Model Of Posterior Capsule Opacification Research Articles

MicroRNA-1225-5p Promotes the Development of Fibrotic Cataracts via Keap1/Nrf2 Signaling

Purpose Fibrotic cataracts, including anterior subcapsular cataract (ASC) as well as posterior capsule opacification (PCO), are a common vision-threatening cause worldwide. Still, little is known about the underlying mechanisms. Here, we demonstrate a miRNA-based pathway regulating the pathological fibrosis process of lens epithelium. Methods Gain- and loss-of-function approaches, as well as multiple fibrosis models of the lens, were applied to validate the crucial role of two miR-1225 family members in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice. Results Both miR-1225-3p and miR-1225-5p prominently stimulate the migration and EMT process of lens epithelial cells (LECs) in vitro as well as lens fibrosis in vivo. Moreover, we demonstrated that the underlying mechanism for these effects of miR-1225-5p is via directly targeting Keap1 to regulate Keap1/Nrf2 signaling. In addition, evidence showed that Keap1/Nrf2 signaling is activated in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice, and inhibition of the Nrf2 pathway can significantly reverse the process of LECs EMT as well as lens fibrosis. Conclusions These results suggest that blockade of miR-1225-5p prevents lens fibrosis via targeting Keap1 thereby inhibiting Nrf2 activation. The ‘miR-1225-Keap1-Nrf2’ signaling axis presumably holds therapeutic promise in the treatment of fibrotic cataracts.

Knockout of TGF-β receptor II by CRISPR/Cas9 delays mesenchymal transition of Lens epithelium and posterior capsule opacification

Posterior capsule opacification (PCO) is the most common postoperative complication of cataract surgery. Transforming growth factor-β (TGF-β) is related to epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) that is proven to induce PCO formation in clinical and experimental studies. In this study, CRISPR sequences targeting exon of TGF-βRII were knocked out with lentiviral transfection in LECs. Rabbits' PCO model was established and recombinant adeno-associated virus (AAV) for transferring the gRNA of TGF βRII were intravitreally injected. SgRNA inhibited TGF-βRII expression and human LECs proliferation. In TGF-βRII knockout group, LECs motility and migration were suppressed, N-cadherin and vimentin expressions were significantly decreased, whereas E-cadherin was increased. The animal model showed that TGF-βRII knockout in vivo was effective in suppressing PCO. The current study suggested that the CRISPR/Cas9 endonuclease system could suppress TGF-βRII secretion, which participates in the EMT procedure of LECs in vitro and PCO in vivo. These findings might provide a new gene-editing approach and insight into a novel therapeutic strategy for PCO.

Fabrication of a 3D bioprinting model for posterior capsule opacification using GelMA and PLMA hydrogel-coated resin.

Posterior capsule opacification (PCO) remains the predominant complication following cataract surgery, significantly impairing visual function restoration. In this study, we developed a PCO model that closely mimics the anatomical structure of the crystalline lens capsule post-surgery. The model incorporated a threaded structure for accurate positioning and observation, allowing for opening and closing. Utilizing 3D printing technology, a stable external support system was created using resin material consisting of a rigid, hollow base and cover. To replicate the lens capsule structure, a thin hydrogel coating was applied to the resin scaffold. The biocompatibility and impact on cellular functionality of various hydrogel compositions were assessed through an array of staining techniques, including calcein-AM/PI staining, rhodamine staining, BODIPY-C11 staining and EdU staining in conjunction with transwell assays. Additionally, the PCO model was utilized to investigate the effects of eight drugs with anti-inflammatory and anti-proliferative properties, including 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), THZ1, sorbinil, 4-octyl itaconate (4-OI), xanthohumol, zebularine, rapamycin and caffeic acid phenethyl ester, on human lens epithelial cells (HLECs). Confocal microscopy facilitated comprehensive imaging of the PCO model. The results demonstrated that the GelMA 60 5% + PLMA 2% composite hydrogel exhibited superior biocompatibility and minimal lipid peroxidation levels among the tested hydrogels. Moreover, compared to using hydrogel as the material for 3D printing the entire model, applying surface hydrogel spin coating with parameters of 2000 rpm × 2 on the resin-based 3D printed base yielded a more uniform cell distribution and reduced apoptosis. Furthermore, rapamycin, 4-OI and AICAR demonstrated potent antiproliferative effects in the drug intervention study. Confocal microscopy imaging revealed a uniform distribution of HLECs along the anatomical structure of the crystalline lens capsule within the PCO model, showcasing robust cell viability and regular morphology. In conclusion, the PCO model provides a valuable experimental platform for studying PCO pathogenesis and exploring potential therapeutic interventions.

Indomethacin and bromfenac may be effective in the prevention of posterior capsule opacification

Posterior capsule opacification (PCO) is the most common long‐term postoperative complication of cataract surgery, leading to secondary vision loss. Optimized intraocular lens (IOL) structure and appropriate pharmacological intervention can provide physical barriers and biological inhibition, respectively, to block the migration, proliferation, and epithelial‐mesenchymal transition (EMT) of lens epithelial cells (LECs) for PCO prophylaxis. We demonstrated that non‐steroidal anti‐inflammatory drugs (NSAIDs) are effective in preventing posterior capsule opacification. Indomethacin (INDOM) not only suppresses cell migration and down‐regulates the expression of cyclooxygenase‐2 (COX‐2) and EMT markers, including alpha‐smooth muscle actin (α‐SMA) and cyclin D1, but also promotes autophagy activation in LECs. Autophagy was also verified as a potential therapeutic target for down‐regulating EMT in LECs. Bromfenac effectively inhibits cell migration, overexpression of EMT markers such as fibronectin (FN), matrix metalloproteinase 2 (MMP2), α‐smooth muscle actin (α‐SMA), and transcription factor Snail, and extracellular signal‐regulated kinase (ERK)/glycogen synthase kinase‐3β (GSK‐3β) signalling induced by transforming growth factor‐β2 (TGF‐β2) in vitro. Based on ultrasonic spray technology, we developed a drug‐eluting intraocular lens (IOL) using poly (lactic‐co‐glycolic acid) (PLGA) with sustained release ability of indomethacin/bromfenac for PCO prevention. The novel IOL, serving as a drug delivery platform, can carry an adjustable dose of drugs with sustained release ability for more than 28 days. In the rabbit PCO model, the novel IOL showed excellent anti‐inflammatory and anti‐PCO effects. In summary, indomethacin and bromfenac are effective pharmacological interventions for PCO prophylaxis, and the novel IOL we developed prevented PCO in vivo, providing a promising approach for PCO prophylaxis in clinical applications.

Prophylaxis of posterior capsule opacification through autophagy activation with indomethacin-eluting intraocular lens.

Posterior capsule opacification (PCO) is the most common long-term postoperative complication of cataract surgery, leading to secondary vision loss. Optimized intraocular lens (IOL) structure and appropriate pharmacological intervention, which provides physical barriers and biological inhibition, respectively, can block the migration, proliferation, and epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) for PCO prophylaxis. Herein, a novel indomethacin-eluting IOL (INDOM-IOL) with an optimized sharper edge and a sustained drug release behavior was developed for PCO prevention. Indomethacin (INDOM), an ophthalmic non-steroidal anti-inflammatory drug (NSAID) used for postoperative ocular inflammation, was demonstrated to not only be able to suppress cell migration and down-regulate the expression of cyclooxygenase-2 (COX-2) and EMT markers, including alpha-smooth muscle actin (α-SMA) and cyclin D1, but also promote the autophagy activation in LECs. Additionally, autophagy was also verified to be a potential therapeutic target for the down-regulation of EMT in LECs. The novel IOL, serving as a drug delivery platform, could carry an adjustable dose of hydrophobic indomethacin with sustained drug release ability for more than 28 days. In the rabbit PCO model, the indomethacin-eluting IOL showed excellent anti-inflammatory and anti-PCO effects. In summary, indomethacin is an effective pharmacological intervention in PCO prophylaxis, and the novel IOL we developed prevented PCO in vivo under its sustained indomethacin release property, which provided a promising approach for PCO prophylaxis in clinical application.

Capsaicin attenuates TGFβ2-induced epithelial-mesenchymal-transition in lens epithelial cells in vivo and in vitro

Posterior capsule opacification (PCO), the most common complication of cataract surgery occurring in 20–50% of patients after 2–5 years of cataract surgery, is a major problem in the aging society. The epithelial-mesenchymal transition (EMT) of lens epithelial cells after cataract surgery has been proposed as a major cause of PCO. Capsaicin, widely used as a food additive and analgesic agent, is a major pungent ingredient in red pepper. Although the effect of capsaicin on EMT has been reported in cancer cells, the biological reaction of capsaicin was unique in each cell type, and there have been no reports describing its effects on EMT earlier. In this study, we demonstrated that treatment with capsaicin inhibited TGFβ2-induced EMT in vitro lens epithelial cells and ex vivo explant lens epithelial cells. Furthermore, eye drops of capsaicin inhibited the PCO model mice in vivo. Finally, we showed that capsaicin inhibited non-canonically induced Smad2/3 activation via suppression of EGFR activation and ERK phosphorylation. Our findings indicate that capsaicin and its derivatives are good candidate compounds for preventing PCO after cataract surgery.

Metformin Reduced Collagen Deposition and Contractility, but Increased Collagen Degradation in in vitro Posterior Capsule Opacification Model

BACKGROUND: Posterior capsule opacification (PCO) often occurs after cataract surgery. Metformin has been known to have an ability to inhibit fibrosis. This study aimed to investigate the effects of metformin on cell contractility, collagen deposition and degradation in human lens epithelial cells (HLEC) of cataract patients.METHODS: HLEC were isolated from the anterior lens capsule of patients undergoing cataract surgery. The HLEC culture was carried out using explant culture technique. The in vitro PCO model was created by scratching technique on HLEC cultures. The treatment groups were given 0.1, 0.5 and 1 mM metformin, respectively, while the control group were given 10% fetal bovine serum (FBS). On the 7th day after scratching technique, the collagen deposition, collagen degradation and cell contractility were evaluated.RESULTS: Collagen deposition in HLEC was significantly reduced after given 0.1 mM, 0.5 mM and 1 mM metformin (17.92±6.16 mg/mL, 12.92±4.31 mg/mL, 11.25±5.30 mg/mL, respectively), compared to the control group (31.46±7.52 μg/mL, p=0.002). Collagen degradation significantly was increased in the 0.1 mM, 0.5 mM and 1 mM metformin groups (4.77±9.27 mg/mL, 6.59±1.16 mg/mL, 6.35±1.90 mg/mL, respectively) compared to the control group (2.21±2.78 μg/mL, p=0.002). While, collagen contractility in HLEC was significantly reduced in 0.1mM, 0.5mM and 1 mM metformin groups (16.39±3.89%, 13.89±2.59%, 11.93±2.44%, respectively), compared to the control group (44.25±4.95%, p=0.000).CONCLUSION: Metformin reduced collagen deposition and contractility, but increased collagen degradation in HLEC of cataract patients through mechanism of extracellular matrix remodeling.KEYWORDS: metformin, human lens epithelial cell, fibrosis

Moderate oxidative stress promotes epithelial-mesenchymal transition in the lens epithelial cells via the TGF-β/Smad and Wnt/β-catenin pathways.

The epithelial-mesenchymal transition (EMT) plays a significant role in fibrosis and migration of lens epithelial cells (LECs), and eventually induces posterior capsule opacification (PCO). In the past, it was generally believed that the TGF-β/Smad pathway regulates lens EMT. A recent study found that attenuated glutathione level promotes LECs EMT via the Wnt/β-catenin pathway, which suggests a more complex pathogenesis of PCO. To test the hypothesis, we used the mouse cataract surgery PCO model and tested both canonical Wnt/β-catenin and TGF-β/Smad signaling pathways. The results showed that both TGF-β/Smad and Wnt/β-catenin pathways were activated during the lens capsule fibrosis. Compared with the freshly isolated posterior capsule, the expression level of phosphorylated Smad2 was highest at day3 and then slightly decreased, but the expression level of Wnt10a gradually increased from day0 to day7. It shows that these two pathways are involved in the lens epithelium's fibrotic process and may play different roles in different periods. Subsequently, we established oxidative stress-induced EMT model in primary porcine lens epithelial cells and found that both the TGF-β/Smad and Wnt/β-catenin pathways were activated. Further study suggests that block Wnt/β-catenin pathway using XAV939 alone or block TGF-β/Smad pathway using LY2109761 could partially block pLECs fibrosis, but blocking Wnt/β-catenin and TGF-β/Smad pathway using combined XAV939 and LY2109761 could completely block pLECs fibrosis. In conclusion, this study demonstrates that both TGF-β/Smad and canonical Wnt/β-catenin pathways play a significant role in regulating epithelial-mesenchymal transformation of lens epithelial cells but might be in a different stage.

Autologous cell regeneration of the crystalline lens

AbstractRegeneration of ocular tissues using stem cells is currently under investigation for the cornea and the retina. Some more recent studies focus also on the regeneration of the crystalline lens. The lens consists of only two cell types, epithelial cells, which can differentiate and act as progenitor cells to the other cell type, fiber cells. Lens epithelial cells are very active, and due to this it is difficult to prevent their proliferation, migration and differentiation when they develop posterior capsule opacification (PCO) after cataract surgery. We have compared the morphology and histopathology of PCO developed in‐vivo with a PCO model of in‐vitro tissue culture. Our in‐vitro tissue culture showed some volumetric growth of cells which expressed the potential to form lens fiber cells. Some, but not all in‐vivo formed PCO showed doughnut shaped lens like structures with anterior epithelial cells, a lens bow and lens fiber like cells, very similar to the natural lens. Special surgical procedures of lens removal have been applied in rabbits and tested to treat human congenital cataract. Both were capable of regenerating the lens to some extent. These studies on PCO and in‐vivo surgery, demonstrate the potential to regenerate the crystalline lens in humans.

Metformin activity in an in vitro model of posterior capsule opacification

Purpose: To determine the activity of metformin in an in vitro model of posterior capsule opacification (PCO).Design: Experimental laboratory research. Methods: The HLE-B3 lens epithelial cell line was treated with PCO induction media (PCOM) supplemented with transforming growth factor-beta (TGF-β) and fibroblast growth factor (FGF). Different metformin concentrations (0-100 mM) were used. The following cellular parameters were assessed: (1) survival, using a viability assay; (2) morphology, via microscopy and image analysis; (3) migration, using the wound assay; (4) and expression of epithelial (Pax6, E-cadherin) and mesenchymal (α-smooth muscle actin or α-SMA, fibronectin) markers via Western blot. Expression of the uptake receptor SLC22A1 was evaluated in HLE-B3 and in human donor eyes with Western blot and immunohistochemistry, respectively. Statistical analysis of variance (ANOVA) with Tukey post-hoc test was done for analysis of cytotoxicity, morphology and migration data. Results: Metformin was lethal to half (LC50) of the cells at 30 mM, and a decrease in viability (P<0.05) was noted at 5 mM. LECs in PCOM treated with 1 mM metformin showed increased Pax6 and E-cadherin and decreased α-SMA and fibronectin expression. LECs in PCOM treated with metformin also maintained epithelial morphology. Migration was inhibited with 0.5 mM metformin (P<0.05). Both HLE-B3 and the lens epithelium in donor eyes were found to express SLC22A1.Conclusion: Metformin decreased survival and migration in LECs, maintaining epithelial phenotype and reducing mesenchymal marker expression. Metformin therefore has potential as an adjunct in PCO prevention.Financial Disclosures: This work was partially funded by Mitacs Canada.

Roles of TGF β and FGF Signals in the Lens: Tropomyosin Regulation for Posterior Capsule Opacity.

Transforming growth factor (TGF) β and fibroblast growth factor (FGF) 2 are related to the development of posterior capsule opacification (PCO) after lens extraction surgery and other processes of epithelial–mesenchymal transition (EMT). Oxidative stress seems to activate TGF β1 largely through reactive oxygen species (ROS) production, which in turn alters the transcription of several survival genes, including lens epithelium-cell derived growth factor (LEDGF). Higher ROS levels attenuate LEDGF function, leading to down-regulation of peroxiredoxin 6 (Prdx6). TGF β is regulated by ROS in Prdx6 knock-out lens epithelial cells (LECs) and induces the up-regulation of tropomyosins (Tpms) 1/2, and EMT of LECs. Mouse and rat PCO are accompanied by elevated expression of Tpm2. Further, the expression of Tpm1/2 is induced by TGF β2 in LECs. Importantly, we previously showed that TGF β2 and FGF2 play regulatory roles in LECs in a contrasting manner. An injury-induced EMT of a mouse lens as a PCO model was attenuated in the absence of Tpm2. In this review, we present findings regarding the roles of TGF β and FGF2 in the differential regulation of EMT in the lens. Tpms may be associated with TGF β2- and FGF2-related EMT and PCO development.

Expression of Dominant Negative K6W-Ubiquitin in the Lens Epithelium via an Adenoviral Vector Delays Posterior Capsule Opacification in a Rabbit Model.

Ubiquitin is involved in cell proliferation and differentiation, and the objective of this study is to investigate the potential of dominant negative Ubiquitin (Ub) with a lysine to tryptophan mutation at the 6 position (K6W) through an adenoviral expression vector in the prevention of posterior capsule opacification (PCO) in a rabbit PCO model. Recombinant dominant negative K6W-Ub adenovirus (RAd-K6W-Ub) with green fluorescent protein (RAd-K6W-Ub/GFP) and RAd-GFP viruses (control) were generated with QBI-HEK 293A cells. New Zealand rabbits receiving lens phacoemulsification were given an intraoperative anterior chamber injection of the viruses. The images of anterior segment photography taken by a slit lamp biomicroscopy were analyzed by posterior capsule opacification manual software (POCOman) for PCO grading. The intraocular pressure (IOP) was detected with a non-contact tonometer (NCT). The expression of α-smooth muscle actin (α-SMA) was assessed by Western blotting. Cell migration ability in cultured rabbit's lens epithelial cells (LECs) was evaluated by scratch healing assay. The expression of GFP and Ub in the lens epithelium was markedly upregulated after 48 hours vector injection. Eyes injected with RAd-K6W-Ub showed a significantly lower PCO degree compared with controls. Meanwhile, higher IOP and corneal edema was observed in groups with a higher RAd-K6W-Ub virus dosage. The expression of α-SMA was down-regulated in the RAd-K6W-Ub eyes as compared to controls at the 15th day after injection. Cell migration was inhibited by RAd-K6W-Ub infection. RAd-K6W-Ub at an appropriate dosage could inhibit the proliferation of LECs and the formation of PCO in rabbit models. However, a higher dosage of Rad- K6W-Ub viral vector caused toxic effects to the surrounding tissues, such as corneal edema and high IOP.

FGF2 antagonizes aberrant TGFβ regulation of tropomyosin: role for posterior capsule opacity.

Transforming growth factor (TGF) β2 and fibroblast growth factor (FGF) 2 are involved in regulation of posterior capsule opacification (PCO) and other processes of epithelial–mesenchymal transition (EMT) such as cancer progression, wound healing and tissue fibrosis as well as normal embryonic development. We previously used an in vivo rodent PCO model to show the expression of tropomyosin (Tpm) 1/2 was aberrantly up‐regulated in remodelling the actin cytoskeleton during EMT. In this in vitro study, we show the Tpms family of cytoskeleton proteins are involved in regulating and stabilizing actin microfilaments (F‐actin) and are induced by TGFβ2 during EMT in lens epithelial cells (LECs). Importantly, we found TGFβ2 and FGF2 played contrasting roles. Stress fibre formation and up‐regulation of α‐smooth muscle actin (αSMA) induced by TGFβ2 could be reversed by Tpm1/2 knock‐down by siRNA. Expression of Tpm1/2 and stress fibre formation induced by TGFβ2 could be reversed by FGF2. Furthermore, FGF2 delivery to TGFβ‐treated LECs perturbed EMT by reactivating the mitogen‐activated protein kinase (MAPK)/ extracellular signal‐regulated kinase (ERK) pathway and subsequently enhanced EMT. Conversely, MEK inhibitor (PD98059) abated the FGF2‐mediated Tpm1/2 and αSMA suppression. However, we found that normal LECs which underwent EMT showed enhanced migration in response to combined TGFβ and FGF2 stimulation. These findings may help clarify the mechanism reprogramming the actin cytoskeleton during morphogenetic EMT cell proliferation and fibre regeneration in PCO. We propose that understanding the physiological link between levels of FGF2, Tpm1/2 expression and TGFβs‐driven EMT orchestration may provide clue(s) to develop therapeutic strategies to treat PCO based on Tpm1/2.

AGEs in human lens capsule promote the TGFβ2-mediated EMT of lens epithelial cells: implications for age-associated fibrosis.

SummaryProteins in basement membrane (BM) are long‐lived and accumulate chemical modifications during aging; advanced glycation endproduct (AGE) formation is one such modification. The human lens capsule is a BM secreted by lens epithelial cells. In this study, we have investigated the effect of aging and cataracts on the AGE levels in the human lens capsule and determined their role in the epithelial‐to‐mesenchymal transition (EMT) of lens epithelial cells. EMT occurs during posterior capsule opacification (PCO), also known as secondary cataract formation. We found age‐dependent increases in several AGEs and significantly higher levels in cataractous lens capsules than in normal lens capsules measured by LC‐MS/MS. The TGFβ2‐mediated upregulation of the mRNA levels (by qPCR) of EMT‐associated proteins was significantly enhanced in cells cultured on AGE‐modified BM and human lens capsule compared with those on unmodified proteins. Such responses were also observed for TGFβ1. In the human capsular bag model of PCO, the AGE content of the capsule proteins was correlated with the synthesis of TGFβ2‐mediated α‐smooth muscle actin (αSMA). Taken together, our data imply that AGEs in the lens capsule promote the TGFβ2‐mediated fibrosis of lens epithelial cells during PCO and suggest that AGEs in BMs could have a broader role in aging and diabetes‐associated fibrosis.

Square-edge intraocular lenses and epithelial lens cell proliferation: implications on posterior capsule opacification in an in vitro model.

BackgroundTo evaluate lens epithelial cell (LEC) proliferation with two different designs (one-piece or three-piece) of hydrophobic acrylic IOLs with 360° square optic edge using an in vitro culture model of posterior capsule opacification (PCO).MethodsThis experimental study was conducted at the Department of NEUROFARBA, Section of Pharmacology, University of Florence, Italy. Human LECs were seeded and cultured in transwell cell culture inserts coated with a type-IV collagen membrane on which an IOL (one-piece Tecnis-1 or three-piece AR40E, Abbott Medical Optics Inc.) had been previously placed. As control, cells were plated on the insert membrane without an IOL. At day six (cells confluent in controls) IOLs were removed and cell counting, viability and cell density under and outside the IOLs were evaluated.ResultsNo statistically significant difference in the number of cells (p > 0.05) between inserts with the one-piece and three-piece IOLs was found. Cell density in the area under each IOL was significantly lower than in the area outside of it (p < 0.05), or in the control insert. (p < 0.05). Cell density under the single-piece IOL was not significantly different from that under the three-piece IOL (p > 0.05).ConclusionsA 360° sharp-edge played a crucial role in avoiding LEC migration under the IOL and preventing the formation of PCO after cataract surgery. Long term clinical evaluation is necessary to estimate functional results.

Sustained-Release Celecoxib from Incubated Acrylic Intraocular Lenses Suppresses Lens Epithelial Cell Growth in anEx VivoModel of Posterior Capsule Opacity

To determine whether celecoxib (CXB) can be released from incubated intraocular lenses (IOLs) sufficiently to inhibit lens epithelial cell (LEC) growth in an ex vivo model of posterior capsule opacification (PCO). LEC growth was evaluated for 14 days in canine lens capsules (LCs) that had been exposed to media containing 20 μM CXB for 1-5 days. After the incubation of hydrophilic and hydrophobic IOLs in CXB solution, the determination of the in vitro release of CXB from the IOLs was performed for up to 28 days. The incubated and nonincubated IOLs were evaluated in the ex vivo model of PCO, and the rate of LEC growth was evaluated over 28 days. The treatment of LCs with 20 μM CXB for 4 and 5 days completely inhibited LEC growth. LEC repopulation did not occur after the removal of CXB. IOLs incubated in CXB for 24 h resulted in a sustained release of CXB in vitro at levels theoretically sufficient to inhibit PCO. LCs in the ex vivo model of PCO treated with acrylic IOLs incubated in CXB had significantly suppressed LEC ingrowth compared with untreated and IOL-only LCs. A 4-day treatment of LCs with a concentration of 20 μM CXB may effectively prevent PCO. IOLs incubated in CXB for 24 h resulted in a sustained release of CXB in vitro at levels sufficient to inhibit LEC growth in the ex vivo model of PCO. Further studies are needed to determine whether CXB-incubated IOLs can effectively prevent the development of PCO in vivo.

Capsular tension ring–based in vitro capsule opacification model

To evaluate a capsular tension ring (CTR)-supported anterior and posterior capsule opacification (PCO) model in cadaver eyes. The effect of CTR designs on lens capsule shape and lens epithelial cell (LEC) growth were investigated in vitro. Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany. Following open-sky extracapsular cataract extraction, CTR models were implanted in 32 eyes of 16 human donors. The lens capsule expansion by the CTRs was evaluated. The capsular bags supported by the CTRs were excised and maintained at physiological conditions for up to 3 months. The area of LEC coverage over the posterior capsule surface was objectively determined twice a day using a graticule. After CTR implantation, all lens capsules could be safely excised and transferred into organ culture. The CTR designs resulted in different shapes of lens capsule expansion. Complete LEC confluence occurred after a mean of 8.25 days+/-2.87 (SD) with the AcriRing KR10 (AcriTec), 6.50+/-1.0 days with the Acrimed, 8.62+/-3.34 days with the InjectoRing (Corneal), 9.00+/-1.87 days with the Morcher 14C, 9.33+/-0.75 days with the Morcher 2A, and 6.25+/-0.5 days with the Ophthalmic Innovation CTR. The CTR-supported in vitro PCO model offers a physiological method to support the lens capsule and is a reproducible system for the study of LEC proliferation.

Safety and efficacy of intracapsular tranilast microspheres in experimental posterior capsule opacification

To evaluate the safety and efficacy of a sustained-release agent designed to reduce posterior capsule opacification (PCO). Department of Ophthalmology, EENT Hospital, Fudan University, Shanghai, Peoples Republic of China. Free tranilast (TFree) was incorporated into polylactic acid microspheres and then tested using a rabbit model of PCO. Twenty-nine rabbits were randomized into 5 groups treated with balanced saline solution (BSS control); TFree; or 0.5, 1.0, or 2.0 mg tranilast microspheres (TMicro). Standard phacoemulsification cataract surgery, including manual aspiration of all visible soft lens matter, was performed in all groups. The selected test agent was then injected into the lens capsule. Postoperative clinical examinations were performed at 1, 3, 7, 14, 30, 60, and 90 days. Posterior capsule opacification was quantified using high-resolution computer image analysis at 1, 2, and 3 months. Histological examination was performed at 3 months. Eyes treated with TMicro had significantly less PCO than the eyes in the BSS and TFree groups. While the BSS control eyes had increased PCO over 3 months, eyes in the TMicro group had reduced PCO over time in a dose-dependent fashion. Histological examination showed reduced lens epithelial cell proliferation in the TMicro groups, with no manifest damage to the cornea, iris, or retina compared with the BSS controls. There was a transient increase in postoperative inflammation in all tranilast-treated groups compared with the BSS controls. Sustained-release intracapsular tranilast reduced PCO in an experimental model of PCO, suggesting further investigation of its therapeutic potential is justified.

061 Correction de la presbytie - l’enjeu de la prévention de l’opacification de la capsule postérieure

Posterior capsule opacification (PCO) still remains one of the major complications in cataract surgery. Problems especially emerge with the design of accommodative and multifocal intraocular lens (IOL). For proper function these IOLs require elastic lens capsules without any tendency of after cataract formation to avoid reduced mobility of the IOL and IOL decentration. Furthermore future concepts of presbyopia correction such as injectable IOL materials also highly depend on elastic lens capsules without any capsule opacification. The most accepted concept of PCO prevention today is the sharp edge design of an IOL. The sharp edge independently of IOL material can inhibit PCO development. Other current investigated strategies focus on the genetic and pharmacological manipulation of lens epithelial cells (LEC) or on the removal of these cells. A new in vitro PCO model for testing new strategies and substances which could influence LEC growth will be presented. This model is based on the stabilisation of the capsular bag by a capsular tension ring (CTR). It offers excellent stabilisation of the capsule and physiological conditions in organ culture. The influence of different CTRs on PCO was evaluated. We found, that CTRs do not completely prevent PCO development in vitro, however different CTR designs show different shapes of capsule expansion and different pattern of LEC growth. Cystamine, β-lactose and alkylphosphocholine, all antiproliferative but non toxic substrates were tested: Although none of the substances evaluated could fully prevent LEC migration in the in vitro PCO model, β-lactose and alkylphosphocholine were highly effective in delaying LEC migration on the capsule bag when compared to untreated LEC. In a third approach the laser photolysis system of A.R.C Laser® was adapted for capsule polishing by ablation of LEC. After cataract extraction multiple laser pulses were applied to mechanically remove LEC. The lowest efficient energy necessary for removal of LEC was evaluated in the in vitro model. The introduced in vitro model offers an easy and safe way to investigate the impact of innovative approaches on PCO prevention.

Lens fiber differentiation in rats posterior capsule opacification

To establish a new model of posterior capsule opacification (PCO) in rat, and detect the expression of alpha-, beta-, and gamma-crystalline gene. An extracapsular lens extraction (ECLE) was performed in SD rats. Eyes were enucleated and processed for light microscopy at various time-points. Semi-quantitive RT-PCR were performed to detect the expression of alphaA, alphaB, betaB1, betaB2, betaA2, and gammaD crystalline. Immediately after ECLE, lens epithelial cells (LECs) were present in the inner surface of the anterior capsule and lens bow. 24 hours after surgery, LECs started to migrate toward the center of the posterior capsule. PCO was noted at first 3 days after ECLE, multilayered LECs were present throughout the lens capsule, and lens fibre differentiation occurred in peripheral capsular bag. All eyes showed development of clinically evident PCO and Soemmering's ring 7 days post-ECLE. 2 weeks after surgery, Soemmering's ring was even more significant. 1 month after surgery, all capsular bags were filled with new semitransparent lenticular structures, displaying an established equator with well differentiated bow regions. 2 - 3 month after surgery, new lenticular structures continue to increase in slower speed. The mRNA-expression quantity of alphaA, alphaB, betaB1, betaB2, betaA2 and gammaD crystalline increased gradually postoperatively. PCO occurs soon after ECLE in SD rat, and express alpha-, beta-, and gamma-crystalline. This model appears to be valuable for studying the pathogenic mechanisms of PCO after cataract surgery or lens regeneration.