Association between aqueous humor cytokines and postoperative corneal endothelial cell loss after Descemet stripping automated endothelial keratoplasty.

This study measured the intraoperative anterior aqueous humor concentrations of various cytokines during corneal endothelial transplantation and searched for relationships between these concentrations and postoperative corneal endothelial cell (CEC) depletion. We recruited 30 consecutive patients who underwent corneal endothelial transplantation with Descemet's stripping automated endothelial keratoplasty (DSAEK) at Tohoku University Hospital between February 2014 and July 2017. During surgery, we obtained aqueous humor samples and later measured the concentrations of 27 cytokines with a Multiplex Bead Assay (Bio-Plex Pro). We counted CECs 1, 6 and 12 months after surgery, and used Spearman's rank correlation coefficient to identify relationships between CEC depletion and the concentrations of detected cytokines. The loss of CECs 1-6 months after surgery was significantly correlated with IL-7, IP-10, MIP-1a and MIP-1b concentrations (-0.67, -0.48, -0.39, and -0.45, respectively, all P <0.01). CEC loss 1-12 months after surgery was significantly correlated with IL-1b, IL-7, IP-10 and RANTES concentrations (-0.46, -0.52, -0.48, and -0.43, respectively). Multiple regression analysis showed that IL-7 concentration was significantly associated with CEC loss 1-6 months after surgery (b = -0.65, P < 0.01) and IP-10 concentration was associated with CEC loss 1-12 months after surgery (ß = -0.38, P < 0.05). These results suggest that not only inflammatory cytokines but also IL-7, a cytokine related to lymphocytes, may be involved in the depletion of CECs after DSAEK, particularly depletion that occurs relatively early.

Ascorbic acid ameliorates corneal endothelial dysfunction and enhances cell proliferation via the noncanonical GLUT1-ERK axis.

BACKGROUND: The pumping function of corneal endothelial cells (CECs) plays a pivotal role in the maintenance of corneal water homeostasis. Corneal endothelial dysfunction (CED) leads to corneal edema and opacity, but with the exception of keratoplasty, no optimal therapeutic strategies have been established for CED. In this study, we aimed to investigate the ameliorative effect of ascorbic acid (AA) on CED and the underlying mechanism of action in the corneal endothelium. METHODS: Rabbit corneal endothelial damage was induced by anterior chamber injection of benzalkonium chloride (BAK). AA was topically administered to the corneal surface, and the transparency and thickness of the cornea were assessed by external eye photography, slit-lamp photography, and ultrasonic pachymetry. To further analyze the mechanism, rabbit CECs and immortalized human CECs (B4G12 cells) were cultured. A ferric reducing/antioxidant and AA (FRASC) assay was performed to measure the AA concentration. Cell proliferation was evaluated by cell counting and bromodeoxyuridine (BrdU) labeling assays, and protein expression was examined by liquid chromatography-mass spectrometry (LC/MS) and immunoblotting. The involvement of glucose transporter 1 (GLUT1) and phospho-ERK was evaluated via GLUT1-siRNA and phospho-ERK inhibitor (PD98059) treatment. INTERPRETATION: We observed that topical AA ameliorates BAK-induced rabbit corneal endothelial damage. Furthermore, we demonstrated that AA is transported into B4G12 cells via GLUT1, and afterward, AA increases ERK phosphorylation and promotes cell proliferation. Our findings indicate that CEC proliferation stimulated via the noncanonical AA-GLUT1-ERK axis contributes to AA-enhanced healing of CED.

Cigarette Smoke Triggers Loss of Corneal Endothelial Cells and Disruption of Descemet's Membrane Proteins in Mice.

Purpose: To investigate changes at a molecular level in the mouse corneal endothelium (CE) exposed to chronic cigarette smoke (CS). Methods: Pregnant mice (gestation days 18-20) were placed in a whole-body exposure smoking chamber, and a few days later pups were born. After 3.5 months of CS exposure, a ConfoScan4 scanning microscope was used to examine the corneal endothelial cells (CECs) of CS-exposed and control (Ct) mice. The CE was peeled under a microscope and maintained as four biological replicates (two male and two female) for CS-exposed and Ct mice; each replicate consisted of 16 CEs. The proteome of the CE was investigated through mass spectrometry. Results: The CE images of CS-exposed and Ct mice revealed a difference in the shape of CECs accompanied by a nearly 10% decrease in CEC density (P < 0.00003) following CS exposure. Proteome profiling identified a total of 524 proteins exhibiting statistically significant changes in CE from CS-exposed mice. Importantly, proteins associated with Descemet's membrane (DM), including COL4α1, COL4α2, COL4α3, COL4α4, COL4α5, COL4α6, COL8α1, COL8α2, and FN1, among others, exhibited diminished protein levels in the CE of CS-exposed mice. Conclusions: Our data confirm that exposure to CS results in reduced CEC density accompanied by diminished levels of multiple collagen and extracellular matrix proteins associated with DM.

[Effects of Benzalkonium Chloride in Ophthalmic Eyedrop Medications on Corneal Epithelium].

Eyedrops often contain additives other than active pharmaceutical ingredients, such as preservatives. The most frequently used preservative is benzalkonium chloride (BAC). When the ocular surface is exposed to eyedrops, the active pharmaceutical ingredients and additives can cause corneal epithelial disorder. Particularly in clinical settings, there is great interest in corneal epithelial disorders resulting from the use of glaucoma eyedrops, which is inevitable when instilled for a long period of time after the onset of disease. At the authors' institute, glaucoma is treated with consideration of reducing corneal epithelial disorder while ensuring the effect of lowering intraocular pressure by the appropriate choice of eyedrops. In this review, we show the examples of the retrospective studies. Sodium hyaluronate eyedrops are prescribed for corneal epithelial disorders such as superficial punctate keratitis associated with dry eye. Prescribable concentrations of sodium hyaluronate in Japan are 0.1% or 0.3%, and the 0.3% formulation does not contain BAC. The authors' study showed that 0.3% sodium hyaluronate pretreatment reduced the cytotoxicity of BAC in cultured corneal epithelial cells, whereas an in vivo study in mice showed that a 0.3% sodium hyaluronate instillation was suggested and that the drug may enhance the cytotoxicity of separately administered BAC. It is suggested that sodium hyaluronate prolonged the retention of BAC on the ocular surface. However, there have been no reports of this problem in the clinical setting. It is important for ophthalmologists to understand the properties of additives other than the active pharmaceutical ingredients in eyedrops.

Characterization of Endothelial Cell Loss in Pre-Descemet Endothelial Keratoplasty Graft Preparation.

PURPOSE: To characterize the pattern and factors affecting endothelial cell loss (ECL) in pre-Descemet Endothelial Keratoplasty (PDEK) graft preparation. METHODS: A prospective study was performed to characterize the pattern of ECL and the impact of inflation pressure in PDEK. Donor corneas were randomized to inflation with air versus Optisol GS storage media. PDEK preparation was performed under continuous pressure monitoring. Trypan blue was used to grade the tissue as acceptable (<25% ECL) or unacceptable (≥25% ECL). Rate of unacceptable ECL was correlated with injection media type and inflation pressure. A retrospective study was then performed of all attempted PDEK preparations at Lions Gift of Sight to evaluate impact of donor tissue factors on ECL. Donor age and tissue preservation time were evaluated and correlated with ECL with PDEK bubbling. RESULTS: Twenty-five corneas were tested prospectively. A reticular pattern of ECL that varied in severity occurred with bubbling. There was no difference in peak inflation pressure or mean expansion pressure between air (706.0, 510.7 mm Hg) and Optisol GS (852.9, 653.0 mm Hg). Increasing peak inflation pressure and mean expansion pressure were associated with an increased risk for unacceptable ECL. On retrospective evaluation of 131 attempted PDEKs, only 44.0% of cases with successful bubbles had acceptable endothelium after processing. Increasing donor age and decreasing preservation time were associated with increased rates of acceptable endothelium. CONCLUSIONS: PDEK processing can result in a reticular pattern of ECL. Higher inflation pressures are associated with greater ECL. Older donor tissues with shorter preservation times might be preferable for PDEK.

Amniotic fluid mesenchymal stem cells repair mouse corneal cold injury by promoting mRNA N4-acetylcytidine modification and ETV4/JUN/CCND2 signal axis activation.

Severe corneal injury is one of the main causes of loss of visual function. Mesenchymal stem cells (MSCs) have the ability to repair damaged cells in vivo. The present study aimed to explore whether MSCs could function as a cell therapy tool to replace traditional methods to treat corneal injury. CD44 + /CD105 + mesenchymal stem cells isolated from mouse amniotic fluid (mAF-MSCs) were injected into mice after cryoinjury to induce corneal endothelial cell injury. Histopathological assays indicated that mAF-MSCs could promote the growth of corneal epithelial cells, reduce keratitis, and repair the corneal damage caused by low temperature. cDNA microarray analysis revealed that the mAF-MSCs affected the expression patterns of mRNAs related to cell proliferation and differentiation pathways in the mice after transplantation. The results of quantitative real-time PCR and western blotting revealed that NAT12, NAT10, and the ETV4/JUN/CCND2 signaling axis were elevated significantly in the mAF-MSC-transplantation group, compared with those in the phosphate-buffered saline-treated groups. High performance liquid chromatography-mass spectroscopy results revealed that mAF-MSCs could promote mRNA N4-acetylcytidine (ac4C) modification and high expression of N-acetyltransferase in the eyeballs. RNA immunoprecipitation-PCR results showed that a specific product comprising Vegfa, Klf4, Ccnd2, Jun, and Etv4 mRNA specific coding region sites could be amplified using PCR from complexes formed in mAF-MSC-transplanted samples cross-linked with anti-ac4C antibodies. Thus, mouse amniotic fluid MSCs could repair the mouse corneal cold injury by promoting the ETV4/JUN/CCND2 signal axis activation and improving its stability by stimulating N4-acetylcytidine modification of their mRNAs.

PAX6, modified by SUMOylation, plays a protective role in corneal endothelial injury.

Treating corneal endothelial diseases tends to be challenging as human corneal endothelial cells (CECs) do not proliferate in vivo. The pathogenesis or mechanisms underlying injured CECs need further studies. The abnormal expression of PAX6, which is an essential transcription factor for corneal homeostasis, exhibits corneal endothelial defects. However, the effects of PAX6 protein involved in corneal endothelial wound process are still unknown. Here, we found the upregulated protein levels of PAX6 in human corneal endothelial monolayer after injury; the expression of PAX6 also increased in murine and rat corneal endothelium injury models. Enforced PAX6 expression could alleviate the damages to CECs via regulating permeability by prompting cellular tight junction. In addition, SUMOylation mainly happened on both K53 and K89 residues of 48-kD PAX6 (the longest and main isoform expressed in cornea), and de-SUMOylation promoted the stability of PAX6 protein in vitro. In CECs of SENP1+/- mice, increased SUMOylation levels leading to instability and low expression of PAX6, delayed the repair of CECs after injury. Furthermore, overexpression of PAX6 accelerated the rate of corneal endothelial repair of SENP1+/- mice. Our findings indicate that SENP1-mediated de-SUMOylation improving the stability of PAX6, amplifies the protective effects of PAX6 on corneal endothelial injuries, highlighting potentials of PAX6 and/or SUMOylation to be used as a treatment target for corneal endothelial disorders.

Calcium Oscillatory Behavior and Its Possible Role during Wound Healing in Bovine Corneal Endothelial Cells in Culture.

In epithelial layers in culture, immediately after an injury a fast calcium wave (FCW) propagates from the wound borders toward the rest of the monolayer. We show here that similarly to other tissues, during the FCW in bovine corneal endothelial (BCE) cells in culture many cells exhibit calcium oscillations mediated by IP3 signaling. In this study we perform a detailed characterization of this oscillatory behavior and explore its possible role in the process of wound healing. In previous work we showed that, in BCE cells in culture, the healing cells undergo two stages of caspase-dependent apoptosis, at approximately two and eight hours after wounding. We determined that inhibition of the FCW greatly increases the apoptotic rate of the two stages, suggesting that the wave prevents excessive apoptosis of the healing cells. Taking this into account, we investigated the possible participation of the calcium oscillations during the FCW in apoptosis of the healing cells. For this, we employed ARL-67156 (ARL), a weak competitive inhibitor of ecto-ATPases, and the calcium chelator EGTA. We show here that, in healing BCE cells, ARL enhances cellular calcium oscillations during the FCW, while EGTA decreases oscillations. We found that ARL produces a significant decrease (to about half the control value) in the apoptotic index of the first stage of apoptosis, while EGTA increases it. Neither drug noticeably affects the second stage. We have interpreted the effect of ARL on apoptosis as due to the maintenance of moderately risen ATP levels during the FCW, which is in turn the cause for the enhancement of ATP-dependent calcium oscillations. Correspondingly, EGTA would increase the apoptotic index of the first stage by promoting a decrease in the calcium oscillatory rate. The fact that the second stage of apoptosis is not affected by the drugs suggests that the two stages are at least partially subject to different signaling pathways.

Biomechanical changes to Descemet's membrane precede endothelial cell loss in an early-onset murine model of Fuchs endothelial corneal dystrophy.

Early-onset Fuchs endothelial corneal dystrophy (FECD) has been associated with nonsynonymous mutations in collagen VIII α2 (COL8A2), a key extracellular matrix (ECM) protein in Descemet's membrane (DM). Two knock-in strains of mice have been generated to each express a mutant COL8A2 protein (Col8a2L450W/L450W and Col8a2Q455K/Q455K) that recapitulate the clinical phenotype of early-onset FECD including endothelial cell loss, cellular polymegathism and pleomorphism, and guttae. Due to abnormalities in ECM protein composition and structure in FECD, the stiffness of DM in Col8a2 knock-in mice and wildtype (WT) controls was measured using atomic force microscopy at 5 and 10 months of age, coinciding with the onset of FECD phenotypic abnormalities. At 5 months, only sporadic guttae were identified via in vivo confocal microscopy (IVCM) in Col8a2Q455K/Q455K mice, otherwise both strains of Col8a2 transgenic mice were indistinguishable from WT controls in terms of endothelial cell density and size. By 10 months of age, Col8a2L450W/L450W and Col8a2Q455K/Q455K mice developed reduced corneal endothelial density, increased endothelial cell area and guttae, with the Col8a2Q455K/Q455K strain exhibiting a more severe phenotype. However, at 5 months of age, prior to the development endothelial cell abnormalities, Col8a2L450W/L450W and Col8a2Q455K/Q455K mice knock-in mice had reduced tissue stiffness of DM that was statistically significant in the Col8a2Q455K/Q455K mice when compared with wildtype controls. These data indicate that alterations in the tissue compliance of DM precede phenotypic changes in endothelial cell count and morphology, and may play a role in onset and progression of FECD.

Preoperative Aqueous Cytokine Levels are Associated With Endothelial Cell Loss After Descemet's Stripping Automated Endothelial Keratoplasty.

Purpose: To evaluate the association between endothelial cell density (ECD) after Descemet's stripping automated endothelial keratoplasty (DSAEK) and preoperative cytokine levels in the aqueous humor (AqH). Methods: This prospective consecutive case series included 97 consecutive patients who underwent DSAEK (64 eyes) or cataract surgery (33 eyes). AqH samples were collected at the beginning of each surgery. The levels of cytokines (IL-1α, IL-1ß, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IFN-α, IFN-γ, monocyte chemotactic protein [MCP]-1, E-selectin, P-selectin, and soluble intercellular adhesion molecule [sICAM]-1) in the AqH were measured by multiplex beads immunoassay. The correlations between preoperative aqueous cytokine levels and the ECD at 12 months after DSAEK were analyzed. Results: The ECD decreased from 2747 ± 259 cells/mm2 in the donor graft to 1235 ± 607 cells/mm2 at 12 months after DSAEK. In all subjects undergoing DSAEK, the postoperative ECD at 12 months was significantly correlated with the preoperative levels of MCP-1 (r = -0.467, 95% confidence interval [CI]: -0.650 to -0.222, P = 0.0003). In an analysis excluding Fuchs endothelial corneal dystrophy (11 eyes), the ECD at 12 months after DSAEK was significantly correlated with preoperative levels of IL-17A (r = -0.635, 95% CI: -0.819 to -0.319, P = 0.0004), MCP-1 (r = -0.605, 95% CI: -0.779 to -0.345, P < 0.0001), IFN-γ (r = -0.633, 95% CI: -0.796 to -0.385, P < 0.0001), E-selectin (r = -0.516, 95% CI: -0.756 to -0.276, P = 0.0004), and sICAM-1 (r = -0.537, 95% CI: -0.735 to -0.253, P = 0.0005). Conclusions: Higher preoperative levels of IL-17A, MCP-1, IFN-γ, E-selectin, and sICAM-1 in the AqH were associated with lower ECD after DSAEK for bullous keratopathy.

Preoperative Aqueous Cytokine Levels Are Associated With a Rapid Reduction in Endothelial Cells After Penetrating Keratoplasty.

PURPOSE: To evaluate the influence of preoperative inflammatory cytokine levels in the aqueous humor (AqH) on the endothelial cell density (ECD) after penetrating keratoplasty (PKP). DESIGN: Prospective, interventional, consecutive case series. METHODS: This study includes 70 consecutive patients (mean age 73.7 ± 10.6 years) who underwent PKP (37 eyes) or cataract surgery (controls, 33 eyes). A total of 70 AqH samples were collected at the beginning of each surgery. The levels of cytokines (interleukin [IL]-1α, IL-1ß, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, interferon [IFN]-α, IFN-γ, monocyte chemotactic protein [MCP]-1, E-selectin and P-selectin) in AqH were measured by multiplex bead immunoassay. The subjects who underwent PKP were classified into 2 groups: ECD ≥ 1200 cells/mm2 at 6 months (24 eyes), and ECD < 1200 cells/mm2 at 6 months (13 eyes). RESULTS: The ECD at 3 months significantly correlated with the preoperative levels of IL-10 (r = -0.428, P = .02) and IFN-γ (r = -0.412, P = .029). The ECD at 6 months significantly correlated with the preoperative levels of IL-10 (r = -0.399, P = .024), MCP-1 (r = -0.444, P = .011), and IFN-γ (r = -0.474, P = .006). The preoperative levels of IL-6, IL-10, MCP-1, IFN-γ, and P-selectin in AqH were significantly higher in eyes with ECD < 1200 cells/mm2 compared with those with ECD ≥ 1200 cells/mm2 at 6 months (P < .05). CONCLUSIONS: Higher preoperative levels of IL-10, MCP-1, and IFN-γ in the AqH were associated with low ECD after PKP.

Near infra-red light attenuates corneal endothelial cell dysfunction in situ and in vitro.

In the present study mechanical damage to the corneal endothelium was induced by elevation of intraocular pressure (IOP, 140 mmHg, 60 min) to one eye of rats, delivered either in complete darkness or in the presence of red light (16.5 W/m2, 3000 lx, 625-635 nm). IOP raised in the dark revealed the endothelium to be damaged as staining for the gap junction protein ZO-1 was irregular in appearance with some cells displaced in position or lost to leave gaps or holes. This damage was clearly attenuated when red light was focused through the pupil during the insult of raised IOP. Moreover, staining of endothelium with JC-1 dye showed mitochondria to be activated by both elevated IOP and red light but the activation of mitochondria persisted longer for red light. We interpret this finding to suggest that raised IOP causes apoptosis of endothelial cells and that their mitochondria are activated in the initial stages of the process. In contrast, red light activates mitochondria to induce a protective mechanism to counteract the negative influence of raised IOP on endothelial cells. Evidence is provided to support this notion by the finding that red light stimulates mitochondrial cytochrome oxidase IV (COX IV). Moreover, mitochondria in corneal endothelial cell cultures are activated by red light, revealed by staining with JC-1, that results in an increased rate of proliferation and are also able to counteract toxic insults (sodium azide or cobalt chloride) to the cultures. The present studies therefore show that a non-toxic level of red light attenuates damage to the corneal endothelium both in situ and in vitro through action on COX IV located in mitochondria that results in an enhancement of a cell's survival mechanisms. The study provides proof of principle for the non-invasive use of red-light therapy to attenuate any dysfunctions associated with the corneal endothelium and so preserve maximum visual acuity.

Cell Homogeneity Indispensable for Regenerative Medicine by Cultured Human Corneal Endothelial Cells.

PURPOSE: To identify the subpopulation (SP) among heterogeneous cultured human corneal endothelial cells (cHCECs) devoid of cell-state transition applicable for cell-based therapy. METHODS: Subpopulation presence in cHCECs was confirmed via surface CD-marker expression level by flow cytometry. CD markers effective for distinguishing distinct SPs were selected by analyzing those on established cHCECs with a small cell area and high cell density. Contrasting features among three typical cHCEC SPs was confirmed by PCR array for extracellular matrix (ECM). Combined analysis of CD markers was performed to identify the SP (effector cells) applicable for therapy. ZO-1 and Na+/K+ ATPase, CD200, and HLA expression were compared among heterogeneous SPs. RESULTS: Flow cytometry analysis identified the effector cell expressing CD166+CD105-CD44-∼+/-CD26-CD24-, but CD200-, and the presence of other SPs with CD166+ CD105-CD44+++ (CD26 and CD24, either + or -) was confirmed. PCR array revealed three distinct ECM expression profiles. Some SPs expressed ZO-1 and Na+/K+ ATPase at comparable levels with effector cells, while only one SP expressed CD200, but not on effector cells. Human leukocyte antigen expression was most reduced in the effector SP. The proportion of effector cells (E-ratio) inversely paralleled donor age and decreased during prolonged culture passages. The presence of Rho-associated protein kinase (ROCK) inhibitor increased the E-ratio in cHCECs. The average area of effector cells was approximately 200∼220 µm2, and the density of cHCECs exceeded 2500 cells/mm2. CONCLUSIONS: A specified cultured effector cell population sharing the surface phenotypes with mature HCECs in corneal tissues may serve as an alternative to donor corneas for the treatment of corneal endothelial dysfunction.

The effects of proinflammatory cytokines on the apoptosis of corneal endothelial cells following argon laser iridotomy.

The aim of this study was to evaluate the relationship between the expression of proinflammatory cytokines and the apoptosis of corneal endothelial cells after argon laser iridotomy (ALI). ALI was performed on each quadrant of the iris in the right eye of mice (ALI1 group). Left eyes were used as control group. The levels of interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-ß, and interferon (IFN)-γ in mice eyes were measured, and TUNEL staining was performed 12 h after ALI. Mice in the ALI-Dexa group were pretreated daily with an intraperitoneal injection of dexamethasone for 4 days before undergoing ALI and compared with mice without dexamethasone pretreatment (ALI2 group). Twelve corneas from six rabbits were incubated ex vivo with (n = 6) or without (n = 6) IL-1ß. TUNEL staining was performed 24 h after ex vivo incubation. In the mice experiment, the levels of IL-1ß, TNF-α, TGF-ß, and IFN-γ were increased in the ALI1 group compared to the control group. Although many TUNEL-positive cells were observed in the ALI1 group, those were not detected in the control group. Dexamethasone pretreatment inhibited the increase in the levels of all four proinflammatory cytokines and reduced TUNEL-positive cells. In the rabbit experiment, TUNEL-positive cells were increased in the incubated corneas with IL-1ß compared to those without IL-1ß. Expression of proinflammatory cytokines following ALI seems to play a role in the apoptosis of corneal endothelial cells after ALI. Dexamethasone pretreatment inhibited increases in proinflammatory cytokines and reduced the apoptosis of corneal endothelial cells.

Manual suction versus femtosecond laser trephination for penetrating keratoplasty: intraocular pressure, endothelial cell damage, incision geometry, and wound healing responses.

PURPOSE: To measure real-time intraocular pressure (IOP) during trephination with a manual suction trephine (MST) and the femtosecond laser (FSL), and to assess endothelial cell damage, incision geometry, and wound healing response with these procedures. METHODS: IOP was monitored with an intracameral sensor. Eight rabbits underwent manual suction trephination. Eight rabbits had FSL trephination (FSL-T). Slit lamp photography, confocal microscopy, and anterior segment optical coherence tomography (AS-OCT) were performed at baseline and postoperatively. Animals were sacrificed at 4 hours and 3 days. Tissue was examined with scanning electron microscopy (SEM) and immunohistochemistry for an array of wound-healing markers. Separately, 6 human corneas had MST (3) and FSL-T (3). Incision geometry was imaged with high resolution Optovue AS-OCT. RESULTS: The average IOP during MST and FSL-T was similar (37 mm Hg). There was wider IOP fluctuation during the MST cutting phase (60 mm Hg maximum). There were 1-2 rows of endothelial loss on either side of the incision for FSL-T and 2-5 rows deep for MST. Immune cell responses at 4 hours (CD11b) were comparable, greater apoptosis with FSL-T (TUNEL) occurred at 4 hours, and there was increased keratocyte proliferation at 3 days (Ki67) with FSL-T. There was significantly greater undercutting of the cornea with MST (46.86 degrees versus 16.72 degrees). CONCLUSIONS: There is more IOP variation during MST. Average IOP is 37 mm Hg for both techniques. More endothelial damage and undercutting of the cornea occurs with MST. The wound healing response to FSL-T appears greater at 3 days.

Clinicopathologic findings in failed descemet stripping automated endothelial keratoplasty.

OBJECTIVE: To evaluate the clinical features of and histologic findings from failed Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This retrospective observational case series evaluated 47 consecutive corneal specimens from 42 patients who underwent either penetrating keratoplasty or repeated DSAEK for failed DSAEK. Clinical information was obtained for the cases. Sections of the specimens were examined using light microscopy. Immunohistochemical staining was performed for cytokeratins AE1/AE3 and for the myogenic marker smooth-muscle actin when indicated. Transmission electron microscopic examination was performed in some cases. RESULTS: Graft survival ranged from 0.5 to 34 months. Histologic examination showed that 94% of the specimens (44 of 47) had endothelial cell loss. Residual host Descemet membrane (19%; 9 of 47), fibrocellular tissue (19%; 9 of 47), epithelial implantation (15%; 7 of 47), and fungal infection (4%; 2 of 47) were also identified. Immunohistochemical stains were positive for AE1/AE3 in the epithelial implantations and for smooth-muscle actin in cells in the fibrocellular proliferations. CONCLUSIONS: The principal cause of failed DSAEK is endothelial cell loss. Residual host Descemet membrane, fibrocellular tissue at the edge of the lenticule, and epithelial implantation are common histologic findings. Fungal infection may occur in the setting of DSAEK.

Protection of thymosin beta-4 on corneal endothelial cells from UVB-induced apoptosis.

Cornea absorbs most of daily ultraviolet (UV) light. An excess of UV damages results in not only keratopathy and cataract but also maculopathy. It has been reported that thymosin beta-4 (Tbeta4) promotes wound healing, decreases inflammatory response and prevents apoptosis of corneal epithelial cells. However, it is not clear whether Tbeta4 protects UVB-induced corneal injury, particularly in corneal endothelial cells because of its non-proliferation in nature. The purpose of this study is to compare the protective effects of Tbeta4 on bovine corneal endothelial (BCE) cells from low- and high-dose UVB damage. In this study, 1 microg/ml of Tbeta4 was added to BCE cells 2 h before low (12.5 mj/cm2) or high dosage (100 mj/cm2) UVB exposure. Using a fluorogenic substrate cleavage assay, we found that Tbeta4 diminished the reactive oxygen species level in BCE cells elicited by UVB. However, the protection of viability by Tbeta4 could only be detected under low-dose UVB exposure. Moreover, both caspase-9 activity and annexin V/propidium iodine staining demonstrated that Tbeta4 only protected BCE cells from low-dose UVB-induced apoptosis but not high-dose UVB-induced necrosis. Together, Tbeta4 protected corneal endothelial cells from UVB-induced oxidative stress and apoptosis after low-dose UVB exposure. The results support further investigation towards topical use or anterior chamber injection of this small hydrophilic peptide in treating and preventing UVB-induced corneal endothelial damage.