Ex vivo excimer laser ablation of cornea guttata and ROCK inhibitor-aided endothelial recolonization of ablated central cornea

Preclinical Models for Studying Fuchs Endothelial Corneal Dystrophy

Fuchs Endothelial Corneal Dystrophy (FECD) is a corneal endothelial disease that causes microenvironment alterations and endothelial cell loss, which leads to vision impairment. It has a high global prevalence, especially in elderly populations. FECD is also one of the leading indications of corneal transplantation globally. Currently, there is no clearly defined canonical pathway for this disease, and it has been proposed that the combinatorial effects of genetic mutations and exogenous factors cause FECD. Clinical studies and observations have provided valuable knowledge and understanding of FECD, while preclinical studies are essential for gaining insights into disease progression and mechanisms for the development and testing of regenerative medicine therapies. In this review, we first introduce the proposed genetic and molecular pathologies of FECD. Notably, we discuss the impact of abnormal extracellular matrix deposition (guttata), endothelial-to-mesenchymal transition, cell senescence, and oxidative stress on the pathology and etiology of FECD. We review and summarize the in vitro cell models, ex vivo tissues, and in vivo animal models used to study FECD. The benefits and challenges of each model are also discussed.

RHO-Associated Coiled-Coil-Containing Protein Kinase Inhibitors Significantly Modulate the Epithelial-Mesenchymal Transition Induced by TGF-β2 in the 2-D and 3-D Cultures of Human Corneal Stroma Fibroblasts

BACKGROUND/OBJECTIVES

The objective of the present study was to examine the unidentified effects that RHO-associated coiled-coil-containing protein kinase 1 and 2 antagonists exert on the transforming growth factor beta2-induced epithelial-mesenchymal transition of the human corneal stroma.

METHODS

In the presence or absence of pan-RHO-associated coiled-coil-containing protein kinase inhibitors, ripasudil or Y27632 and RHO-associated coiled-coil-containing protein kinase 2 inhibitor, KD025, we analyzed the following: (1) planar proliferation caused by trans-endothelial electrical resistance and the cellular metabolic characteristics of the two-dimensional cultures of human corneal stroma fibroblasts; (2) the physical properties of a three-dimensional human corneal stroma fibroblasts spheroid; and (3) the gene expressions and their regulators in the extracellular matrix, along with the tissue inhibitors of metalloproteinases and matrix metalloproteinases and the endoplasmic reticulum stress-related factors of the two-dimensional and three-dimensional cultures in human corneal stroma fibroblasts.

RESULTS

Exposure to 5 nM of the transforming growth factor beta2 markedly increased the trans-endothelial electrical resistance values as well as the metabolic function in two-dimensional cultures of human corneal stroma fibroblasts. With an increase in stiffening, this exposure also reduced the size of three-dimensional human corneal stroma fibroblast spheroids, which are typical cellular phenotypes of the epithelial-mesenchymal transition. Both pan-RHO-associated coiled-coil-containing protein kinase inhibitors and RHO-associated coiled-coil-containing protein kinase 2 inhibitors substantially modulated these transforming growth factor beta2-induced effects, albeit in a different manner. Gene expression analysis supported such biological alterations via either with transforming growth factor beta2 alone or with the RHO-associated coiled-coil-containing protein kinase inhibitors variants with the noted exception being the transforming growth factor beta2-induced effects toward the three-dimensional human corneal stroma fibroblast spheroid.

CONCLUSIONS

The findings presented herein suggest the following: (1) the epithelial-mesenchymal transition could be spontaneously evoked in the three-dimensional human corneal stroma fibroblast spheroid, and, therefore, the epithelial-mesenchymal transition induced by transforming growth factor beta2 could differ between two-dimensional and three-dimensional cultured HCSF cells; and (2) the inhibition of ROCK1 and 2 significantly modulates the transforming growth factor beta2-induced an epithelial-mesenchymal transition in both two-dimensionally and three-dimensionally cultured human corneal stroma fibroblasts, albeit in a different manner.

Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet's Stripping Only Model

Descemet's Stripping Only (DSO) is a surgical technique that utilizes the peripheral corneal endothelial cell (CEnC) migration for wound closure. Ripasudil, a Rho-associated protein kinase (ROCK) inhibitor, has shown potential in DSO treatment; however, its mechanism in promoting CEnC migration remains unclear. We observed that ripasudil-treated immortalized normal and Fuchs endothelial corneal dystrophy (FECD) cells exhibited significantly enhanced migration and wound healing, particularly effective in FECD cells. Ripasudil upregulated mRNA expression of Snail Family Transcriptional Repressor (SNAI1/2) and Vimentin (VIM) while decreasing Cadherin (CDH1), indicating endothelial-to-mesenchymal transition (EMT) activation. Ripasudil activated Rac1, driving the actin-related protein complex (ARPC2) to the leading edge, facilitating enhanced migration. Ex vivo studies on cadaveric and FECD Descemet's membrane (DM) showed increased migration and proliferation of CEnCs after ripasudil treatment. An ex vivo DSO model demonstrated enhanced migration from the DM to the stroma with ripasudil. Coating small incision lenticule extraction (SMILE) tissues with an FNC coating mix and treating the cells in conjunction with ripasudil further improved migration and resulted in a monolayer formation, as detected by the ZO-1 junctional marker, thereby leading to the reduction in EMT. In conclusion, ripasudil effectively enhanced cellular migration, particularly in a novel ex vivo DSO model, when the stromal microenvironment was modulated. This suggests ripasudil as a promising adjuvant for DSO treatment, highlighting its potential clinical significance.

Rho-kinase inhibitors: Role in corneal endothelial disorders

PURPOSE

This exhaustive review of published literature aims to put forth the current understanding, and experiences of the role Rho-kinase inhibitors play in the management of corneal endothelial disorders.

METHODS

A meticulous search for PubMed and Medline databases was carried out using keywords 'rho-kinase inhibitors', 'corneal endothelial disorders', 'rho-kinase inhibitors in corneal endothelial disorders', and 'fuchs endothelial corneal dystrophy'. The articles published in last five years relevant to the area of interest were selected and compiled in a chronological order to write this review.

RESULTS

Published research shows the proven role of rho-kinase inhibitors in promoting endothelial proliferation and suppressing its apoptosis. It has shown to be effective in the treatment of endothelial diseases and endothelial cell loss due to other causes in small clinical studies. It has also shown to promote growth of human corneal endothelial cell culture suitable for transplantation. The side effects of topical rho-kinase inhibitors are minimal and self-limiting.

CONCLUSION

Rho-kinase inhibitors show immense promise in providing a non-surgical therapy for treatment of endothelial disorders. If consistent results are demonstrated through large clinical trials then this can be a major breakthrough in treating endothelial decompensation and reduce our dependence on endothelial keratoplasty for the same.

Corneal endothelial wound healing: understanding the regenerative capacity of the innermost layer of the cornea

Currently, there are very few well-established treatments to stimulate corneal endothelial cell regeneration in vivo as a cure for corneal endothelial dysfunctions. The most frequently performed intervention for a damaged or dysfunctional corneal endothelium nowadays is corneal endothelial keratoplasty, also known as lamellar corneal transplantation surgery. Newer medical therapies are emerging and are targeting the regeneration of the corneal endothelium, helping the patients regain their vision without the need for donor tissue. Alternatives to donor tissues are needed as the aging population requiring transplants, has further exacerbated the pressure on the corneal eye banking system. Significant ongoing research efforts in the field of corneal regenerative medicine have been made to elucidate the underlying pathways and effector proteins involved in corneal endothelial regeneration. However, the literature offers little guidance and selective attention to the question of how to fully exploit these pathways. The purpose of this paper is to provide an overview of wound healing characteristics from a biochemical level in the lab to the regenerative features seen in the clinic. Studying the pathways involved in corneal wound healing together with their key effector proteins, can help explain the effect on the proliferation and migration capacity of the corneal endothelial cells.

Descemetorhexis Without Endothelial Keratoplasty in Fuchs Endothelial Corneal Dystrophy: A Systematic Review and Meta-Analysis

PURPOSE

Descemetorhexis without endothelial keratoplasty (DWEK) is an innovative corneal intervention and potentially effective against Fuchs endothelial corneal dystrophy (FECD). We aimed to conduct a systematic review and meta-analysis on the outcomes of DWEK, associated or not with phacoemulsification (PKE) and rho-kinase inhibitor (RHOKI) in FECD.

METHOD

PubMed, Cochrane Library, Embase, ClinicalTrials.gov , and Science Direct were searched for studies until November 29, 2020. We performed random-effects meta-analyses and meta-regressions, stratified by the type of intervention and descemetorhexis size (PROSPERO CRD42020167566).

RESULTS

We included 11 articles (mainly case series, both prospective and retrospective), representing 127 eyes of 118 patients. DWEK globally improved visual acuity (effect size = -1.11, 95% confidence interval, -1.70 to -0.52, P < 0.001) and pachymetry (-1.25, -1.92 to -0.57, P < 0.001), without significant effects on endothelial cell count (-0.59, -2.00 to 0.83, P = 0.419). The 3 types of interventions (ie, DWEK ± RHOKI, DWEK ± PKE, and DWEK ± PKE ± RHOKI) improved visual acuity and pachymetry in FECD. A descemetorhexis size ≤4 mm improved visual acuity (-0.72, -1.29 to -0.14, P < 0.001) and pachymetry (-0.68, -0.98 to -0.38, P < 0.001), whereas >4 mm did not. Overall, DWEK failure (ie, the prevalence of EK after DWEK) was 17% (7%-27%, P < 0.001), with 4% (0%-8%, P = 0.08) for a descemetorhexis size ≤4 mm.

CONCLUSIONS

Despite the lack of comparative studies, DWEK seemed to improve visual acuity and pachymetry in early stages of FECD. A descemetorhexis size ≤4 mm was associated with the best visual outcomes and pachymetry.

Crosslinking-Induced Corneal Endothelium Dysfunction and Its Protection by Topical Ripasudil Treatment

Purpose

To investigate the changes of corneal endothelium under different crosslinking conditions and the protective effect of ripasudil.

Methods

Corneal crosslinking groups were infiltrated with riboflavin and subsequently irradiated with 0.54 J/cm² or 1.08 J/cm² UVA, while noncrosslinking groups included neither UVA nor riboflavin treatment, only 1.08 J/cm² UVA and only riboflavin treatment. Corneal opacity, variations in corneal endothelial cells, and corneal thickness of all groups were observed by slit lamp, in vivo confocal microscopy, and optical coherence tomography. Immunofluorescence staining and scanning electron microscopy were performed to evaluate changes in the structure and function of the corneal endothelium. The mice that received a corneal crosslinking dose of 1.08 J/cm² were instilled with ripasudil to explore its protective effect on the corneal endothelium.

Results

Treatment with UVA and riboflavin caused an increase in corneal opacity and corneal thickness and decreased endothelial cell density. Furthermore, treatment with UVA and riboflavin caused endothelial cell DNA damage and destroyed the tight junction and pump function of the endothelium, while riboflavin or the same dose of UVA alone did not affect the endothelium. Ripasudil reduced DNA damage in endothelial cells, increased the density of cells, and protected the endothelium's integrity and function.

Conclusion

Riboflavin combined with UVA can damage the corneal endothelium's normal functioning. The corneal endothelium's wound healing is dose-dependent, and the ROCK inhibitor ripasudil maintains the endothelium's pump and barrier functions.

New developments in corneal endothelial cell replacement

Corneal transplantation is currently the most effective treatment to restore corneal clarity in patients with endothelial disorders. Endothelial transplantation, either by Descemet membrane endothelial keratoplasty (DMEK) or by Descemet stripping (automated) endothelial keratoplasty (DS(A)EK), is a surgical approach that replaces diseased Descemet membrane and endothelium with tissue from a healthy donor eye. Its application, however, is limited by the availability of healthy donor tissue. To increase the pool of endothelial grafts, research has focused on developing new treatment options as alternatives to conventional corneal transplantation. These treatment options can be considered as either 'surgery-based', that is tissue-efficient modifications of the current techniques (e.g. Descemet stripping only (DSO)/Descemetorhexis without endothelial keratoplasty (DWEK) and Quarter-DMEK), or 'cell-based' approaches, which rely on in vitro expansion of human corneal endothelial cells (hCEC) (i.e. cultured corneal endothelial cell sheet transplantation and cell injection). In this review, we will focus on the most recent developments in the field of the 'cell-based' approaches. Starting with the description of aspects involved in the isolation of hCEC from donor tissue, we then describe the different natural and bioengineered carriers currently used in endothelial cell sheet transplantation, and finally, we discuss the current 'state of the art' in novel therapeutic approaches such as endothelial cell injection.

Descemet stripping only in Fuchs' endothelial dystrophy without use of topical Rho-kinase inhibitors: 5-year follow-up

OBJECTIVE

To describe 5-year postoperative outcomes of a small series of Fuchs' endothelial dystrophy (FED) patients who underwent Descemet stripping only (DSO) with a scraping technique.

METHODS

DSO technique and early clinical outcomes of 5 patients with mild central FED were previously reported. In the same cohort of patients, corrected distance visual acuity, central corneal ultrasound pachymetry, refractive spherical equivalent, endothelial cell count, slit-lamp photography, and corneal Scheimpflug tomography were obtained at baseline, 6 months, and 1 and 5 years postoperatively. No patient used topical Rho-kinase inhibitors at any point in time.

RESULTS

One patient (20%) failed to clear the early postoperative edema and 1 patient (20%) developed corneal decompensation 1 year after DSO. Both patients underwent successful Descemet stripping automated endothelial keratoplasty. The remaining 3 patients had stable corrected distance visual acuity, progressive reduction of corneal ultrasound pachymetry, and mild myopic shift of the refractive spherical equivalent over the follow-up time. An improvement in posterior stromal opacities and irregular astigmatism was observed, whereas posterior elevation at Scheimpflug tomography remained unchanged.

CONCLUSION

At 5 years postoperatively, DSO with a scraping technique and without Rho-kinase inhibitors resulted in sustained clinical amelioration of 3 of 5 patients (60%) with mild FED.

Rosiglitasone and ROCK Inhibitors Modulate Fibrogenetic Changes in TGF-β2 Treated Human Conjunctival Fibroblasts (HconF) in Different Manners

Purpose: The effects of Rho-associated coiled-coil containing protein kinase (ROCK) 1 and 2 inhibitor, ripasudil hydrochloride hydrate (Rip), ROCK2 inhibitor, KD025 or rosiglitazone (Rosi) on two-dimension (2D) and three-dimension (3D) cultured human conjunctival fibroblasts (HconF) treated by transforming growth factor (TGFβ2) were studied. Methods: Two-dimension and three-dimension cultured HconF were examined by transendothelial electrical resistance (TEER, 2D), size and stiffness (3D), and the expression of the extracellular matrix (ECM) including collagen1 (COL1), COL4 and COL6, fibronectin (FN), and α-smooth muscle actin (αSMA) by quantitative PCR (2D, 3D) in the presence of Rip, KD025 or Rosi. Results: TGFβ2 caused a significant increase in (1) the TEER values (2D) which were greatly reduced by Rosi, (2) the stiffness of the 3D organoids which were substantially reduced by Rip or KD025, and (3) TGFβ2 induced a significant up-regulation of all ECMs, except for COL6 (2D) or αSMA (3D), and down-regulation of COL6 (2D). Rosi caused a significant up-regulation of COL1, 4 and 6 (3D), and down-regulation of COL6 (2D) and αSMA (3D). Most of these TGFβ2-induced expressions in the 2D and αSMA in the 3D were substantially inhibited by KD025, but COL4 and αSMA in 2D were further enhanced by Rip. Conclusion: The findings reported herein indicate that TGFβ2 induces an increase in fibrogenetic changes on the plane and in the spatial space, and are inhibited by Rosi and ROCK inhibitors, respectively.

Potential Functional Restoration of Corneal Endothelial Cells in Fuchs Endothelial Corneal Dystrophy by ROCK Inhibitor (Ripasudil)

PURPOSE

Rho-associated kinase (ROCK) inhibitors have been successfully used as a rescue strategy in eyes that failed to clear after descemetorhexis without endothelial graft for treatment of Fuchs endothelial corneal dystrophy (FECD). The functional mechanisms by which ROCK inhibitors modulate corneal endothelial cell regeneration in FECD patients have, however, not been clarified. Here, we analyzed the effect of the ROCK inhibitor ripasudil on corneal endothelial cells of FECD patients and normal donors using ex vivo tissue and in vitro cellular models.

DESIGN

Experimental study: laboratory investigation.

METHODS

This institutional study used endothelial cell-Descemet membrane lamellae from FECD patients (n = 450) undergoing Descemet membrane endothelial keratoplasty (FECD ex vivo model), normal research-grade donor corneas (n = 30) after scraping off central endothelial cells (ex vivo wound healing model), normal donor corneas (n = 20) without endothelial injury, and immortalized cell lines (n = 3) generated from FECD patients (FECD in vitro model). Descemet membrane lamellae were dissected into halves and incubated for 24-72 hours in storage medium with or without a single dose of 30 μM ripasudil. The effects of ripasudil on expression of genes and proteins related to endothelial cell proliferation, migration, functionality, and endothelial-to-mesenchymal transition were analyzed and complemented by functional assays on FECD cell lines.

RESULTS

A single dose of ripasudil induced significant upregulation of genes and proteins related to cell cycle progression, cell-matrix adhesion and migration, as well as endothelial barrier and pump function up to 72 hours, whereas classical markers of endothelial-to-mesenchymal transition were downregulated in both FECD and normal specimens compared to unstimulated controls ex vivo. In addition to stimulation of proliferation and migration, ripasudil-induced changes in expression of functional signature genes could be also verified in FECD cell lines in vitro.

CONCLUSIONS

These data support the concept that inhibition of ROCK signaling represents a potent tool in regenerative therapies in FECD patients through reactivation of cell proliferation and migration as well as restoration of endothelial pump and barrier function without inducing adverse phenotypic changes.

ROCK inhibitors beneficially alter the spatial configuration of TGFβ2-treated 3D organoids from a human trabecular meshwork (HTM)

To elucidate molecular pharmacology of Rho-associated coiled-coil containing protein kinase inhibitors (ROCK-i, Ripasudil and Y27632) on their efficiency for aqueous outflow, 2D or 3D cultures of a human trabecular meshwork (HTM) were prepared in the presence of TGFβ2. Those were examined by transendothelial electrical resistance (TEER, 2D), electronic microscopy (EM, 2D and 3D), expression of the extracellular matrix (ECM) including collagen1 (COL1), COL4 and COL6, and fibronectin (FN) by immunolabeling and/or quantitative PCR (3D), and solidity of 3D organoids by a micro-squeezer. TGFβ2 significantly increased the TEER values in 2D cultures, and the ECM expression indicated that the 3D organoids assumed a more densely packed shape. ROCK-i greatly reduced the TGFβ2-induced enhancement of TEER and the immunolabeled ECM expression of the 3D organoids. In contrast, the mRNA expression of COL1 was increased, and those of COL4 and FN were unchanged. EM revealed that TGFβ2 caused the HTM cells to become more compact and abundant ECM deposits within the 3D organoids were observed. These were significantly inhibited by ROCK-i. The dense solids caused by the presence of TGFβ2 were significantly suppressed by ROCK-i. Current study indicates that ROCK-i cause beneficial effects toward the spatial configuration of TGFβ2-induced HTM 3D organoids.

Automated diagnosis and staging of Fuchs' endothelial cell corneal dystrophy using deep learning

Background

To describe the diagnostic performance of a deep learning algorithm in discriminating early-stage Fuchs’ endothelial corneal dystrophy (FECD) without clinically evident corneal edema from healthy and late-stage FECD eyes using high-definition optical coherence tomography (HD-OCT).

Methods

In this observational case-control study, 104 eyes (53 FECD eyes and 51 healthy controls) received HD-OCT imaging (Envisu R2210, Bioptigen, Buffalo Grove, IL, USA) using a 6 mm radial scan pattern centered on the corneal vertex. FECD was clinically categorized into early (without corneal edema) and late-stage (with corneal edema). A total of 18,720 anterior segment optical coherence tomography (AS-OCT) images (9180 healthy; 5400 early-stage FECD; 4140 late-stage FECD) of 104 eyes (81 patients) were used to develop and validate a deep learning classification network to differentiate early-stage FECD eyes from healthy eyes and those with clinical edema. Using 5-fold cross-validation on the dataset containing 11,340 OCT images (63 eyes), the network was trained with 80% of these images (3420 healthy; 3060 early-stage FECD; 2700 late-stage FECD), then tested with 20% (720 healthy; 720 early-stage FECD; 720 late-stage FECD). Thereafter, a final model was trained with the entire dataset consisting the 11,340 images and validated with a remaining 7380 images of unseen AS-OCT scans of 41 eyes (5040 healthy; 1620 early-stage FECD 720 late-stage FECD). Visualization of learned features was done, and area under curve (AUC), specificity, and sensitivity of the prediction outputs for healthy, early and late-stage FECD were computed.

Results

The final model achieved an AUC of 0.997 ± 0.005 with 91% sensitivity and 97% specificity in detecting early-FECD; an AUC of 0.974 ± 0.005 with a specificity of 92% and a sensitivity up to 100% in detecting late-stage FECD; and an AUC of 0.998 ± 0.001 with a specificity 98% and a sensitivity of 99% in discriminating healthy corneas from all FECD.

Conclusion

Deep learning algorithm is an accurate autonomous novel diagnostic tool of FECD with very high sensitivity and specificity that can be used to grade FECD severity with high accuracy.