Posterior capsule opacification: a cell biological perspective

Evaluation of Dose-Response Relationship in Novel Extended Release of Targeted Nucleic Acid Nanocarriers to Treat Secondary Cataracts

Purpose: The present study aimed to determine the dose-response relationship between targeted nanocarriers released from a novel, sustained release formulation and their ability to specifically deplete cells responsible for the development of posterior capsular opacification (PCO) in month-long, dynamic cell cultures. Methods: Injectable, thermosensitive poly(D,L-lactic-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic-co-glycolic acid) triblock copolymer hydrogels were loaded with either a low or a high dose of doxorubicin-loaded antibody-targeted nanocarriers (G8:3DNA:Dox). Human rhabdomyosarcoma cells, selected for their expression of PCO marker brain-specific angiogenesis inhibitor 1 (BAI1), were kept under dynamic media flow and received either a low or high dose of nanocarriers. Cells were fixed and stained at predetermined time points to evaluate targeted depletion of BAI1+ cells. Results: A lower dose of nanocarriers in hydrogel depleted BAI1+ cells at a slower rate than the higher dose, whereas both reached over 90% BAI1+ cellular nonviability at 28 days. Both treatment groups also significantly lowered the relative abundance of BAI1+ cells in the population compared with the control group. Conclusions: Controlled release of a lower dose of nanocarriers can still achieve therapeutically relevant effects in the prevention of PCO, while avoiding potential secondary effects associated with the administration of a higher dose.

Smurf1 Modulates Smad Signaling Pathway in Fibrotic Cataract Formation

Purpose

TGF-β/BMP signaling pathway plays a significant role in fibrotic cataract. Smurf1, a ubiquitin protein ligase, regulates the TGF-β/BMP signaling pathway through the ubiquitin-proteasome system (UPS). This study aims to investigate the role of Smurf1 in the progression of fibrotic cataract and its underlying mechanism.

Methods

We used a mouse model of injury-induced anterior subcapsular cataract (ASC) and administered the Smurf1 inhibitor A01 for in vivo investigations. RNA sequencing was performed to examine global gene expression changes. Protein levels were assessed by Simple Western analysis. The volume of subcapsular opacity was determined using whole-mount immunofluorescence of lens anterior capsules. Lentivirus was utilized to establish cell lines with Smurf1 knockdown or overexpression in SRA01/04. Lens epithelial cell (LEC) proliferation was evaluated by CCK8 and EdU assays. Cell cycle profile was determined by flow cytometry. LEC migration was measured using Transwell and wound healing assays.

Results

The mRNA levels of genes associated with cell proliferation, migration, epithelial-mesenchymal transition (EMT), TGF-β/BMP pathway, and UPS were upregulated in mouse ASC model. Smurf1 mRNA and protein levels were upregulated in lens capsules of patients and mice with ASC. Anterior chamber injection of A01 inhibited ASC formation and EMT. In vitro, Smurf1 knockdown reduced proliferation, migration and TGF-β2-induced EMT of LECs, concomitant with the upregulation of Smad1, Smad5, and pSmad1/5. Conversely, overexpression of Smurf1 showed opposite phenotypes.

Conclusions

Smurf1 regulates fibrotic cataract progression by influencing LEC proliferation, migration, and EMT through the modulation of the Smad signaling pathway, offering a novel target for the fibrotic cataract treatment.

The E156K mutation in the CRYAA gene affects the epithelial-mesenchymal transition and migration of human lens epithelial cells

Purpose

To investigated the biological effects of E156K-mutated αA-crystallin (CRYAA) in human lens epithelial cells (HLECs).

Methods

FLAG-tagged, human, full-length, wild-type (WT), or E156K-mutated CRYAA was expressed in HLECs under CRYAA knockdown. CRYAA expression was determined by quantitative reverse transcription polymerase chain reaction and western blotting (WB). Rhodamine cytoskeleton staining was used to observe the changes in cell morphology following transfection with WT or E156K-mutated CRYAA plasmids. WB was performed to assess the expression of markers related to epithelial-mesenchymal transition (EMT) and migration.

Results

Rhodamine cytoskeleton staining revealed changes in the morphology of cells transfected with E156K-mutated CRYAA and opposite responses occurred after treatment with a β-catenin inhibitor. Cells transfected with E156K-mutated CRYAA expressed remarkably higher levels of the mesenchymal biomarkers N-cadherin and vimentin but decreased levels of the epithelial biomarker E-cadherin, whereas opposite trends were observed in cells treated with the β-catenin inhibitor, ICG001. The migratory capability of E156K-mutated CRYAA cells was significantly greater than that of WT cells (P < 0.001). This effect was accompanied by significantly increased expression levels of phosphorylated (p)-focal adhesion kinase (FAK) and p-Src. These changes were decreased significantly by treatment with FAK and Src inhibitors.

Conclusion

E156K-mutated CRYAA induced EMT, in which the HLECs lost cell polarity, and acquired a mesenchymal phenotype with greater migratory capability. These biological effects may be associated with activation of the Wnt/β-Catenin and FAK/Src signaling pathways.

The Role of Early Nd:YAG Laser Capsulotomy in Improving Visual Performance in Mild to Moderately Symptomatic Trifocal Patients

Purpose

To determine the effect of early Nd:YAG (neodymium:yttrium-aluminum-garnet) laser capsulotomy on objective and subjective visual quality in symptomatic trifocal intraocular lens (IOL) patients.

Methods

A single-center, prospective study examined symptomatic patients after bilateral cataract extraction with trifocal IOL implantation. A ten-question survey was conducted one month after surgery. Study endpoints included the assessment of monocular and binocular uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), contrast sensitivity (CS), and subjective visual quality before and after Nd:YAG capsulotomy prior to 4 months after cataract surgery.

Results

A total of 38 eyes from 21 patients were included with a TFAT00 (n = 23) or TFAT30-60 (n = 15). Overall satisfaction with the IOL was 8.55 ± 1.77 (range 5-10). A Nd:YAG capsulotomy was performed at 55 ± 26 days. Monocular UDVA and UNVA > 20/25 before Nd:YAG were 53.0% and 42.0%, which improved post-Nd:YAG to 63.0% and 66.0%, respectively (P = 0.41, P = 0.051). Binocular UDVA and UNVA >20/25 before Nd:YAG were 82.0% and 63.0%, which increased to 97% and 97%, respectively (P < 0.05, P < 0.001). CS increased in all post-Nd:YAG capsulotomies (P < 0.01). The presence of glare was documented at 74% pre-Nd:YAG, which decreased to 41% post-Nd:YAG (P < 0.01). Glare which limited activities was documented at 24%, which decreased to 5% post-Nd:YAG (P = 0.21).

Conclusion

Early treatment of posterior capsule opacities in mild to moderately dissatisfied trifocal IOL patients may be beneficial in improving CS, visual quality, and reducing the presence and severity of dysphotopsias.

Pantothenate Kinase 4 Governs Lens Epithelial Fibrosis by Negatively Regulating Pyruvate Kinase M2-Related Glycolysis

Lens fibrosis is one of the leading causes of cataract in the elderly population. The primary energy substrate of the lens is glucose from the aqueous humor, and the transparency of mature lens epithelial cells (LECs) is dependent on glycolysis for ATP. Therefore, the deconstruction of reprogramming of glycolytic metabolism can contribute to further understanding of LEC epithelial-mesenchymal transition (EMT). In the present study, we found a novel pantothenate kinase 4 (PANK4)-related glycolytic mechanism that regulates LEC EMT. The PANK4 level was correlated with aging in cataract patients and mice. Loss of function of PANK4 significantly contributed to alleviating LEC EMT by upregulating pyruvate kinase M2 isozyme (PKM2), which was phosphorylated at Y105, thus switching oxidative phosphorylation to glycolysis. However, PKM2 regulation did not affect PANK4, demonstrating the downstream role of PKM2. Inhibition of PKM2 in Pank4-/- mice caused lens fibrosis, which supports the finding that the PANK4-PKM2 axis is required for LEC EMT. Glycolytic metabolism-governed hypoxia inducible factor (HIF) signaling is involved in PANK4-PKM2-related downstream signaling. However, HIF-1α elevation was independent of PKM2 (S37) but PKM2 (Y105) when PANK4 was deleted, which demonstrated that PKM2 and HIF-1α were not involved in a classic positive feedback loop. Collectively, these results indicate a PANK4-related glycolysis switch that may contribute to HIF-1 stabilization and PKM2 phosphorylation at Y105 and inhibit LEC EMT. The mechanism elucidation in our study may also shed light on fibrosis treatments for other organs.

Posterior capsular opacification and Nd:YAG capsulotomy rates in patients implanted with square-edged and non-square-edged intraocular lenses in manual small-incision cataract surgery: A randomized controlled study

Purpose

To study posterior capsular opacification (PCO) and neodymium-doped yttrium aluminum garnet (Nd:YAG) capsulotomy rates in patients implanted with square-edged and non-square-edged intraocular lenses (IOLs) in manual small-incision cataract surgery (MSICS).

Setting

Tertiary eye care center.

Design

Prospective, comparative, and randomized controlled study.

Methods

This study included patients with senile cataracts scheduled for MSICS and IOL implantation. One eye of each patient was randomized to the implantation of square-edged (S group) or non-square-edged IOL (NSQ group). An independent observer analyzed PCO at 6, 12, 18, and 24 months under slit-lamp illumination.

Results

A total of 104 eyes were included in this study. The mean age of the participants in the two groups was 63.2 (±8.2) years, and there were 65 (62.5%) men and 39 women (37.5%). The mean best-corrected visual acuity (BCVA) values at 6, 12, and 18 months were 0.157 (±0.10), 0.11 (±0.12), and 0.12 (±0.11), respectively, in the S group and 0.17 (±0.10), 0.17 (±0.12), and 0.20 (±0.17), respectively, in the NSQ group. At 12 (P = 0.03) and 18 months (P = 0.01) follow-up, the BCVA of the S group was significantly better than that of the NSQ group. Four eyes in the NSQ group and one eye in the S group required Nd:YAG.

Conclusion

Evaluation of PCO and Nd:YAG capsulotomy rates showed that the 360° square of the posterior IOL edge plays a role in the prevention of PCO. Owing to the low cost of the material and the easy availability of IOLs manufactured from it, square-edged IOL has a definite role in the prevention of PCO in MSICS.

Heparan sulfate proteoglycans (HSPGs) of the ocular lens

Heparan sulfate proteoglycans (HSPGs) reside in most cells; on their surface, in the pericellular milieu and/or extracellular matrix. In the eye, HSPGs can orchestrate the activity of key signalling molecules found in the ocular environment that promote its development and homeostasis. To date, our understanding of the specific roles played by individual HSPG family members, and the heterogeneity of their associated sulfated HS chains, is in its infancy. The crystalline lens is a relatively simple and well characterised ocular tissue that provides an ideal stage to showcase and model the expression and unique roles of individual HSPGs. Individual HSPG core proteins are differentially localised to eye tissues in a temporal and spatial developmental- and cell-type specific manner, and their loss or functional disruption results in unique phenotypic outcomes for the lens, and other ocular tissues. More recent work has found that different HS sulfation enzymes are also presented in a cell- and tissue-specific manner, and that disruption of these different sulfation patterns affects specific HS-protein interactions. Not surprisingly, these sulfated HS chains have also been reported to be required for lens and eye development, with dysregulation of HS chain structure and function leading to pathogenesis and eye-related phenotypes. In the lens, HSPGs undergo significant and specific changes in expression and function that can drive pathology, or in some cases, promote tissue repair. As master signalling regulators, HSPGs may one day serve as valuable biomarkers, and even as putative targets for the development of novel therapeutics, not only for the eye but for many other systemic pathologies.

Role of Oxidative Stress in Ocular Diseases: A Balancing Act

Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.

The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens

The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.

Role of Decorin in the Lens and Ocular Diseases

Decorin is an archetypal member of the small leucine-rich proteoglycan gene family and is involved in various biological functions and many signaling networks, interacting with extra-cellular matrix (ECM) components, growth factors, and receptor tyrosine kinases. Decorin also modulates the growth factors, cell proliferation, migration, and angiogenesis. It has been reported to be involved in many ischemic and fibrotic eye diseases, such as congenital stromal dystrophy of the cornea, anterior subcapsular fibrosis of the lens, proliferative vitreoretinopathy, et al. Furthermore, recent evidence supports its role in secondary posterior capsule opacification (PCO) after cataract surgery. The expression of decorin mRNA in lens epithelial cells in vitro was found to decrease upon transforming growth factor (TGF)-β-2 addition and increase upon fibroblast growth factor (FGF)-2 addition. Wound healing of the injured lens in mice transgenic for lens-specific human decorin was promoted by inhibiting myofibroblastic changes. Decorin may be associated with epithelial-mesenchymal transition and PCO development in the lens. Gene therapy and decorin administration have the potential to serve as excellent therapeutic approaches for modifying impaired wound healing, PCO, and other eye diseases related to fibrosis and angiogenesis. In this review, we present findings regarding the roles of decorin in the lens and ocular diseases.

The Immediate Early Response of Lens Epithelial Cells to Lens Injury

Cataracts are treated by lens fiber cell removal followed by intraocular lens (IOL) implantation into the lens capsule. While effective, this procedure leaves behind numerous lens epithelial cells (LECs) which undergo a wound healing response that frequently leads to posterior capsular opacification (PCO). In order to elucidate the acute response of LECs to lens fiber cell removal which models cataract surgery (post cataract surgery, PCS), RNA-seq was conducted on LECs derived from wild type mice at 0 and 6 h PCS. This analysis found that LECs upregulate the expression of numerous proinflammatory cytokines and profibrotic regulators by 6 h PCS suggesting rapid priming of pathways leading to inflammation and fibrosis PCS. LECs also highly upregulate the expression of numerous immediate early transcription factors (IETFs) by 6 h PCS and immunolocalization found elevated levels of these proteins by 3 h PCS, and this was preceded by the phosphorylation of ERK1/2 in injured LECs. Egr1 and FosB were among the highest expressed of these factors and qRT-PCR revealed that they also upregulate in explanted mouse lens epithelia suggesting potential roles in the LEC injury response. Analysis of lenses lacking either Egr1 or FosB revealed that both genes may regulate a portion of the acute LEC injury response, although neither gene was essential for expression of either proinflammatory or fibrotic markers at later times PCS suggesting that IETFs may work in concert to mediate the LEC injury response following cataract surgery.

Evaluation of posterior capsular opacification and neodymium-doped yttrium aluminum garnet capsulotomy rates in patients with hydrophilic intraocular lens implantation with and without ocular viscoelastic device

Purpose

To study the effect of intraocular lens (IOL) implantation with and without ocular viscoelastic device (OVD) on posterior capsular opacification (PCO) in eyes with phacoemulsification.

Methods

This prospective, comparative, and randomized case series included 70 patients (140 eyes) with senile cataracts scheduled for phacoemulsification and IOL implantation in a tertiary eye c are center. One eye of each patient was randomized to one of the two groups, namely, control and OVD. After phacoemulsification, the IOL was placed in the capsular bag under balanced salt solution (BSS) in the control group, whereas the IOL was placed under OVD in the OVD group. PCO was analyzed by an independent observer at 6, 12, and 18 months under slit-lamp illumination.

Results

The mean age of the participants in the two groups was 61.2 (±9.9) years. Of the total participants, 68 (48.5%) were men and 72 (51.5%) were women. The mean keratometry (K1, K2) values of the OVD (44.26 ± 1.43, 44.93 ± 1.66) and control (44.51 ± 1.74, 44.69 ± 1.49) groups were similar. The mean IOL powers of the control and OVD groups were 21.25 (±1.94) and 21.53 (±1.86), respectively (P = 0.463). The mean best-corrected visual acuity (BCVA) of the control group at 6-, 12-, and 18-month follow-ups were 0.622 (±0.253), 0.315 (±0.203), and 0.063 (±0.163), respectively, whereas those of the OVD group were 0.592 (±0.253), 0.336 (±0.169), and 0.066 (±0.118), respectively (P = 0.922). None of the patients had postoperative raised intraocular pressure (IOP), uveitis, or endophthalmitis. Three and four eyes in the control and OVD groups, respectively, required neodymium-doped yttrium aluminum garnet (ND: YAG) capsulotomy at study termination (P = 0.999).

Conclusion

The hydroimplantation technique of the placement of hydrophilic IOL did not reduce the PCO rate in the 18-month follow-up period. The ND: YAG capsulotomy rate did not differ between the groups.

Noncoding RNAs in cataract formation: star molecules emerge in an endless stream

For decades, research on the pathological mechanism of cataracts has usually focused on the abnormal protein changes caused by a series of risk factors. However, an entire class of molecules, termed non-coding RNA (ncRNA), was discovered in recent years and proven to be heavily involved in cataract formation. Recent studies have recognized the key regulatory roles of ncRNAs in cataracts by shaping cellular activities such as proliferation, apoptosis, migration and epithelial-mesenchymal transition (EMT). This review summarizes our current insight into the biogenesis, properties and functions of ncRNAs and then discusses the development of research on ncRNAs in cataracts. Considering the significant role of ncRNA in cataract formation, research on novel associated regulatory mechanisms is urgently needed, and the development of therapeutic alternatives for the treatment of cataracts seems promising.

Celastrol-based nanomedicine hydrogels eliminate posterior capsule opacification

Aim: To formulate an injectable thermosensitive micelle-hydrogel hybrid system loaded with celastrol (celastrol-loaded micelle hydrogel: CMG) to prevent posterior capsule opacification (PCO). Materials & methods: Celastrol-loaded micelles were embedded in a thermosensitive hydrogel matrix to enable controlled on-demand celastrol delivery into the residual capsule. The efficacy and mechanisms of the system for eliminating PCO were evaluated in rabbits. Results: Celastrol-loaded micelles inhibited the migration and proliferation of lens epithelial cells induced by TGF-β1. Celastrol prevents epithelial-mesenchymal transition in lens epithelial cells induced by TGF-β1 through the TGF-β1/Smad2/3/TEAD1 signaling pathway. In vivo efficiency evaluations showed that CMG demonstrated an excellent inhibitory effect on PCO in rabbits and had no obvious tissue toxicity. Conclusion: Injectable CMG may represent a promising ophthalmic platform for preventing PCO. This versatile injectable micelle-hydrogel hybrid represents a clinically relevant platform to achieve localized therapy and controlled release of drugs in other disease therapies.

BMP3 inhibits TGFβ2-mediated myofibroblast differentiation during wound healing of the embryonic cornea

Often acute damage to the cornea initiates drastic tissue remodeling, resulting in fibrotic scarring that disrupts light transmission and precedes vision impairment. Very little is known about the factors that can mitigate fibrosis and promote scar-free cornea wound healing. We previously described transient myofibroblast differentiation during non-fibrotic repair in an embryonic cornea injury model. Here, we sought to elucidate the mechanistic regulation of myofibroblast differentiation during embryonic cornea wound healing. We found that alpha-smooth muscle actin (αSMA)-positive myofibroblasts are superficial and their presence inversely correlates with wound closure. Expression of TGFβ2 and nuclear localization of pSMAD2 were elevated during myofibroblast induction. BMP3 and BMP7 were localized in the corneal epithelium and corresponded with pSMAD1/5/8 activation and absence of myofibroblasts in the healing stroma. In vitro analyses with corneal fibroblasts revealed that BMP3 inhibits the persistence of TGFβ2-induced myofibroblasts by promoting disassembly of focal adhesions and αSMA fibers. This was confirmed by the expression of vinculin and pFAK. Together, these data highlight a mechanism to inhibit myofibroblast persistence during cornea wound repair.

Aged Lens Epithelial Cells Suppress Proliferation and Epithelial–Mesenchymal Transition-Relevance for Posterior Capsule Opacification

Posterior capsule opacification (PCO) is a frequent complication after cataract surgery, and advanced PCO requires YAG laser (Nd: YAG) capsulotomy, which often gives rise to more complications. Lens epithelial cell (LEC) proliferation and transformation (i.e., epithelial–mesenchymal transition (EMT)) are two critical elements in PCO initiation and progression pathogenesis. While PCO marginally impacts aged cataract surgery patients, PCO incidences are exceptionally high in infants and children undergoing cataract surgery. The gene expression of lens epithelial cell aging and its role in the discrepancy of PCO prevalence between young and older people have not been fully studied. Here, we conducted a comprehensive differentially expressed gene (DEG) analysis of a cell aging model by comparing the early and late passage FHL124 lens epithelial cells (LECs). In vitro, TGFβ2, cell treatment, and in vivo mouse cataract surgical models were used to validate our findings. We found that aged LECs decelerated rates of cell proliferation accompanied by dysregulation of cellular immune response and cell stress response. Surprisingly, we found that LECs systematically downregulated epithelial–mesenchymal transition (EMT)-promoting genes. The protein expression of several EMT hallmark genes, e.g., fibronectin, αSMA, and cadherin 11, were gradually decreased during LECs aging. We then confirmed these findings in vitro and found that aged LECs markedly alleviated TGFβ2-mediated EMT. Importantly, we explicitly confirmed the in vitro findings from the in vivo mouse cataract surgery studies. We propose that both the high proliferation rate and EMT-enriched young LECs phenotypic characteristics contribute to unusually high PCO incidence in infants and children.

REPS2 downregulation facilitates FGF-induced adhesion and migration in human lens epithelial cells through FAK/Cdc42 signaling and contributes to posterior capsule opacification

Posterior capsular opacification (PCO) can cause postoperative visual loss after cataract surgery. Residual human lens epithelial cell (HLEC) proliferation, migration, epithelial-mesenchymal transition (EMT) and synthesis of extracellular matrix (ECM) are the entitative reasons for PCO. Low expression of Ral-binding protein 1-associated Eps domain-containing 2 (REPS2) and high levels of basic fibroblast growth factor (b-FGF) were observed in the lens and postoperative aqueous humor of cataract patients. REPS2 was identified as a negative regulator in growth factor signaling; however, its function in HLECs is unknown. This was first investigated in the present study by evaluating REPS2 expression in anterior lens capsules from cataract patients, a mouse cataract model, and HLE-b3 cells. The biological function of REPS2 in HLE-B3 cells was assessed by REPS2 silencing and Cell Counting Kit 8, wound healing, Transwell migration, F-actin staining, G-protein pulldown and western blot assays. In the present study, REPS2 was significantly downregulated in human and mouse cataract capsules and H₂O₂-treated HLE-B3 cells. REPS2 knockdown increased fibronectin, type I collagen, and α-smooth muscle actin expression levels and stimulated HLECs proliferation and migration; these effects were enhanced by FGF treatment and accompanied with focal adhesion kinase (FAK) phosphorylation, cell division cycle 42 (Cdc42) activation, focal adhesion protein upregulation, and F-actin cytoskeleton reorganization. However, treatment with the FAK inhibitor PF573228 abolished these effects. Thus, REPS2 downregulation in cataract HLECs induces their proliferation and facilitates FGF-induced ECM synthesis, EMT, cell adhesion and migration by activating FAK/Cdc42 signaling, which may underlie PCO pathogenesis.

NIR-triggered drug delivery system for chemo-photothermal therapy of posterior capsule opacification

Posterior capsule opacification (PCO) is the most common complication after cataract surgery and is likely to cause the second loss of vision. Pharmacological PCO prophylaxis has been proved to be effective, yet no clinical option is available due to the lack of a suitable mode of administration. In this work, we propose a unique concept of NIR dual-triggered drug release from black phosphorus (BP)-based implantable intraocular lens (IOL) for controlled drug release and chemo-photothermal combination therapy of PCO. Here, IOL is used as a "reservoir" of doxorubicin-loaded black phosphorus (BP-DOX), and BP is used as NIR activation agent for controlled drug release and photothermal therapy. This BP-DOX integrated IOL, namely BP-DOX@IOL, shows the characteristics of good transmittance, good mechanical property, NIR dual-triggered drug release behaviors, and excellent photothermal efficacy. In vivo studies reveal that there is no PCO occurrence in rabbits' model by using BP-DOX@IOL combined NIR irradiation, which exhibits distinct superiority on inhibiting PCO than the control group (100% PCO occurrence) 28 days post-surgery. This novel IOL drug delivery system would be a promising strategy for the future clinical application for PCO prophylaxis and treatment.

MMP9 Differentially Regulates Proteins Involved in Actin Polymerization and Cell Migration during TGF-β-Induced EMT in the Lens

Fibrotic cataracts have been attributed to transforming growth factor-beta (TGF-β)-induced epithelial-to-mesenchymal transition (EMT). Using mouse knockout (KO) models, our laboratory has identified MMP9 as a crucial protein in the TGF-β-induced EMT process. In this study, we further revealed an absence of alpha-smooth muscle actin (αSMA) and filamentous-actin (F-actin) stress fibers in MMP9KO mouse lens epithelial cell explants (LECs). Expression analysis using NanoString revealed no marked differences in αSMA (ACTA2) and beta-actin (β-actin) (ACTB) mRNA between the lenses of TGF-β-overexpressing (TGF-βtg) mice and TGF-βtg mice on a MMP9KO background. We subsequently conducted a protein array that revealed differential regulation of proteins known to be involved in actin polymerization and cell migration in TGF-β-treated MMP9KO mouse LECs when compared to untreated controls. Immunofluorescence analyses using rat LECs and the novel MMP9-specific inhibitor, JNJ0966, revealed similar differential regulation of cortactin, FAK, LIMK1 and MLC2 as observed in the array. Finally, a reduction in the nuclear localization of MRTF-A, a master regulator of cytoskeletal remodeling during EMT, was observed in rat LECs co-treated with JNJ0966 and TGF-β. In conclusion, MMP9 deficiency results in differential regulation of proteins involved in actin polymerization and cell migration, and this in turn prevents TGF-β-induced EMT in the lens.

Biofabrication of Artificial Stem Cell Niches in the Anterior Ocular Segment

The anterior segment of the eye is a complex set of structures that collectively act to maintain the integrity of the globe and direct light towards the posteriorly located retina. The eye is exposed to numerous physical and environmental insults such as infection, UV radiation, physical or chemical injuries. Loss of transparency to the cornea or lens (cataract) and dysfunctional regulation of intra ocular pressure (glaucoma) are leading causes of worldwide blindness. Whilst traditional therapeutic approaches can improve vision, their effect often fails to control the multiple pathological events that lead to long-term vision loss. Regenerative medicine approaches in the eye have already had success with ocular stem cell therapy and ex vivo production of cornea and conjunctival tissue for transplant recovering patients' vision. However, advancements are required to increase the efficacy of these as well as develop other ocular cell therapies. One of the most important challenges that determines the success of regenerative approaches is the preservation of the stem cell properties during expansion culture in vitro. To achieve this, the environment must provide the physical, chemical and biological factors that ensure the maintenance of their undifferentiated state, as well as their proliferative capacity. This is likely to be accomplished by replicating the natural stem cell niche in vitro. Due to the complex nature of the cell microenvironment, the creation of such artificial niches requires the use of bioengineering techniques which can replicate the physico-chemical properties and the dynamic cell-extracellular matrix interactions that maintain the stem cell phenotype. This review discusses the progress made in the replication of stem cell niches from the anterior ocular segment by using bioengineering approaches and their therapeutic implications.

Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery

BACKGROUND

Posterior capsule opacification (PCO) is a clouding of the posterior part of the lens capsule, a skin-like transparent structure, which surrounds the crystalline lens in the human eye. PCO is the most common postoperative complication following modern cataract surgery with implantation of a posterior chamber intraocular lens (IOL). The main symptoms of PCO are a decrease in visual acuity, 'cloudy', blurred vision and reduced contrast sensitivity. PCO is treated with a neodymium:YAG (Nd:YAG) laser to create a small opening in the opaque capsule and regain a clear central visual axis. This capsulotomy might cause further ocular complications, such as raised intraocular pressure or swelling of the central retina (macular oedema). This procedure is also a significant financial burden for health care systems worldwide. In recent decades, there have been advances in the selection of IOL materials and optimisation of IOL designs to help prevent PCO formation after cataract surgery. These include changes to the side structures holding the lens in the centre of the lens capsule bag, called IOL haptics, and IOL optic edge designs.

OBJECTIVES

To compare the effects of different IOL optic edge designs on PCO after cataract surgery.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, Latin American and Caribbean Health Sciences Literature Database (LILACS), the ISRCTN registry, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) up to 17 November 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared different types of IOL optic edge design. Our prespecified primary outcome was the proportion of eyes with Nd:YAG capsulotomy one year after surgery. Secondary outcomes included PCO score, best-corrected distance visual acuity (BCDVA) and quality of life score at one year. Due to availability of important long-term data, we also presented data at longer-term follow-up which is a post hoc change to our protocol.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane and the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

We included 10 studies (1065 people, 1834 eyes) that compared sharp- and round-edged IOLs. Eight of these studies were within-person studies whereby one eye received a sharp-edged IOL and the fellow eye a round-edged IOL. The IOL materials were acrylic (2 studies), silicone (4 studies), polymethyl methacrylate (PMMA, 3 studies) and different materials (1 study). The studies were conducted in Austria, Germany, India, Japan, Sweden and the UK. Five studies were at high risk of bias in at least one domain. We judged two studies to be at low risk of bias in all domains. There were few cases of Nd:YAG capsulotomy at one year (primary outcome): 1/371 in sharp-edged and 4/371 in round-edged groups. The effect estimate was in favour of sharp-edged IOLs but the confidence intervals were very wide and compatible with higher or lower chance of Nd:YAG capsulotomy in sharp-edged compared with round-edged lenses (Peto odds ratio (OR) 0.30, 95% CI 0.05 to 1.74; I² = 0%; 6 studies, 742 eyes). This corresponds to seven fewer cases of Nd:YAG capsulotomy per 1000 sharp-edged IOLs inserted compared with round-edged IOLs (95% CI 9 fewer to 7 more). We judged this as low-certainty evidence, downgrading for imprecision and risk of bias. A similar reduced risk of Nd:YAG capsulotomy in sharp-edge compared with round-edge IOLs was seen at two, three and five years but as the number of Nd:YAG capsulotomy events increased with longer follow-up this effect was more precisely measured at longer follow-up: two years, risk ratio (RR) 0.35 (0.16 to 0.80); 703 eyes (6 studies); 89 fewer cases per 1000; three years, RR 0.21 (0.11 to 0.41); 538 eyes (6 studies); 170 fewer cases per 1000; five years, RR 0.21 (0.10 to 0.45); 306 eyes (4 studies); 331 fewer cases per 1000. Data at 9 years and 12 years were only available from one study. All studies reported a PCO score. Four studies reported the AQUA (Automated Quantification of After-Cataract) score, four studies reported the EPCO (Evaluation of PCO) score and two studies reported another method of quantifying PCO. It was not possible to pool these data due to the way they were reported, but all studies consistently reported a statistically significant lower average PCO score (of the order of 0.5 to 3 units) with sharp-edged IOLs compared with round-edged IOLs. We judged this to be moderate-certainty evidence downgrading for risk of bias. The logMAR visual acuity score was lower (better) in eyes that received a sharp-edged IOL but the difference was small and likely to be clinically unimportant at one year (mean difference (MD) -0.06 logMAR, 95% CI -0.12 to 0; 2 studies, 153 eyes; low-certainty evidence). Similar effects were seen at longer follow-up periods but non-statistically significant data were less fully reported: two years MD -0.01 logMAR (-0.05 to 0.02); 2 studies, 311 eyes; three years MD -0.09 logMAR (-0.22 to 0.03); 2 studies, 117 eyes; data at five years only available from one study. None of the studies reported quality of life. Very low-certainty evidence on adverse events did not suggest any important differences between the groups.

AUTHORS' CONCLUSIONS

This review provides evidence that sharp-edged IOLs are likely to be associated with less PCO formation than round-edged IOLs, with less Nd:YAG capsulotomy. The effects on visual acuity were less certain. The impact of these lenses on quality of life has not been assessed and there are only very low-certainty comparative data on adverse events.

Repression of Smad4 by MicroRNA-1285 moderates TGF-β-induced epithelial-mesenchymal transition in proliferative vitreoretinopathy

The purpose of this study was to assess whether microRNA (miR)-1285 can suppress the epithelial-mesenchymal transition (EMT) in retinal pigment epithelial cells. Expression of miR-1285 was evaluated using quantitative real-time polymerase chain reaction (RT-qPCR). The features of EMT were assessed using Western blotting, immunocytochemical staining, scratch wound healing tests, modified Boyden chamber assay, and collagen gel contraction assay. A rabbit model of proliferative vitreoretinopathy (PVR) was used for in vivo testing, which involved the induction of PVR by injection of transfected ARPE cells into the vitreous chamber. Luciferase reporter assay was performed to identify the putative target of miR-1285. The expression of miR-1285 was downregulated in ARPE-19 cells treated with transforming growth factor (TGF)-β. Overexpression of miR-1285 led to upregulation of zonula occludens-1, downregulation of α-smooth muscle actin and vimentin, cell migration and cell contractility-all EMT features-in the TGF-β2-treated ARPE-19 cells. The reporter assay indicated that the 3' untranslated region of Smad4 was the direct target of miR1285. PVR progression was alleviated in the miR-1285 transfected rabbits. In conclusion, overexpression of miR-1285 attenuates TGF-β2-induced EMT in a rabbit model of PVR, and the effect of miR-1285 in PVR is dependent on Smad4. Further research is warranted to develop a feasible therapeutic approach for the prevention and treatment of PVR.

Nanogel-Facilitated In-Situ Delivery of a Cataract Inhibitor

Cataracts are a leading cause of blindness worldwide. Surgical removal of cataracts is a safe and effective procedure to restore vision. However, a large number of patients later develop vision loss due to regrowth of lens cells and subsequent degradation of the visual axis leading to visual disability. This postsurgical complication, known as posterior capsular opacification (PCO), occurs in up to 30% of cataract patients and has no clinically proven pharmacological means of prevention. Despite the availability of many compounds capable of preventing early steps in PCO development, there is currently no effective means to deliver such therapies into the eye for a suitable duration. To model a solution to this unmet medical need, we fabricated acrylic substrates as intraocular lens (IOL) mimics scaled to place into the capsular bag of the mouse lens following a mock-cataract surgery. Substrates were coated with a hydrophilic crosslinked acrylate nanogel designed to elute Sorbinil, an aldose reductase inhibitor previously shown to suppress PCO. Insertion of the Sorbinil-eluting device into the lens capsule at the time of cataract surgery resulted in substantial prevention of cellular changes associated with PCO development. This model demonstrates that a cataract inhibitor can be delivered into the postsurgical lens capsule at therapeutic levels.

Lens-specific conditional knockout of tropomyosin 1 gene in mice causes abnormal fiber differentiation and lens opacity

Tropomyosin (Tpm) 1 and 2 are important in the epithelial mesenchymal transition of lens epithelial cells; however, the effect of Tpm1 depletion during aging remains obscure. We analyzed the age-related changes in the crystalline lens of Tpm1- conditional knockout mice (Tpm1-CKO). Floxed alleles of Tpm1 were conditionally deleted in the lens, using Pax6-cre transgenic mice. Lenses of embryonic day (ED) 14, postnatal 1-, 11-, and 48-week-old Tpm1-CKO and wild type mice were dissected to prepare paraffin sections, which subsequently underwent histological and immunohistochemical analysis. Tpm1 and α smooth muscle actin (αSMA) mRNA expression were assessed using RT-PCR. The homozygous Tpm1-CKO (Tpm1^-/-) lenses displayed a dramatic reduction in Tpm1 transcript, with no change to αSMA mRNA expression. Tpm1^-/- mice had small lenses with disorganized, vesiculated fiber cells, and loss of epithelial cells. The lenses of Tpm1^-/- mice had abnormal and disordered lens fiber cells with cortical and peri-nuclear liquefaction. Expression of filamentous-actin was reduced in the equator region of lenses derived from ED14, 1-, 11-, and 48-week-old Tpm1^-/- mice. Therefore, Tpm1 plays an integral role in mediating the integrity and fate of lens fiber differentiation and lens homeostasis during aging. Age-related Tpm1 dysregulation or deficiency may induce cataract formation.

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.

Relationship between Axial Length and Levels of TGF-β in the Aqueous Humor and Plasma of Myopic Patients

Purpose

To investigate the levels of transforming growth factor-β (TGF-β) in human aqueous humor (AH) and plasma (PL) of patients with myopia, and verify whether there is an association between these levels and their association with axial length (AL).

Methods

Thirty-eight myopic patients who received intraocular collamer lens (ICL) implantation were enrolled in this cross-sectional study. Patients were divided into three groups based on AL with cut-off points of 26 and 28 mm. AH and PL samples were obtained during ICL implantation surgery. The levels of TGF-β1, TGF-β2, and TGF-β3 in the AH and PL samples were measured using Luminex xMAP Technology kits (Milliplex xMAP kits). The protein levels of TGF-βs in both AH and PL samples and their relationships with AL were analyzed.

Results

In all, 38 patients (59 eyes) were enrolled and divided into the three groups: group A contained 7 people (10 eyes), group B contained 22 people (37 eyes), and group C contained 9 people (12 eyes). In the AH group, we detected TGF-β1 (P₅₀: 19.97 pg/mL), TGF-β2 (2446.00 pg/mL), and TGF-β3 (26.33 pg/mL); in PL, these concentrations were 8984.00, 523.44, and 210.47 pg/mL, respectively. The levels of TGF-β1 and TGF-β3 in AH were positively associated with AL. None of the three isoforms in PL were related to those in AH or to AL.

Conclusions

The levels of TGF-β1 and TGF-β3 in AH were more strongly associated with the severity of myopia than the types of TGF-β in PL.

Leukocyte chemotactic receptor Fpr1 protects against aging-related posterior subcapsular cataract formation

Cataracts are a common consequence of aging; however, pathogenesis remains poorly understood. Here, we observed that after 3 months of age mice lacking the G protein-coupled leukocyte chemotactic receptor Fpr1 (N-formyl peptide receptor 1) began to develop bilateral posterior subcapsular cataracts that progressed to lens rupture and severe degeneration, without evidence of either systemic or local ocular infection or inflammation. Consistent with this, Fpr1 was detected in both mouse and human lens in primary lens epithelial cells (LECs), the only cell type present in the lens; however, expression was confined to subcapsular LECs located along the anterior hemispheric surface. To maximize translucency, LECs at the equator proliferate and migrate posteriorly, then differentiate into lens fiber cells by nonclassical apoptotic signaling, which results in loss of nuclei and other organelles, including mitochondria which are a rich source of endogenous N-formyl peptides. In this regard, denucleation and posterior migration of LECs were abnormal in lenses from Fpr1-/- mice, and direct stimulation of LECs with the prototypic N-formyl peptide agonist fMLF promoted apoptosis. Thus, Fpr1 is repurposed beyond its immunoregulatory role in leukocytes to protect against cataract formation and lens degeneration during aging.

Comparison of posterior capsule opacification between Clareon CNA0T0 and Tecnis ZCB00 intraocular lenses

INTRODUCTION

The purpose is to compare posterior capsule opacification (PCO) and its impact on vision between Clareon CNA0T0 (Alcon) and Tecnis ZCB00 intraocular lenses (IOLs) (Johnson&Johnson) 1, 6, and 12 months after implantation.

METHODS

A prospective observational study was performed at the Nuestra Señora de Gracia Hospital (Zaragoza, Spain). Fifty eyes (50 patients) with Tecnis IOL (group 1) and 60 eyes (60 patients) with Clareon IOL (group 2) were enrolled. One, 6, and 12 months after age-related cataract surgery by five different surgeons, the following tests were performed: mesopic corrected distance visual acuity (CDVA), CSV1000-E test, KR-1W wavefront analyzer, OQAS II, Catquest-9SF questionnaire and mydriatic slit-lamp pictures. PCO intensity was quantified and the area of opacification was measured using ImageJ (NIH).

RESULTS

Mean age was 71.20 ± 6.79 years in group 1, and 71.73 ± 8.17 years in group 2 (p = 0.72); mean axial length was 23.46 ± 1.14 and 23.53 ± 0.91 mm, respectively (p = 0.72); mean IOL power was 21.69 ± 2.26 D and 21.28 ± 2.44 D, respectively (p = 0.37). One month after surgery there were differences in intensity of PCO (0.73 ± 0.60 and 1.05 ± 0.71, respectively, p = 0.02). Six months after surgery statistical differences were found in VA with 20% CS in mydriatic conditions (0.26 ± 0.21 logMAR (20/36) and 0.18 ± 0.17 logMAR (20/30), respectively, p = 0.04). Twelve months after surgery, no differences were detected between groups. As for the evolution of PCO within the Clareon group, high order aberrations (p < 0.05) and the Strehl ratio (p = 0.02) decreased.

CONCLUSION

There are no differences in slit-lamp pictures or visual function between both IOLs during the first 12 months after implantation.

Utility of the optical quality analysis system for decision-making in Nd: YAG laser posterior capsulotomy in patients with light posterior capsule opacity

Background

A prospective cohort study was performed to evaluate whether the Optical Quality Analysis System (OQAS) can serve as a valuable additional indicator for appropriate posterior capsulotomy referral.

Methods

One hundred and five eyes from 96 patients undergoing capsulotomy were divided into precapsulotomy logMAR CDVA ≤0.1 group and logMAR CDVA > 0.1 group. CDVA, and the Visual Function 14 index (VF-14) score were estimated before and 1 month after capsulotomy. The objective scattering index (OSI) value was measured by using the OQAS. Posterior capsule opacification (PCO) severity was assessed with Evaluation of PCO 2000 (EPCO 2000) software.

Results

In logMAR CDVA > 0.1 group, the correlations of OSI, logMAR CDVA, EPCO score and VF-14 score were very strong preoperatively. In logMAR CDVA ≤0.1 group, preoperatively, OSI was correlated with logMAR CDVA (r = 0.451), EPCO score (r = 0.789), and VF-14 score (r = 0.852). LogMAR CDVA has weak correlation with VF-14 score (r = − 0.384) and EPCO score (r = 0.566). VF-14 score was correlated with EPCO score (r = − 0.669). In the logMAR CDVA ≤0.1 group, there was no significant difference in logMAR CDVA between precapsulotomy and postcapsulotomy (P > 0.05). In the two groups, all the other optical quality parameters were significantly improved after capsulotomy (P < 0.05). In logMAR CDVA > 0.1 group, the area under the curve of the ROC of the OSI was 0.996 (P = 0.000). In logMAR CDVA ≤0.1 group, the area under the curve of the ROC of the OSI was 0.943 (P = 0.000).

Conclusions

The OSI was useful for evaluating of PCO and prediction of beneficial capsulotomy. Especially for patients with slight PCO and better visual acuity, OSI is more valuable than CDVA and completely objective examination.

Trial registration

The study protocol was registered at the Chinese Clinical Trial Registry. Register: ChiCTR1800018842 (Registered Date: October 13th, 2018).

Polymeric Materials for Eye Surface and Intraocular Applications

Ocular applications of polymeric materials have been widely investigated for medical diagnostics, treatment, and vision improvement. The human eye is a vital organ that connects us to the outside world so when the eye is injured, infected, or impaired, it needs immediate medical treatment to maintain clear vision and quality of life. Moreover, several essential parts of the eye lose their functions upon aging, causing diminished vision. Modern polymer science and polymeric materials offer various alternatives, such as corneal and scleral implants, artificial ocular lenses, and vitreous substitutes, to replace the damaged parts of the eye. In addition to the use of polymers for medical treatment, polymeric contact lenses can provide not only vision correction, but they can also be used as wearable electronics. In this Review, we highlight the evolution of polymeric materials for specific ocular applications such as intraocular lenses and current state-of-the-art polymeric systems with unique properties for contact lens, corneal, scleral, and vitreous body applications. We organize this Review paper by following the path of light as it travels through the eye. Starting from the outside of the eye (contact lenses), we move onto the eye's surface (cornea and sclera) and conclude with intraocular applications (intraocular lens and vitreous body) of mostly synthetic polymers and several biopolymers. Initially, we briefly describe the anatomy and physiology of the eye as a reminder of the eye parts and their functions. The rest of the Review provides an overview of recent advancements in next-generation contact lenses and contact lens sensors, corneal and scleral implants, solid and injectable intraocular lenses, and artificial vitreous body. Current limitations for future improvements are also briefly discussed.

Long-term myofibroblast persistence in the capsular bag contributes to the late spontaneous in-the-bag intraocular lens dislocation

Late spontaneous in-the-bag intraocular lens (IOL) dislocation is a complication presenting 6 months or later after cataract surgery. We aimed to characterize the cells in the lens capsules (LCs) of 18 patients with spontaneous late in-the-bag IOL dislocation. Patients' average age was 82.6 ± 1.5 years (range 72-98), and most of them had pseudoexfoliation syndrome (PEX). Cells from the LCs were positive for myofibroblast (αSMA), proliferation (Ki-67, PCNA), early lens development/lens progenitor (SOX2, PAX6), chemokine receptor (CXCR4), and transmembrane (N-cadherin) markers, while negative for epithelial (E-cadherin) marker. Moreover, the cells produced abundant fibronectin, type I and type V collagen in the nearby extracellular matrix (ECM). During ex vivo cultivation of dislocated IOL-LCs in toto, the cells proliferated and likely migrated onto the IOL's anterior side. EdU proliferation assay confirmed the proliferation potential of the myofibroblasts (MFBs) in dislocated IOL-LCs. Primary cultured lens epithelial cells/MFBs isolated from the LC of dislocated IOLs could induce collagen matrix contraction and continuously proliferated, migrated, and induced ECM remodeling. Taken together, this indicates that long-lived MFBs of dislocated IOLs might contribute to the pathogenic mechanisms in late in-the-bag IOL dislocation.

Extracellular vesicles promote epithelial-to-mesenchymal transition of lens epithelial cells under oxidative stress

Posterior capsule opacification (PCO), resulting from residual lens epithelial cell (LEC) epithelial-mesenchymal transition (EMT), abnormal proliferation, and migration, is the most common complication of cataract surgery. A recent study determined that extracellular vesicles (EVs) and reactive oxygen species (ROS) regulate the EMT process during cutaneous wound healing and tumour metastasis. However, their underlying mechanism in PCO is unclear. In this study, we examined the secreted EVs from a scratch model in vitro. We found that the production of ROS was increased after mechanical injury, especially at the wound edge, and there was an increased viability of LECs, which can be blocked by diphenyleneiodonium, an NADPH oxidase inhibitor. Cell viability and migration were increased upon treatment with 1 μM H₂O₂, but significantly reduced when the concentration of H₂O₂ increased to 100 μM. Transwell assay showed that both post-surgery LECs and LECs treated with 1 μM H₂O₂ significantly induced the migration of normal LECs by EV secretion. Extraction and quantification of EVs derived from injured and H₂O₂-treated LECs showed a similar increase in production. Co-incubation of EVs from both injured and H₂O₂-treated LECs with normal LECs and organ-cultured mouse lenses activated EMT, which was attenuated by a ROS inhibitor. These results suggest that EVs participate in ROS-induced lens EMT, making EVs a potential target for treating PCO.

Nd:YAG Laser Accidentally Hitting the Corneal Layers During Treatment of Posterior Capsule Opacification After Cataract Surgery and Its Postoperative Process

Posterior capsule opacification (PCO) is the most common cause of deterioration of vision and contrast sensitivity and glare after cataract surgery. Neodymium (Nd): yttrium aluminum garnet (YAG) laser capsulotomy is an effective and standard procedure to treat these symptoms. The incidence rate of PCO requiring Nd:YAG laser treatment varies and depends on published studies, ranging from 2.2% to 10.0%. Although Nd:YAG laser treatment is largely safe, it still has complications, such as transient increase of intraocular pressure, anterior uveitis, intraocular lenses pitting, cystoid macula edema, endophthalmitis, and retinal detachment. We encountered a rare complication related to Nd:YAG laser treatment, where the laser accidentally hits the cornea. This occurred because the PCO was mistaken for the corneal layers during the laser procedure. This report presents the 3-year post-treatment process, and the findings herein may help raise the awareness of the possibility of this rare complication and provide measures for its treatment.

Evaluation of posterior capsule opacification of the Alcon Clareon IOL vs the Alcon Acrysof IOL using a human capsular bag model

BACKGROUND

Posterior capsule opacification (PCO) after cataract surgery is influenced by intraocular lens (IOL) design and material. The following is an ex vivo comparison of PCO between the Clareon vs. the AcrySof IOL in human capsular bags.

METHODS

Twenty cadaver capsular bags from 10 human donors were used, with the novel hydrophobic IOL (Clareon, CNA0T0) being implanted in one eye and the other eye of the same donor receiving the AcrySof IOL (SN60WF) following phacoemulsification cataract surgery. Five capsular bags of 3 donors served as controls without IOL. Cellular growth of lens epithelial cells was photo-documented daily. The primary endpoint was the time until full coverage of the posterior capsule by cells. Furthermore, immunofluorescence staining of capsular bags for the fibrotic markers f-actin, fibronectin, alpha smooth muscle actin, and collagen type 1 were performed.

RESULTS

The new Clareon IOL did not show any disadvantages in terms of days until full cell coverage of the posterior capsule in comparison to the AcrySof (p > 0.99). Both, the Clareon (p = 0.01, 14.8 days) and the AcrySof IOL (p = 0.005, 15.7 days) showed a slower PCO development in comparison to the control (8.6 days). The fibrotic markers f-actin, fibronectin, alpha smooth muscle actin, and collagen type 1 were equally distributed between the two IOLs and differed from the control.

CONCLUSIONS

A comparable performance has been found in the ex vivo formation of PCO between the two IOLs. Long-term clinical studies are necessary to reach final conclusions.

Capsular fibrosis: a review of prevention methods and management

Opacification of the posterior capsule caused by residual lens epithelial cells (LEC) is still the most frequent long-term complication of cataract surgery. Beside the opacification of the visual axis with posterior capsule opacification (PCO), resulting in a decrease in visual function, fibrotic changes may also have a mechanical effect on intraocular lens (IOL) position such as axial shift, decentration, tilt and capsule striae. In this article, two types of capsular fibrosis are explored, on the one hand the anterior capsule fibrosis and on the other hand PCO. Results from clinical trials concerning their causes, natural course, incidence, influencing factors and possible methods of prophylaxis are presented.

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.

Osmotically induced removal of lens epithelial cells to prevent PCO after pediatric cataract surgery: Pilot study to assess feasibility

PURPOSE

Development of an osmotic-shock technique to remove human lens epithelial cells (LECs) as a preventive measure to address posterior capsule opacification (PCO) after pediatric cataract surgery.

SETTING

Department of Genetics, UCL Institute of Ophthalmology, London, England, and Department of Ophthalmology, Ruijin Hospital, Jiao Tong University, Shanghai, China.

DESIGN

Laboratory study.

METHODS

Various tissue preparations of human LECs (cultured on coverslips/collagen-coated membrane inserts, human lens capsule biopsies, and lens organ cultured PCO models) were subjected to a single or incremental hyperosmotic shock (NaCl, 350-4000 mOsm/L) in the presence of inhibitors of the Na+-K+-2Cl- cotransporter (NKCC) (to disable the regulatory volume increase [RVI] process). The integrity of the cell monolayer was determined by phase-contrast microscopy, viability assays, and measurement of transepithelial resistance.

RESULTS

Hyperosmotic shock (400 mOsm/L) caused rapid cell shrinkage (<5 minutes) in all the LEC models studied. In the absence of the NKCC inhibitor, the shrunk cells gradually returned to their original cell volume and architecture over time, while still exposed to the hyperosmotic shock. However, inhibition of the RVI process disabled the ability for restoration of cell volume leading to persistent cell shrinkage, subsequently resulting in cell detachment from the underlying support medium.

CONCLUSION

Hyperosmotic shock in the presence of inhibitors of the RVI process was effective in rapidly detaching LECs from their basement membranes. This technique could potentially facilitate removal of residual LECs left on the lens capsule after cataract surgery, thus decreasing or eliminating the risk for aggressive cell proliferation and the development of PCO.

The secretome of adipose-derived mesenchymal stem cells attenuates epithelial-mesenchymal transition in human corneal epithelium

Introduction

Epithelial–mesenchymal transition (EMT) induces the loss of cell–cell interactions in polarized epithelial cells and converts these cells to invasive mesenchymal-like cells. It is also involved in tissue fibrosis including that occurring in some ocular surface diseases such as pterygium and in subepithelial corneal fibrosis in limbal stem cell deficiency. Here, we examined the effects of the secretome of human adipose-derived mesenchymal stem cells (AdMSCs) on EMT in human corneal epithelial cells (CECs).

Methods

EMT was induced with transforming growth factor-β (TGF-β) in primary human CECs isolated from the human corneal limbus. The effects of the AdMSC secretome on EMT in these cells or stratified CEC sheets were analyzed by co-cultivation experiments with the addition of AdMSC conditioned-medium. The expression of EMT-related genes and proteins in CECs was analyzed. The superstructure of CECs was observed by scanning electron microscopy. Furthermore, the barrier function of CEC sheets was analyzed by measuring transepithelial electrical resistance (TER).

Results

The AdMSC secretome was found to suppress EMT-related gene expression and attenuate TGF-β-induced corneal epithelial dysfunction including the dissociation of cell–cell interactions and decreases in TER in constructed CEC sheets.

Conclusions

The secretome of AdMSCs can inhibit TGF-β-induced EMT in CECs. These findings suggest that this could be a useful source for the treatment for EMT-related ocular surface diseases.

•

Application of MSC secretome has potential as a cell-free therapy.

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AdMSC secretome attenuates EMT-related expression in corneal epithelial cells (CECs).

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AdMSC secretome mitigates TGF-β-induced inhibition of cell–cell interactions in CECs.

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AdMSC secretome abrogates TGF-β-mediated barrier disruption in CEC sheets.

Expression of miR-181a and TGF-β2 in lens epithelial cells of patients with cataractous retinal detachment and its clinical significance

Expression and clinical significance of miR-181a and TGF-β2 in lens epithelial cells of patients with cataract-induced retinal detachment were investigated. Forty patients with rhegmatogenous retinal detachment combined with age-related cataract (cast-off group) and another 40 patients with simple age-related cataract (non-exfoliated group) in Tongren Hospital were enrolled between January 2017 and June 2018. Lens epithelial cells were collected, and expression levels of miR-181a and TGF-β2 mRNA in lens epithelial cells were measured by RT-qPCR. Expression of protein was detected by western blot analysis. miR-181a overexpression vector (miR-181a-mimic group) was constructed and transfected into lens epithelial cells isolated from patients with rhegmatogenous retinal detachment combined with age-related cataract. Empty vector (miR-control group) transfection was performed. Untransfected lens epithelial cells were the control group. Independent sample t-test was performed for comparison between groups. Correlation between miR-181a and TGF-β2 protein expression levels was analyzed by Pearson's correlation analysis. Relative expression level of miR-181a in the non-exfoliated group was significantly higher than that in the cast-off group (P<0.05). Relative expression levels of TGF-β2 mRNA and TGF-β2 protein in the cast-off group were significantly higher than those in the non-exfoliated group (P<0.05). Relative expression level of E-cadherin in the miR-control group was significantly lower than that in the miR-181a-mimic group (P<0.05). Relative expression level of vimentin in the miR-control group was significantly higher than that in the miR-181a-mimic group (P<0.05). Relative expression level of TGF-β2 protein in the miR-control group was significantly higher than that in the miR-181a-mimic group (P<0.05). The expression level of miR-181a was negatively correlated with the expression level of TGF-β2 protein (r= −0.875, P<0.001). miR-181a expression is decreased, while TGF-β2 expression is increased in lens epithelial cells of patients with rhegmatogenous retinal detachment combined with age-related cataract. Over-expression of miR-181a may inhibit epithelial cell epithelial-inhibition by inhibiting TGF-β2 expression. Our findings may provide guidance for future postoperative prevention and treatment of rhegmatogenous retinal detachment in cataract patients.

Determination of trypan blue efficacy in the mitigation of ex vivo canine PCO formation

PURPOSE

To determine whether trypan blue (TB) reduces canine lens epithelial cell (LEC) or corneal endothelial cell (CEC) viability in vitro; if cell death is noted, to subsequently evaluate the molecular mechanism.

METHODS

Cellular viability was determined using a lactate dehydrogenase (LDH) assay. In TB-treated LECs, caspase 3/7 activity was assessed to evaluate apoptosis; autophagy was evaluated using immunoblotting against LC3 and p62. To evaluate the effects of TB on ex vivo posterior capsule opacification (PCO), following mock cataract surgery, lens capsules were treated with TB and subsequently maintained in culture to determine LEC migration and proliferation.

RESULTS

Following acute exposure, TB did not significantly reduce LEC or CEC viability at any of the concentrations tested. Increased caspase 3/7 activity was found in LEC cultures treated with TB for an extended period of time; no change in LC3 or p62 expression was noted. Ex vivo PCO formation was not significantly altered by TB treatment.

CONCLUSIONS

Acute exposure to TB did not reduce LEC or CEC viability, and only longer exposure to TB was able to initiate apoptosis. Treatment with intraocular TB at the time of cataract surgery is likely safe to the CECs but will not prevent PCO formation.

Effect of intraoperative trypan blue on lens epithelial cells - Histomorphological analysis

Introduction

Trypan Blue is an acid azo dye commonly used as a stain to distinguish viable from non-viable cells. It is a vital stain used intra operatively during cataract surgery to stain the external surface of the anterior lens capsule for better visualization.

Aim

To analyze the histomorphological effects of trypan blue on Lens Epithelial cells and the Basement Membrane on direct exposure by staining the internal surface of the anterior lens capsule during Small Incision Cataract Surgery.

Methods

Analytical cross sectional case control study. Anterior capsule specimens of 14 Patients undergoing small incision cataract surgery at Department of Ophthalmology, Govt Medical College Hospital, Thrissur were studied. Two specimens of anterior capsule taken from the same eye form the case and control. Control specimen (sample A) was removed first, after the routine external staining with trypan blue 0.06% (w/v) for 10 seconds. The stain was washed off by balanced salt solution in every case. Then trypan blue was injected under the remaining anterior capsule and case (Test) specimen (sample B) was obtained after direct contact of trypan blue to the internal surface (lens epithelial cells) for 1 minute. Histomorphological (qualitative and quantitative) examination of both specimens done.

Results

Qualitative data analysis was done by EPI INFO software.v.7. Intactness of LECs throughout the length was statistically significant in Sample A (p = 0.000027). Partial and complete detachment of Lens Epithelial Cells, degeneration, and nuclear smudging were significantly higher in Sample B. Qualitative analysis of the basement membrane showed significant edema of the basement membrane in sample B. Basement membrane splitting observed in sample B was not statistically significant. Quantitative data analyzed using independent t test. There was a statistically significant decrease in cell density in sample B with p value less than 0.05.

Discussion

Our study demonstrated that direct staining of the internal surface of anterior capsule with trypan blue affected LECs and the basement membrane. There were reduction in cell density, irreversible degeneration of Lens Epithelial Cells and basement membrane edema. Hence treating the internal surface of capsular bag with trypan blue may reduce incidence of Posterior capsular opacification.

Anti-cataract Effect of Resveratrol in High-Glucose-Treated Streptozotocin-Induced Diabetic Rats

Resveratrol, which is a polyphenol found in grapes, peanuts, and other plants, has health benefits for various chronic diseases. The aim of the present study was to examine the effect of resveratrol on cataract formation in diabetic rats. Male Wistar rats (7-week-old) were treated with streptozotocin, and the streptozotocin-treated animals were administered 5% D-glucose in drinking water to promote the formation of cataracts by inducing severe hyperglycemia. Resveratrol supplementation (10 or 30 mg/kg/d) in drinking water was initiated immediately after induction of diabetes was confirmed. The full lens images of the horizontal plane were captured with the digital camera system which we developed. Cataract formation was assessed by an observer-based scoring method and by quantitative analysis of digital images of the lens. Cataracts at the peripheral region of the lens were detected 2 weeks after induction of hyperglycemia and progressed depending on the length of the diabetic period. The majority of them developed severe cataracts after 9 weeks of hyperglycemia. Resveratrol did not prevent the appearance of diabetic cataracts but significantly delayed the progression of cataracts compared with controls. The contents of sorbitol and protein carbonyls in lenses of diabetic rats were higher than those of control rats. Resveratrol suppressed the increase in protein carbonyls, but not of sorbitol, in diabetic lenses. These results suggest that resveratrol delays the progression of diabetic cataracts partially through attenuation of oxidative damage to lens proteins. Resveratrol may be beneficial in preventing the progression of diabetic cataracts.

Comparison of Surgically Excised Premacular Membranes in Eyes with Macular Pucker and Proliferative Vitreoretinopathy

PURPOSE

To describe and compare characteristics of premacular membranes in idiopathic macular pucker (iMP) and proliferative vitreoretinopathy (PVR) using immunofluorescence and transmission electron microscopy.

MATERIALS AND METHODS

For immunocytochemical and ultrastructural analyses, premacular membranes were harvested during vitrectomy from 16 eyes with iMP and 12 eyes with PVR. All specimens were processed as flat mounts for phase-contrast and fluorescence microscopy. We used 19 different primary antibodies such as anti-α-smooth muscle actin (α-SMA), anti-integrin-αv, anti-galectin, anti-IBA-1, anti-EMMPRIN (CD147), anti-ricinus (RCS) and anti-collagen-type I. Eight of 28 eyes were also prepared for transmission electron microscopy.

RESULTS

In all eyes with iMP and PVR, positive immunoreactivity of integrins, especially αvβ3 was found. There was also a strong staining of anti-α-SMA, anti-galectin, anti-EMMPRIN, anti-RCS, anti-IBA1 and anti-collagen-type I. Transmission electron microscopy showed that premacular membrane of iMP composed of myofibroblasts, glial cells and fibroblasts. In eyes with PVR, retinal pigment epithelial cells and myofibroblasts were seen as predominant cell types.

CONCLUSION

Premacular membranes of iMP and PVR presented with similarities in cell distribution and immunoreactivity, but showed differences in cell composition. Herein, we demonstrate immunocytochemical characteristics involved in fibrotic processes. Cell transdifferentiation into myofibroblasts represents an important process in pathogenesis of both entities. In order to address future anti-fibrotic treatment strategies, we emphasize that both fibrotic diseases share distinct immunocytochemical and ultrastructural features.

Transforming Growth Factor β1 (TGF-β1)-Stimulated Integrin-Linked Kinase (ILK) Regulates Migration and Epithelial-Mesenchymal Transition (EMT) of Human Lens Epithelial Cells via Nuclear Factor κB (NF-κB)

BACKGROUND In view of the high incidence of posterior capsule opacification (PCO) and the effects of TGF-β signaling on the epithelial-mesenchymal transition (EMT) of human lens epithelial cells (LECs), our study aimed to explore the mechanism of the function of TGF-β signaling in LECs EMT. MATERIAL AND METHODS Human lens epithelial cells (HLEC-h3) were treated with TGF-β, ILK siRNA, ILK inhibitor, and NF-κB inhibitor to study the effects of TGF-β, ILK, and NF-κB on cell migration and EMT. Cell migration assay was used to measure cell migration ability. Western blot was performed to detect the expression of ILK, E-cadherin, and a-SMA at the protein level. QRT-PCR was used to detect the expression of ILK at the mRNA level. RESULTS Compared with control cells, TGF-β treatment increased the expression level of ILK HLEC-h3, promoted migration of HLEC-h3 cells, increased the expression level of E-cadherin protein, and decreased the expression level of a-SMA protein. However, treatment with ILK siRNA, ILK inhibitor, and NF-κB inhibitor reversed the effects of TGF-β on HLEC-h3 cells. CONCLUSIONS TGF-β-stimulated ILK regulates the migration and EMT of human LECs via NF-κB.

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.

The role of focal adhesion kinase in transforming growth factor-β2 induced migration of human lens epithelial cells

The migration of lens epithelial cells towards the posterior capsule is a key event in the development of posterior capsule opacification (PCO). Accumulating evidence has described crosstalk between growth factors and adhesive signaling pathways in wound healing and cell migration. The aim of the present study was to elucidate an aberrant transforming growth factor (TGF)‑β2 signaling pathway that regulated the migration of lens epithelial cells in the pathological context of PCO. The expression of fibronectin, focal adhesion kinase (FAK) and phosphorylated (p)‑FAK in HLE‑B3 cells following TGF‑β2 treatment was determined by western blot analysis and the expression of integrin α5β1 was detected by flow cytometry. Cell migration capacity was measured by wound healing and Transwell assays in the presence of 1,2,4,5‑tetraaminobenzene tetrahydrochloride, a selective FAK inhibitor, fibronectin small interfering RNA interference, arginylglycylaspartic acid peptides or α5β1‑integrin neutralizing antibodies. The 1,2,4,5‑tetraaminobenzene tetrahydrochloride was administered daily to 16 rabbits following cataract surgery. Fibronectin and TGF‑β expression were increased in the PCO group, demonstrated by immunofluorescence assays. PCO grading was conducted by slit‑lamp biomicroscopy and evaluation of posterior capsule opacification software. It was observed that TGF‑β2 promoted HLE‑B3 cell migration and upregulated fibronectin expression, which was followed by an increased phosphorylation of FAK. In addition, TGF‑β2 treatment and fibronectin surface coating significantly increased cell migration and FAK activation, which was inhibited by disrupting fibronectin‑integrin α5β1 interaction with the arginylglycylaspartic acid peptide, α5β1‑integrin neutralizing antibody or fibronectin depletion. Finally, suppression of FAK signaling by its inhibitor significantly decreased cell migration in vitro and attenuated PCO development in vivo. In summary, TGF‑β2 was indicated to promote the migration of lens epithelial cells through the TGF‑β2/fibronectin/integrin/FAK axis. Inhibition of FAK activity decreased TGF‑β2‑mediated cell migration in vitro and improved the symptoms of PCO in a rabbit model.

MicroRNA-486-5p suppresses TGF-β2-induced proliferation, invasion and epithelial-mesenchymal transition of lens epithelial cells by targeting Smad2

The pathological development of lens epithelial cells (LECs) leads to posterior capsular opacification (PCO). This study was undertaken to investigate the effects of microRNA-486-5p (miR-486-5p) on TGF-β2-induced proliferation, invasion and epithelial-mesenchymal transition (EMT) in the lens epithelial cell line SRA01/04, and to explore the underlying molecular mechanisms. The expression of miR-486-5p in TGF-β2-induced SRA01/04 cells was down-regulated, and the expression of Smad2, p-Smad2 and p-Smad3 was up-regulated. A dual-luciferase reporter assay revealed that miR-486-5p directly targets the 30'-UTR of Smad2. MiR-486-5p mimic transfection markedly down-regulated the expression levels of Smad2, thus inhibiting the expression of p-Smad2 and p-Smad3. MiR-486-5p overexpression in SRA01/04 cells markedly suppressed TGF-β2-induced proliferation and invasion, inhibited protein expression of CDK2 and CDK4, down-regulated fibronectin, α-SMA and vimentin and up-regulated E-cadherin; these effects were partly reversed by Smad2 overexpression. In short, these data show that miR-486-5p overexpression can inhibit TGF-β2-induced proliferation, invasion and EMT in SRA01/04 cells by repressing Smad2/Smad3 signalling, implying that miR-486-5p may be an effective target to interfere in the progression of PCO.

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.

HPV16-E6 Oncoprotein Activates TGF-β and Wnt/β-Catenin Pathways in the Epithelium-Mesenchymal Transition of Cataracts in a Transgenic Mouse Model

Objective

This work aimed to determine if cataractous changes associated with EMT occurring in the K14E6 mice lenses are associated with TGF-β and Wnt/β-catenin signaling activation.

Materials and Methods

Cataracts of K14E6 mice were analysed histologically; and components of TGF-β and Wnt/β-catenin signaling were evaluated by Western blot, RT-qPCR, in situ RT-PCR, IHC, or IF technics. Metalloproteinases involved in EMT were also assayed using zymography. The endogenous stabilisation of Smad7 protein was also assessed using an HDAC inhibitor.

Results

The K14E6 mice, which displayed binocular cataracts in 100% of the animals, exhibited loss of tissue organisation, cortical liquefaction, and an increase in the number of hyperproliferative-nucleated cells with mesenchymal-like characteristics in the lenses. Changes in lenses' cell morphology were due to actin filaments reorganisation, activation of TGF-β and Wnt/β-catenin pathways, and the accumulation of MTA1 protein. Finally, the stabilisation of Smad7 protein diminishes cell proliferation, as well as MTA1 protein levels.

Conclusion

The HPV16-E6 oncoprotein induces EMT in transgenic mice cataracts. The molecular mechanism may involve TGF-β and Wnt/β-catenin pathways, suggesting that the K14E6 transgenic mouse could be a useful model for the study or treatment of EMT-induced cataracts.