures. Moreover, 3D-printed orbital implants and scaffolds offer innovative solutions for repairing traumatic, post-tumor resection, and congenital defects, with the potential for improved biocompatibility and precision.Molecular and gene-based therapies, including exosome delivery systems, nanoparticle-based interventions, and gene-editing techniques, are expanding the therapeutic arsenal for ophthalmic disorders. These approaches aim to enhance the efficacy of regenerative treatments by addressing underlying pathophysiological mechanisms of diseases. This chapter provides an overview of these advancements and the challenges of translating laboratory discoveries into effective therapies in clinical practice.

3D printed biomimetic bilayer limbal implants for regeneration of the corneal structure in limbal stem cell deficiency

Limbal stem cell deficiency (LSCD) causes vision loss and is often treated by simple corneal epithelial cell transplantation with poor long-term efficiency. Here, we present a biomimetic bilayer limbal implant using digital light processing 3D printing technology with gelatin methacrylate (GelMA) and poly (ethylene glycol) diacrylate (PEGDA) bioinks containing corneal epithelial cells (CECs) and corneal stromal stem cells (CSSCs), which can transplant CECs and improve the limbal niche simultaneously. The GelMA/PEGDA hydrogel possessed robust mechanical properties to support surgical transplantation and had good transparency, suitable swelling and degradation rate as a corneal implant. Encapsulated CECs and CSSCs maintained viability and proliferative activity in the bilayer limbal implant. In vivo, both CEC-loaded and CEC/CSSC-loaded hydrogel could repair the corneal surface in the LSCD model effectively. Notably, the corneal epithelial healing was faster, and corneal opacity and neovascularization were minimal in CEC/CSSC-loaded group. These findings highlight the feasibility of 3D printing in limbal construction, providing CEC/CSSC-loaded limbal implants as a treatment strategy for LSCD and corneal blindness. STATEMENT OF SIGNIFICANCE: This study aimed to enhance the long-term prognosis of limbal epithelial cell transplantation in patients with limbal stem cell deficiency by developing a 3D limbal implant that encapsulates corneal epithelial cells and limbal niche cells simultaneously. The 3D printed implant offers the advantages of mimicking the natural layered limbal structure and were found to enhance the regenerative capacity of corneal epithelial cells, suppress inflammation, and alleviate corneal scarring in vivo. This study highlights the importance of limbal microenvironment remodeling in the treatment of limbal stem cell deficiency and the potential of 3D printing in the treatment of corneal diseases.

Isolation, Culture, and Quality Assessment of Clinical-Grade Corneal Stromal Stem Cells

The challenge of treating corneal scarring through keratoplasties lies in the limited availability of donor tissue. Various studies have shown the therapeutic use of cultivated corneal stromal stem cells (CSSCs) to mitigate tissue inflammation and suppress fibrosis and scar tissue formation in preclinical corneal wound models. To develop CSSC therapy for clinical trials on patients with corneal scarring, it is necessary to generate clinical-grade CSSCs in compliant to Good Manufacturing Practice (GMP) regulations. This chapter elucidates human CSSC isolation, culture, and cryopreservation under GMP-compliant conditions. It underscores quality assessment encompassing morphological traits, expression of stemness markers, anti-inflammatory activity, and keratocyte differentiation potency.

A Full Good Manufacturing Practice-Compliant Protocol for Corneal Stromal Stem Cell Cultivation

Corneal scarring, a significant cause of global blindness, results from various insults, including trauma, infections, and genetic disorders. The conventional treatment to replace scarred corneal tissues includes partial or full-thickness corneal transplantation using healthy donor corneas. However, only 1 in 70 individuals with treatable corneal scarring can undergo surgery, due to the limited supply of transplantable donor tissue. Our research focuses on cell-based strategies, specifically ex vivo-expanded corneal stromal stem cells (CSSCs), to address corneal scarring. Preclinical studies have demonstrated the efficacy of CSSC treatment in reducing corneal inflammation and fibrosis, inhibiting scar formation, and regenerating native stromal tissue. Mechanisms include CSSC differentiation into stromal keratocytes and the expression of regenerative cytokines. Here, we present a good manufacturing practice (GMP)-compliant protocol to isolate and expand human CSSCs. This method paves the way to produce clinical-grade CSSCs for transplantation and clinical trials. Key features • This protocol utilizes surgical skills to dissect human corneal tissues for CSSC isolation. • The yield and features of CSSCs rely on donor tissue quality (freshness) and have donor-to-donor variability. • Up to 0.5 billion CSSCs can be generated from a single cornea specimen, and cells at passage 3 are suitable for treatment uses.

Anti-Inflammatory and Anti-(Lymph)angiogenic Properties of an ABCB5+ Limbal Mesenchymal Stem Cell Population

Corneal transparency and avascularity are essential for vision. The avascular cornea transitions into the vascularized conjunctiva at the limbus. Here, we explore a limbal stromal cell sub-population that expresses ABCB5 and has mesenchymal stem cell characteristics. Human primary corneal stromal cells were enriched for ABCB5 by using FACS sorting. ABCB5+ cells expressed the MSC markers CD90, CD73, and CD105. ABCB5+ but not ABCB5- cells from the same donor displayed evidence of pluripotency with a significantly higher colony-forming efficiency and the ability of trilineage differentiation (osteogenic, adipogenic, and chondrogenic). The ABCB5+ cell secretome demonstrated lower levels of the pro-inflammatory protein MIF (macrophage migration inhibitory factor) as well as of the pro-(lymph)angiogenic growth factors VEGFA and VEGFC, which correlated with reduced proliferation of Jurkat cells co-cultured with ABCB5+ cells and decreased proliferation of blood and lymphatic endothelial cells cultured in ABCB5+ cell-conditioned media. These data support the hypothesis that ABCB5+ limbal stromal cells are a putative MSC population with potential anti-inflammatory and anti-(lymph)angiogenic effects. The therapeutic modulation of ABCB5+ limbal stromal cells may prevent cornea neovascularization and inflammation and, if transplanted to other sites in the body, provide similar protective properties to other tissues.

Cell therapy in the cornea: The emerging role of microenvironment

The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.

Advances in Extracellular-Vesicles-Based Diagnostic and Therapeutic Approaches for Ocular Diseases

Extracellular vesicles (EVs) are nanoscale membrane vesicles of various sizes that can be secreted by most cells. EVs contain a diverse array of cargo, including RNAs, lipids, proteins, and other molecules with functions of intercellular communication, immune modulation, and regulation of physiological and pathological processes. The biofluids in the eye, including tears, aqueous humor, and vitreous humor, are important sources for EV-based diagnosis of ocular disease. Because the molecular cargos may reflect the biology of their parental cells, EVs in these biofluids, as well as in the blood, have been recognized as promising candidates as biomarkers for early diagnosis of ocular disease. Moreover, EVs have also been used as therapeutics and targeted drug delivery nanocarriers in many ocular disorders because of their low immunogenicity and superior biocompatibility in nature. In this review, we provide an overview of the recent advances in the field of EV-based studies on the diagnosis and therapeutics of ocular disease. We summarized the origins of EVs applied in ocular disease, assessed different methods for EV isolation from ocular biofluid samples, highlighted bioengineering strategies of EVs as drug delivery systems, introduced the latest applications in the diagnosis and treatment of ocular disease, and presented their potential in the current clinical trials. Finally, we briefly discussed the challenges of EV-based studies in ocular disease and some issues of concern for better focusing on clinical translational studies of EVs in the future.

Regenerative Therapy for Corneal Scarring Disorders

The cornea is a transparent and vitally multifaceted component of the eye, playing a pivotal role in vision and ocular health. It has primary refractive and protective functions. Typical corneal dysfunctions include opacities and deformities that result from injuries, infections, or other medical conditions. These can significantly impair vision. The conventional challenges in managing corneal ailments include the limited regenerative capacity (except corneal epithelium), immune response after donor tissue transplantation, a risk of long-term graft rejection, and the global shortage of transplantable donor materials. This review delves into the intricate composition of the cornea, the landscape of corneal regeneration, and the multifaceted repercussions of scar-related pathologies. It will elucidate the etiology and types of dysfunctions, assess current treatments and their limitations, and explore the potential of regenerative therapy that has emerged in both in vivo and clinical trials. This review will shed light on existing gaps in corneal disorder management and discuss the feasibility and challenges of advancing regenerative therapies for corneal stromal scarring.

Good manufacturing practice production of human corneal limbus-derived stromal stem cells and in vitro quality screening for therapeutic inhibition of corneal scarring

BACKGROUND

Mesenchymal stem cells in the adult corneal stroma (named corneal stromal stem cells, CSSCs) inhibit corneal inflammation and scarring and restore corneal clarity in pre-clinical corneal injury models. This cell therapy could alleviate the heavy reliance on donor materials for corneal transplantation to treat corneal opacities. Herein, we established Good Manufacturing Practice (GMP) protocols for CSSC isolation, propagation, and cryostorage, and developed in vitro quality control (QC) metric for in vivo anti-scarring potency of CSSCs in treating corneal opacities.

METHODS

A total of 24 donor corneal rims with informed consent were used-18 were processed for the GMP optimization of CSSC culture and QC assay development, while CSSCs from the remaining 6 were raised under GMP-optimized conditions and used for QC validation. The cell viability, growth, substrate adhesion, stem cell phenotypes, and differentiation into stromal keratocytes were assayed by monitoring the electric impedance changes using xCELLigence real-time cell analyzer, quantitative PCR, and immunofluorescence. CSSC's conditioned media were tested for the anti-inflammatory activity using an osteoclastogenesis assay with mouse macrophage RAW264.7 cells. In vivo scar inhibitory outcomes were verified using a mouse model of anterior stromal injury caused by mechanical ablation using an Algerbrush burring.

RESULTS

By comparatively assessing various GMP-compliant reagents with the corresponding non-GMP research-grade chemicals used in the laboratory-based protocols, we finalized GMP protocols covering donor limbal stromal tissue processing, enzymatic digestion, primary CSSC culture, and cryopreservation. In establishing the in vitro QC metric, two parameters-stemness stability of ABCG2 and nestin and anti-inflammatory ability (rate of inflammation)-were factored into a novel formula to calculate a Scarring Index (SI) for each CSSC batch. Correlating with the in vivo scar inhibitory outcomes, the CSSC batches with SI < 10 had a predicted 50% scar reduction potency, whereas cells with SI > 10 were ineffective to inhibit scarring.

CONCLUSIONS

We established a full GMP-compliant protocol for donor CSSC cultivation, which is essential toward clinical-grade cell manufacturing. A novel in vitro QC-in vivo potency correlation was developed to predict the anti-scarring efficacy of donor CSSCs in treating corneal opacities. This method is applicable to other cell-based therapies and pharmacological treatments.

Intra-stromal injection of honey-treated keratocytes as a cell-based therapy for experimental corneal laceration

OBJECTIVES

This study aimed to investigate the potential of honey-supplemented medium (HSM) for expanding corneal keratocytes and its transplantation in a model of corneal laceration.

METHODS

Keratocytes were cultured in 1 % HSM- or 10 % fetal bovine serum (FBS)-supplemented medium for 24 h. The effect of HSM on keratocyte proliferation was evaluated using the MTT assay. The relative expression of Lum, Kera, and ALDH3A1, known markers of native keratocytes, was quantified by real-time PCR. The safety and efficacy of HSM-treated keratocyte intrastromal injection in a rabbit model of corneal laceration were also evaluated.

RESULTS

The MTT assay showed that HSM treatment did not significantly affect cell viability compared to FBS-supplemented medium (84.71 ± 2.38 vs. 100.08 ± 10.92, respectively; p=0.076). Moreover, HSM-treated keratocytes had significantly increased expression of Lum, Kera, and ALDH3A1 compared to cells treated with FBS, while the expression of the proliferation biomarker Thy-1 did not significantly differ between the two treatments. Intrastromal injection of HSM-treated keratocytes in the laceration animal model was safe and uneventful, resulting in less stromal inflammation and neovascularization, and consequently, better final architecture with less residual haze compared to the group injected with FBS-treated keratocytes.

CONCLUSIONS

These findings suggest that honey is a suitable supplement for keratocyte treatment and corneal cell therapy. The use of HSM may have potential applications in the treatment of corneal injuries and diseases.

Posterior corneoscleral limbus: Architecture, stem cells, and clinical implications

The limbus is a transition from the cornea to conjunctiva and sclera. In human eyes, this thin strip has a rich variation of tissue structures and composition, typifying a change from scleral irregularity and opacity to corneal regularity and transparency; a variation from richly vascularized conjunctiva and sclera to avascular cornea; the neural passage and drainage of aqueous humor. The limbal stroma is enriched with circular fibres running parallel to the corneal circumference, giving its unique role in absorbing small pressure changes to maintain corneal curvature and refractivity. It contains specific niches housing different types of stem cells for the corneal epithelium, stromal keratocytes, corneal endothelium, and trabecular meshwork. This truly reflects the important roles of the limbus in ocular physiology, and the limbal functionality is crucial for corneal health and the entire visual system. Since the anterior limbus containing epithelial structures and limbal epithelial stem cells has been extensively reviewed, this article is focused on the posterior limbus. We have discussed the structural organization and cellular components of the region beneath the limbal epithelium, the characteristics of stem cell types: namely corneal stromal stem cells, endothelial progenitors and trabecular meshwork stem cells, and recent advances leading to the emergence of potential cell therapy options to replenish their respective mature cell types and to correct defects causing corneal abnormalities. We have reviewed different clinical disorders associated with defects of the posterior limbus and summarized the available preclinical and clinical evidence about the developing topic of cell-based therapy for corneal disorders.

Extracellular Vesicle MicroRNAs From Corneal Stromal Stem Cell Enhance Stemness of Limbal Epithelial Stem Cells by Targeting the Notch Pathway

Purpose

The limbal niche supports the self-renewal of limbal epithelial stem cells (LESCs). The corneal stromal stem cell (CSSC) is an important component in the niche that regulates the LESC phenotype. However, the intercellular communication between LESCs and CSSCs has yet to be elucidated.

Methods

A traditional two-dimensional (2D) system, a direct three-dimensional (3D) system, and an indirect 3D coculture system of LESCs and CSSCs were used to elucidate the paracrine pathway effect of CSSCs on LESCs. To reveal the impact of CSSC derived extracellular vesicles (CSSC-EVs) on LESCs, GW4869 and CSSC-EVs were added separately to the LESC culture medium. The outgrowth rate, cell density, differentiation, and stemness maintenance were compared among these methods. The miRNAs in the CSSC-EVs were sequenced, and the targeted Notch pathway was further confirmed by RT‒qPCR and Western blotting.

Results

Compared with 2D culture, both the direct and indirect 3D coculture systems yielded a higher outgrowth rate and expression of stem cell markers of LESCs. The phenotypes of LESCs cultivated using the two coculture approaches were also comparable. Nevertheless, GW4869 inhibited the effect of CSSCs on LESCs, and the addition of CSSC-EVs to the 2D culture system could increase cell density, and the proportion of p63αbright cells, which indicated that CSSC-EVs were crucial in regulating LESCs. Furthermore, the EV-AlixKD with reduced miRNA partly lost its regulating function. The abundant miRNAs in CSSC-EVs, such as hsa-miR-663b, hsa-miR-16-5p, and hsa-miR-1290, target the Notch pathway. The LESCs transfected with miR-663b had higher p63 expression via downregulating of the Notch pathway.

Conclusions

CSSC-EV played an important role in promoting LESC proliferation and stemness maintenance by targeting Notch signaling via miRNAs, which will increase our understanding of the limbal niche and provide a potential new approach for LESC culture and the treatment of corneal epithelial disorders.

Transcriptomic Profiling of Human Limbus-Derived Stromal/Mesenchymal Stem Cells-Novel Mechanistic Insights into the Pathways Involved in Corneal Wound Healing

Limbus-derived stromal/mesenchymal stem cells (LMSCs) are vital for corneal homeostasis and wound healing. However, despite multiple pre-clinical and clinical studies reporting the potency of LMSCs in avoiding inflammation and scarring during corneal wound healing, the molecular basis for the ability of LMSCs remains unknown. This study aimed to uncover the factors and pathways involved in LMSC-mediated corneal wound healing by employing RNA-Sequencing (RNA-Seq) in human LMSCs for the first time. We characterized the cultured LMSCs at the stages of initiation (LMSC−P0) and pure population (LMSC−P3) and subjected them to RNA-Seq to identify the differentially expressed genes (DEGs) in comparison to native limbus and cornea, and scleral tissues. Of the 28,000 genes detected, 7800 DEGs were subjected to pathway-specific enrichment Gene Ontology (GO) analysis. These DEGs were involved in Wnt, TGF-β signaling pathways, and 16 other biological processes, including apoptosis, cell motility, tissue remodeling, and stem cell maintenance, etc. Two hundred fifty-four genes were related to wound healing pathways. COL5A1 (11.81 ± 0.48) and TIMP1 (20.44 ± 0.94) genes were exclusively up-regulated in LMSC−P3. Our findings provide new insights involved in LMSC-mediated corneal wound healing.

Combined Therapy Using Human Corneal Stromal Stem Cells and Quiescent Keratocytes to Prevent Corneal Scarring after Injury

Corneal blindness due to scarring is conventionally treated by corneal transplantation, but the shortage of donor materials has been a major issue affecting the global success of treatment. Pre-clinical and clinical studies have shown that cell-based therapies using either corneal stromal stem cells (CSSC) or corneal stromal keratocytes (CSK) suppress corneal scarring at lower levels. Further treatments or strategies are required to improve the treatment efficacy. This study examined a combined cell-based treatment using CSSC and CSK in a mouse model of anterior stromal injury. We hypothesize that the immuno-regulatory nature of CSSC is effective to control tissue inflammation and delay the onset of fibrosis, and a subsequent intrastromal CSK treatment deposited collagens and stromal specific proteoglycans to recover a native stromal matrix. Using optimized cell doses, our results showed that the effect of CSSC treatment for suppressing corneal opacities was augmented by an additional intrastromal CSK injection, resulting in better corneal clarity. These in vivo effects were substantiated by a further downregulated expression of stromal fibrosis genes and the restoration of stromal fibrillar organization and regularity. Hence, a combined treatment of CSSC and CSK could achieve a higher clinical efficacy and restore corneal transparency, when compared to a single CSSC treatment.

Human amniotic epithelial cell-derived extracellular vesicles provide an extracellular matrix-based microenvironment for corneal injury repair

To study the biological functions and applications of human amniotic epithelial cell-derived extracellular vesicles (hAEC-EVs), the cargos of hAEC-EVs were analyzed using miRNA sequencing and proteomics analysis. The hAECs and hAEC-EVs in this study had specific characteristics. Multi-omics analyses showed that extracellular matrix (ECM) reorganization, inhibition of excessive myofibroblasts, and promotion of target cell adhesion to the ECM were their primary functions. We evaluated the application of hAEC-EVs for corneal alkali burn healing in rabbits and elucidated the fundamental mechanisms. Slit-lamp images revealed that corneal alkali burns induced central epithelial loss, stromal haze, iris, and pupil obscurity in rabbits. Slit-lamp examination and histological findings indicated that hAEC-EVs facilitated re-epithelialization of the cornea after alkali burns, reduced scar formation and promoted the restoration of corneal tissue transparency. Significantly fewer α-SMA-positive myofibroblasts were observed in the hAEC-EV-treated group than the PBS group. HAEC-EVs effectively promoted the proliferation and migration of hCECs and hCSCs in vitro and activated the focal adhesion signaling pathway. We demonstrated that hAEC-EVs were excellent cell-free candidates for the treatment of ECM lesion-based diseases, including corneal alkali burns. HAEC-EVs promoted ECM reorganization and cell adhesion of target tissues or cells via orderly activation of the focal adhesion signaling pathway.