EGFR inhibitor Gefitinib attenuates posterior capsule opacification in vitro and in the ex vivo human capsular bag model

TGFβ overcomes FGF-induced transinhibition of EGFR in lens cells to enable fibrotic secondary cataract

To cause vision-disrupting fibrotic secondary cataract (PCO), lens epithelial cells that survive cataract surgery must migrate to the posterior of the lens capsule and differentiate into myofibroblasts. During this process, the cells become exposed to the FGF that diffuses out of the vitreous body. In normal development, such relatively high levels of FGF induce lens epithelial cells to differentiate into lens fiber cells. It has been a mystery as to how lens cells could instead undergo a mutually exclusive cell fate, namely epithelial to myofibroblast transition, in the FGF-rich environment of the posterior capsule. We and others have reported that the ability of TGFβ to induce lens cell fibrosis requires the activity of endogenous ErbBs. We show here that lens fiber-promoting levels of FGF induce desensitization of ErbB1 (EGFR) that involves its phosphorylation on threonine 669 mediated by both ERK and p38 activity. Transinhibition of ErbB1 by FGF is overcome by a time-dependent increase in ErbB1 levels induced by TGFβ, the activation of which is increased after cataract surgery. Our studies provide a rationale for why TGFβ upregulates ErbB1 in lens cells and further support the receptor as a therapeutic target for PCO.

Tonic ErbB signaling underlies TGFβ-induced activation of ERK and is required for lens cell epithelial to myofibroblast transition

Fibrosis is a major, but incompletely understood, component of many diseases. The most common vision-disrupting complication of cataract surgery involves differentiation of residual lens cells into myofibroblasts. In serum-free primary cultures of lens epithelial cells (DCDMLs), inhibitors of either ERK or of ErbB signaling prevent TGFβ from upregulating both early (fibronectin) and late (αSMA) markers of myofibroblast differentiation. TGFβ stimulates ERK in DCDMLs within 1.5 h. Kinase inhibitors of ErbBs, but not of several other growth factor receptors in lens cells, reduce phospho ERK to below basal levels in the absence or presence of TGFβ. This effect is attributable to constitutive ErbB activity playing a major role in regulating the basal levels pERK. Additional studies support a model in which TGFβ-generated reactive oxygen species serve to indirectly amplify ERK signaling downstream of tonically active ErbBs to mediate myofibroblast differentiation. ERK activity is in turn essential for expression of ErbB1 and ErbB2, major inducers of ERK signaling. By mechanistically linking TGFβ, ErbB, and ERK signaling to myofibroblast differentiation, our data elucidate a new role for ErbBs in fibrosis and reveal a novel mode by which TGFβ directs lens cell fate.

Identification of Small Molecules for Prevention of Lens Epithelium-Derived Cataract Using Zebrafish

Cataract is the leading cause of blindness worldwide. It can be treated by surgery, whereby the damaged crystalline lens is replaced by a synthetic lens. Although cataract surgery is highly effective, a relatively common complication named posterior capsular opacification (PCO) leads to secondary loss of vision. PCO is caused by abnormal proliferation and migration of residual lens epithelial cells (LECs) that were not removed during the surgery, which results in interruption to the passage of light. Despite technical improvements to the surgery, this complication has not been eradicated. Efforts are being made to identify drugs that can be applied post-surgery, to inhibit PCO development. Towards the goal of identifying such drugs, we used zebrafish embryos homozygous for a mutation in plod3 that develop a lens phenotype with characteristics of PCO. Using both biased and unbiased approaches, we identified small molecules that can block the lens phenotype of the mutants. Our findings confirm the relevance of zebrafish plod3 mutants' lens phenotype as a model for lens epithelium-derived cataract and add to our understanding of the molecular mechanisms that contribute to the development of this pathology. This understanding should help in the development of strategies for PCO prevention.

Risk assessment and molecular mechanism study of drug-drug interactions between rivaroxaban and tyrosine kinase inhibitors mediated by CYP2J2/3A4 and BCRP/P-gp

Cancer patients generally has a high risk of thrombotic diseases. However, anticoagulant therapy always aggravates bleeding risks. Rivaroxaban is one of the most widely used direct oral anticoagulants, which is used as anticoagulant treatment or prophylaxis in clinical practice. The present study aimed to systemically estimate the combination safety of rivaroxaban with tyrosine kinase inhibitors (TKIs) based on human cytochrome P450 (CYPs) and efflux transporters and to explore the drug–drug interaction (DDI) mechanisms in vivo and in vitro. In vivo pharmacokinetic experiments and in vitro enzyme incubation assays and bidirectional transport studies were conducted. Imatinib significantly increased the rivaroxaban C_max value by 90.43% (p < 0.05) and the area under the curve value by 119.96% (p < 0.01) by inhibiting CYP2J2- and CYP3A4-mediated metabolism and breast cancer resistance protein (BCRP)- and P-glycoprotein (P-gp)-mediated efflux transportation in the absorption phase. In contrast, the combination of sunitinib with rivaroxaban reduced the exposure in vivo by 62.32% (p < 0.05) and the C_max value by 72.56% (p < 0.05). In addition, gefitinib potently inhibited CYP2J2- and CYP3A4-mediated rivaroxaban metabolism with K_i values of 2.99 μΜ and 4.91 μΜ, respectively; however, it almost did not affect the pharmacokinetics of rivaroxaban in vivo. Taken together, clinically significant DDIs were observed in the combinations of rivaroxaban with imatinib and sunitinib. Imatinib increased the bleeding risks of rivaroxaban, while sunitinib had a risk of reducing therapy efficiency. Therefore, more attention should be paid to aviod harmful DDIs in the combinations of rivaroxaban with TKIs.

Posterior Capsule Opacification: A Review of Experimental Studies

Posterior capsule opacification (PCO) is the most common complication of cataract surgery. It causes a gradual deterioration of visual acuity, which would otherwise improve after a successful procedure. Despite recent advances in ophthalmology, this complication has not been eradicated, and the incidence of PCO can be as high as 10%. This article reviews the literature concerning the pathomechanism of PCO and examines the biochemical pathways involved in its formation and methods to prevent this complication. We also review the reported tests performed in cell cultures under laboratory conditions and in experimental animal models and in ex vivo human lens capsules. Finally, we describe research involving human eyes in the clinical setting and pharmacological methods that may reduce the frequency of PCO. Due to the multifactorial etiology of PCO, in vitro studies make it possible to assess the factors contributing to its complications and search for new therapeutic targets. Not all pathways involved in cell proliferation, migration, and contraction of the lens capsule are reproducible in laboratory conditions; moreover, PCO in humans and laboratory animals may be additionally stimulated by various degrees of postoperative reactions depending on the course of surgery. Therefore, further studies are necessary.

Role of Decorin in Posterior Capsule Opacification and Eye Lens Development

Decorin (DCN) is involved in a variety of physiological and pathological processes. Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) has been proposed as a major cause for the development of posterior capsule opacification (PCO) after cataract surgery. We investigated the plausible target gene(s) that suppress PCO. The expression of Dcn was significantly upregulated in rat PCO tissues compared to that observed in the control using a microarray-based approach. LECs treated with fibroblast growth factor (FGF) 2 displayed an enhanced level of DCN expression, while LECs treated with transforming growth factor (TGF)β-2 showed a decrease in DCN expression. The expression of tropomyosin 1 (Tpm1), a marker of lens EMT increased after the addition of TGFβ-2 in human LEC; however, upregulation of Tpm1 mRNA or protein expression was reduced in human LECs overexpressing human DCN (hDCN). No phenotypic changes were observed in the lenses of 8- and 48-week-old transgenic mice for lens-specific hDCN (hDCN-Tg). Injury-induced EMT of the mouse lens, and the expression patterns of α smooth muscle actin, were attenuated in hDCN-Tg mice lenses. Overexpression of DCN inhibited the TGFβ-2-induced upregulation of Tpm1 and EMT observed during wound healing of the lens, but it did not affect mouse lens morphology until 48 weeks of age. Our findings demonstrate that DCN plays a significant role in regulating EMT formation of LECs and PCO, and suggest that for therapeutic intervention, maintenance of physiological expression of DCN is essential to attenuate EMT progression and PCO formation.

A Critical Appraisal of New Developments in Intraocular Lens Modifications and Drug Delivery Systems for the Prevention of Cataract Surgery Complications

Cataract surgery is the commonest ophthalmic surgery worldwide. The replacement of the diseased lens with a synthetic one (intraocular lens-IOL) remains the treatment of choice, despite its potential complications that include infection, inflammation and posterior capsule opacification. The potential for drug delivery via the IOL has been researched extensively over a period of twenty-five years, yet there is very limited progress in transferring the findings from research to everyday practice. The objective of this review is to assess the progress made in the field of IOL lens modifications and drug delivery systems over the past five years. Thirty-six studies that were conducted during the past five years were identified and deemed suitable for inclusion. They were grouped in three broad categories, studies that described new methods for loading a drug onto the IOL, assessment of the effects of drugs that were loaded to the IOL and studies that assessed the effects of non-pharmaceutical modifications of IOLs. While considerable progress is continually being made with regard to methods and materials, there is still little capitalization upon these research studies, with no commercially available IOL-based drug delivery system being available. Close cooperation between researchers in basic sciences (chemistry, physics, materials science and pharmacy), clinical researchers, IOL manufacturers and the pharmaceutical industry is an important prerequisite for further development.

Posterior capsule opacification: What's in the bag?

Cataract, a clouding of the lens, is the most common cause of blindness in the world. It has a marked impact on the wellbeing and productivity of individuals and has a major economic impact on healthcare providers. The only means of treating cataract is by surgical intervention. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior capsule and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens (IOL). The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. Lens epithelial cells, however, remain attached to the anterior capsule, and in response to surgical trauma initiate a wound-healing response that ultimately leads to light scatter and a reduction in visual quality known as posterior capsule opacification (PCO). There are two commonly-described forms of PCO: fibrotic and regenerative. Fibrotic PCO follows classically defined fibrotic processes, namely hyperproliferation, matrix contraction, matrix deposition and epithelial cell trans-differentiation to a myofibroblast phenotype. Regenerative PCO is defined by lens fibre cell differentiation events that give rise to Soemmerring's ring and Elschnig's pearls and becomes evident at a later stage than the fibrotic form. Both fibrotic and regenerative forms of PCO contribute to a reduction in visual quality in patients. This review will highlight the wealth of tools available for PCO research, provide insight into our current knowledge of PCO and discuss putative management of PCO from IOL design to pharmacological interventions.

Research Progress of Drug Prophylaxis for Lens Capsule Opacification after Cataract Surgery

Phacoemulsification combined with intraocular lens (IOL) implantation is the international standard operation procedure for cataract and has been generalized worldwide. However, lens capsule opacification, one of the common complications after cataract surgery, impacts the recovery of patients' visual function to a large extent. Lens capsule opacification has two types, anterior capsule opacification (ACO) and posterior capsule opacification (PCO), according to the location. There is not an accepted approach to treat ACO. Nd : YAG laser capsulotomy, the common treatment of PCO, can effectively improve the vision, but may cause a series of complications and is inappropriate for children who are too young to cooperate with this treatment. It is generally known that the responses of lens epithelial cells (LECs) after cataract surgery, including cell proliferation, migration, and epithelial-mesenchymal transition (EMT), play a key role in the pathogenesis of lens capsule opacification. Scholars found that substantial drugs can reduce the occurrence of lens capsule opacification by inhibiting, clearing, or killing LECs, and made great efforts as well as innovations on the exploration of drug species or modes of administration. This article is a systematic interpretation and elaboration about how to prevent lens capsule opacification after cataract surgery via different drugs.

The human capsular bag model of posterior capsule opacification

Posterior capsule opacification (PCO) is the most common complication following cataract surgery and affects millions of patients. PCO is a consequence of surgical injury promoting a wound-healing response. Following surgery, residual lens epithelial cells grow on acellular regions of the lens capsule, including the central posterior capsule. These cells can undergo fibrotic changes, such that cell transdifferentiation to myofibroblasts, matrix deposition and matrix contraction can occur, which contribute to light scatter and the need for further corrective Nd:YAG laser capsulotomy in many patients. It is therefore of great importance to better understand how PCO develops and determine better approaches to manage the condition. To achieve this, experimental systems are required, and many are available to study PCO. While there may be a number of common features associated with PCO in different species, the mechanisms governing the condition can differ. Consequently, where possible, human systems should be employed. The human capsular bag model was established in a laboratory setting on donor eyes. A capsulorhexis is performed to create an opening in the anterior capsule followed by removal of the lens fibre mass. Residual fibre cells can be removed by irrigation/aspiration and if required, an intraocular lens can be implanted. The capsular bag is isolated from the eye and transferred to a dish for culture. The human capsular bag model has played an important role in understanding the biological processes driving PCO and enables evaluation of surgical approaches, IOLs and putative therapeutic agents to better manage PCO.

Development of a drug-eluting intraocular lens to deliver epidermal growth factor receptor inhibitor gefitinib for posterior capsule opacification prophylaxis

PURPOSE

Different molecular targets, such as the epidermal growth factor receptor, have been identified for the prophylaxis of posterior capsule opacification. This led to the proposal of several drugs, yet drug delivery into the capsular bag remains challenging. The intraocular lens as a drug delivery device would provide a convenient method to allow drug release in the location needed. This is to evaluate the effect of a drug-eluting intraocular lens using an epidermal growth factor receptor inhibitor.

METHODS

Hydrophobic and hydrophilic intraocular lenses were coated with gefitinib using the dip coating technique. The cellular response on the modified intraocular lenses was tested in a human lens epithelial cell line (FHL-124) in an anterior segment model. Furthermore, modified intraocular lenses were implanted into human capsular bags ex vivo. Drug release was determined as well as the biocompatibility on human corneal endothelial cells. Unmodified intraocular lenses served as controls. In addition, immunofluorescence staining with fibronectin as a marker for fibrotic response was conducted.

RESULTS

Both coated hydrophilic and hydrophobic intraocular lenses could attenuate the cell growth of FHL-124 cells in the human capsular bag in comparison to the unmodified controls. Furthermore, gefitinib-soaked intraocular lenses showed a constant drug release over the first 10 days. No reduction in cell viability of corneal endothelial cells occurred. A decrease in fibronectin expression under gefitinib treatment could be observed.

CONCLUSION

In vitro epidermal growth factor receptor seems to be a valuable target for the prevention of posterior capsule opacification. The gefitinib-eluting intraocular lens in this study could inhibit cell growth in non-toxic concentrations.

Cataract surgeon viewpoints on the need for novel preventative anti-inflammatory and anti-posterior capsular opacification therapies

Purpose: To determine cataract surgeon viewpoints on the efficacy of available therapies/preventatives for two common sequelae of cataract surgery: inflammation and posterior capsular opacification (PCO). Methods: Cataract surgeons practicing worldwide specializing in adult, pediatric and veterinary patients were interviewed between March and August 2018. Results: Ocular inflammation following cataract surgery is treated by either corticosteroids and/or nonsteroidal anti-inflammatories (NSAIDs). Adult and pediatric cataract surgeons are satisfied with current treatments whereas this inflammation is still considered a problem by some in veterinary practice due to its slow resolution. Yttrium-aluminum-garnet (YAG) laser therapy is the PCO treatment of choice for adult cataract surgeons and they are generally pleased with its outcome. However, pediatric cataract surgeons find YAG problematic, especially in patients under 6 years of age, and invasive surgery is often needed to correct PCO/visual axis opacification (VAO). Veterinary ophthalmologists report that YAG is not effective for PCO in animals, especially dogs, due to the density of the fibrotic plaques; 86% of adult and 100% of veterinary and pediatric cataract surgeons surveyed agree that effective anti-PCO therapeutics would improve clinical care. Conclusions: Surgeons treating human patients are pleased with the available treatments for ocular inflammation following cataract surgery, although some veterinary ophthalmologists disagree. The surgeons surveyed agree that PCO/VAO remains an unsolved problem in pediatric and veterinary cataract surgery while the long-term outcome of adult cataract surgery could be improved by additional attention to this issue.

ERK1/2-mediated EGFR-signaling is required for TGFβ-induced lens epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) plays a critical role in the pathogenesis of fibrotic cataract. Transforming growth factor-beta (TGFβ) is a potent inducer of this fibrotic process in lens. Recent studies in cancer progression have shown that in addition to activating the canonical Smad signaling pathway, TGFβ can also transactivate the epidermal growth factor receptor (EGFR) to enhance invasive cell migration. The present study aims to elucidate the involvement of EGFR-signaling in TGFβ-induced EMT in LECs. Treatment with TGFβ2 induced transdifferentiation of LECs into myofibroblastic cells, typical of an EMT. TGFβ2 induced the phosphorylation of the EGFR and upregulation of Egfr and Hb-egf gene expression. Pharmacologic inhibition of EGFR-signaling using PD153035 inhibited TGFβ-induced EMT, including the upregulation of mesenchymal markers and downregulation of epithelial markers. Crosstalk between TGFβ2-induced EGFR and ERK1/2 was evident, with both pathways impacting on Smad2/3-signaling. Our finding that TGFβ2 transactivates downstream EGFR-signaling reveals a previously unknown mechanism in the pathogenesis of cataract. Understanding the complex interplay between divergent canonical and non-canonical signaling pathways, as well as downstream target genes involved in TGFβ-induced EMT, will enable the development of more effective targeted therapies in the pharmacological treatment of cataract.

Premacular membranes in tissue culture

PURPOSE

To investigate integrity and characteristics of human premacular membranes (PMM) with and without standard tissue culturing using mechanical traction.

METHODS

Premacular membranes were harvested from 32 eyes of 32 patients with idiopathic macular pucker during standard vitrectomy. By flat-mount preparation with phase contrast and interference microscopy, specimens were prepared for time-lapse microscopy, immunocytochemistry, and transmission electron microscopy. Sixteen of 32 specimens were held in tissue culture with tangential traction by using entomological pins. Of these, specimens of 7 eyes were analyzed with and without tissue culturing for comparison. Primary antibodies were used for myofibroblasts, hyalocytes, macro-/microglial cells, and retinal pigment epithelial and immune cells.

RESULTS

Hyalocytes, macroglia, and microglia composed the main cell composition of surgically removed PMM. Correlation of time-lapse microscopy with immunofluorescence microscopy identified fast and unidirectional moving small round cells as microglia. Slowly moving elongated large cells were characterized as alpha-smooth muscle actin (α-SMA)-positive myofibroblasts. Following tissue culturing with tangential stretch, enhanced positive immunolabelling for α-SMA and integrins-αv was seen. All other labelling results were demonstrated to be similar with pre-culture conditions. Ultrastructural analysis revealed fibroblasts, myofibroblasts, and proliferation of glial cells following tissue culture.

CONCLUSION

This study demonstrates abundance of fibroblasts, myofibroblasts, and glial cells in PMM from idiopathic macular pucker following tissue culture with tangential stretch application. We found enhanced contractive properties of the cultured PPM that appear to indicate transdifferentiation of the cell composition. This in vitro model may improve understanding of pathogenesis in traction maculopathies and help to establish further anti-fibrosis treatment strategies.

Comparison of fibrotic response in the human lens capsular bag after femtosecond laser-assisted cataract surgery and conventional phacoemulsification

PURPOSE

To compare the effect of different laser pulse energy settings in femtosecond laser-assisted cataract surgery with that of standard phacoemulsification and no energy at all used on posterior capsule opacification (PCO) in vitro.

SETTING

Cell and Molecular Biology Research Laboratory, Department of Ophthalmology, Ludwig-Maximilians-University Munich, Real Eyes, Ophthalmology Center, Munich, and Institute for Clinical Pathology, Goethe University Frankfurt, Frankfurt, Germany.

DESIGN

Experimental study.

METHODS

Fifteen cadaver capsular bags were cultivated from 8 human donors under standard cell culture conditions. For preparation of the capsular bag, 4 groups were established as follows: femtosecond laser-assisted cataract surgery standard energy (n = 3), femtosecond laser-assisted cataract surgery high energy (n = 3), phacoemulsification (n = 6), and hydrodissection without energy (extracapsular cataract extraction) (n = 3). Growth of lens epithelial cells was observed and photodocumented. The days until full cell coverage of the posterior capsule were documented. Capsular bags were stained for fibronectin, α-smooth muscle actin, and collagen type 1.

RESULTS

Cell growth patterns in all treatment groups were comparable, with no statistically significant differences detected at any timepoint measured (P = .81, Kruskal-Wallis). The markers for fibrosis were equally distributed in all groups, indicating an equal fibrotic reaction in all groups.

CONCLUSION

Femtosecond laser-assisted cataract surgery did not increase different cellular responses in PCO formation comparison with phacoemulsification in vitro, even when higher laser pulse energy levels were used.

Advances in studies of tyrosine kinase inhibitors and their acquired resistance

Protein tyrosine kinase (PTK) is one of the major signaling enzymes in the process of cell signal transduction, which catalyzes the transfer of ATP-γ-phosphate to the tyrosine residues of the substrate protein, making it phosphorylation, regulating cell growth, differentiation, death and a series of physiological and biochemical processes. Abnormal expression of PTK usually leads to cell proliferation disorders, and is closely related to tumor invasion, metastasis and tumor angiogenesis. At present, a variety of PTKs have been used as targets in the screening of anti-tumor drugs. Tyrosine kinase inhibitors (TKIs) compete with ATP for the ATP binding site of PTK and reduce tyrosine kinase phosphorylation, thereby inhibiting cancer cell proliferation. TKI has made great progress in the treatment of cancer, but the attendant acquired acquired resistance is still inevitable, restricting the treatment of cancer. In this paper, we summarize the role of PTK in cancer, TKI treatment of tumor pathways and TKI acquired resistance mechanisms, which provide some reference for further research on TKI treatment of tumors.

Poly(lactic-co-glycolic) Acid as a Slow-Release Drug-Carrying Matrix for Methotrexate Coated onto Intraocular Lenses to Conquer Posterior Capsule Opacification

PURPOSE

Posterior capsule opacification (PCO) still represents the main long-term complication of cataract surgery. Research into pharmacologic PCO prophylaxis is extensive. One promising candidate drug is methotrexate (MTX). Our aim is to determine the in vitro feasibility of MTX-loaded poly(lactic-co-glycolic) (PLGA) biomatrices sprayed on intraocular lenses (IOLs) as a drug-delivery implant.

METHODS

Hydrophilic and hydrophobic acrylic IOLs were spray-coated with MTX-loaded PLGA. Unsprayed, solvent only, and solvent-PLGA-sprayed IOLs served as controls. All IOLs were evaluated for their growth-inhibiting properties in an in vitro anterior segment model and the ex vivo human capsular bag. The release kinetics of MTX from the IOLs was determined. The toxicity of MTX on corneal endothelial cells was evaluated by using a dye reduction colorimetric assay. MTX was also used in a scratch assay.

RESULTS

MTX-PLGA-IOL showed a significant difference in cell proliferation and migration compared with all controls in the anterior segment model (p < 0.001) and in the human capsular bag model (p = 0.04). No difference in viability was observed on corneal endothelial cells (p = 0.43; p = 0.61). MTX significantly inhibited cells in the scratch assay (p = 0.02). At all measured points, the released MTX dose remained above EC50 and below the toxic dose for the endothelium.

CONCLUSIONS

In view of the strong inhibition of PCO in vitro with the lack of toxic effects on a corneal cell line, MTX encapsulating microspheres seem to be a promising method for modifying IOL.

Non-invasive strategies for targeting the posterior segment of eye

The safe and effective treatment of eye diseases has been remained a global myth. Several advancements have been done and various drug delivery and treatment techniques have been suggested. The Posterior segment disorders are the leading cause of visual impairments and blindness. Targeting the therapeutic agents to the anterior and posterior segments of the eye has attracted extensive attention from the scientific community. Significant key factors in the success of ocular therapy are the development of safe, effective, economic and non-invasive novel drug delivery systems. These specialized non-invasive ocular drug delivery systems revolutionized the drug delivery strategies by overcoming the limitations, provided targeted delivery to the ocular tissues by avoiding larger doses, and reducing the toxicity encountered by the conventional approaches. These non-invasive systems are fabricated by ingredients encompassing biodegradability, biocompatibility, mucoadhesion, solubility and permeability enhancement and stimuli responsiveness. The variety of routes are utilized to provide minimally invasive drug delivery to the patients without any discomfort and pain. This review is focused on the brief introduction, types, significance, preparation techniques, components and mechanism of drug release of non-invasive systems, including in situ gelling systems, microspheres, iontophoresis, nanoparticles, nanosuspensions and specialized novel emulsions.

Effect of femtosecond laser-assisted lens surgery on posterior capsule opacification in the human capsular bag in vitro

PURPOSE

To compare posterior capsule opacification (PCO) by observing lens epithelial cell growth in the human capsular bag in vitro between conventional lens surgery using phacoemulsification (Phaco) technique and femtosecond laser-assisted lens surgery (FLACS).

METHODS

For the in vitro human capsular bag model, 18 cadaver eyes from nine human donors underwent three types of lens surgery. Three groups consisting of six capsular bags were established, that is FLACS, Phaco and extracapsular lens extraction (ECCE). The capsular bag was transferred into equal cell culture conditions after using one of the defined surgical approaches. Cellular growth of lens epithelial cells was observed and photo-documented. The time until full cell-coverage of the capsular bag was measured.

RESULTS

The human capsular bag model can be successfully prepared using FLACS. There was no statistically significant difference in time until cell-coverage of the human donor capsular bag in vitro in all three surgical settings (ECCE versus Phaco p = 0.6; ECCE versus FLACS p = 1.0; Phaco versus FLACS p = 1.0).

CONCLUSIONS

In our in vitro human capsular bag model, we could not observe a statistically significant difference in PCO formation using different surgical approaches of lens extraction. Therefore, PCO formation might not be attributed to the type of surgery. Furthermore, this study shows that FLACS can be used for the human capsular bag model preparation and validates the human capsular bag model for future research.

Evaluation of laser capsule polishing for prevention of posterior capsule opacification in a human ex vivo model

PURPOSE

To evaluate the efficacy of a laser photolysis (LP) system in preventing posterior capsule opacification (PCO) in a human ex vivo PCO model.

SETTING

Ars Ophthalmica Study Center, Department of Ophthalmology, General Hospital Linz, Medical Faculty of Johannes Kepler University, Linz, Austria, and the Department of Ophthalmology, Ludwig-Maximillians-University, Munich, Germany.

DESIGN

Prospective randomized controlled laboratory trial.

METHODS

Open sky extracapsular cataract extraction following implantation of a capsular tension ring (CTR) into the capsular bag was performed in 28 human donor eyes. Donor eyes received LP treatment of the capsular bag fornix and the anterior capsule for 180 or 360 degrees, whereas the contralateral eyes served as a control group. Lens epithelial cell (LEC) growth onto the posterior capsule was determined objectively during 3 months of organ culture incubation.

RESULTS

The mean interval until a complete monolayer of LECs on the posterior capsule had formed was 8.2 days ± 1.2 (SD) for control eyes and 9.4 days ± 1.1 for eyes with 180-degree LP treatment (P = .042). Eyes with 360-degree treatment showed no sign of LEC growth or migration onto the posterior capsule during the entire observation period. Transmission light microscopy revealed many residual LECs on the anterior lens capsule of untreated areas, whereas no evidence of remaining LEC in areas treated with LP was found.

CONCLUSIONS

This study demonstrates complete and sustained PCO prevention by a prototype LP system in a capsular tension ring-based human ex vivo model. Laser capsule polishing has the potential to serve as a successful surgical strategy for PCO prevention.

FINANCIAL DISCLOSURE

The authors have no proprietary or financial interest in any of the materials or equipment mentioned in this study.

Sprouty2 Suppresses Epithelial-Mesenchymal Transition of Human Lens Epithelial Cells through Blockade of Smad2 and ERK1/2 Pathways

Transforming growth factor β (TGFβ)-induced epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) plays a key role in the pathogenesis of anterior subcapsular cataract (ASC) and capsule opacification. In mouse lens, Sprouty2 (Spry2) has a negative regulatory role on TGFβ signaling. However, the regulation of Spry2 during ASC development and how Spry2 modulates TGFβ signaling pathway in human LECs have not been characterized. Here, we demonstrate that Spry2 expression level is decreased in anterior capsule LECs of ASC patients. Spry2 negatively regulates TGFβ2-induced EMT and migration of LECs through inhibition of Smad2 and ERK1/2 phosphorylation. Also, blockade of Smad2 or ERK1/2 activation suppresses EMT caused by Spry2 downregulation. Collectively, our results for the first time show in human LECs that Spry2 has an inhibitory role in TGFβ signaling pathway. Our findings in human lens tissue and epithelial cells suggest that Spry2 may become a novel therapeutic target for the prevention and treatment of ASC and capsule opacification.